WorldWideScience

Sample records for above-ground insect herbivores

  1. Interactions of ectomycorrhizas and above-ground insect herbivores on silver birch

    Nerg, Anne-Marja; Kasurinen, Anne; Holopainen, Toini; Julkunen-Tiitto, Riitta; Neuvonen, Seppo; Holopainen, Jarmo K.

    2009-01-01

    Mycorrhizas are mostly beneficial to host plant growth and survival, e.g., due to improved water and nutrient uptake and enhanced pathogen protection, but also a significant amount of host plant carbon is allocated below-ground to support the mycorrhizal growth. These facts and on the other hand the possibility of mycorrhizas to mediate changes in above-ground defensive chemistry may affect performance of above-ground insect herbivores with different feeding guilds. To see the functionality o...

  2. Facilitation and inhibition: changes in plant nitrogen and secondary metabolites mediate interactions between above-ground and below-ground herbivores

    Huang, Wei; Siemann, Evan; Yang, Xuefang; Wheeler, Gregory S.; Ding, Jianqing

    2013-01-01

    To date, it remains unclear how herbivore-induced changes in plant primary and secondary metabolites impact above-ground and below-ground herbivore interactions. Here, we report effects of above-ground (adult) and below-ground (larval) feeding by Bikasha collaris on nitrogen and secondary chemicals in shoots and roots of Triadica sebifera to explain reciprocal above-ground and below-ground insect interactions. Plants increased root tannins with below-ground herbivory, but above-ground herbivo...

  3. Below-ground herbivory limits induction of extrafloral nectar by above-ground herbivores

    Huang, Wei; Siemann, Evan; Carrillo, Juli; Ding, Jianqing

    2015-01-01

    Background and Aims Many plants produce extrafloral nectar (EFN), and increase production following above-ground herbivory, presumably to attract natural enemies of the herbivores. Below-ground herbivores, alone or in combination with those above ground, may also alter EFN production depending on the specificity of this defence response and the interactions among herbivores mediated through plant defences. To date, however, a lack of manipulative experiments investigating EFN production induc...

  4. Plant Defense against Insect Herbivores

    Søren Bak

    2013-05-01

    Full Text Available Plants have been interacting with insects for several hundred million years, leading to complex defense approaches against various insect feeding strategies. Some defenses are constitutive while others are induced, although the insecticidal defense compound or protein classes are often similar. Insect herbivory induce several internal signals from the wounded tissues, including calcium ion fluxes, phosphorylation cascades and systemic- and jasmonate signaling. These are perceived in undamaged tissues, which thereafter reinforce their defense by producing different, mostly low molecular weight, defense compounds. These bioactive specialized plant defense compounds may repel or intoxicate insects, while defense proteins often interfere with their digestion. Volatiles are released upon herbivory to repel herbivores, attract predators or for communication between leaves or plants, and to induce defense responses. Plants also apply morphological features like waxes, trichomes and latices to make the feeding more difficult for the insects. Extrafloral nectar, food bodies and nesting or refuge sites are produced to accommodate and feed the predators of the herbivores. Meanwhile, herbivorous insects have adapted to resist plant defenses, and in some cases even sequester the compounds and reuse them in their own defense. Both plant defense and insect adaptation involve metabolic costs, so most plant-insect interactions reach a stand-off, where both host and herbivore survive although their development is suboptimal.

  5. Plant defense against insect herbivores

    Fürstenberg-Hägg, Joel; Zagrobelny, Mika; Bak, Søren

    2013-01-01

    , defense compounds. These bioactive specialized plant defense compounds may repel or intoxicate insects, while defense proteins often interfere with their digestion. Volatiles are released upon herbivory to repel herbivores, attract predators or for communication between leaves or plants, and to induce...

  6. Environmental RNAi in herbivorous insects.

    Ivashuta, Sergey; Zhang, Yuanji; Wiggins, B Elizabeth; Ramaseshadri, Partha; Segers, Gerrit C; Johnson, Steven; Meyer, Steve E; Kerstetter, Randy A; McNulty, Brian C; Bolognesi, Renata; Heck, Gregory R

    2015-05-01

    Environmental RNAi (eRNAi) is a sequence-specific regulation of endogenous gene expression in a receptive organism by exogenous double-stranded RNA (dsRNA). Although demonstrated under artificial dietary conditions and via transgenic plant presentations in several herbivorous insects, the magnitude and consequence of exogenous dsRNA uptake and the role of eRNAi remains unknown under natural insect living conditions. Our analysis of coleopteran insects sensitive to eRNAi fed on wild-type plants revealed uptake of plant endogenous long dsRNAs, but not small RNAs. Subsequently, the dsRNAs were processed into 21 nt siRNAs by insects and accumulated in high quantities in insect cells. No accumulation of host plant-derived siRNAs was observed in lepidopteran larvae that are recalcitrant to eRNAi. Stability of ingested dsRNA in coleopteran larval gut followed by uptake and transport from the gut to distal tissues appeared to be enabling factors for eRNAi. Although a relatively large number of distinct coleopteran insect-processed plant-derived siRNAs had sequence complementarity to insect transcripts, the vast majority of the siRNAs were present in relatively low abundance, and RNA-seq analysis did not detect a significant effect of plant-derived siRNAs on insect transcriptome. In summary, we observed a broad genome-wide uptake of plant endogenous dsRNA and subsequent processing of ingested dsRNA into 21 nt siRNAs in eRNAi-sensitive insects under natural feeding conditions. In addition to dsRNA stability in gut lumen and uptake, dosage of siRNAs targeting a given insect transcript is likely an important factor in order to achieve measurable eRNAi-based regulation in eRNAi-competent insects that lack an apparent silencing amplification mechanism. PMID:25802407

  7. Plant Defense against Insect Herbivores

    Søren Bak; Joel Fürstenberg-Hägg; Mika Zagrobelny

    2013-01-01

    Plants have been interacting with insects for several hundred million years, leading to complex defense approaches against various insect feeding strategies. Some defenses are constitutive while others are induced, although the insecticidal defense compound or protein classes are often similar. Insect herbivory induce several internal signals from the wounded tissues, including calcium ion fluxes, phosphorylation cascades and systemic- and jasmonate signaling. These are perceived in undamaged...

  8. Multi-factor climate change effects on insect herbivore performance

    Scherber, Christoph; Gladbach, David J; Stevnbak, Karen;

    2013-01-01

    The impact of climate change on herbivorous insects can have far-reaching consequences for ecosystem processes. However, experiments investigating the combined effects of multiple climate change drivers on herbivorous insects are scarce. We independently manipulated three climate change drivers (CO......, nitrogen, and water content. Overall, drought was the most important factor for this insect herbivore. Our study shows that weight and survival of insect herbivores may decline under future climate. The complexity of insect herbivore responses increases with the number of combined climate change drivers....

  9. Alien interference: disruption of infochemical networks by invasive insect herbivores

    Desurmont, Gaylord A.; Harvey, Jeff A.; van Dam, Nicole M.; Cristescu, Simona M.; Schiestl, Florian P.; Cozzolino, Salvatore; Anderson, Peter; Larsson, Mattias C.; Kindlmann, Pavel; Danner, Holger; Turlings, Ted C. J.

    2014-01-01

    Insect herbivores trigger various biochemical changes in plants, and as a consequence, affect other organisms that are associated with these plants. Such plant-mediated indirect effects often involve herbivore-induced plant volatiles (HIPVs) that can be used as cues for foraging herbivores and their

  10. Mechanisms of plant defense against insect herbivores

    War, Abdul Rashid; Paulraj, Michael Gabriel; Ahmad, Tariq; BUHROO, Abdul Ahad; Hussain, Barkat; Ignacimuthu, Savarimuthu; Sharma, Hari Chand

    2012-01-01

    Plants respond to herbivory through various morphological, biochemicals, and molecular mechanisms to counter/offset the effects of herbivore attack. The biochemical mechanisms of defense against the herbivores are wide-ranging, highly dynamic, and are mediated both by direct and indirect defenses. The defensive compounds are either produced constitutively or in response to plant damage, and affect feeding, growth, and survival of herbivores. In addition, plants also release volatile organic c...

  11. When herbivores eat predators: predatory insects effectively avoid incidental ingestion by mammalian herbivores.

    Ben-Ari, Matan; Inbar, Moshe

    2013-01-01

    The direct trophic links between mammalian herbivores and plant-dwelling insects have been practically ignored. Insects are ubiquitous on plants consumed by mammalian herbivores and are thus likely to face the danger of being incidentally ingested by a grazing mammal. A few studies have shown that some herbivorous hemipterans are able to avoid this peril by dropping to the ground upon detecting the heat and humidity on the mammal's breath. We hypothesized that if this risk affects the entire plant-dwelling insect community, other insects that share this habitat are expected to develop similar escape mechanisms. We assessed the ability of three species (adults and larvae) of coccinellid beetles, important aphid predators, to avoid incidental ingestion. Both larvae and adults were able to avoid incidental ingestion effectively by goats by dropping to the ground, demonstrating the importance of this behavior in grazed habitats. Remarkably, all adult beetles escaped by dropping off the plant and none used their functional wings to fly away. In controlled laboratory experiments, we found that human breath caused 60-80% of the beetles to drop. The most important component of mammalian herbivore breath in inducing adult beetles and larvae to drop was the combination of heat and humidity. The fact that the mechanism of dropping in response to mammalian breath developed in distinct insect orders and disparate life stages accentuates the importance of the direct influence of mammalian herbivores on plant-dwelling insects. This direct interaction should be given its due place when discussing trophic interactions. PMID:23424674

  12. Detecting changes in insect herbivore communities along a pollution gradient

    The forests surrounding the urban areas of the Los Angeles basin are impacted by ozone and nitrogen pollutants arising from urban areas. We examined changes in the herbivore communities of three prominent plant species (ponderosa pine, California black oak and bracken fern) at six sites along an air pollution gradient. Insects were extracted from foliage samples collected in spring, as foliage reached full expansion. Community differences were evaluated using total herbivore abundance, richness, Shannon-Weiner diversity, and discriminant function analysis. Even without conspicuous changes in total numbers, diversity or richness of herbivores, herbivore groups showed patterns of change that followed the air pollution gradient that were apparent through discriminant function analysis. For bracken fern and oak, chewing insects were more dominant at high pollution sites. Oak herbivore communities showed the strongest effect. These changes in herbivore communities may affect nutrient cycling in forest systems. - Differences in insect herbivore communities were associated with an ambient air pollution gradient in the mixed conifer forest outside the Los Angeles area

  13. Genomics of adaptation to host-plants in herbivorous insects.

    Simon, Jean-Christophe; d'Alençon, Emmanuelle; Guy, Endrick; Jacquin-Joly, Emmanuelle; Jaquiéry, Julie; Nouhaud, Pierre; Peccoud, Jean; Sugio, Akiko; Streiff, Réjane

    2015-11-01

    Herbivorous insects represent the most species-rich lineages of metazoans. The high rate of diversification in herbivorous insects is thought to result from their specialization to distinct host-plants, which creates conditions favorable for the build-up of reproductive isolation and speciation. These conditions rely on constraints against the optimal use of a wide range of plant species, as each must constitute a viable food resource, oviposition site and mating site for an insect. Utilization of plants involves many essential traits of herbivorous insects, as they locate and select their hosts, overcome their defenses and acquire nutrients while avoiding intoxication. Although advances in understanding insect-plant molecular interactions have been limited by the complexity of insect traits involved in host use and the lack of genomic resources and functional tools, recent studies at the molecular level, combined with large-scale genomics studies at population and species levels, are revealing the genetic underpinning of plant specialization and adaptive divergence in non-model insect herbivores. Here, we review the recent advances in the genomics of plant adaptation in hemipterans and lepidopterans, two major insect orders, each of which includes a large number of crop pests. We focus on how genomics and post-genomics have improved our understanding of the mechanisms involved in insect-plant interactions by reviewing recent molecular discoveries in sensing, feeding, digesting and detoxifying strategies. We also present the outcomes of large-scale genomics approaches aimed at identifying loci potentially involved in plant adaptation in these insects. PMID:25846754

  14. Multi-factor climate change effects on insect herbivore performance

    Scherber, Christoph; Gladbach, David J; Stevnbak, Karen;

    2013-01-01

    the drought treatment, and there was a three-way interaction between time, CO2, and drought. Survival was lowest when drought, warming, and elevated CO2 were combined. Effects of climate change drivers depended on other co-acting factors and were mediated by changes in plant secondary compounds, nitrogen......The impact of climate change on herbivorous insects can have far-reaching consequences for ecosystem processes. However, experiments investigating the combined effects of multiple climate change drivers on herbivorous insects are scarce. We independently manipulated three climate change drivers (CO...... suturalis Thomson), an important herbivore on heather, to ambient versus elevated drought, temperature, and CO2 (plus all combinations) for 5 weeks. Larval weight and survival were highest under ambient conditions and decreased significantly with the number of climate change drivers. Weight was lowest under...

  15. Inducible direct plant defense against insect herbivores: A review

    Ming-Shun Chen

    2008-01-01

    Plants respond to insect herbivory with responses broadly known as direct defenses, indirect defenses, and tolerance. Direct defenses include all plant traits that affect susceptibility of host plants by themselves. Overall categories of direct plant defenses against insect herbivores include limiting food supply, reducing nutrient value, reducing preference, disrupting physical structures, and inhibiting chemical pathways of the attacking insect. Major known defense chemicals include plant secondary metabolites, protein inhibitors of insect digestive enzymes, proteases, lectins, amino acid deaminases and oxidases. Multiple factors with additive or even synergistic impact are usually involved in defense against a specific insect species, and factors of major importance to one insect species may only be of secondary importance or not effective at all against another insect species. Extensive qualitative and quantitative high throughput analyses of temporal and spatial variations in gene expression, protein level and activity, and metabolite concentration will accelerate not only the understanding of the overall mechanisms of direct defense, but also accelerate the identification of specific targets for enhancement of plant resistance for agriculture.

  16. Spatially Heterogeneous Perturbations Homogenize the Regulation of Insect Herbivores.

    Harvey, Eric; MacDougall, Andrew S

    2015-11-01

    Anthropogenic influences on resources and consumers can affect food web regulation, with impacts on trophic structure and ecosystem processes. Identifying how these impacts unfold is challenging because alterations to one or both resources and consumers can similarly transform community structure, especially for intermediate consumers. To date, empirical testing of perturbations on trophic regulation has been limited by the difficulty in separating the direct effect of perturbations on species composition and diversity from those unfolding indirectly via altered feeding pathways. Moreover, disentangling the independent and interactive impacts of covarying stressors that characterize human-altered systems has been an ongoing analytical challenge. We used a large-scale metacommunity experiment in grasslands to test how resource inputs, stand perturbation, and spatial factors affect regulation of insect herbivores in tritrophic grassland food webs. Using path-model comparisons, we observed significant simplification of food web regulation on insect herbivores, shifting from mixed predator-resource regulation in unaltered mainland areas to strictly resource-based regulation with landscape perturbation and fragmentation. Most changes were attributed to homogenization of plant community caused by landscape fragmentation and the deterministic influence of eutrophication that reduced among-patch beta diversity. This led to a simplified food web dominated by fewer but more abundant herbivore taxa. Our work implies that anthropogenic perturbation relating to resources and spatial isolation can transform the regulation of food web diversity, structure, and function. PMID:26655775

  17. Cycads: their evolution, toxins, herbivores and insect pollinators

    Schneider, Dietrich; Wink, Michael; Sporer, Frank; Lounibos, Philip

    2002-06-01

    Palaeobiological evidence indicates that gymnosperms were wind-pollinated and that insect pollination began in angiosperms in the Lower Cretaceous (ca. 135 mya) leading to close associations between higher plants and their pollinators. Cycads, which were widespread and pervasive throughout the Mesozoic (250-65 mya) are among the most primitive living seed-plants found today. Because pollination by beetles and by thrips has now been detected in several modern cycads, it is attractive to speculate that some insects and cycads had already developed similar mutualistic interactions in the Triassic (250-205 mya), long before the advent of angiosperms. We also draw attention to another key factor in this insect-plant relationship, namely secondary, defensive plant substances which must always have controlled interspecific interactions. Cycads mainly produce toxic azoglucosides and neurotoxic non-protein amino acids (e.g. BMAA), which apparently are crucial elements in the development and maintenance of mutualism (pollination) and parasitism (herbivory) by cycad-linked herbivores. We now add new results on the uptake and storage of the main toxin, cycasin, of the Mexican cycad Zamia furfuracea by its pollinator, the weevil Rhopalotria mollis, and by a specialist herbivore of Zamia integrifolia, the aposematic Atala butterfly Eumaeus atala.

  18. LINE-ABOVE-GROUND ATTENUATOR

    Wilds, R.B.; Ames, J.R.

    1957-09-24

    The line-above-ground attenuator provides a continuously variable microwave attenuator for a coaxial line that is capable of high attenuation and low insertion loss. The device consists of a short section of the line-above- ground plane type transmission lime, a pair of identical rectangular slabs of lossy material like polytron, whose longitudinal axes are parallel to and indentically spaced away from either side of the line, and a geared mechanism to adjust amd maintain this spaced relationship. This device permits optimum fineness and accuracy of attenuator control which heretofore has been difficult to achieve.

  19. Herbivory in global climate change research: direct effects of rising temperature on insect herbivores

    Bale, J.S.; Masters, G.J.; Hodkinson, I.D.; Awmack, C.; Bezemer, T.M.; Brown, V.K.; Butterfield, J.; Buse, A.; Coulson, J.C.; Farrar, J.; Good, J.E.G.; Harrington, R.; Hartley, S.; Jones, T.H.; Lindroth, R.L.; Press, M.C.; Symrnioudis, I.; Watt, A.D.; Whittaker, J.B.

    2002-01-01

    This review examines the direct effects of climate change on insect herbivores. Temperature is identified as the dominant abiotic factor directly affecting herbivorous insects. There is little evidence of any direct effects Of CO2 or UVB. Direct impacts of precipitation have been largely neglected i

  20. Influence of polyploidy on insect herbivores of native and invasive genotypes of Solidago gigantea (Asteraceae)

    Helen M. Hull-Sanders; Johnson, Robert H.; Owen, Heather A.; Meyer, Gretchen A.

    2009-01-01

    Herbivores are sensitive to the genetic structure of plant populations, as genetics underlies plant phenotype and host quality. Polyploidy is a widespread feature of angiosperm genomes, yet few studies have examined how polyploidy influences herbivores. Introduction to new ranges, with consequent changes in selective regimes, can lead to evolution of changes in plant defensive characteristics and also affect herbivores. Here, we examine how insect herbivores respond to polyploidy in Solidago ...

  1. Chemical phenotype matching between a plant and its insect herbivore.

    Berenbaum, M R; Zangerl, A R

    1998-11-10

    Two potential outcomes of a coevolutionary interaction are an escalating arms race and stable cycling. The general expectation has been that arms races predominate in cases of polygenic inheritance of resistance traits and permanent cycling predominates in cases in which resistance is controlled by major genes. In the interaction between Depressaria pastinacella, the parsnip webworm, and Pastinaca sativa, the wild parsnip, traits for plant resistance to insect herbivory (production of defensive furanocoumarins) as well as traits for herbivore "virulence" (ability to metabolize furanocoumarins) are characterized by continuous heritable variation. Furanocoumarin production in plants and rates of metabolism in insects were compared among four midwestern populations; these traits then were classified into four clusters describing multitrait phenotypes occurring in all or most of the populations. When the frequency of plant phenotypes belonging to each of the clusters is compared with the frequency of the insect phenotypes in each of the clusters across populations, a remarkable degree of frequency matching is revealed in three of the populations. That frequencies of phenotypes vary among populations is consistent with the fact that spatial variation occurs in the temporal cycling of phenotypes; such processes contribute in generating a geographic mosaic in this coevolutionary interaction on the landscape scale. Comparisons of contemporary plant phenotype distributions with phenotypes of herbarium specimens collected 9-125 years ago from across a similar latitudinal gradient, however, suggest that for at least one resistance trait-sphondin concentration-interactions with webworms have led to escalatory change. PMID:9811871

  2. Insect herbivores change the outcome of plant competition through both inter- and intraspecific processes.

    Kim, Tania N; Underwood, Nora; Inouye, Brian D

    2013-08-01

    Insect herbivores can affect plant abundance and community composition, and theory suggests that herbivores influence plant communities by altering interspecific interactions among plants. Because the outcome of interspecific interactions is influenced by the per capita competitive ability of plants, density dependence, and intrinsic rates of increase, measuring herbivore effects on all these processes is necessary to understand the mechanisms by which herbivores influence plant communities. We fit alternative competition models to data from a response surface experiment conducted over four years to examine how herbivores affected the outcome of competition between two perennial plants, Solidago altissima and Solanum carolinense. Within a growing season, herbivores reduced S. carolinense plant size but did not affect the size of S. altissima, which exhibited compensatory growth. Across seasons, herbivores did not affect S. carolinense density or biomass but reduced both the density and population growth of S. altissima. The best-fit models indicated that the effects of herbivores varied with year. In some years, herbivores increased the per capita competitive effect of S. altissima on S. carolinense; in other years, herbivores influenced the intrinsic rate of increase of S. altissima. We examined possible herbivore effects on the longer-term outcome of competition (over the time scale of a typical old-field habitat), using simulations based on the best-fit models. In the absence of herbivores, plant coexistence was observed. In the presence of herbivores, S. carolinense was excluded by S. altissima in 72.3% of the simulations. We demonstrate that herbivores can influence the outcome of competition through changes in both per capita competitive effects and intrinsic rates of increase. We discuss the implications of these results for ecological succession and biocontrol. PMID:24015519

  3. Land-use history alters contemporary insect herbivore community composition and decouples plant-herbivore relationships.

    Hahn, Philip G. [University of Wisconsin; Orrock, John L. [University of Wisconsin

    2015-04-01

    1. Past land use can create altered soil conditions and plant communities that persist for decades, although the effects of these altered conditions on consumers are rarely investigated. 2. Using a large-scale field study at 36 sites in longleaf pine (Pinus palustris) woodlands, we examined whether historic agricultural land use leads to differences in the abundance and community composition of insect herbivores (grasshoppers, families Acrididae and Tettigoniidae). 3. We measured the cover of six plant functional groups and several environmental variables to determine whether historic agricultural land use affects the relationships between plant cover or environmental conditions and grasshopper assemblages. 4. Land-use history had taxa-specific effects and interacted with herbaceous plant cover to alter grasshopper abundances, leading to significant changes in community composition. Abundance of most grasshopper taxa increased with herbaceous cover in woodlands with no history of agriculture, but there was no relationship in post-agricultural woodlands. We also found that grasshopper abundance was negatively correlated with leaf litter cover. Soil hardness was greater in post-agricultural sites (i.e. more compacted) and was associated with grasshopper community composition. Both herbaceous cover and leaf litter cover are influenced by fire frequency, suggesting a potential indirect role of fire on grasshopper assemblages. 5. Our results demonstrate that historic land use may create persistent differences in the composition of grasshopper assemblages, while contemporary disturbances (e.g. prescribed fire) may be important for determining the abundance of grasshoppers, largely through the effect of fire on plants and leaf litter. Therefore, our results suggest that changes in the contemporary management regimes (e.g. increasing prescribed fire) may not be sufficient to shift the structure of grasshopper communities in post-agricultural sites towards communities in

  4. Plant quantity affects development and survival of a gregarious insect herbivore and its endoparasitoid wasp.

    Minghui Fei; Rieta Gols; Feng Zhu; Harvey, Jeffrey A.

    2016-01-01

    Virtually all studies of plant-herbivore-natural enemy interactions focus on plant quality as the major constraint on development and survival. However, for many gregarious feeding insect herbivores that feed on small or ephemeral plants, the quantity of resources is much more limiting, yet this area has received virtually no attention. Here, in both lab and semifield experiments using tents containing variably sized clusters of food plants, we studied the effects of periodic food deprivation...

  5. Toxicity of a furanocoumarin to armyworms: a case of biosynthetic escape from insect herbivores.

    Berenbaum, M

    1978-08-11

    When the linear furanocoumarin xanthotoxin, found in many plants of the families Rutaceae and Umbelliferae, was administered to larvae of Spodoptera eridania, a generalist insect herbivore, it displayed toxic properties lacking in its biosynthetic precursor umbelliferone. Reduced toxicity observed in the absence of ultraviolet light is consistent with the known mechanism of photoinactivation of DNA by furanocoumarins through ultraviolet-catalyzed cross-linkage of strands. Thus, the ability of a plant to convert umbelliferone to linear furanocoumarins appears to confer broader protection against insect herbivores. PMID:17790440

  6. Insect attraction to herbivore-induced beech volatiles under different forest management regimes.

    Gossner, Martin M; Weisser, Wolfgang W; Gershenzon, Jonathan; Unsicker, Sybille B

    2014-10-01

    Insect herbivore enemies such as parasitoids and predators are important in controlling herbivore pests. From agricultural systems we know that land-use intensification can negatively impact biological control as an important ecosystem service. The aim of our study was to investigate the importance of management regime for natural enemy pressure and biological control possibilities in forests dominated by European beech. We hypothesize that the volatile blend released from herbivore-infested beech trees functions as a signal, attracting parasitoids and herbivore enemies. Furthermore, we hypothesize that forest management regime influences the composition of species attracted by these herbivore-induced beech volatiles. We installed flight-interception traps next to Lymantria dispar caterpillar-infested young beech trees releasing herbivore-induced volatiles and next to non-infested control trees. Significantly more parasitoids were captured next to caterpillar-infested trees compared to non-infested controls, irrespective of forest type. However, the composition of the trophic guilds in the traps did vary in response to forest management regime. While the proportion of chewing insects was highest in non-managed forests, the proportion of sucking insects peaked in forests with low management and of parasitoids in young, highly managed, forest stands. Neither the number of naturally occurring beech saplings nor herbivory levels in the proximity of our experiment affected the abundance and diversity of parasitoids caught. Our data show that herbivore-induced beech volatiles attract herbivore enemies under field conditions. They further suggest that differences in the structural complexity of forests as a consequence of management regime only play a minor role in parasitoid activity and thus in indirect tree defense. PMID:25080178

  7. Insect Leaf-Chewing Damage Tracks Herbivore Richness in Modern and Ancient Forests

    Carvalho, Mónica R.; Peter Wilf; Héctor Barrios; Windsor, Donald M.; Currano, Ellen D.; Labandeira, Conrad C.; Jaramillo, Carlos A

    2014-01-01

    The fossil record demonstrates that past climate changes and extinctions significantly affected the diversity of insect leaf-feeding damage, implying that the richness of damage types reflects that of the unsampled damage makers, and that the two are correlated through time. However, this relationship has not been quantified for living leaf-chewing insects, whose richness and mouthpart convergence have obscured their value for understanding past and present herbivore diversity. We hypothesize...

  8. Plant-resistance to insect herbivores and semiochemicals

    Mendesil, Esayas

    2014-01-01

    Field pea is one of the important pulse crops which play a key role in human and animal nutrition as well as soil fertility in cropping systems. Insect pests are among the main biotic production constraints causing a considerable amount of losses worldwide. Like any other pulse crops, insect management of field pea pests mainly depends on the use of chemical insecticides. For sustainable and environmentally friendly pest management methods, it is crucial to understand plant-insect interaction...

  9. The Multiple Strategies of an Insect Herbivore to Overcome Plant Cyanogenic Glucoside Defence

    Stefan Pentzold; Mika Zagrobelny; Pernille Sølvhøj Roelsgaard; Birger Lindberg Møller; Søren Bak

    2014-01-01

    Cyanogenic glucosides (CNglcs) are widespread plant defence compounds that release toxic hydrogen cyanide by plant bglucosidaseactivity after tissue damage. Specialised insect herbivores have evolved counter strategies and some sequesterCNglcs, but the underlying mechanisms to keep CNglcs intact during feeding and digestion are unknown. We show thatCNglc-sequestering Zygaena filipendulae larvae combine behavioural, morphological, physiological and biochemicalstrategies at different time point...

  10. Genetic and environmental determinants of insect herbivore community structure in a Betula pendula population.

    Silfver, Tarja; Rousi, Matti; Oksanen, Elina; Roininen, Heikki

    2014-01-01

    A number of recent studies have shown that intraspecific genetic variation of plants may have a profound effect on the herbivorous communities which depend on them. However less is known about the relative importance of intraspecific variation compared to other ecological factors, for example environmental variation or the effects of herbivore damage. We randomly selected 22 Betula pendula genotypes from a local population (block) variation on a local scale, while on a regional scale, genotypic and environmental (site) variation accounted for 4-14% of the arthropod community structure. The genetic effects were modified by environmental variation on both a local and regional scale over one study year, and locally, the largest part of the variation (38%) could be explained by the genotype × environment (block) interactions. Suppression of insect herbivores during one growing season led to changed arthropod community structure in the following growing season, but this effect was minimal and could explain only 4% of the total variation in insect community structure. Our results suggest that both genetic and environmental factors are important determinants of the community structure of herbivorous insects. Together these mechanisms appear to maintain the high diversity of insects in B. pendula forest ecosystems. PMID:24715977

  11. Oak-insect herbivore interactions along a temperature and precipitation gradient

    Leckey, Erin H.; Smith, Dena M.; Nufio, César R.; Fornash, Katherine F.

    2014-11-01

    The interactions between herbivorous insects and their host plants are expected to be influenced by changing climates. Modern oaks provide an excellent system to examine this assumption because their interactions with herbivores occur over broad climatic and spatial scales, they vary in their defensive and nutritional investment in leaves by being deciduous or evergreen, and their insect herbivores range from generalists to highly specialized feeders. In this study, we surveyed leaf-litter samples of four oak species along an elevation gradient, from coastal northern California, USA, to the upper montane woodlands of the Sierra Nevada, to examine the relationship between climatic factors (mean annual temperature and precipitation) and oak herbivory levels at multiple scales; across all oak species pooled, between evergreen and deciduous species and within species. Overall, temperature and precipitation did not appear to have a significant effect on most measures of total herbivore damage (percent leaves damaged per tree, percent leaf area removed and average number of feeding damage marks per leaf) and the strongest predictor of herbivore damage overall was the identity of the host species. However, increases in precipitation were correlated with an increase in the actual leaf area removed, and specialized insects, such as those that make leaf mines and galls, were the most sensitive to differences in precipitation levels. This suggests that the effects of changing climate on some plant-insect interactions is less likely to result in broad scale increases in damage with increasing temperatures or changing precipitation levels, but is rather more likely to be dependent on the type of herbivore (specialist vs. generalist) and the scale (species vs. community) over which the effect is examined.

  12. Plant Quantity Affects Development and Survival of a Gregarious Insect Herbivore and Its Endoparasitoid Wasp.

    Fei, Minghui; Gols, Rieta; Zhu, Feng; Harvey, Jeffrey A

    2016-01-01

    Virtually all studies of plant-herbivore-natural enemy interactions focus on plant quality as the major constraint on development and survival. However, for many gregarious feeding insect herbivores that feed on small or ephemeral plants, the quantity of resources is much more limiting, yet this area has received virtually no attention. Here, in both lab and semi-field experiments using tents containing variably sized clusters of food plants, we studied the effects of periodic food deprivation in a tri-trophic system where quantitative constraints are profoundly important on insect performance. The large cabbage white Pieris brassicae, is a specialist herbivore of relatively small wild brassicaceous plants that grow in variable densities, with black mustard (Brassica nigra) being one of the most important. Larvae of P. brassicae are in turn attacked by a specialist endoparasitoid wasp, Cotesia glomerata. Increasing the length of food deprivation of newly molted final instar caterpillars significantly decreased herbivore and parasitoid survival and biomass, but shortened their development time. Moreover, the ability of caterpillars to recover when provided with food again was correlated with the length of the food deprivation period. In outdoor tents with natural vegetation, we created conditions similar to those faced by P. brassicae in nature by manipulating plant density. Low densities of B. nigra lead to potential starvation of P. brassicae broods and their parasitoids, replicating nutritional conditions of the lab experiments. The ability of both unparasitized and parasitized caterpillars to find corner plants was similar but decreased with central plant density. Survival of both the herbivore and parasitoid increased with plant density and was higher for unparasitized than for parasitized caterpillars. Our results, in comparison with previous studies, reveal that quantitative constraints are far more important that qualitative constraints on the performance of

  13. Plant Quantity Affects Development and Survival of a Gregarious Insect Herbivore and Its Endoparasitoid Wasp

    Fei, Minghui; Gols, Rieta; Zhu, Feng; Harvey, Jeffrey A.

    2016-01-01

    Virtually all studies of plant-herbivore-natural enemy interactions focus on plant quality as the major constraint on development and survival. However, for many gregarious feeding insect herbivores that feed on small or ephemeral plants, the quantity of resources is much more limiting, yet this area has received virtually no attention. Here, in both lab and semi-field experiments using tents containing variably sized clusters of food plants, we studied the effects of periodic food deprivation in a tri-trophic system where quantitative constraints are profoundly important on insect performance. The large cabbage white Pieris brassicae, is a specialist herbivore of relatively small wild brassicaceous plants that grow in variable densities, with black mustard (Brassica nigra) being one of the most important. Larvae of P. brassicae are in turn attacked by a specialist endoparasitoid wasp, Cotesia glomerata. Increasing the length of food deprivation of newly molted final instar caterpillars significantly decreased herbivore and parasitoid survival and biomass, but shortened their development time. Moreover, the ability of caterpillars to recover when provided with food again was correlated with the length of the food deprivation period. In outdoor tents with natural vegetation, we created conditions similar to those faced by P. brassicae in nature by manipulating plant density. Low densities of B. nigra lead to potential starvation of P. brassicae broods and their parasitoids, replicating nutritional conditions of the lab experiments. The ability of both unparasitized and parasitized caterpillars to find corner plants was similar but decreased with central plant density. Survival of both the herbivore and parasitoid increased with plant density and was higher for unparasitized than for parasitized caterpillars. Our results, in comparison with previous studies, reveal that quantitative constraints are far more important that qualitative constraints on the performance of

  14. Odor uniformity among tomato individuals in response to herbivore depends on insect species.

    Alicia Bautista-Lozada

    Full Text Available Plants produce specific volatile organic compound (VOC blends in response to herbivory. Herbivore-induced blends may prime the plant for future attack or attract carnivorous insects; these responses have been considered adaptive for plants. If herbivores differentially modify the VOC emission among individuals within a group of plants they feed upon, then plant responses to herbivores will not only produce specific blends but also variation in odor among individuals, i.e. individuals smell the same, then having a uniform odor. We investigated the VOC emission variation or uniformity among tomato individuals (Solanum lycopersicum L. cv. Castlemart in response to moderate wounding by (1 nymphs of the psyllid Bactericera cockerelli (Sulc. (TP; (2 Lepidoptera chewing-feeding larvae of Fall Armyworm (Spodoptera frugiperda Smith (FAW and (3 of Cabbage Looper (Trichoplusia ni Hübner (CL, and (4 mechanical damage (MD. We used a ratio-based analysis to compare the fold-change in concentration from constitutive to induced VOC emission. We also used size and shape analysis to compare the emission of damaged and non-damaged individuals. Aside of finding herbivore-specific blends in line with other studies, we found patterns not described previously. We detected constitutive and induced odor variation among individuals attacked by the same herbivore, with the induced odor uniformity depending on the herbivore identity. We also showed that the fold-change of VOCs from constitutive to induced state differed among individuals independently of the uniformity of the blends before herbivore attack. We discuss our findings in the context of the ecological roles of VOCs in plant-plant and plant-carnivore insects' interactions.

  15. Review - Host specificity of insect herbivores in tropical forests

    Novotný, Vojtěch; Basset, Y.

    2005-01-01

    Roč. 272, č. 1568 (2005), s. 1083-1090. ISSN 0962-8452 R&D Projects: GA AV ČR(CZ) IAA6007106; GA ČR(CZ) GD206/03/H034; GA ČR(CZ) GA206/04/0725; GA MŠk(CZ) ME 646 Grant ostatní: US Nationals Science Foundation(US) DEB-02-11591; Darwin Initiative for the Survival of Species(US) 162/10/030 Institutional research plan: CEZ:AV0Z50070508 Keywords : food web * herbivore guild * host plant range Subject RIV: EH - Ecology, Behaviour Impact factor: 3.510, year: 2005

  16. Alien interference: disruption of infochemical networks by invasive insect herbivores

    Desurmont, G.A.; Harvey, J.; Van Dam, N. M.; Cristescu, S. M.; Schiestl, F.P.; Cozzolino, S.; Anderson, P.; Larsson, M. C.; Kindlmann, Pavel; Danner, H.; Turlings, C. J.

    2014-01-01

    Roč. 37, č. 8 (2014), s. 1854-1865. ISSN 0140-7791 Institutional support: RVO:67179843 Keywords : invasive species * multitrophic interactions * plant–insect interactions * plant volatiles Subject RIV: EH - Ecology, Behaviour Impact factor: 6.960, year: 2014

  17. Potential impact of insect herbivores on orchid conservation

    Marilyn H. S. Light

    2012-02-01

    Full Text Available When an orchid is deliberately or inadvertently relocated, it is likely to encounter a range of biological challenges to long term survival including a complex and dynamic insect community which could alter conservation expectations yet there have been few studies of the phytophagous insects associated with wild orchids. We have investigated the assemblage of such insects associated with terrestrial orchids being monitored in our long term studies in Gatineau Park, Québec, Canada. Aphids, leafminers, moths, thrips, weevils, and whiteflies were found to be injurious to orchids although in different combinations and with varying impact according to the orchid host, habitat and year. Loss of seeds and even complete desiccation of plants was observed. Where the leafminer, Parallelomma vittatum Meigen (Diptera: Scathophagidae infested Cypripedium reginae Walter randomly, this was not the case with Cypripedium parviflorum var. pubescens (Willd. Knight where specific plants were repeatedly infested. Some infestations such as with the leafminers seemed to be in equilibrium with parasitoids thus minimizing potential impact. A likely climate-related asynchrony of parasitoid and leafminer led to an outbreak in 2009 which heavily impacted the introduced Epipactis helleborine (L. Crantz while a phenological shift in a thrips primary host, Trillium grandiflorum (Michaux Salisb. (Melanthiaceae, in 2010, contributed to severe herbivory in habitats where both E. helleborine and trillium occurred. If climate change can lead to changes in insect abundance and impact on orchids, it would be useful to investigate the potential impact of phytophagous insects before assisted migration is considered as a conservation measure.

  18. Effect of Nitrogen Fertilizer on Herbivores and Its Stimulation to Major Insect Pests in Rice

    LU Zhong-xian; YU Xiao-ping; Kong-luen HEONG; HU Cui

    2007-01-01

    Nitrogen is one of the most important factors in development of herbivore populations. The application of nitrogen fertilizer in plants can normally increase herbivore feeding preference, food consumption, survival, growth, reproduction, and population density, except few examples that nitrogen fertilizer reduces the herbivore performances. In most of the rice growing areas in Asia, the great increases in populations of major insect pests of rice, including planthoppers (Nilaparvata lugens and Sogatella furcifera), leaffolder (Cnaphalocrocis medinalis), and stem borers (Scirpophaga incertulas, Chilo suppressalis, S. innotata, C. polychrysus and Sesamia inferens) were closely related to the long-term excessive application of nitrogen fertilizers. The optimal regime of nitrogen fertilizer in irrigated paddy fields is proposed to improve the fertilizer-nitrogen use efficiency and reduce the environmental pollution.

  19. Insects on plants: Diversity of herbivore assemblages revisited

    Lewinsohn, T. M.; Novotný, Vojtěch; Basset, Y.

    2005-01-01

    Roč. 36, - (2005), s. 597-620. ISSN 1543-592X R&D Projects: GA ČR(CZ) GA206/04/0725; GA ČR(CZ) GD206/03/H034; GA AV ČR(CZ) IAA6007106; GA MŠk(CZ) ME 646 Grant ostatní: Fundacao de Amaparo a Pesquisa do Estado de Sao Paulo(BR) Biota/Fapesp 98/05085-2; Conselho Nacional de Densenvolvimento Cientifico e Tecnologico-Brasil(BR) 306049/2004-0; U. S. National Science Foundation(US) DEB-02-11591; Darwin Initiative fior the Survival of Species(GB) 162/10/030 Institutional research plan: CEZ:AV0Z5007907 Keywords : herbivory * insect-plant interactions * tropical insects Subject RIV: EH - Ecology, Behaviour Impact factor: 10.104, year: 2005

  20. Chemical phenotype matching between a plant and its insect herbivore

    Berenbaum, May R; Zangerl, Arthur R.

    1998-01-01

    Two potential outcomes of a coevolutionary interaction are an escalating arms race and stable cycling. The general expectation has been that arms races predominate in cases of polygenic inheritance of resistance traits and permanent cycling predominates in cases in which resistance is controlled by major genes. In the interaction between Depressaria pastinacella, the parsnip webworm, and Pastinaca sativa, the wild parsnip, traits for plant resistance to insect herbivory (production of defensi...

  1. Adaptive evolution of threonine deaminase in plant defense against insect herbivores

    Gonzales-Vigil, Eliana; Bianchetti, Christopher M.; Phillips, Jr., George N.; Howe, Gregg A. (MSU); (UW)

    2011-11-07

    Gene duplication is a major source of plant chemical diversity that mediates plant-herbivore interactions. There is little direct evidence, however, that novel chemical traits arising from gene duplication reduce herbivory. Higher plants use threonine deaminase (TD) to catalyze the dehydration of threonine (Thr) to {alpha}-ketobutyrate and ammonia as the committed step in the biosynthesis of isoleucine (Ile). Cultivated tomato and related Solanum species contain a duplicated TD paralog (TD2) that is coexpressed with a suite of genes involved in herbivore resistance. Analysis of TD2-deficient tomato lines showed that TD2 has a defensive function related to Thr catabolism in the gut of lepidopteran herbivores. During herbivory, the regulatory domain of TD2 is removed by proteolysis to generate a truncated protein (pTD2) that efficiently degrades Thr without being inhibited by Ile. We show that this proteolytic activation step occurs in the gut of lepidopteran but not coleopteran herbivores, and is catalyzed by a chymotrypsin-like protease of insect origin. Analysis of purified recombinant enzymes showed that TD2 is remarkably more resistant to proteolysis and high temperature than the ancestral TD1 isoform. The crystal structure of pTD2 provided evidence that electrostatic interactions constitute a stabilizing feature associated with adaptation of TD2 to the extreme environment of the lepidopteran gut. These findings demonstrate a role for gene duplication in the evolution of a plant defense that targets and co-opts herbivore digestive physiology.

  2. Incorporation of an invasive plant into a native insect herbivore food web

    Schilthuizen, Menno; Santos Pimenta, Lúcia P.; Lammers, Youri; Steenbergen, Peter J.; Flohil, Marco; Beveridge, Nils G.P.; van Duijn, Pieter T.; Meulblok, Marjolein M.; Sosef, Nils; van de Ven, Robin; Werring, Ralf; Beentjes, Kevin K.; Meijer, Kim; Vos, Rutger A; Vrieling, Klaas

    2016-01-01

    The integration of invasive species into native food webs represent multifarious dynamics of ecological and evolutionary processes. We document incorporation of Prunus serotina (black cherry) into native insect food webs. We find that P. serotina harbours a herbivore community less dense but more diverse than its native relative, P. padus (bird cherry), with similar proportions of specialists and generalists. While herbivory on P. padus remained stable over the past century, that on P. seroti...

  3. Global Change Effects on Plant Chemical Defenses against Insect Herbivores

    M. Gabriela Bidart-Bouzat; Adebobola Imeh-Nathaniel

    2008-01-01

    This review focuses on individual effects of major global change factors, such as elevated CO2, Oa, UV light and temperature,on plant secondary chemistry. These secondary metabolites are well-known for their role in plant defense against insect herbivory. Global change effects on secondary chemicals appear to be plant species-specific and dependent on the chemical type. Even though plant chemical responses induced by these factors are highly variable, there seems to be some specificity in the response to different environmental stressors. For example, even though the production of phenolic compounds is enhanced by both elevated CO2 and UV light levels, the latter appears to primarily increase the concentrations of fiavonoids. Likewise, specific phenolic metabolites seem to be induced by O3 but not by other factors, and an increase in volatile organic compounds has been particularly detected under elevated temperature. More information is needed regarding how global change factors influence inducibility of plant chemical defenses as well as how their indirect and direct effects impact insect performance and behavior, herbivory rates and pathogen attack. This knowledge is crucial to better understand how plants and their associated natural enemies will be affected in future changing environments.

  4. Are Tree Species Diversity and Genotypic Diversity Effects on Insect Herbivores Mediated by Ants?

    Campos-Navarrete, María José; Abdala-Roberts, Luis; Munguía-Rosas, Miguel A.; Parra-Tabla, Víctor

    2015-01-01

    Plant diversity can influence predators and omnivores and such effects may in turn influence herbivores and plants. However, evidence for these ecological feedbacks is rare. We evaluated if the effects of tree species (SD) and genotypic diversity (GD) on the abundance of different guilds of insect herbivores associated with big-leaf mahogany (Swietenia macrophylla) were contingent upon the protective effects of ants tending extra-floral nectaries of this species. This study was conducted within a larger experiment consisting of mahogany monocultures and species polycultures of four species and –within each of these two plot types– mahogany was represented by either one or four maternal families. We selected 24 plots spanning these treatment combinations, 10 mahogany plants/plot, and within each plot experimentally reduced ant abundance on half of the selected plants, and surveyed ant and herbivore abundance. There were positive effects of SD on generalist leaf-chewers and sap-feeders, but for the latter group this effect depended on the ant reduction treatment: SD positively influenced sap-feeders under ambient ant abundance but had no effect when ant abundance was reduced; at the same time, ants had negative effects on sap feeders in monoculture but no effect in polyculture. In contrast, SD did not influence specialist stem-borers or leaf-miners and this effect was not contingent upon ant reduction. Finally, GD did not influence any of the herbivore guilds studied, and such effects did not depend on the ant treatment. Overall, we show that tree species diversity influenced interactions between a focal plant species (mahogany) and ants, and that such effects in turn mediated plant diversity effects on some (sap-feeders) but not all the herbivores guilds studied. Our results suggest that the observed patterns are dependent on the combined effects of herbivore identity, diet breadth, and the source of plant diversity. PMID:26241962

  5. Are Tree Species Diversity and Genotypic Diversity Effects on Insect Herbivores Mediated by Ants?

    María José Campos-Navarrete

    Full Text Available Plant diversity can influence predators and omnivores and such effects may in turn influence herbivores and plants. However, evidence for these ecological feedbacks is rare. We evaluated if the effects of tree species (SD and genotypic diversity (GD on the abundance of different guilds of insect herbivores associated with big-leaf mahogany (Swietenia macrophylla were contingent upon the protective effects of ants tending extra-floral nectaries of this species. This study was conducted within a larger experiment consisting of mahogany monocultures and species polycultures of four species and -within each of these two plot types- mahogany was represented by either one or four maternal families. We selected 24 plots spanning these treatment combinations, 10 mahogany plants/plot, and within each plot experimentally reduced ant abundance on half of the selected plants, and surveyed ant and herbivore abundance. There were positive effects of SD on generalist leaf-chewers and sap-feeders, but for the latter group this effect depended on the ant reduction treatment: SD positively influenced sap-feeders under ambient ant abundance but had no effect when ant abundance was reduced; at the same time, ants had negative effects on sap feeders in monoculture but no effect in polyculture. In contrast, SD did not influence specialist stem-borers or leaf-miners and this effect was not contingent upon ant reduction. Finally, GD did not influence any of the herbivore guilds studied, and such effects did not depend on the ant treatment. Overall, we show that tree species diversity influenced interactions between a focal plant species (mahogany and ants, and that such effects in turn mediated plant diversity effects on some (sap-feeders but not all the herbivores guilds studied. Our results suggest that the observed patterns are dependent on the combined effects of herbivore identity, diet breadth, and the source of plant diversity.

  6. Are Tree Species Diversity and Genotypic Diversity Effects on Insect Herbivores Mediated by Ants?

    Campos-Navarrete, María José; Abdala-Roberts, Luis; Munguía-Rosas, Miguel A; Parra-Tabla, Víctor

    2015-01-01

    Plant diversity can influence predators and omnivores and such effects may in turn influence herbivores and plants. However, evidence for these ecological feedbacks is rare. We evaluated if the effects of tree species (SD) and genotypic diversity (GD) on the abundance of different guilds of insect herbivores associated with big-leaf mahogany (Swietenia macrophylla) were contingent upon the protective effects of ants tending extra-floral nectaries of this species. This study was conducted within a larger experiment consisting of mahogany monocultures and species polycultures of four species and -within each of these two plot types- mahogany was represented by either one or four maternal families. We selected 24 plots spanning these treatment combinations, 10 mahogany plants/plot, and within each plot experimentally reduced ant abundance on half of the selected plants, and surveyed ant and herbivore abundance. There were positive effects of SD on generalist leaf-chewers and sap-feeders, but for the latter group this effect depended on the ant reduction treatment: SD positively influenced sap-feeders under ambient ant abundance but had no effect when ant abundance was reduced; at the same time, ants had negative effects on sap feeders in monoculture but no effect in polyculture. In contrast, SD did not influence specialist stem-borers or leaf-miners and this effect was not contingent upon ant reduction. Finally, GD did not influence any of the herbivore guilds studied, and such effects did not depend on the ant treatment. Overall, we show that tree species diversity influenced interactions between a focal plant species (mahogany) and ants, and that such effects in turn mediated plant diversity effects on some (sap-feeders) but not all the herbivores guilds studied. Our results suggest that the observed patterns are dependent on the combined effects of herbivore identity, diet breadth, and the source of plant diversity. PMID:26241962

  7. The multiple strategies of an insect herbivore to overcome plant cyanogenic glucoside defence

    Pentzold, Stefan; Zagrobelny, Mika; Roelsgaard, Pernille Sølvhøj;

    2014-01-01

    Cyanogenic glucosides (CNglcs) are widespread plant defence compounds that release toxic hydrogen cyanide by plant bglucosidase activity after tissue damage. Specialised insect herbivores have evolved counter strategies and some sequester CNglcs, but the underlying mechanisms to keep CNglcs intact...... during feeding and digestion are unknown. We show that CNglc-sequestering Zygaena filipendulae larvae combine behavioural, morphological, physiological and biochemical strategies at different time points during feeding and digestion to avoid toxic hydrolysis of the CNglcs present in their Lotus food......, a highly alkaline midgut lumen inhibited the activity of ingested plant b-glucosidases significantly. Moreover, insect b-glucosidases from the saliva and gut tissue did not hydrolyse the CNglcs present in Lotus. The strategies disclosed may also be used by other insect species to overcome CNglc...

  8. Insect leaf-chewing damage tracks herbivore richness in modern and ancient forests.

    Mónica R Carvalho

    Full Text Available The fossil record demonstrates that past climate changes and extinctions significantly affected the diversity of insect leaf-feeding damage, implying that the richness of damage types reflects that of the unsampled damage makers, and that the two are correlated through time. However, this relationship has not been quantified for living leaf-chewing insects, whose richness and mouthpart convergence have obscured their value for understanding past and present herbivore diversity. We hypothesized that the correlation of leaf-chewing damage types (DTs and damage maker richness is directly observable in living forests. Using canopy access cranes at two lowland tropical rainforest sites in Panamá to survey 24 host-plant species, we found significant correlations between the numbers of leaf chewing insect species collected and the numbers of DTs observed to be made by the same species in feeding experiments, strongly supporting our hypothesis. Damage type richness was largely driven by insect species that make multiple DTs. Also, the rank-order abundances of DTs recorded at the Panamá sites and across a set of latest Cretaceous to middle Eocene fossil floras were highly correlated, indicating remarkable consistency of feeding-mode distributions through time. Most fossil and modern host-plant pairs displayed high similarity indices for their leaf-chewing DTs, but informative differences and trends in fossil damage composition became apparent when endophytic damage was included. Our results greatly expand the potential of insect-mediated leaf damage for interpreting insect herbivore richness and compositional heterogeneity from fossil floras and, equally promisingly, in living forests.

  9. Evolutionary response of the egg hatching date of a herbivorous insect under climate change

    van Asch, Margriet; Salis, Lucia; Holleman, Leonard J. M.; van Lith, Bart; Visser, Marcel E.

    2013-03-01

    Under changing climatic conditions, species need to adapt to their new environment. Genetic adaptation is crucial to prevent population extinction but examples where climate change leads to genetic changes in wild populations have been few. The synchronization between the timing of egg hatching of a herbivorous insect, the winter moth (Operophtera brumata), and the seasonal bud burst of its food plant, oak (Quercus robur), has been disrupted by climate change and a quantitative genetic model predicts that selection will delay the egg hatching date. Here we show, using both long-term observational data and experiments, that the egg hatching date has changed genetically, resulting in closer synchrony with oak bud burst. The observed rate of change matches the predicted rate of change of one day per year. Hence, altered selection pressures, caused by environmental change, result in a rapid adaptive response in insect phenology. These genetic changes in a key life-history trait in this herbivorous insect therefore seem to be fast enough to match the climate-change-induced advancement of their host phenology.

  10. Effects of protein and carbohydrate on an insect herbivore: the vista from a fitness landscape.

    Le Gall, Marion; Behmer, Spencer T

    2014-11-01

    Protein and carbohydrates are important nutrients driving the growth of herbivores; however, their content in plants is highly variable. Multiple studies have explored their effect on herbivores, but only one other study (using a caterpillar) has provided a comprehensive overview that includes a simultaneous evaluation of their ratios and concentrations. In the present work, we ran two experiments using nymphs of the generalist grasshopper Melanoplus differentialis. Grasshoppers and caterpillars differ in a number of important ways, which might affect their feeding and physiological responses to foods with variable content of protein and carbohydrates. First, in a choice experiment, we measured performance and related this to the self-selected intake of nutrients. No differences were found for duration of development across treatments, but gain in mass was lower on a diet of low macronutrient concentration. Consumption of protein was always tightly regulated, but intake of carbohydrate was significantly reduced when consuming diluted food. In the second experiment, insects were constrained to one of nine diets and we plotted performance and consumption using a fitness-landscape approach that mimics the natural variation of nutrients in plants. We found significant effects of protein and carbohydrate content on gain in mass and in duration of development. The concentration of macronutrients in the food had more pronounced effects than did the protein-to-carbohydrate ratio. The protein-carbohydrate content also significantly affected the intake of food and energy (calories), production of frass, and digestive efficiency. On foods with low macronutrient concentration consumption was high, but digestive efficiency was low. Our results suggest that insects will favor protein-biased foods when the total macronutrient content of available foods is low, and that in the short-term compensatory feeding responses can overcome nutritional deficits and/or imbalances. However

  11. An Insect Herbivore Microbiome with High Plant Biomass-Degrading Capacity

    Suen, Garret; Barry, Kerrie; Goodwin, Lynne; Scott, Jarrod; Aylward, Frank; Adams, Sandra; Pinto-Tomas, Adrian; Foster, Clifton; Pauly, Markus; Weimer, Paul; Bouffard, Pascal; Li, Lewyn; Osterberger, Jolene; Harkins, Timothy; Slater, Steven; Donohue, Timothy; Currie, Cameron; Tringe, Susannah G.

    2010-09-23

    Herbivores can gain indirect access to recalcitrant carbon present in plant cell walls through symbiotic associations with lignocellulolytic microbes. A paradigmatic example is the leaf-cutter ant (Tribe: Attini), which uses fresh leaves to cultivate a fungus for food in specialized gardens. Using a combination of sugar composition analyses, metagenomics, and whole-genome sequencing, we reveal that the fungus garden microbiome of leaf-cutter ants is composed of a diverse community of bacteria with high plant biomass-degrading capacity. Comparison of this microbiome?s predicted carbohydrate-degrading enzyme profile with other metagenomes shows closest similarity to the bovine rumen, indicating evolutionary convergence of plant biomass degrading potential between two important herbivorous animals. Genomic and physiological characterization of two dominant bacteria in the fungus garden microbiome provides evidence of their capacity to degrade cellulose. Given the recent interest in cellulosic biofuels, understanding how large-scale and rapid plant biomass degradation occurs in a highly evolved insect herbivore is of particular relevance for bioenergy.

  12. An insect herbivore microbiome with high plant biomass-degrading capacity.

    Garret Suen

    2010-09-01

    Full Text Available Herbivores can gain indirect access to recalcitrant carbon present in plant cell walls through symbiotic associations with lignocellulolytic microbes. A paradigmatic example is the leaf-cutter ant (Tribe: Attini, which uses fresh leaves to cultivate a fungus for food in specialized gardens. Using a combination of sugar composition analyses, metagenomics, and whole-genome sequencing, we reveal that the fungus garden microbiome of leaf-cutter ants is composed of a diverse community of bacteria with high plant biomass-degrading capacity. Comparison of this microbiome's predicted carbohydrate-degrading enzyme profile with other metagenomes shows closest similarity to the bovine rumen, indicating evolutionary convergence of plant biomass degrading potential between two important herbivorous animals. Genomic and physiological characterization of two dominant bacteria in the fungus garden microbiome provides evidence of their capacity to degrade cellulose. Given the recent interest in cellulosic biofuels, understanding how large-scale and rapid plant biomass degradation occurs in a highly evolved insect herbivore is of particular relevance for bioenergy.

  13. The Effect of Host-Plant Phylogenetic Isolation on Species Richness, Composition and Specialization of Insect Herbivores: A Comparison between Native and Exotic Hosts.

    Julio Miguel Grandez-Rios

    Full Text Available Understanding the drivers of plant-insect interactions is still a key issue in terrestrial ecology. Here, we used 30 well-defined plant-herbivore assemblages to assess the effects of host plant phylogenetic isolation and origin (native vs. exotic on the species richness, composition and specialization of the insect herbivore fauna on co-occurring plant species. We also tested for differences in such effects between assemblages composed exclusively of exophagous and endophagous herbivores. We found a consistent negative effect of the phylogenetic isolation of host plants on the richness, similarity and specialization of their insect herbivore faunas. Notably, except for Jaccard dissimilarity, the effect of phylogenetic isolation on the insect herbivore faunas did not vary between native and exotic plants. Our findings show that the phylogenetic isolation of host plants is a key factor that influences the richness, composition and specialization of their local herbivore faunas, regardless of the host plant origin.

  14. Compensatory responses in plant-herbivore interactions: Impacts of insects on leaf water relations

    Peschiutta, María L.; Bucci, Sandra J.; Scholz, Fabián G.; Goldstein, Guillermo

    2016-05-01

    Herbivore damage to leaves has been typically evaluated in terms of fractions of area removed; however morpho-physiological changes in the remaining tissues can occur in response to removal. We assessed the effects of partial removal of the leaf mesophyll by Caliroa cerasi (Hymenoptera) on leaf hydraulic conductance (Kleaf), vascular architecture, water relations and leaf size of three Prunus avium cultivars. The insect feeds on the leaf mesophyll leaving the vein network intact (skeletonization). Within each cultivar there were trees without infestations and trees chronically infested, at least over the last three years. Leaf size of intact leaves tended to be similar during leaf expansion before herbivore attack occurs across infested and non-infested trees. However, after herbivore attack and when the leaves were fully expanded, damaged leaves were smaller than leaves from non-infested trees. Damaged area varied between 21 and 31% depending on cultivar. The non-disruption of the vascular system together with either vein density or capacitance increased in damaged leaves resulted in similar Kleaf and stomatal conductance in infested and non-infested trees. Non-stomatal water loss from repeated leaf damage led to lower leaf water potentials in two of the infested cultivars. Lower leaf osmotic potentials and vulnerability to loss of Kleaf were observed in infested plants. Our results show that skeletonization resulted in compensatory changes in terms of water relations and hydraulics traits and in cultivar-specific physiological changes in phylogenetic related P. avium. Our findings indicate that detrimental effects of herbivory on the photosynthetic surface are counterbalanced by changes providing higher drought resistance, which has adaptive significance in ecosystems where water availability is low and furthermore where global climate changes would decrease soil water availability in the future even further.

  15. Incorporation of an invasive plant into a native insect herbivore food web

    Santos Pimenta, Lúcia P.; Lammers, Youri; Steenbergen, Peter J.; Flohil, Marco; Beveridge, Nils G.P.; van Duijn, Pieter T.; Meulblok, Marjolein M.; Sosef, Nils; van de Ven, Robin; Werring, Ralf; Beentjes, Kevin K.; Meijer, Kim; Vos, Rutger A.; Vrieling, Klaas; Gravendeel, Barbara; Choi, Young; Verpoorte, Robert; Smit, Chris; Beukeboom, Leo W.

    2016-01-01

    The integration of invasive species into native food webs represent multifarious dynamics of ecological and evolutionary processes. We document incorporation of Prunus serotina (black cherry) into native insect food webs. We find that P. serotina harbours a herbivore community less dense but more diverse than its native relative, P. padus (bird cherry), with similar proportions of specialists and generalists. While herbivory on P. padus remained stable over the past century, that on P. serotina gradually doubled. We show that P. serotina may have evolved changes in investment in cyanogenic glycosides compared with its native range. In the leaf beetle Gonioctena quinquepunctata, recently shifted from native Sorbus aucuparia to P. serotina, we find divergent host preferences on Sorbus- versus Prunus-derived populations, and weak host-specific differentiation among 380 individuals genotyped for 119 SNP loci. We conclude that evolutionary processes may generate a specialized herbivore community on an invasive plant, allowing prognoses of reduced invasiveness over time. On the basis of the results presented here, we would like to caution that manual control might have the adverse effect of a slowing down of processes of adaptation, and a delay in the decline of the invasive character of P. serotina. PMID:27190702

  16. Forest Above Ground Biomass Estimation in China

    Zhao, D.; Zeng, Y.; Wu, B.; Li, X.

    2013-12-01

    In order to study the carbon cycling in China deeply, a forest above ground biomass (AGB) estimation research is carried out under the support of 'Strategic Priority Research Program - Climate Change: Carbone Budget and Related Issues' of the Chinese Academy of Sciences (Carbon Project). The research aims to estimate the forest AGB in 2000, 2005 and 2010 in China, and analyzes its dynamic changes. The overall thinking of the research is using field works and airborne LiDAR data as basis to estimate the AGB in GLAS footprints, and then extrapolating discrete AGB to continuous results with optical and auxiliary data. Due to the large area of China, totally 8 sub-areas are marked out based on the different forest ecosystems and some other factors (Table 1 and Fig. 1). Here, a latest China's land cover product (the background of Fig 1), named 'ChinaCover', and also supported by the 'Carbon Project', is imported to classify the forest types. There are around 5000 sample plots (Table 1) surveyed by the 'Carbon Project'. It can provide a large number of training and validation data. At the same time, the research sets 6 other typical sample areas, which have areas of 60 to 200 km2, and airborne LiDAR flights are carried out to obtain high accuracy AGB in these areas. With the sample plots and 6 typical sample areas, the AGB in GLAS footprint is estimated. Since the sample plots and LiDAR flights were carried out in 2012, the height and area parameters extracted from GLAS footprint are corrected by tree growth model of different forest types. In a further step, extrapolation models are built together with time-series MODIS and auxiliary data. These models fully consider the time-series features and propose several long time-series indices to minimize the influence of spectral saturation. Results are validated by samples and compared to the result of some other researches. At last, the models are applied to the data of 2000, 2005 and 2010 to get the corresponding AGB maps

  17. Isotopic fractionation in a large herbivorous insect, the Auckland tree weta.

    Wehi, Priscilla M; Hicks, Brendan J

    2010-12-01

    Determining diet and trophic position of species with stable isotopes requires appropriate trophic enrichment estimates between an animal and its potential foods. These estimates are particularly important for cryptic foragers where there is little comparative dietary information. Nonetheless, many trophic enrichment estimates are based on related taxa, without confirmation of accuracy using laboratory trials. We used stable isotope analysis to investigate diet and to resolve trophic relationships in a large endemic insect, the Auckland tree weta (Hemideina thoracica White). Comparisons of isotopes in plant foods fed to captive wetas with isotope ratios in their frass provided variable results, so frass isotope values had limited usefulness as a proxy indicator of trophic level. Isotopic values varied between different tissues, with trophic depletion of (15)N highest in body fat and testes. Tissue fractionation was consistent in captive and wild caught wetas, and isotopic values were not significantly different between the two groups, suggesting that this weta species is primarily herbivorous. Whole-body values in captive wetas demonstrated trophic depletion (Δδ) for δ(15)N of about -0.77 ‰ and trophic enrichment of 4.28 ‰ for δ(13)C. These values differ from commonly estimated trophic enrichments for both insects and herbivores and indicate the importance of laboratory trials to determine trophic enrichment. Isotopic values for femur muscles from a number of local wild weta populations did not vary consistently with body weight or size, suggesting that juveniles eat the same foods as adults. Considerable variation among individuals within and between populations suggests that isotopic values are strongly influenced by food availability and individual foraging traits. PMID:20709068

  18. Climate change triggers effects of fungal pathogens and insect herbivores on litter decomposition

    Butenschoen, Olaf; Scheu, Stefan

    2014-10-01

    Increasing infestation by insect herbivores and pathogenic fungi in response to climate change will inevitably impact the amount and quality of leaf litter inputs into the soil. However, little is known on the interactive effect of infestation severity and climate change on litter decomposition, and no such study has been published for deciduous forests in Central Europe. We assessed changes in initial chemical quality of beech (Fagus sylvatica L.) and maple litter (Acer platanoides L.) in response to infestation by the gall midge Mikiola fagi Hart. and the pathogenic fungus Sawadaea tulasnei Fuckel, respectively, and investigated interactive effects of infestation severity, changes in temperature and soil moisture on carbon mineralization in a short-term laboratory study. We found that infestation by the gall midge M. fagi and the pathogenic fungus S. tulasnei significantly changed the chemical quality of beech and maple litter. Changes in element concentrations were generally positive and more pronounced, and if negative less pronounced for maple than beech litter most likely due to high quality fungal tissue remaining on litter after abscission. More importantly, alterations in litter chemical quality did not translate to distinct patterns of carbon mineralization at ambient conditions, but even low amounts of infested litter accelerated carbon mineralization at moderately increased soil moisture and in particular at higher temperature. Our results indicate that insect herbivores and fungal pathogens can markedly alter initial litter chemical quality, but that afterlife effects on carbon mineralization depend on soil moisture and temperature, suggesting that increased infestation severity under projected climate change potentially increases soil carbon release in deciduous forests in Central Europe.

  19. VOC emissions and protein expression mediated by the interactions between herbivorous insects and Arabidopsis plant. A review

    Truong, DH.

    2014-01-01

    Full Text Available Herbivorous insects, such as phloem-sap feeders and chewers, induce resistance response in plants. There is a long-standing hypothesis that herbivores increase the emission of volatile organic compounds (VOCs in the Arabidopsis plant model. However, most works were restricted to the study of the regulation of plant VOCs emissions and only in some cases to the effects of insects on such emissions. Often these investigations do not establish a link between quantitative and qualitative emission of plant VOCs with actual damages caused by insects. Moreover, information remain limited about the processes that occur at the protein level encoded of the host plant under stress conditions. Here, we briefly summarize the effects of specific chewing and phloem-sap feeding insects on the emission of VOCs by Arabidopsis thaliana Col-, and review some predictions about pathogenesis-related (PR- proteins, based on current evolutionary hypotheses. Further investigation of the effects of herbivorous insects on VOC emissions and protein expression is expected to improve our knowledge about their patterns and functions in plant responses to stresses.

  20. Relative importance of biotic and abiotic soil components to plant growth and insect herbivore population dynamics.

    Martijn L Vandegehuchte

    Full Text Available BACKGROUND: Plants are affected by several aspects of the soil, which have the potential to exert cascading effects on the performance of herbivorous insects. The effects of biotic and abiotic soil characteristics have however mostly been investigated in isolation, leaving their relative importance largely unexplored. Such is the case for the dune grass Ammophila, whose decline under decreasing sand accretion is argued to be caused by either biotic or abiotic soil properties. METHODOLOGY/PRINCIPAL FINDINGS: By manipulating dune soils from three different regions, we decoupled the contributions of region, the abiotic and biotic soil component to the variation in characteristics of Ammophila arenaria seedlings and Schizaphis rufula aphid populations. Root mass fraction and total dry biomass of plants were affected by soil biota, although the latter effect was not consistent across regions. None of the measured plant properties were significantly affected by the abiotic soil component. Aphid population characteristics all differed between regions, irrespective of whether soil biota were present or absent. Hence these effects were due to differences in abiotic soil properties between regions. Although several chemical properties of the soil mixtures were measured, none of these were consistent with results for plant or aphid traits. CONCLUSIONS/SIGNIFICANCE: Plants were affected more strongly by soil biota than by abiotic soil properties, whereas the opposite was true for aphids. Our results thus demonstrate that the relative importance of the abiotic and biotic component of soils can differ for plants and their herbivores. The fact that not all effects of soil properties could be detected across regions moreover emphasizes the need for spatial replication in order to make sound conclusions about the generality of aboveground-belowground interactions.

  1. Insect herbivore feeding and their excretion contribute to volatile organic compounds emission to the atmosphere

    Zebelo, S.; Gnavi, G.; Bertea, C.; Bossi, S.; Andrea, O.; Cordero, C.; Rubiolo, P.; Bicchi, C.; Maffei, M.

    2011-12-01

    Secondary plant metabolites play an important role in insect plant interactions. The Lamiaceae family, especially Mentha species, accumulate secondary plant metabolites in their glandular trichomes, mainly mono and sesquiterpenes. Here we show that mint plants respond to herbivory by changing the quality and quantity of leaf secondary plant metabolite components. The volatiles from herbivore damaged, mechanical damage and healthy plant were collected by HS-SPME and analyzed by GC-MS. Plants with the same treatment were kept for genomic analysis. Total RNA was extracted from the above specified treatments. The terpenoid quantitative gene expressions (qPCR) were then assayed. Upon herbivory, M. aquatica synthesizes and emits (+)-menthofuran and the other major monoterpene (+)-pulegone emitted by healthy and mechanically damaged plants. Herbivory was found to up-regulate the expression of genes involved in terpenoid biosynthesis. The increased emission of (+)-menthofuran was correlated with the upregulation of (+)-menthofuran synthase. In addition we analysed the VOC composition of C. herbacea frass from insects feeding on Mentha aquatica. VOCs were sampled by HS-SPME and analyzed by GCxGC-qMS, and the results compared through quantitative comparative analysis of 2D chromatographic data. Most terpenoids from M. aquatica were completely catabolized by C. herbacea and were absent in the frass volatile fraction. On the other hand, the monoterpene 1,8-cineole was oxidized and frass yielded several new hydroxy-1,8-cineoles, among which 2α-OH-, 3α-OH-, 3β-OH- and 9-OH-1,8-cineole. The role of VOC emitted during herbivory and frass excretion on secondary organic aerosol formation is discussed.

  2. Induced responses to grazing by an insect herbivore (Acentria ephemerella) in an immature macrophyte (Myriophyllum spicatum): an isotopic study

    Rothhaupt, Karl-Otto; Fornoff, Felix; Yohannes, Elizabeth

    2015-01-01

    While the mechanisms by which adult terrestrial plants deploy constitutive and induced responses to grazing pressure are well known, the means by which young aquatic plants defend themselves from herbivory are little studied. This study addresses nitrogen transport in the aquatic angiosperm Myriophyllum spicatum in response to herbivore exposure. Nitrogen tracers were used to monitor nitrogen uptake and reallocation in young plants in response to grazing by the generalist insect herbivore Acentria ephemerella. Total nitrogen content (N%) and patterns of nitrogen uptake and allocation (δ15N) were assessed in various plant tissues after 24 and 48 h. Following 24 h exposure to herbivore damage (Experiment 1), nitrogen content of plant apices was significantly elevated. This rapid early reaction may be an adaptation allowing the grazer to be sated as fast as possible, or indicate the accumulation of nitrogenous defense chemicals. After 48 h (Experiment 2), plants' tips showed depletion in nitrogen levels of ca. 60‰ in stem sections vulnerable to grazing. In addition, nitrogen uptake by grazed and grazing-prone upper plant parts was reduced and nutrient allocation into the relatively secure lower parts increased. The results point to three conclusions: (1) exposure to an insect herbivore induces a similar response in immature M. spicatum as previously observed in mature terrestrial species, namely a rapid (within 48 h) reduction in the nutritional value (N%) of vulnerable tissues, (2) high grazing intensity (100% of growing tips affected) did not limit the ability of young plants to induce resistance; and (3) young plants exposed to herbivory exhibit different patterns of nutrient allocation in vulnerable and secure tissues. These results provide evidence of induced defense and resource reallocation in immature aquatic macrophytes which is in line with the responses shown for mature aquatic macrophytes and terrestrial plants. PMID:26380694

  3. Infestation of transgenic powdery mildew-resistant wheat by naturally occurring insect herbivores under different environmental conditions.

    Fernando Álvarez-Alfageme

    Full Text Available A concern associated with the growing of genetically modified (GM crops is that they could adversely affect non-target organisms. We assessed the impact of several transgenic powdery mildew-resistant spring wheat lines on insect herbivores. The GM lines carried either the Pm3b gene from hexaploid wheat, which confers race-specific resistance to powdery mildew, or the less specific anti-fungal barley seed chitinase and β-1,3-glucanase. In addition to the non-transformed control lines, several conventional spring wheat varieties and barley and triticale were included for comparison. During two consecutive growing seasons, powdery mildew infection and the abundance of and damage by naturally occurring herbivores were estimated under semi-field conditions in a convertible glasshouse and in the field. Mildew was reduced on the Pm3b-transgenic lines but not on the chitinase/glucanase-expressing lines. Abundance of aphids was negatively correlated with powdery mildew in the convertible glasshouse, with Pm3b wheat plants hosting significantly more aphids than their mildew-susceptible controls. In contrast, aphid densities did not differ between GM plants and their non-transformed controls in the field, probably because of low mildew and aphid pressure at this location. Likewise, the GM wheat lines did not affect the abundance of or damage by the herbivores Oulema melanopus (L. and Chlorops pumilionis Bjerk. Although a previous study has revealed that some of the GM wheat lines show pleiotropic effects under field conditions, their effect on herbivorous insects appears to be low.

  4. Induced responses to grazing by an insect herbivore (Acentria ephemerella) in an immature macrophyte (Myriophyllum spicatum): an isotopic study.

    Rothhaupt, Karl-Otto; Fornoff, Felix; Yohannes, Elizabeth

    2015-09-01

    While the mechanisms by which adult terrestrial plants deploy constitutive and induced responses to grazing pressure are well known, the means by which young aquatic plants defend themselves from herbivory are little studied. This study addresses nitrogen transport in the aquatic angiosperm Myriophyllum spicatum in response to herbivore exposure. Nitrogen tracers were used to monitor nitrogen uptake and reallocation in young plants in response to grazing by the generalist insect herbivore Acentria ephemerella. Total nitrogen content (N%) and patterns of nitrogen uptake and allocation (δ(15)N) were assessed in various plant tissues after 24 and 48 h. Following 24 h exposure to herbivore damage (Experiment 1), nitrogen content of plant apices was significantly elevated. This rapid early reaction may be an adaptation allowing the grazer to be sated as fast as possible, or indicate the accumulation of nitrogenous defense chemicals. After 48 h (Experiment 2), plants' tips showed depletion in nitrogen levels of ca. 60‰ in stem sections vulnerable to grazing. In addition, nitrogen uptake by grazed and grazing-prone upper plant parts was reduced and nutrient allocation into the relatively secure lower parts increased. The results point to three conclusions: (1) exposure to an insect herbivore induces a similar response in immature M. spicatum as previously observed in mature terrestrial species, namely a rapid (within 48 h) reduction in the nutritional value (N%) of vulnerable tissues, (2) high grazing intensity (100% of growing tips affected) did not limit the ability of young plants to induce resistance; and (3) young plants exposed to herbivory exhibit different patterns of nutrient allocation in vulnerable and secure tissues. These results provide evidence of induced defense and resource reallocation in immature aquatic macrophytes which is in line with the responses shown for mature aquatic macrophytes and terrestrial plants. PMID:26380694

  5. Biomechanical Properties of Hemlocks: A Novel Approach to Evaluating Physical Barriers of the Plant–Insect Interface and Resistance to a Phloem-Feeding Herbivore

    Paul Ayayee; Fuqian Yang; Lynne K. Rieske

    2014-01-01

    Micromechanical properties that help mediate herbivore access may be particularly important when considering herbivorous insects that feed with piercing-sucking stylets. We used microindentation to quantify the micromechanical properties of hemlock, Tsuga spp., to quantify the hardness of the feeding site of the invasive hemlock woolly adelgid, Adelges tsugae. We measured hardness of the hemlock leaf cushion, the stylet insertion point of the adelgid, across four seasons in a 1 y period for...

  6. Differential and Synergistic Functionality of Acylsugars in Suppressing Oviposition by Insect Herbivores.

    Brian M Leckie

    Full Text Available Acylsugars are secondary metabolites exuded from type IV glandular trichomes that provide broad-spectrum insect suppression for Solanum pennellii Correll, a wild relative of cultivated tomato. Acylsugars produced by different S. pennellii accessions vary by sugar moieties (glucose or sucrose and fatty acid side chains (lengths and branching patterns. Our objective was to determine which acylsugar compositions more effectively suppressed oviposition of the whitefly Bemisia tabaci (Gennadius (Middle East--Asia Minor 1 Group, tobacco thrips, Frankliniella fusca (Hinds, and western flower thrips, Frankliniella occidentalis (Pergande. We extracted and characterized acylsugars from four S. pennellii accessions with different compositions, as well as from an acylsugar-producing tomato breeding line. We also fractionated the acylsugars of one S. pennellii accession to examine the effects of its components. Effects of acylsugars on oviposition were evaluated by administering a range of doses to oviposition sites of adult whiteflies and thrips in non-choice and choice bioassays, respectively. The acylsugars from S. pennellii accessions and the tomato breeding line demonstrated differential functionality in their ability to alter the distribution of whitefly oviposition and suppress oviposition on acylsugar treated substrates. Tobacco thrips were sensitive to all compositions while western flower thrips and whiteflies were more sensitive to acylsugars from a subset of S. pennellii accessions. It follows that acylsugars could thus mediate plant-enemy interactions in such a way as to affect evolution of host specialization, resistance specificity, and potentially host differentiation or local adaptation. The acylsugars from S. pennellii LA1376 were separated by polarity into two fractions that differed sharply for their sugar moieties and fatty acid side chains. These fractions had different efficacies, with neither having activity approaching that of the

  7. Differential and Synergistic Functionality of Acylsugars in Suppressing Oviposition by Insect Herbivores.

    Leckie, Brian M; D'Ambrosio, Damon A; Chappell, Thomas M; Halitschke, Rayko; De Jong, Darlene M; Kessler, André; Kennedy, George G; Mutschler, Martha A

    2016-01-01

    Acylsugars are secondary metabolites exuded from type IV glandular trichomes that provide broad-spectrum insect suppression for Solanum pennellii Correll, a wild relative of cultivated tomato. Acylsugars produced by different S. pennellii accessions vary by sugar moieties (glucose or sucrose) and fatty acid side chains (lengths and branching patterns). Our objective was to determine which acylsugar compositions more effectively suppressed oviposition of the whitefly Bemisia tabaci (Gennadius) (Middle East-Asia Minor 1 Group), tobacco thrips, Frankliniella fusca (Hinds), and western flower thrips, Frankliniella occidentalis (Pergande). We extracted and characterized acylsugars from four S. pennellii accessions with different compositions, as well as from an acylsugar-producing tomato breeding line. We also fractionated the acylsugars of one S. pennellii accession to examine the effects of its components. Effects of acylsugars on oviposition were evaluated by administering a range of doses to oviposition sites of adult whiteflies and thrips in non-choice and choice bioassays, respectively. The acylsugars from S. pennellii accessions and the tomato breeding line demonstrated differential functionality in their ability to alter the distribution of whitefly oviposition and suppress oviposition on acylsugar treated substrates. Tobacco thrips were sensitive to all compositions while western flower thrips and whiteflies were more sensitive to acylsugars from a subset of S. pennellii accessions. It follows that acylsugars could thus mediate plant-enemy interactions in such a way as to affect evolution of host specialization, resistance specificity, and potentially host differentiation or local adaptation. The acylsugars from S. pennellii LA1376 were separated by polarity into two fractions that differed sharply for their sugar moieties and fatty acid side chains. These fractions had different efficacies, with neither having activity approaching that of the original exudate

  8. Domestication in Murtilla (Ugni molinae) Reduced Defensive Flavonol Levels but Increased Resistance Against a Native Herbivorous Insect.

    Chacón-Fuentes, Manuel; Parra, Leonardo; Rodriguez-Saona, Cesar; Seguel, Ivette; Ceballos, Ricardo; Quiroz, Andres

    2015-06-01

    Plant domestication can have negative consequences for defensive traits against herbivores, potentially reducing the levels of chemical defenses in plants and consequently their resistance against herbivores. We characterized and quantified the defensive flavonols from multiple cultivated ecotypes with wild ancestors of murtilla, Ugni molinae Turcz, an endemic plant from Chile, at different times of the year, and examined their effects on a native insect herbivore, Chilesia rudis Butler (Lepidoptera: Arctiidae). We hypothesized that domestication results in a decrease in flavonol levels in U. molinae plants, and that this negatively affected C. rudis performance and preference. Ethanolic extracts were made from leaves, stems, and fruit of murtilla plants for flavonol analysis. Flavonols identified were kaempferol, quercetin, rutin, and quercetin 3-D-β-glucoside, the last two being the most abundant. More interestingly, we showed differences in flavonol composition between wild and cultivated U. molinae that persisted for most of the year. Relative amounts of all four flavonols were higher in wild U. molinae leaves; however, no differences were found in the stem and fruit between wild and cultivated plants. In choice and no-choice assays, C. rudis larvae gained more mass on, and consumed more leaf material of, wild as compared with cultivated U. molinae plants. Moreover, when applied to leaves, larvae ate more leaf material with increasing concentrations of each flavonol compound. Our study demonstrates that domestication in U. molinae reduced the amount of flavonols in leaves as well as the performance and preference of C. rudis, indicating that these compounds stimulate feeding of C. rudis. PMID:26313969

  9. An Insect Herbivore Microbiome with High Plant Biomass-Degrading Capacity

    Suen, Garret

    2011-01-01

    Herbivores can gain indirect access to recalcitrant carbon present in plant cell walls through symbiotic associations with lignocellulolytic microbes. A paradigmatic example is the leaf-cutter ant (Tribe: Attini), which uses fresh leaves to cultivate a fungus for food in specialized gardens. Using a combination of sugar composition analyses, metagenomics, and whole-genome sequencing, we reveal that the fungus garden microbiome of leaf-cutter ants is composed of a diverse community of bacteria...

  10. An insect herbivore microbiome with high plant biomass-degrading capacity.

    Garret Suen; Scott, Jarrod J.; Aylward, Frank O.; Adams, Sandra M.; Tringe, Susannah G.; Pinto-Tomás, Adrián A.; Foster, Clifton E.; Markus Pauly; Paul J. Weimer; Kerrie W Barry; Goodwin, Lynne A.; Pascal Bouffard; Lewyn Li; Jolene Osterberger; Harkins, Timothy T.

    2010-01-01

    Herbivores can gain indirect access to recalcitrant carbon present in plant cell walls through symbiotic associations with lignocellulolytic microbes. A paradigmatic example is the leaf-cutter ant (Tribe: Attini), which uses fresh leaves to cultivate a fungus for food in specialized gardens. Using a combination of sugar composition analyses, metagenomics, and whole-genome sequencing, we reveal that the fungus garden microbiome of leaf-cutter ants is composed of a diverse community of bacteria...

  11. MICROCOSM METHOD TO ASSESS SURVIVAL OF RECOMBINANT BACTERIA ASSOCIATED WITH PLANTS AND HERBIVOROUS INSECTS (JOURNAL VERSION)

    A microcosm method was developed to investigate survival and fate of genetically engineered bacteria associated with plant surfaces and a plant-feeding insect, the variegated cutworm, Peridroma saucia. Larvae on radish plants in microcosms were sprayed with nonrecombinant Pseudom...

  12. Slaves of the environment: the movement of herbivorous insects in relation to their ecology and genotype

    Loxdale, H.D.

    1999-01-01

    The majority of insect species do not show an innate behavioural migration, but rather populations expand into favourable new habitats or contract away from unfavourable ones by random changes of spatial scale. Over the past 50 years, the scientific fascination with dramatic long-distance and directed mass migratory events has overshadowed the more universal mode of population movement, involving much smaller stochastic displacement during the lifetime of the insects concerned. This may be li...

  13. Biodiversity and Activity of the Gut Microbiota across the Life History of the Insect Herbivore Spodoptera littoralis

    Chen, Bosheng; Teh, Beng-Soon; Sun, Chao; Hu, Sirui; Lu, Xingmeng; Boland, Wilhelm; Shao, Yongqi

    2016-01-01

    Microbes that live inside insects play critical roles in host nutrition, physiology, and behavior. Although Lepidoptera (butterflies and moths) are one of the most diverse insect taxa, their microbial symbionts are little-studied, particularly during metamorphosis. Here, using ribosomal tag pyrosequencing of DNA and RNA, we investigated biodiversity and activity of gut microbiotas across the holometabolous life cycle of Spodoptera littoralis, a notorious agricultural pest worldwide. Proteobacteria and Firmicutes dominate but undergo a structural “metamorphosis” in tandem with its host. Enterococcus, Pantoea and Citrobacter were abundant and active in early-instar, while Clostridia increased in late-instar. Interestingly, only enterococci persisted through metamorphosis. Female adults harbored high proportions of Enterococcus, Klebsiella and Pantoea, whereas males largely shifted to Klebsiella. Comparative functional analysis with PICRUSt indicated that early-instar larval microbiome was more enriched for genes involved in cell motility and carbohydrate metabolism, whereas in late-instar amino acid, cofactor and vitamin metabolism increased. Genes involved in energy and nucleotide metabolism were abundant in pupae. Female adult microbiome was enriched for genes relevant to energy metabolism, while an increase in the replication and repair pathway was observed in male. Understanding the metabolic activity of these herbivore-associated microbial symbionts may assist the development of novel pest-management strategies. PMID:27389097

  14. Biodiversity and Activity of the Gut Microbiota across the Life History of the Insect Herbivore Spodoptera littoralis.

    Chen, Bosheng; Teh, Beng-Soon; Sun, Chao; Hu, Sirui; Lu, Xingmeng; Boland, Wilhelm; Shao, Yongqi

    2016-01-01

    Microbes that live inside insects play critical roles in host nutrition, physiology, and behavior. Although Lepidoptera (butterflies and moths) are one of the most diverse insect taxa, their microbial symbionts are little-studied, particularly during metamorphosis. Here, using ribosomal tag pyrosequencing of DNA and RNA, we investigated biodiversity and activity of gut microbiotas across the holometabolous life cycle of Spodoptera littoralis, a notorious agricultural pest worldwide. Proteobacteria and Firmicutes dominate but undergo a structural "metamorphosis" in tandem with its host. Enterococcus, Pantoea and Citrobacter were abundant and active in early-instar, while Clostridia increased in late-instar. Interestingly, only enterococci persisted through metamorphosis. Female adults harbored high proportions of Enterococcus, Klebsiella and Pantoea, whereas males largely shifted to Klebsiella. Comparative functional analysis with PICRUSt indicated that early-instar larval microbiome was more enriched for genes involved in cell motility and carbohydrate metabolism, whereas in late-instar amino acid, cofactor and vitamin metabolism increased. Genes involved in energy and nucleotide metabolism were abundant in pupae. Female adult microbiome was enriched for genes relevant to energy metabolism, while an increase in the replication and repair pathway was observed in male. Understanding the metabolic activity of these herbivore-associated microbial symbionts may assist the development of novel pest-management strategies. PMID:27389097

  15. Synergistic effects of an extreme weather event and habitat fragmentation on a specialised insect herbivore.

    Piessens, Katrien; Adriaens, Dries; Jacquemyn, Hans; Honnay, Olivier

    2009-02-01

    Habitat fragmentation is considered to be one of the main causes of population decline and species extinction worldwide. Furthermore, habitat fragmentation can decrease the ability of populations to resist and to recover from environmental disturbances such as extreme weather events, which are expected to occur at an increasing rate as a result of climate change. In this study, we investigated how calcareous grassland fragmentation affected the impact of the climatically extreme summer of 2003 on egg deposition rates, population size variation and survival of the blue butterfly Cupido minimus, a specialist herbivore of Anthyllis vulneraria. Immediately after the 2003 summer heat wave, populations of the host plant declined in size; this was paralleled with decreases in population size of the herbivore and altered egg deposition rates. In 2006 at the end of the monitoring period, however, most A. vulneraria populations had recovered and only one population went extinct. In contrast, several butterfly populations had gone extinct between 2003 and 2006. Extinction probability was significantly related to initial population size, with small populations having a higher risk of extinction than large populations. These results support the prediction that species of higher trophic levels are more susceptible to extinction due to habitat fragmentation and severe disturbances. PMID:19002504

  16. Regional analysis of ground and above-ground climate

    1981-12-01

    The regional suitability of underground construction as a climate control technique is discussed with reference to (1) a bioclimatic analysis of long-term weather data for 29 locations in the United States to determine appropriate above ground climate control techniques, (2) a data base of synthesized ground temperatures for the coterminous United States, and (3) monthly dew point ground temperature comparisons for identifying the relative likelihood of condensation from one region to another. It is concluded that the suitability of earth tempering as a practice and of specific earth-sheltered design stereotypes varies geographically; while the subsurface almost always provides a thermal advantage on its own terms when compared to above ground climatic data, it can, nonetheless, compromise the effectiveness of other, regionally more important climate control techniques. Also contained in the report are reviews of above and below ground climate mapping schemes related to human comfort and architectural design, and detailed description of a theoretical model of ground temperature, heat flow, and heat storage in the ground. Strategies of passive climate control are presented in a discussion of the building bioclimatic analysis procedure which has been applied in a computer analysis of 30 years of weather data for each of 29 locations in the United States.

  17. Regional analysis of ground and above-ground climate

    1981-12-01

    The regional suitability of underground construction as a climate control technique is discussed with reference to (1) a bioclimatic analysis of long term weather data for 29 locations in the United States to determine appropriate above ground climate control techniques, (2) a data base of synthesized ground temperatures for the coterminous United States, and (3) monthly dew point ground temperature comparisons for identifying the relative likelihood of condensation from one region to another. It is concluded that the suitability of Earth tempering as a practice and of specific Earth sheltered design stereotypes varies geographically; while the subsurface almost always provides a thermal advantage on its own terms when compared to above ground climatic data, it can, nonetheless, compromise the effectiveness of other, regionally more important climate control techniques. Reviews of above and below ground climate mapping schemes related to human comfort and architectural design, and detailed description of a theoretical model of ground temperature, heat flow, and heat storage in the ground are included. Strategies of passive climate control are presented in a discussion of the building bioclimatic analysis procedure which has been applied in a computer analysis of 30 years of weather data for each of 20 locations in the United States.

  18. Sequestration, tissue distribution and developmental transmission of cyanogenic glucosides in a specialist insect herbivore

    Zagrobelny, Mika; Olsen, Carl Erik; Pentzold, Stefan;

    2014-01-01

    Considering the staggering diversity of bioactive natural products present in plants, insects are only able to sequester a small number of phytochemicals from their food plants. The mechanisms of how only some phytochemicals are sequestered and how the sequestration process takes place remains...

  19. Climate change, nutrition and immunity: Effects of elevated CO2 and temperature on the immune function of an insect herbivore.

    Gherlenda, Andrew N; Haigh, Anthony M; Moore, Ben D; Johnson, Scott N; Riegler, Markus

    2016-02-01

    Balanced nutrition is fundamental to health and immunity. For herbivorous insects, nutrient-compositional shifts in host plants due to elevated atmospheric CO2 concentrations and temperature may compromise this balance. Therefore, understanding their immune responses to such shifts is vital if we are to predict the outcomes of climate change for plant-herbivore-parasitoid and pathogen interactions. We tested the immune response of Paropsis atomaria Olivier (Coleoptera: Chrysomelidae) feeding on Eucalyptus tereticornis Sm. seedlings exposed to elevated CO2 (640 μmol mol(-1); CE) and temperature (ambient plus 4 °C; TE). Larvae were immune-challenged with a nylon monofilament in order to simulate parasitoid or pathogen attack without other effects of actual parasitism or pathology. The cellular (in vivo melanisation) and humoral (in vitro phenoloxidase PO activity) immune responses were assessed, and linked to changes in leaf chemistry. CE reduced foliar nitrogen (N) concentrations and increased C:N ratios and concentrations of total phenolics. The humoral response was reduced at CE. PO activity and haemolymph protein concentrations decreased at CE, while haemolymph protein concentrations were positively correlated with foliar N concentrations. However, the cellular response increased at CE and this was not correlated with any foliar traits. Immune parameters were not impacted by TE. Our study revealed that opposite cellular and humoral immune responses occurred as a result of plant-mediated effects at CE. In contrast, elevated temperatures within the tested range had minimal impact on immune responses. These complex interactions may alter the outcomes of parasitoid and pathogen attack in future climates. PMID:26678330

  20. Transgenic wheat and non-target impacts on insect herbivores and food webs

    Von Burg, S K

    2011-01-01

    This PhD thesis combines research on ecological risks of genetically modified (GM) plants with plant-insect interactions and food web ecology. In this chapter I will review the current global state of GM crops, give a short overview over the concerns about ecological impacts of GM plants and introduce the study system. At the end of the chapter the goals of this thesis are stated.

  1. Sequestration, tissue distribution and developmental transmission of cyanogenic glucosides in a specialist insect herbivore.

    Zagrobelny, Mika; Olsen, Carl Erik; Pentzold, Stefan; Fürstenberg-Hägg, Joel; Jørgensen, Kirsten; Bak, Søren; Møller, Birger Lindberg; Motawia, Mohammed Saddik

    2014-01-01

    Considering the staggering diversity of bioactive natural products present in plants, insects are only able to sequester a small number of phytochemicals from their food plants. The mechanisms of how only some phytochemicals are sequestered and how the sequestration process takes place remains largely unknown. In this study the model system of Zygaena filipendulae (Lepidoptera) and their food plant Lotus corniculatus is used to advance the knowledge of insect sequestration. Z. filipendulae larvae are dependent on sequestration of the cyanogenic glucosides linamarin and lotaustralin from their food plant, and have a much lower fitness if reared on plants without these compounds. This study investigates the fate of the cyanogenic glucosides during ingestion, sequestration in the larvae, and in the course of insect ontogeny. To this purpose, double-labeled linamarin and lotaustralin were chemically synthesized carrying two stable isotopes, a (2)H labeled aglucone and a (13)C labeled glucose moiety. In addition, a small amount of (14)C was incorporated into the glucose residue. The isotope-labeled compounds were applied onto cyanogenic L. corniculatus leaves that were subsequently presented to the Z. filipendulae larvae. Following ingestion by the larvae, the destiny of the isotope labeled cyanogenic glucosides was monitored in different tissues of larvae and adults at selected time points, using radio-TLC and LC-MS analyses. It was shown that sequestered compounds are taken up intact, contrary to earlier hypotheses where it was suggested that the compounds would have to be hydrolyzed before transport across the gut. The uptake from the larval gut was highly stereo selective as the β-glucosides were retained while the α-glucosides were excreted and recovered in the frass. Sequestered compounds were rapidly distributed into all analyzed tissues of the larval body, partly retained throughout metamorphosis and transferred into the adult insect where they were

  2. Above-ground biomass functions for Scots pine in Lithuania

    Miksys, Virgilijus; Varnagiryte-Kabasinskiene, Iveta; Armolaitis, Kestutis [Lithuanian Forest Research Institute, Liepu 1, Girionys, LT-53101 Kaunas District (Lithuania); Stupak, Inge [Forest and Landscape Denmark, Hoersholm Kongevej 11, DK-2970 Hoersholm (Denmark); Kukkola, Mikko [The Finnish Forest Research Institute, Vantaa Research Centre, Vantaa Unit, PL 18, 01301 Vantaa (Finland); Wojcik, Josef [Forest Research Institute, Sekocin-Las, 05-090 Raszyn (Poland)

    2007-10-15

    This study presents biomass functions applicable to Scots pine (Pinus sylvestris L.) on Arenosols in Lithuania, and exemplifies the potential biomass removal from Scots pine stands during thinnings. Scots pine is the most common tree species on Arenosols in Lithuania. Stands of ages 10, 20, 40, 50 and 65 years were chosen for the biomass study. We sampled 5 Scots pine trees per plot (in total 25 trees) that were stratified according to the basal area. The sampling was performed in April 2003, before the vegetative period. The following components of each tree were sampled for the above-ground biomass measurements: (1) 5 stem discs, (2) 1 branch with needles from each whorl and (3) 1 dead branch per tree. Observed biomasses of above-ground components were examined using a non-linear regression model, using stem diameter (D), tree height (H) and D{sup 2}H as independent variables. For stemwood biomass, the best approximation was D{sup 2}H. However, D{sup 2}H was not the best parameter for crown biomass because it does not allow evaluation of the opposite effects of diameter and height on crown biomass. The calculations at stand level showed that crown biomass changed insignificantly with the increase in stand age. However, the total stand biomass increased with age due to the growth of the stem. The removal of all logging residues from the Scots pine stand over a 100-year rotation could increase extraction of forest fuel by 15-20% compared with conventional harvesting. (author)

  3. Expansion of a bitter taste receptor family in a polyphagous insect herbivore.

    Xu, Wei; Papanicolaou, Alexie; Zhang, Hui-Jie; Anderson, Alisha

    2016-01-01

    The Insect taste system plays a central role in feeding behaviours and co-evolution of insect-host interactions. Gustatory receptors form the interface between the insect taste system and the environment. From genome and transcriptome sequencing we identified 197 novel gustatory receptor (GR) genes from the polyphagous pest Helicoverpa armigera. These GRs include a significantly expanded bitter receptor family (180 GRs) that could be further divided into three categories based on polypeptide lengths, gene structure and amino acid sequence. Type 1 includes 29 bitter Gr genes that possess introns. Type 2 includes 13 long intronless bitter Gr genes, while Type 3 comprises 131 short intronless bitter Gr genes. Calcium imaging analysis demonstrated that three Type 3 GRs (HarmGR35, HarmGR50 and HarmGR195) can be activated by a crude extract of cotton leaves. HarmGR195, a GR specifically and selectively expressed in adult tarsi, showed a specific response to proline, an amino acid widely present in plant tissues. We hypothesise that the expansion in the H. armigera GR family may be functionally tied to its polyphagous behavior. Understanding the molecular basis of polyphagy may provide opportunities for the development of new environmentally friendly pest control strategies. PMID:27032373

  4. Turning the ‘Mustard Oil Bomb’ into a ‘Cyanide Bomb’ : aromatic glucosinolate metabolism in a specialist insect herbivore

    Stauber, Einar J.; Petrissa Kuczka; Maike van Ohlen; Birgit Vogt; Tim Janowitz; Markus Piotrowski; Till Beuerle; Ute Wittstock

    2012-01-01

    Plants have evolved a variety of mechanisms for dealing with insect herbivory among which chemical defense through secondary metabolites plays a prominent role. Physiological, behavioural and sensorical adaptations to these chemicals provide herbivores with selective advantages allowing them to diversify within the newly occupied ecological niche. In turn, this may influence the evolution of plant metabolism giving rise to e.g. new chemical defenses. The association of Pierid butterflies and ...

  5. Development of specific ITS markers for plant DNA identification within herbivorous insects.

    Pumariño, L; Alomar, O; Agustí, N

    2011-06-01

    DNA-based techniques have proved to be very useful methods to study trophic relationships between pests and their natural enemies. However, most predators are best defined as omnivores, and the identification of plant-specific DNA should also allow the identification of the plant species the predators have been feeding on. In this study, a PCR approach based on the development of specific primers was developed as a self-marking technique to detect plant DNA within the gut of one heteropteran omnivorous predator (Macrolophus pygmaeus) and two lepidopteran pest species (Helicoverpa armigera and Tuta absoluta). Specific tomato primers were designed from the ITS 1-2 region, which allowed the amplification of a tomato DNA fragment of 332 bp within the three insect species tested in all cases (100% of detection at t=0) and did not detect DNA of other plants nor of the starved insects. Plant DNA half-lives at 25°C ranged from 5.8 h, to 27.7 h and 28.7 h within M. pygmaeus, H. armigera and T. absoluta, respectively. Tomato DNA detection within field-collected M. pygmaeus suggests dietary mixing in this omnivorous predator and showed a higher detection of tomato DNA in females and nymphs than males. This study provides a useful tool to detect and to identify plant food sources of arthropods and to evaluate crop colonization from surrounding vegetation in conservation biological control programs. PMID:21092379

  6. Mode of action of the sesquiterpene lactone, tenulin, from Helenium amarum against herbivorous insects.

    Arnason, J T; Isman, M B; Philogène, B J; Waddell, T G

    1987-01-01

    Tenulin [1], a sesquiterpene lactone from Helenuim amarum, is a potent antifeedant to the European corn borer Ostrinia nubilalis. At 3 mumol/g in artificial diets, 1 reduced growth and delayed larval development of O. nubilalis and the variegated cutworm Peridroma saucia larvae. An especially pronouned carry-over effect in O. nubilis was substantial reduction in fecundity of adult moths resulting from treated larvae. The LD50 (lethal dose for 50% mortality) of 1 by injection in the migratory grasshopper Melanoplus sanguinipes was 0.88 mumol/insect. Toxicity in M. sanguinipes was antagonized by co-administration of cysteine, suggesting that the cyclopentenone group of tenulin undergoes Michael addition of biological nucleophiles in vivo. This mechanism was partially confirmed by the finding that only tenulin analogues capable of acting as electrophic acceptors had significant antifeedant activity. PMID:3430166

  7. Nuclear Reactor Monitoring With an Above Ground Antineutrino Detector

    Classen, Timothy

    2011-04-01

    Technology to detect νe 's emitted from nuclear reactors has existed for more than 50 years. This technology has been used in a range of experiments probing the neutrino parameter space. A continuing effort has been made at LLNL to test whether this technology may be used for a more practical purpose, the monitoring of nuclear reactors with a focus on safeguarding dangerous nuclear materials. As part of this role a new detector is being developed for deployment above ground at the Point Lepreau Nuclear Generating Station in New Brunswick Canada. The detector will observe a reactor core through a full start-up phase, to determine how well it can measure changes in nuclear fuel composition. This talk will focus on the challenges of the experiment, and how the techniques of fundamental neutrino research may be used to overcome them. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  8. Cathodic protection for the bottoms of above ground storage tanks

    Mohr, John P. [Tyco Adhesives, Norwood, MA (United States)

    2004-07-01

    Impressed Current Cathodic Protection has been used for many years to protect the external bottoms of above ground storage tanks. The use of a vertical deep ground bed often treated several bare steel tank bottoms by broadcasting current over a wide area. Environmental concerns and, in some countries, government regulations, have introduced the use of dielectric secondary containment liners. The dielectric liner does not allow the protective cathodic protection current to pass and causes corrosion to continue on the newly placed tank bottom. In existing tank bottoms where inadequate protection has been provided, leaks can develop. In one method of remediation, an old bottom is covered with sand and a double bottom is welded above the leaking bottom. The new bottom is welded very close to the old bottom, thus shielding the traditional cathodic protection from protecting the new bottom. These double bottoms often employ the use of dielectric liner as well. Both the liner and the double bottom often minimize the distance from the external tank bottom. The minimized space between the liner, or double bottom, and the bottom to be protected places a challenge in providing current distribution in cathodic protection systems. This study examines the practical concerns for application of impressed current cathodic protection and the types of anode materials used in these specific applications. One unique approach for an economical treatment using a conductive polymer cathodic protection method is presented. (author)

  9. Tracking the elusive history of diversification in plant-herbivorous insect-parasitoid food webs: insights from figs and fig wasps.

    Kjellberg, Finn; Proffit, Magali

    2016-02-01

    The food webs consisting of plants, herbivorous insects and their insect parasitoids are a major component of terrestrial biodiversity. They play a central role in the functioning of all terrestrial ecosystems, and the number of species involved is mind-blowing (Nyman et al. ). Nevertheless, our understanding of the evolutionary and ecological determinants of their diversity is still in its infancy. In this issue of Molecular Ecology, Sutton et al. () open a window into the comparative analysis of spatial genetic structuring in a set of comparable multitrophic models, involving highly species-specific interactions: figs and fig wasps. This is the first study to compare genetic structure using population genetics tools in a fig-pollinating wasp (Pleistodontes imperialis sp1) and its main parasitoid (Sycoscapter sp.A). The fig-pollinating wasp has a discontinuous spatial distribution that correlates with genetic differentiation, while the parasitoid bridges the discontinuity by parasitizing other pollinator species on the same host fig tree and presents basically no spatial genetic structure. The full implications of these results for our general understanding of plant-herbivorous insect-insect parasitoids diversification become apparent when envisioned within the framework of recent advances in fig and fig wasp biology. PMID:26876231

  10. Above-ground antineutrino detection for nuclear reactor monitoring

    Antineutrino monitoring of nuclear reactors has been demonstrated many times (Klimov et al., 1994 [1]; Bowden et al., 2009 [2]; Oguri et al., 2014 [3]), however the technique has not as of yet been developed into a useful capability for treaty verification purposes. The most notable drawback is the current requirement that detectors be deployed underground, with at least several meters-water-equivalent of shielding from cosmic radiation. In addition, the deployment of liquid-based detection media presents a challenge in reactor facilities. We are currently developing a detector system that has the potential to operate above ground and circumvent deployment problems associated with a liquid detection media: the system is composed of segments of plastic scintillator surrounded by 6LiF/ZnS:Ag. ZnS:Ag is a radio-luminescent phosphor used to detect the neutron capture products of 6Li. Because of its long decay time compared to standard plastic scintillators, pulse-shape discrimination can be used to distinguish positron and neutron interactions resulting from the inverse beta decay (IBD) of antineutrinos within the detector volume, reducing both accidental and correlated backgrounds. Segmentation further reduces backgrounds by identifying the positron's annihilation gammas, a signature that is absent for most correlated and uncorrelated backgrounds. This work explores different configurations in order to maximize the size of the detector segments without reducing the intrinsic neutron detection efficiency. We believe that this technology will ultimately be applicable to potential safeguards scenarios such as those recently described by Huber et al. (2014) [4,5

  11. Above-ground antineutrino detection for nuclear reactor monitoring

    Sweany, M.; Brennan, J.; Cabrera-Palmer, B.; Kiff, S.; Reyna, D.; Throckmorton, D.

    2015-01-01

    Antineutrino monitoring of nuclear reactors has been demonstrated many times (Klimov et al., 1994 [1]; Bowden et al., 2009 [2]; Oguri et al., 2014 [3]), however the technique has not as of yet been developed into a useful capability for treaty verification purposes. The most notable drawback is the current requirement that detectors be deployed underground, with at least several meters-water-equivalent of shielding from cosmic radiation. In addition, the deployment of liquid-based detection media presents a challenge in reactor facilities. We are currently developing a detector system that has the potential to operate above ground and circumvent deployment problems associated with a liquid detection media: the system is composed of segments of plastic scintillator surrounded by {sup 6}LiF/ZnS:Ag. ZnS:Ag is a radio-luminescent phosphor used to detect the neutron capture products of {sup 6}Li. Because of its long decay time compared to standard plastic scintillators, pulse-shape discrimination can be used to distinguish positron and neutron interactions resulting from the inverse beta decay (IBD) of antineutrinos within the detector volume, reducing both accidental and correlated backgrounds. Segmentation further reduces backgrounds by identifying the positron's annihilation gammas, a signature that is absent for most correlated and uncorrelated backgrounds. This work explores different configurations in order to maximize the size of the detector segments without reducing the intrinsic neutron detection efficiency. We believe that this technology will ultimately be applicable to potential safeguards scenarios such as those recently described by Huber et al. (2014) [4,5].

  12. Turning the 'mustard oil bomb' into a 'cyanide bomb': aromatic glucosinolate metabolism in a specialist insect herbivore.

    Einar J Stauber

    Full Text Available Plants have evolved a variety of mechanisms for dealing with insect herbivory among which chemical defense through secondary metabolites plays a prominent role. Physiological, behavioural and sensorical adaptations to these chemicals provide herbivores with selective advantages allowing them to diversify within the newly occupied ecological niche. In turn, this may influence the evolution of plant metabolism giving rise to e.g. new chemical defenses. The association of Pierid butterflies and plants of the Brassicales has been cited as an illustrative example of this adaptive process known as 'coevolutionary armsrace'. All plants of the Brassicales are defended by the glucosinolate-myrosinase system to which larvae of cabbage white butterflies and related species are biochemically adapted through a gut nitrile-specifier protein. Here, we provide evidence by metabolite profiling and enzyme assays that metabolism of benzylglucosinolate in Pieris rapae results in release of equimolar amounts of cyanide, a potent inhibitor of cellular respiration. We further demonstrate that P. rapae larvae develop on transgenic Arabidopsis plants with ectopic production of the cyanogenic glucoside dhurrin without ill effects. Metabolite analyses and fumigation experiments indicate that cyanide is detoxified by β-cyanoalanine synthase and rhodanese in the larvae. Based on these results as well as on the facts that benzylglucosinolate was one of the predominant glucosinolates in ancient Brassicales and that ancient Brassicales lack nitrilases involved in alternative pathways, we propose that the ability of Pierid species to safely handle cyanide contributed to the primary host shift from Fabales to Brassicales that occured about 75 million years ago and was followed by Pierid species diversification.

  13. Effects of plant identity and diversity on the dietary choice of a soil-living insect herbivore.

    Schallhart, Nikolaus; Tusch, Manuel Josef; Wallinger, Corinna; Staudacher, Karin; Traugott, Michael

    2012-12-01

    Plant identity and diversity influence herbivore communities in many different ways. While it is well known how they affect the feeding preferences of aboveground herbivores, this information is lacking for soil ecosystems, where examining plant-herbivore trophic interactions is difficult. We performed a mesocosm experiment assessing how plant identity and diversity affect the food choice of Agriotes larvae, which are soil-living generalist herbivores. We offered four plant species, (maize, a grass, a legume, and a forb) at varying combinations and diversity levels to these larvae, and analyzed their feeding behavior using stable isotopes. We hypothesized that (1) their food choice is driven by preference for certain plant species rather than by root abundance and that (2) the preference for specific plants changes with increasing plant diversity. We found that larvae preferred the grass and legume but avoided maize and the forb. Whether a plant was preferred or avoided was independent of diversity, but the extent of avoidance or preference changed with increasing plant diversity. Our findings reveal that the dietary choice of soil-living generalist herbivores is determined by plant-specific traits rather than root abundance. Our data also suggest that soil herbivore feeding preferences are modulated by plant diversity. PMID:23431595

  14. Biomechanical Properties of Hemlocks: A Novel Approach to Evaluating Physical Barriers of the Plant–Insect Interface and Resistance to a Phloem-Feeding Herbivore

    Paul Ayayee

    2014-06-01

    Full Text Available Micromechanical properties that help mediate herbivore access may be particularly important when considering herbivorous insects that feed with piercing-sucking stylets. We used microindentation to quantify the micromechanical properties of hemlock, Tsuga spp., to quantify the hardness of the feeding site of the invasive hemlock woolly adelgid, Adelges tsugae. We measured hardness of the hemlock leaf cushion, the stylet insertion point of the adelgid, across four seasons in a 1 y period for four hemlock species growing in a common garden, including eastern, western, mountain, and northern Japanese hemlocks. Leaf cushion hardness was highest in the fall and winter and lowest in summer for all species. Northern Japanese hemlock had relatively greater hardness than the remaining species. Our data contributes an additional perspective to the existing framework within which greater susceptibility and subsequent mortality of eastern hemlocks is observed. The potential application of microindentation to understanding the nature and relevance of plant mechanical defenses in plant–herbivore interactions is also demonstrated and highlighted.

  15. Estimating Above-Ground Carbon Biomass in a Newly Restored Coastal Plain Wetland Using Remote Sensing

    Riegel, Joseph B.; Emily Bernhardt; Jennifer Swenson

    2013-01-01

    Developing accurate but inexpensive methods for estimating above-ground carbon biomass is an important technical challenge that must be overcome before a carbon offset market can be successfully implemented in the United States. Previous studies have shown that LiDAR (light detection and ranging) is well-suited for modeling above-ground biomass in mature forests; however, there has been little previous research on the ability of LiDAR to model above-ground biomass in areas with young, aggradi...

  16. EnviroAtlas - Above Ground Live Biomass Carbon Storage for the Conterminous United States- Forested

    U.S. Environmental Protection Agency — This EnviroAtlas dataset includes the average above ground live dry biomass estimate for the Watershed Boundary Dataset (WBD) 12-digit Hydrologic Unit (HUC) in kg/m...

  17. Root absorption of 222Rn and its transfer into above-ground plant organs

    Experimental data are given on the content of genetically related pairs of radionuclides (226Ra and 222Rn; 224Ra and 220Rn) in soils and the above-ground phytomass of plants growing on plots with differing genesis of the higher concentrations of natural radionuclides in soils. Methods for determining gaseous radionuclides in the above-ground phytomass are described. Different transport routes of 222Rn and 220Rn into above-ground plant organs are considered. The noted absence of balance between 222Rn and 226Ra in plants as well as higher 222Rn/226Ra ratios in the above-ground phytomass as compared to that of the root-containing soil layer (25- to 185-fold) appears to be accounted for by the root pathway of 222Rn uptake and transport of this radionuclide to above-ground plants organs. The existence of the root pathway for 222Rn uptake is proved by direct observations of daily radionuclide movement with bleeding sap in experiments on pumpkins. For the short-lived Rn isotopes, 220Rn and 218Rn, the root pathway of uptake and transport to the above-ground phytomass is less probable, and this causes a notable redistribution of gaseous radionuclides during their movement along the soil-plant route

  18. Plant diversity effects on insect herbivores and their natural enemies: current thinking, recent findings, and future directions.

    Moreira, Xoaquín; Abdala-Roberts, Luis; Rasmann, Sergio; Castagneyrol, Bastien; Mooney, Kailen A

    2016-04-01

    A rich body of theory has been developed to predict the effects of plant diversity on communities at higher trophic levels and the mechanisms underpinning such effects. However, there are currently a number of key gaps in knowledge that have hindered the development of a predictive framework of plant diversity effects on consumers. For instance, we still know very little about how the magnitude of plant trait variation (e.g. intra-specific vs. inter-specific), as well as the identity and combined effects of plant, herbivore and natural enemy traits, mediate plant diversity effects on consumers. Moreover, the fine-scale mechanisms (e.g. changes in consumer behaviour or recruitment responses) underlying such diversity effects in many cases remain elusive or have been overlooked. In addition, most studies of plant diversity effects on associated consumers have been developed under a static, unidirectional (bottom-up) framework of effects on herbivores and predators without taking into account the potential for dynamic feedbacks across trophic levels. Here we seek to address these key gaps in knowledge as well as to capitalize on recent advances and emerging frameworks in plant biodiversity research. In doing so, we provide new insights as well as recommendations which will stimulate new research and advance this field of study. PMID:27436639

  19. Comparative genomic analysis of the microbiome [corrected] of herbivorous insects reveals eco-environmental adaptations: biotechnology applications.

    Weibing Shi

    Full Text Available Metagenome analysis of the gut symbionts of three different insects was conducted as a means of comparing taxonomic and metabolic diversity of gut microbiomes to diet and life history of the insect hosts. A second goal was the discovery of novel biocatalysts for biorefinery applications. Grasshopper and cutworm gut symbionts were sequenced and compared with the previously identified metagenome of termite gut microbiota. These insect hosts represent three different insect orders and specialize on different food types. The comparative analysis revealed dramatic differences among the three insect species in the abundance and taxonomic composition of the symbiont populations present in the gut. The composition and abundance of symbionts was correlated with their previously identified capacity to degrade and utilize the different types of food consumed by their hosts. The metabolic reconstruction revealed that the gut metabolome of cutworms and grasshoppers was more enriched for genes involved in carbohydrate metabolism and transport than wood-feeding termite, whereas the termite gut metabolome was enriched for glycosyl hydrolase (GH enzymes relevant to lignocellulosic biomass degradation. Moreover, termite gut metabolome was more enriched with nitrogen fixation genes than those of grasshopper and cutworm gut, presumably due to the termite's adaptation to the high fiber and less nutritious food types. In order to evaluate and exploit the insect symbionts for biotechnology applications, we cloned and further characterized four biomass-degrading enzymes including one endoglucanase and one xylanase from both the grasshopper and cutworm gut symbionts. The results indicated that the grasshopper symbiont enzymes were generally more efficient in biomass degradation than the homologous enzymes from cutworm symbionts. Together, these results demonstrated a correlation between the composition and putative metabolic functionality of the gut microbiome and host

  20. Confirmation bias leads to overestimation of losses of woody plant foliage to insect herbivores in tropical regions

    Mikhail V. Kozlov

    2014-12-01

    Full Text Available Confirmation bias, i.e., the tendency of humans to seek out evidence in a manner that confirms their hypotheses, is almost overlooked in ecological studies. For decades, insect herbivory was commonly accepted to be highest in tropical regions. By comparing the data collected blindly (when the observer was not aware of the research hypothesis being tested with the results of non-blind studies (when the observer knew what results could be expected, we tested the hypothesis that the records made in the tropics could have overestimated community-wide losses of plant foliage to insects due to the confirmation bias. The average loss of leaf area of woody plants to defoliating insects in Brazil, when measured by a blind method (1.11%, was significantly lower than the loss measured in non-blind studies, both original (5.14% and published (6.37%. We attribute the overestimation of the community-wide losses of plant foliage to insects in non-blind studies to the unconsciously preconceived selection of study species with higher-than-average levels of herbivory. Based on our findings, we urge for caution in obtaining community-wide characteristics from the results of multiple single-species studies. Our data suggest that we may need to revise the paradigm of the highest level of background insect herbivory in the tropical regions. More generally, we argue that more attention should be paid by ecologists to the problem of biases occurring at the pre-publication phases of the scientific research and, consequently, to the development and the wide application of methods that avoid biases occurring due to unconscious psychological processes.

  1. ERC hazard classification matrices for above ground structures and groundwater and soil remediation activities

    This document provides the status of the preliminary hazard classification (PHC) process for the Environmental Restoration Contractor (ERC) above ground structures and groundwater and soil remediation activities currently underway for planned for fiscal year (FY) 1997. This classification process is based on current US Department of Energy (DOE), Richland Operations Office (RL) guidance for the classification of facilities and activities containing radionuclide and nonradiological hazardous material inventories. The above ground structures presented in the matrices were drawn from the Bechtel Hanford, Inc. (BHI) Decontamination and Decommissioning (D and D) Project Facility List (DOE 1996), which identifies the facilities in the RL-Environmental Restoration baseline contract in 1997. This document contains the following two appendices: (1) Appendix A, which consists of a matrix identifying PHC documents that have been issued for BHI's above ground structures and groundwater and soil remediation activities underway or planned for FY 1997, and (2) Appendix B, which consists of a matrix showing anticipated PHCs for above ground structures, and groundwater and soil remediation activities underway or planned for FY 1997. Appendix B also shows the schedule for finalization of PHCs for above ground structures with an anticipated classification of Nuclear

  2. Final Harvest of Above-Ground Biomass and Allometric Analysis of the Aspen FACE Experiment

    Mark E. Kubiske

    2013-04-15

    The Aspen FACE experiment, located at the US Forest Service Harshaw Research Facility in Oneida County, Wisconsin, exposes the intact canopies of model trembling aspen forests to increased concentrations of atmospheric CO2 and O3. The first full year of treatments was 1998 and final year of elevated CO2 and O3 treatments is scheduled for 2009. This proposal is to conduct an intensive, analytical harvest of the above-ground parts of 24 trees from each of the 12, 30 m diameter treatment plots (total of 288 trees) during June, July & August 2009. This above-ground harvest will be carefully coordinated with the below-ground harvest proposed by D.F. Karnosky et al. (2008 proposal to DOE). We propose to dissect harvested trees according to annual height growth increment and organ (main stem, branch orders, and leaves) for calculation of above-ground biomass production and allometric comparisons among aspen clones, species, and treatments. Additionally, we will collect fine root samples for DNA fingerprinting to quantify biomass production of individual aspen clones. This work will produce a thorough characterization of above-ground tree and stand growth and allocation above ground, and, in conjunction with the below ground harvest, total tree and stand biomass production, allocation, and allometry.

  3. A Perspective on the Consequences for Insect Herbivores and Their Natural Enemies When They Share Plant Resources

    Patrik Kehrli; Wratten, Steve D.

    2011-01-01

    Thousands of insect species consume both animal and plant-derived food resources. However, little recognition is given to the fact that omnivory is a general feeding strategy common to all higher trophic levels. Species in multitrophic interactions can all directly rely on the same plant resources. Nonetheless, little is known about the effect of a change in the relative abundance of a shared plant resource on trophic dynamics. Here we describe how a relative change of resource availability c...

  4. Impacts of local adaptation of forest trees on associations with herbivorous insects: implications for adaptive forest management.

    Sinclair, Frazer H; Stone, Graham N; Nicholls, James A; Cavers, Stephen; Gibbs, Melanie; Butterill, Philip; Wagner, Stefanie; Ducousso, Alexis; Gerber, Sophie; Petit, Rémy J; Kremer, Antoine; Schönrogge, Karsten

    2015-12-01

    Disruption of species interactions is a key issue in climate change biology. Interactions involving forest trees may be particularly vulnerable due to evolutionary rate limitations imposed by long generation times. One mitigation strategy for such impacts is Climate matching - the augmentation of local native tree populations by input from nonlocal populations currently experiencing predicted future climates. This strategy is controversial because of potential cascading impacts on locally adapted animal communities. We explored these impacts using abundance data for local native gallwasp herbivores sampled from 20 provenances of sessile oak (Quercus petraea) planted in a common garden trial. We hypothesized that non-native provenances would show (i) declining growth performance with increasing distance between provenance origin and trial site, and (ii) phenological differences to local oaks that increased with latitudinal differences between origin and trial site. Under a local adaptation hypothesis, we predicted declining gallwasp abundance with increasing phenological mismatch between native and climate-matched trees. Both hypotheses for oaks were supported. Provenance explained significant variation in gallwasp abundance, but no gall type showed the relationship between abundance and phenological mismatch predicted by a local adaptation hypothesis. Our results show that climate matching would have complex and variable impacts on oak gall communities. PMID:26640522

  5. Fluorescence reports intact quantum dot uptake into roots and translocation to leaves of Arabidopsis thaliana and subsequent ingestion by insect herbivores.

    Koo, Yeonjong; Wang, Jing; Zhang, Qingbo; Zhu, Huiguang; Chehab, E Wassim; Colvin, Vicki L; Alvarez, Pedro J J; Braam, Janet

    2015-01-01

    We explored the impact of quantum dot (QD) coat characteristics on NP stability, uptake, and translocation in Arabidopsis thaliana, and subsequent transfer to primary consumers, Trichoplusia ni (T. ni). Arabidopsis was exposed to CdSe/CdZnS QDs with three different coatings: Poly(acrylic acid-ethylene glycol) (PAA-EG), polyethylenimine (PEI) and poly(maleic anhydride-alt-1-octadecene)-poly(ethylene glycol) (PMAO-PEG), which are anionic, cationic, and relatively neutral, respectively. PAA-EG-coated QDs were relatively stable and taken up from a hydroponic medium through both Arabidopsis leaf petioles and roots, without apparent aggregation, and showed generally uniform distribution in leaves. In contrast, PEI- and PMAO-PEG-coated QDs displayed destabilization in the hydroponic medium, and generated particulate fluorescence plant tissues, suggesting aggregation. PAA-EG QDs moved faster than PEI QDs through leaf petioles; however, 8-fold more cadmium accumulated in PEI QD-treated leaves than in those exposed to PAA-EG QDs, possibly due to PEI QD dissolution and direct metal uptake. T. ni caterpillars that fed on Arabidopsis exposed to QDs had reduced performance, and QD fluorescence was detected in both T. ni bodies and frass, demonstrating trophic transfer of intact QDs from plants to insects. Overall, this paper demonstrates that QD coat properties influence plant nanoparticle uptake and translocation and can impact transfer to herbivores. PMID:25437125

  6. Population Dynamics of an Insect Herbivore over 32 Years are Driven by Precipitation and Host-Plant Effects: Testing Model Predictions.

    Price, Peter W; Hunter, Mark D

    2015-06-01

    The interaction between the arroyo willow, Salix lasiolepis Bentham, and its specialist herbivore, the arroyo willow stem-galling sawfly, Euura lasiolepis Smith (Hymenoptera: Tenthredinidae), was studied for 32 yr in Flagstaff, AZ, emphasizing a mechanistic understanding of insect population dynamics. Long-term weather records were evaluated to provide a climatic context for this study. Previously, predictive models of sawfly dynamics were developed from estimates of sawfly gall density made between 1981 and 2002; one model each for drier and wetter sites. Predictor variables in these models included winter precipitation and the Palmer Drought Severity Index, which impact the willow growth, with strong bottom-up effects on sawflies. We now evaluate original model predictions of sawfly population dynamics using new data (from 2003-2012). Additionally, willow resources were evaluated in 1986 and in 2012, using as criteria clone area, shoot density, and shoot length. The dry site model accounted for 40% of gall population density variation between 2003 and 2012 (69% over the 32 yr), providing strong support for the bottom-up, mechanistic hypothesis that water supply to willow hosts impacts sawfly populations. The current drying trend stressed willow clones: in drier sites, willow resources declined and gall density decreased by 98%. The wet site model accounted for 23% of variation in gall population density between 2003 and 2012 (48% over 30 yr), consistent with less water limitation. Nonetheless, gall populations were reduced by 72%. PMID:26313951

  7. Nondestructive estimates of above-ground biomass using terrestrial laser scanning

    Calders, K.; Newnham, G.; Burt, A.; Murphy, S.; Raumonen, P.; Herold, M.; Culvenor, D.; Avitabile, V.; Disney, M.; Armston, J.; Kaasalainen, M.

    2015-01-01

    Allometric equations are currently used to estimate above-ground biomass (AGB) based on the indirect relationship with tree parameters. Terrestrial laser scanning (TLS) can measure the canopy structure in 3D with high detail. In this study, we develop an approach to estimate AGB from TLS data, which

  8. Grass allometry and estimation of above-ground biomass in tropical alpine tussock grasslands

    Oliveras Menor, I.; Eynden, van der M.; Malhi, Y.; Cahuana, N.; Menor, C.; Zamora, F.; Haugaasen, T.

    2014-01-01

    The puna/páramo grasslands span across the highest altitudes of the tropical Andes, and their ecosystem dynamics are still poorly understood. In this study we examined the above-ground biomass and developed species specific and multispecies power-law allometric equations for four tussock grass speci

  9. Generating Within-Plant Spatial Distributions of an Insect Herbivore Based on Aggregation Patterns and Per-Node Infestation Probabilities.

    Rincon, Diego F; Hoy, Casey W; Cañas, Luis A

    2015-04-01

    Most predator-prey models extrapolate functional responses from small-scale experiments assuming spatially uniform within-plant predator-prey interactions. However, some predators focus their search in certain plant regions, and herbivores tend to select leaves to balance their nutrient uptake and exposure to plant defenses. Individual-based models that account for heterogeneous within-plant predator-prey interactions can be used to scale-up functional responses, but they would require the generation of explicit prey spatial distributions within-plant architecture models. The silverleaf whitefly, Bemisia tabaci biotype B (Gennadius) (Hemiptera: Aleyrodidae), is a significant pest of tomato crops worldwide that exhibits highly aggregated populations at several spatial scales, including within the plant. As part of an analytical framework to understand predator-silverleaf whitefly interactions, the objective of this research was to develop an algorithm to generate explicit spatial counts of silverleaf whitefly nymphs within tomato plants. The algorithm requires the plant size and the number of silverleaf whitefly individuals to distribute as inputs, and includes models that describe infestation probabilities per leaf nodal position and the aggregation pattern of the silverleaf whitefly within tomato plants and leaves. The output is a simulated number of silverleaf whitefly individuals for each leaf and leaflet on one or more plants. Parameter estimation was performed using nymph counts per leaflet censused from 30 artificially infested tomato plants. Validation revealed a substantial agreement between algorithm outputs and independent data that included the distribution of counts of both eggs and nymphs. This algorithm can be used in simulation models that explore the effect of local heterogeneity on whitefly-predator dynamics. PMID:26313173

  10. Estimating above-ground carbon biomass in a newly restored coastal plain wetland using remote sensing.

    Joseph B Riegel

    Full Text Available Developing accurate but inexpensive methods for estimating above-ground carbon biomass is an important technical challenge that must be overcome before a carbon offset market can be successfully implemented in the United States. Previous studies have shown that LiDAR (light detection and ranging is well-suited for modeling above-ground biomass in mature forests; however, there has been little previous research on the ability of LiDAR to model above-ground biomass in areas with young, aggrading vegetation. This study compared the abilities of discrete-return LiDAR and high resolution optical imagery to model above-ground carbon biomass at a young restored forested wetland site in eastern North Carolina. We found that the optical imagery model explained more of the observed variation in carbon biomass than the LiDAR model (adj-R(2 values of 0.34 and 0.18 respectively; root mean squared errors of 0.14 Mg C/ha and 0.17 Mg C/ha respectively. Optical imagery was also better able to predict high and low biomass extremes than the LiDAR model. Combining both the optical and LiDAR improved upon the optical model but only marginally (adj-R(2 of 0.37. These results suggest that the ability of discrete-return LiDAR to model above-ground biomass may be rather limited in areas with young, small trees and that high spatial resolution optical imagery may be the better tool in such areas.

  11. 1977 Kansas Field Crop Insect Control Recommendations.

    Brooks, Leroy; Gates, Dell E.

    This publication is prepared to aid producers in selecting methods of insect population management that have proved effective under Kansas conditions. Topics covered include insect control on alfalfa, soil insects attacking corn, insects attacking above-ground parts of corn, and sorghum, wheat, and soybean insect control. The insecticides…

  12. Pendugaan Cadangan Karbon Above Ground Biomass pada Ruang Terbuka Hijau di Kota Medan

    Sitorus, Novita Ariani

    2015-01-01

    NOVITA ARIANI SITORUS : The Estimate of Carbon Stocks Above Ground Biomass at Green Open Space in Medan City. Under the supervision of RAHMAWATY and ABDUL RAUF. Global warming is the main environmental problems of this millennium. Carbon dioxide (CO2) is the main cause for global warming. Green open space such as urban forest and urban park play a role in mitigating global warming in urban areas because the vegetation that is capable to absorb CO2 from the atmosphere through photosynthes...

  13. Landsat Imagery-Based Above Ground Biomass Estimation and Change Investigation Related to Human Activities

    Chaofan Wu; Huanhuan Shen; Ke Wang; Aihua Shen; Jinsong Deng; Muye Gan

    2016-01-01

    Forest biomass is a significant indicator for substance accumulation and forest succession, and a spatiotemporal biomass map would provide valuable information for forest management and scientific planning. In this study, Landsat imagery and field data cooperated with a random forest regression approach were used to estimate spatiotemporal Above Ground Biomass (AGB) in Fuyang County, Zhejiang Province of East China. As a result, the AGB retrieval showed an increasing trend for the past decade...

  14. Disposal facility in olkiluoto, description of above ground facilities in lift transport alternative

    The above ground facilities of the disposal plant on the Olkiluoto site are described in this report as they will be when the operation of the disposal facility starts in the year 2020. The disposal plant is visualised on the Olkiluoto site. Parallel construction of the deposition tunnels and disposal of the spent fuel canisters constitute the principal design basis of the disposal plant. The annual production of disposal canisters for spent fuel amounts to about 40. Production of 100 disposal canisters has been used as the capacity basis. Fuel from the Olkiluoto plant and from the Loviisa plant will be encapsulated in the same production line. The disposal plant will require an area of about 15 to 20 hectares above ground level. The total building volume of the above ground facilities is about 75000 m3. The purpose of the report is to provide the base for detailed design of the encapsulation plant and the repository spaces, as well as for coordination between the disposal plant and ONKALO. The dimensioning bases for the disposal plant are shown in the Tables at the end of the report. The report can also be used as a basis for comparison in deciding whether the fuel canisters are transported to the repository by a lift or by a vehicle along the access tunnel. (orig.)

  15. Diversity, Population Structure, and Above Ground Biomass in Woody Species on Ngomakurira Mountain, Domboshawa, Zimbabwe

    Clemence Zimudzi

    2016-01-01

    Full Text Available The diversity, structure, species composition, and above ground biomass of woody plants on Ngomakurira mountain in Zimbabwe were studied. A systematic random sampling approach was adopted to establish 52 sampling plots measuring 10 × 10 m across 3 study strata in the 1266 ha study area. Woody species occurring in each plot were identified and the circumferences of trees with diameters >8.0 cm at 1.3 m height were measured. A total of 91 species belonging to 74 genera and 39 families were identified in the sample plots. A Shannon-Wiener index mean value of 3.12 was obtained indicating high species diversity on the mountain. The DBH size class distribution showed inverse J distribution patterns across the three study strata, but with only 3 individual plants with DBH > 30 cm. Mean basal area was 15.21 m2 ha−1 with U. kirkiana and J. globiflora contributing approximately 30% of the basal area. The estimated above ground biomass ranged from 34.5 to 65.1 t ha−1. Kruskal-Wallis-H test showed no significant differences in species richness, stem density, basal area, above ground biomass, and evenness, across the study strata (p<0.05. Ngomakurira woodland has potential to regenerate due to the presence of many stems in the small diameter size classes.

  16. Above Ground Biomass-carbon Partitioning, Storage and Sequestration in a Rehabilitated Forest, Bintulu, Sarawak, Malaysia

    Forest degradation and deforestation are some of the major global concerns as it can reduce forest carbon storage and sequestration capacity. Forest rehabilitation on degraded forest areas has the potential to improve carbon stock, hence mitigate greenhouse gases emission. However, the carbon storage and sequestration potential in a rehabilitated tropical forest remains unclear due to the lack of information. This paper reports an initiative to estimate biomass-carbon partitioning, storage and sequestration in a rehabilitated forest. The study site was at the UPM-Mitsubishi Corporation Forest Rehabilitation Project, UPM Bintulu Sarawak Campus, Bintulu, Sarawak. A plot of 20 x 20 m2 was established each in site 1991 (Plot 1991), 1999 (Plot 1999) and 2008 (Plot 2008). An adjacent natural regenerating secondary forest plot (Plot NF) was also established for comparison purposes. The results showed that the contribution of tree component biomass/ carbon to total biomass/ carbon was in the order of main stem > branch > leaf. As most of the trees were concentrated in diameter size class = 10 cm for younger rehabilitated forests, the total above ground biomass/ carbon was from this class. These observations suggest that the forests are in the early successional stage. The total above ground biomass obtained for the rehabilitated forest ranged from 4.3 to 4,192.3 kg compared to natural regenerating secondary forest of 3,942.3 kg while total above ground carbon ranged from 1.9 to 1,927.9 kg and 1,820.4 kg, respectively. The mean total above ground biomass accumulated ranged from 1.3 x 10-2 to 20.5 kg/ 0.04 ha and mean total carbon storage ranged from 5.9 x 10-3 to 9.4 kg/ 0.04 ha. The total CO2 sequestrated in rehabilitated forest ranged from 6.9 to 7,069.1 kg CO2/ 0.04 ha. After 19 years, the rehabilitated forest had total above ground biomass and carbon storage comparable to the natural regeneration secondary forest. The forest rehabilitated activities have the potential

  17. Above-ground biomass investments and light interception of tropical forest trees and lianas early in succession

    Selaya, N.G.; Anten, N.P.R.; Oomen, R.J.; Matthies, M.; Werger, M.J.A.

    2007-01-01

    Background and Aims Crown structure and above-ground biomass investment was studied in relation to light interception of trees and lianas growing in a 6-month-old regenerating forest. Methods The vertical distribution of total above-ground biomass, height, diameter, stem density, leaf angles and cro

  18. Forest soil respiration rate and delta13C is regulated by recent above ground weather conditions.

    Ekblad, Alf; Boström, Björn; Holm, Anders; Comstedt, Daniel

    2005-03-01

    Soil respiration, a key component of the global carbon cycle, is a major source of uncertainty when estimating terrestrial carbon budgets at ecosystem and higher levels. Rates of soil and root respiration are assumed to be dependent on soil temperature and soil moisture yet these factors often barely explain half the seasonal variation in soil respiration. We here found that soil moisture (range 16.5-27.6% of dry weight) and soil temperature (range 8-17.5 degrees C) together explained 55% of the variance (cross-validated explained variance; Q2) in soil respiration rate (range 1.0-3.4 micromol C m(-2) s(-1)) in a Norway spruce (Picea abies) forest. We hypothesised that this was due to that the two components of soil respiration, root respiration and decomposition, are governed by different factors. We therefore applied PLS (partial least squares regression) multivariate modelling in which we, together with below ground temperature and soil moisture, used the recent above ground air temperature and air humidity (vapour pressure deficit, VPD) conditions as x-variables. We found that air temperature and VPD data collected 1-4 days before respiration measurements explained 86% of the seasonal variation in the rate of soil respiration. The addition of soil moisture and soil temperature to the PLS-models increased the Q2 to 93%. delta13C analysis of soil respiration supported the hypotheses that there was a fast flux of photosynthates to root respiration and a dependence on recent above ground weather conditions. Taken together, our results suggest that shoot activities the preceding 1-6 days influence, to a large degree, the rate of root and soil respiration. We propose this above ground influence on soil respiration to be proportionally largest in the middle of the growing season and in situations when there is large day-to-day shifts in the above ground weather conditions. During such conditions soil temperature may not exert the major control on root respiration. PMID

  19. Applications of above-ground gas stores. Demand-oriented supply; Einsatzmoeglichkeiten von Obertagespeichern. Kundenorientierte Bedarfsdeckung

    Deschkan, Peter [Wien Energie Speicher GmbH, Wien (Austria)

    2010-07-01

    From the view of municipal utilities in Austria, the applications and uses of above-ground gas stores have changed considerably during the past few years as a result of the deregulation of the natural gas markets. While it used to be normal to consider spherical or tubular natural gas reservoirs as part of the gas grid, new legal and commercial aspects have since then come to the fore and must be taken into account if these niche products of the natural gas store market are to be used successfully. (orig.)

  20. Temperature and Plant Genotype Alter Alkaloid Concentrations in Ryegrass Infected with an Epichloë Endophyte and This Affects an Insect Herbivore

    Hennessy, Louise M.; Popay, Alison J.; Finch, Sarah C.; Clearwater, Michael J.; Cave, Vanessa M.

    2016-01-01

    Asexual Epichloë endophytes colonize agricultural forage grasses in a relationship which is mutually beneficial and provides the host plant with protection against herbivorous insects. The endophyte strain AR37 (Epichloë festucae var. lolii) produces epoxy-janthitrem alkaloids and is the only endophyte known to provide ryegrass with resistance against porina larvae (Wiseana cervinata (Walker)), a major pasture pest in cooler areas of New Zealand. This study examined the effect of temperature on concentrations of epoxy-janthitrems in AR37-infected ryegrass and determined how the resulting variations in concentration affected consumption, growth and survival of porina larvae. Twenty replicate pairs of perennial (Lolium perenne L.) and Italian ryegrass (L. multiflorum Lam.) plants with and without endophyte were prepared by cloning, with one of each pair grown at either high (20°C) or low (7°C) temperature. After 10 weeks, herbage on each plant was harvested, divided into leaf and pseudostem, then freeze dried and ground. Leaf and pseudostem material was then incorporated separately into semi-synthetic diets which were fed to porina larvae in a bioassay over 3 weeks. Epoxy-janthitrem concentrations within the plant materials and the semi-synthetic diets were analyzed by high performance liquid chromatography. AR37-infected ryegrass grown at high temperature contained high in planta concentrations of epoxy-janthitrem (30.6 μg/g in leaves and 83.9 μg/g in pseudostems) that had a strong anti-feedant effect on porina larvae when incorporated into their diets, reducing their survival by 25–42% on pseudostems. In comparison, in planta epoxy-janthitrem concentrations in AR37-infected ryegrass grown at low temperature were very low (0.67 μg/g in leaves and 7.4 μg/g in pseudostems) resulting in a small anti-feedant effect in perennial but not in Italian ryegrass. Although alkaloid concentrations were greatly reduced by low temperature this reduction did not occur

  1. Deep Neural Networks for Above-Ground Detection in Very High Spatial Resolution Digital Elevation Models

    Marmanis, D.; Adam, F.; Datcu, M.; Esch, T.; Stilla, U.

    2015-03-01

    Deep Learning techniques have lately received increased attention for achieving state-of-the-art results in many classification problems, including various vision tasks. In this work, we implement a Deep Learning technique for classifying above-ground objects within urban environments by using a Multilayer Perceptron model and VHSR DEM data. In this context, we propose a novel method called M-ramp which significantly improves the classifier's estimations by neglecting artefacts, minimizing convergence time and improving overall accuracy. We support the importance of using the M-ramp model in DEM classification by conducting a set of experiments with both quantitative and qualitative results. Precisely, we initially train our algorithm with random DEM tiles and their respective point-labels, considering less than 0.1% over the test area, depicting the city center of Munich (25 km2). Furthermore with no additional training, we classify two much larger unseen extents of the greater Munich area (424 km2) and Dongying city, China (257 km2) and evaluate their respective results for proving knowledge-transferability. Through the use of M-ramp, we were able to accelerate the convergence by a magnitude of 8 and achieve a decrease in above-ground relative error by 24.8% and 5.5% over the different datasets.

  2. The importance of phenology in studies of plant-herbivore-parasitoid interactions

    Fei, Minghui

    2016-01-01

    Thesis title: The importance of phenology in studies of plant-herbivore-parasitoid interactions Author: Minghui Fei Abstract As food resources of herbivorous insects, the quality and quantity of plants can directly affect the performance of herbivorous insects and indirectly affect the performance of natural enemies of the herbivorous insects. In nature, plant quality and quantity are dynamic and can change in individual plants over the course of a single growing season. Many multivoltine ins...

  3. Molecular interactions between the specialist herbivore Manduca sexta (Lepidoptera, Sphingidae) and its natural host Nicotiana attenuata. IV. Insect-Induced ethylene reduces jasmonate-induced nicotine accumulation by regulating putrescine N-methyltransferase transcripts.

    Winz, R A; Baldwin, I T

    2001-04-01

    Attack by the specialist herbivore, Manduca sexta, on its native host Nicotiana attenuata Torr. ex Wats. produces a dramatic ethylene release, a jasmonate burst, and a suppression of the nicotine accumulation that results from careful simulations of the herbivore's damage. Methyl-jasmonate (MeJA) treatment induces nicotine biosynthesis. However, this induction can be suppressed by ethylene as pretreatment of plants with 1-methylcyclopropene (1-MCP), a competitive inhibitor of ethylene receptors, restores the full MeJA-induced nicotine response in herbivore attacked plants (J. Kahl, D.H. Siemens, R.J. Aerts, R. Gäbler, F. Kühnemann, C.A. Preston, I.T. Baldwin [2000] Planta 210: 336-342). To understand whether this herbivore-induced signal cross-talk occurs at the level of transcript accumulation, we cloned the putrescine methyltransferase genes (NaPMT1 and NaPMT2) of N. attenuata, which are thought to represent the rate limiting step in nicotine biosynthesis, and measured transcript accumulations by northern analysis after various jasmonate, 1-MCP, ethephon, and herbivory treatments. Transcripts of both root putrescine N-methyltransferase (PMT) genes and nicotine accumulation increased dramatically within 10 h of shoot MeJA treatment and immediately after root treatments. Root ethephon treatments suppressed this response, which could be reversed by 1-MCP pretreatment. Moreover, 1-MCP pretreatment dramatically amplified the transcript accumulation resulting from both wounding and M. sexta herbivory. We conclude that attack from this nicotine-tolerant specialist insect causes N. attenuata to produce ethylene, which directly suppresses the nitrogen-intensive biosynthesis of nicotine. PMID:11299398

  4. A first map of tropical Africa's above-ground biomass derived from satellite imagery

    Observations from the moderate resolution imaging spectroradiometer (MODIS) were used in combination with a large data set of field measurements to map woody above-ground biomass (AGB) across tropical Africa. We generated a best-quality cloud-free mosaic of MODIS satellite reflectance observations for the period 2000-2003 and used a regression tree model to predict AGB at 1 km resolution. Results based on a cross-validation approach show that the model explained 82% of the variance in AGB, with a root mean square error of 50.5 Mg ha-1 for a range of biomass between 0 and 454 Mg ha-1. Analysis of lidar metrics from the Geoscience Laser Altimetry System (GLAS), which are sensitive to vegetation structure, indicate that the model successfully captured the regional distribution of AGB. The results showed a strong positive correlation (R2 = 0.90) between the GLAS height metrics and predicted AGB.

  5. Risk Assessment of Genetically Engineered Maize Resistant to Diabrotica spp.: Influence on Above-Ground Arthropods in the Czech Republic.

    Zdeňka Svobodová

    Full Text Available Transgenic maize MON88017, expressing the Cry3Bb1 toxin from Bacillus thuringiensis (Bt maize, confers resistance to corn rootworms (Diabrotica spp. and provides tolerance to the herbicide glyphosate. However, prior to commercialization, substantial assessment of potential effects on non-target organisms within agroecosystems is required. The MON88017 event was therefore evaluated under field conditions in Southern Bohemia in 2009-2011, to detect possible impacts on the above-ground arthropod species. The study compared MON88017, its near-isogenic non-Bt hybrid DK315 (treated or not treated with the soil insecticide Dursban 10G and two non-Bt reference hybrids (KIPOUS and PR38N86. Each hybrid was grown on five 0.5 ha plots distributed in a 14-ha field with a Latin square design. Semiquantitative ELISA was used to verify Cry3Bb1 toxin levels in the Bt maize. The species spectrum of non-target invertebrates changed during seasons and was affected by weather conditions. The thrips Frankliniella occidentalis was the most abundant species in all three successive years. The next most common species were aphids Rhopalosiphum padi and Metopolophium dirhodum. Frequently observed predators included Orius spp. and several species within the Coccinellidae. Throughout the three-year study, analysis of variance indicated some significant differences (P<0.05. Multivariate analysis showed that the abundance and diversity of plant dwelling insects was similar in maize with the same genetic background, for both Bt (MON88017 and non-Bt (DK315 untreated or insecticide treated. KIPOUS and PR38N86 showed some differences in species abundance relative to the Bt maize and its near-isogenic hybrid. However, the effect of management regime on arthropod community was insignificant and accounted only for a negligible portion of the variability.

  6. Estimating Stand Volume and Above-Ground Biomass of Urban Forests Using LiDAR

    Vincenzo Giannico

    2016-04-01

    Full Text Available Assessing forest stand conditions in urban and peri-urban areas is essential to support ecosystem service planning and management, as most of the ecosystem services provided are a consequence of forest stand characteristics. However, collecting data for assessing forest stand conditions is time consuming and labor intensive. A plausible approach for addressing this issue is to establish a relationship between in situ measurements of stand characteristics and data from airborne laser scanning (LiDAR. In this study we assessed forest stand volume and above-ground biomass (AGB in a broadleaved urban forest, using a combination of LiDAR-derived metrics, which takes the form of a forest allometric model. We tested various methods for extracting proxies of basal area (BA and mean stand height (H from the LiDAR point-cloud distribution and evaluated the performance of different models in estimating forest stand volume and AGB. The best predictors for both models were the scale parameters of the Weibull distribution of all returns (except the first (proxy of BA and the 95th percentile of the distribution of all first returns (proxy of H. The R2 were 0.81 (p < 0.01 for the stand volume model and 0.77 (p < 0.01 for the AGB model with a RMSE of 23.66 m3·ha−1 (23.3% and 19.59 Mg·ha−1 (23.9%, respectively. We found that a combination of two LiDAR-derived variables (i.e., proxy of BA and proxy of H, which take the form of a forest allometric model, can be used to estimate stand volume and above-ground biomass in broadleaved urban forest areas. Our results can be compared to other studies conducted using LiDAR in broadleaved forests with similar methods.

  7. Above ground standing biomass and carbon storage in village bamboos in North East India

    Jyoti Nath, Arun; Das, Ashesh Kumar [Department of Ecology and Environmental Science, Assam University, Silchar 788011, Assam (India); Das, Gitasree [Department of Statistics, North Eastern Hill University, Shillong 793022, Meghalaya (India)

    2009-09-15

    Bamboo forms an important component in the traditional landscape of North East India. For biomass estimation of village bamboos of Barak Valley, North East India, allometric relationships were developed by harvest method describing leaf, branch and culm biomass with DBH as an independent variable using a log linear model. The culm density of the stand was 8950 culms ha{sup -1} during 2005 of which 67% of growing stock was represented by Bambusa cacharensis, 17.88% by Bambusa vulgaris and 15.12% by Bambusa balcooa. Above ground stand biomass was 121.51 t ha{sup -1} of which 86% was contributed by culm component followed by branch (10%) and leaf (4%). With respect to species, B. cacharensis made up to 46% of total stand biomass followed by B. vulgaris (28%) and B. balcooa (26%). Carbon storage in the above ground biomass was 61.05 t ha{sup -1}. Allocation of C was more in culm components (53.05 t ha{sup -1}) than in branch (5.81 t ha{sup -1}) and leaf (2.19 t ha{sup -1}). Carbon storage in the litter floor mass was 2.40 t ha{sup -1}, of which leaf litter made up the highest amount (1.37 t ha{sup -1}) followed by sheath (0.86 t ha{sup -1}) and branch (0.17 t ha{sup -1}). Carbon stock in the soil up to 30 cm depth was 57.3 t ha{sup -1}. Gross C stock in the plantation was estimated to be 120.75 t ha{sup -1}. Carbon storage estimated in the bamboo stand of present study offers insights into the opportunity of village bamboos in the rural landscape for carbon storage through carbon sequestration. Management and utilization of village bamboos as a potential source of carbon sink by smallholder farmers are discussed in the context of their livelihood security and the Millennium Development Goals of the United Nations. (author)

  8. A terrestrial biosphere model optimized to atmospheric CO2 concentration and above ground woody biomass

    Saito, M.; Ito, A.; Maksyutov, S. S.

    2013-12-01

    This study documents an optimization of a prognostic biosphere model (VISIT; Vegetation Integrative Similator for Trace gases) to observations of atmospheric CO2 concentration and above ground woody biomass by using a Bayesian inversion method combined with an atmospheric tracer transport model (NIES-TM; National Institute for Environmental Studies / Frontier Research Center for Global Change (NIES/FRCGC) off-line global atmospheric tracer transport model). The assimilated observations include 74 station records of surface atmospheric CO2 concentration and aggregated grid data sets of above ground woody biomass (AGB) and net primary productivity (NPP) over the globe. Both the biosphere model and the atmospheric transport model are used at a horizontal resolution of 2.5 deg x 2.5 deg grid with temporal resolutions of a day and an hour, respectively. The atmospheric transport model simulates atmospheric CO2 concentration with nine vertical levels using daily net ecosystem CO2 exchange rate (NEE) from the biosphere model, oceanic CO2 flux, and fossil fuel emission inventory. The models are driven by meteorological data from JRA-25 (Japanese 25-year ReAnalysis) and JCDAS (JMA Climate Data Assimilation System). Statistically optimum physiological parameters in the biosphere model are found by iterative minimization of the corresponding Bayesian cost function. We select thirteen physiological parameter with high sensitivity to NEE, NPP, and AGB for the minimization. Given the optimized physiological parameters, the model shows error reductions in seasonal variation of the CO2 concentrations especially in the northern hemisphere due to abundant observation stations, while errors remain at a few stations that are located in coastal coastal area and stations in the southern hemisphere. The model also produces moderate estimates of the mean magnitudes and probability distributions in AGB and NPP for each biome. However, the model fails in the simulation of the terrestrial

  9. Landsat Imagery-Based Above Ground Biomass Estimation and Change Investigation Related to Human Activities

    Chaofan Wu

    2016-02-01

    Full Text Available Forest biomass is a significant indicator for substance accumulation and forest succession, and a spatiotemporal biomass map would provide valuable information for forest management and scientific planning. In this study, Landsat imagery and field data cooperated with a random forest regression approach were used to estimate spatiotemporal Above Ground Biomass (AGB in Fuyang County, Zhejiang Province of East China. As a result, the AGB retrieval showed an increasing trend for the past decade, from 74.24 ton/ha in 2004 to 99.63 ton/ha in 2013. Topography and forest management were investigated to find their relationships with the spatial distribution change of biomass. In general, the simulated AGB increases with higher elevation, especially in the range of 80–200 m, wherein AGB acquires the highest increase rate. Moreover, the forest policy of ecological forest has a positive effect on the AGB increase, particularly within the national level ecological forest. The result in this study demonstrates that human activities have a great impact on biomass distribution and change tendency. Furthermore, Landsat image-based biomass estimates would provide illuminating information for forest policy-making and sustainable development.

  10. Roles for jasmonate- and ethylene-induced transcription factors in the ability of Arabidopsis to respond differentially to damage caused by two insect herbivores

    Rehrig, Erin M.; Appel, Heidi M.; Jones, A. Daniel; Schultz, Jack C.

    2014-01-01

    Plant responses to insects and wounding involve substantial transcriptional reprogramming that integrates hormonal, metabolic, and physiological events. The ability to respond differentially to various stresses, including wounding, generally involves hormone signaling and trans-acting regulatory factors. Evidence of the importance of transcription factors (TFs) in responses to insects is also accumulating. However, the relationships among hormone signaling, TF activity, and ability to respond...

  11. Roles for jasmonate- and ethylene-induced transcription factors in the ability of Arabidopsis to respond differentially to damage caused by two insect herbivores.

    Rehrig, Erin M; Appel, Heidi M; Jones, A Daniel; Schultz, Jack C

    2014-01-01

    Plant responses to insects and wounding involve substantial transcriptional reprogramming that integrates hormonal, metabolic, and physiological events. The ability to respond differentially to various stresses, including wounding, generally involves hormone signaling and trans-acting regulatory factors. Evidence of the importance of transcription factors (TFs) in responses to insects is also accumulating. However, the relationships among hormone signaling, TF activity, and ability to respond specifically to different insects are uncertain. We examined transcriptional and hormonal changes in Arabidopsis thaliana after herbivory by larvae of two lepidopteran species, Spodoptera exigua (Hübner) and Pieris rapae L. over a 24-h time course. Transcriptional responses to the two insects differed and were frequently weaker or absent in response to the specialist P. rapae. Using microarray analysis and qRT-PCR, we found 141 TFs, including many AP2/ERFs (Ethylene Response Factors) and selected defense-related genes, to be differentially regulated in response to the two insect species or wounding. Jasmonic Acid (JA), JA-isoleucine (JA-IL), and ethylene production by Arabidopsis plants increased after attack by both insect species. However, the amounts and timing of ethylene production differed between the two herbivory treatments. Our results support the hypothesis that the different responses to these two insects involve modifications of JA-signaling events and activation of different subsets of ERF TFs, resulting in different degrees of divergence from responses to wounding alone. PMID:25191332

  12. Modelling Growth and Partitioning of Annual Above-Ground Vegetative and Reproductive Biomass of Grapevine

    Meggio, Franco; Vendrame, Nadia; Maniero, Giovanni; Pitacco, Andrea

    2014-05-01

    In the current climate change scenarios, both agriculture and forestry inherently may act as carbon sinks and consequently can play a key role in limiting global warming. An urgent need exists to understand which land uses and land resource types have the greatest potential to mitigate greenhouse gas (GHG) emissions contributing to global change. A common believe is that agricultural fields cannot be net carbon sinks due to many technical inputs and repeated disturbances of upper soil layers that all contribute to a substantial loss both of the old and newly-synthesized organic matter. Perennial tree crops (vineyards and orchards), however, can behave differently: they grow a permanent woody structure, stand undisturbed in the same field for decades, originate a woody pruning debris, and are often grass-covered. In this context, reliable methods for quantifying and modelling emissions and carbon sequestration are required. Carbon stock changes are calculated by multiplying the difference in oven dry weight of biomass increments and losses with the appropriate carbon fraction. These data are relatively scant, and more information is needed on vineyard management practices and how they impact vineyard C sequestration and GHG emissions in order to generate an accurate vineyard GHG footprint. During the last decades, research efforts have been made for estimating the vineyard carbon budget and its allocation pattern since it is crucial to better understand how grapevines control the distribution of acquired resources in response to variation in environmental growth conditions and agronomic practices. The objective of the present study was to model and compare the dynamics of current year's above-ground biomass among four grapevine varieties. Trials were carried out over three growing seasons in field conditions. The non-linear extra-sums-of-squares method demonstrated to be a feasible way of growth models comparison to statistically assess significant differences among

  13. Detection of large above ground biomass variability in lowland forest ecosystems by airborne LiDAR

    J. Jubanski

    2012-08-01

    Full Text Available Quantification of tropical forest Above Ground Biomass (AGB over large areas as input for Reduced Emissions from Deforestation and forest Degradation (REDD+ projects and climate change models is challenging. This is the first study which attempts to estimate AGB and its variability across large areas of tropical lowland forests in Central Kalimantan (Indonesia through correlating airborne Light Detection and Ranging (LiDAR to forest inventory data. Two LiDAR height metrics were analysed and regression models could be improved through the use of LiDAR point densities as input (R2 = 0.88; n = 52. Surveying with a LiDAR point density per square meter of 2–4 resulted in the best cost-benefit ratio. We estimated AGB for 600 km of LiDAR tracks and showed that there exists a considerable variability of up to 140% within the same forest type due to varying environmental conditions. Impact from logging operations and the associated AGB losses dating back more than 10 yr could be assessed by LiDAR but not by multispectral satellite imagery. Comparison with a Landsat classification for a 1 million ha study area where AGB values were based on site specific field inventory data, regional literature estimates, and default values by the Intergovernmental Panel on Climate Change (IPCC showed an overestimation of 46%, 102%, and 137%, respectively. The results show that AGB overestimation may lead to wrong GHG emission estimates due to deforestation in climate models. For REDD+ projects this leads to inaccurate carbon stock estimates and consequently to significantly wrong REDD+ based compensation payments.

  14. Contrasting patterns of herbivore and predator pressure on invasive and native plants

    Engelkes, T.; Wouters, B.; Bezemer, T.M.; Harvey, J.A.; Putten, van der W.H.

    2012-01-01

    Invasive non-native plant species often harbor fewer herbivorous insects than related native plant species. However, little is known about how herbivorous insects on non-native plants are exposed to carnivorous insects, and even less is known on plants that have recently expanded their ranges within

  15. Investigating Appropriate Sampling Design for Estimating Above-Ground Biomass in Bruneian Lowland Mixed Dipterocarp Forest

    Lee, S.; Lee, D.; Abu Salim, K.; Yun, H. M.; Han, S.; Lee, W. K.; Davies, S. J.; Son, Y.

    2014-12-01

    Mixed tropical forest structure is highly heterogeneous unlike plantation or mixed temperate forest structure, and therefore, different sampling approaches are required. However, the appropriate sampling design for estimating the above-ground biomass (AGB) in Bruneian lowland mixed dipterocarp forest (MDF) has not yet been fully clarified. The aim of this study was to provide supportive information in sampling design for Bruneian forest carbon inventory. The study site was located at Kuala Belalong lowland MDF, which is part of the Ulu Tembulong National Park, Brunei Darussalam. Six 60 m × 60 m quadrats were established, separated by a distance of approximately 100 m and each was subdivided into quadrats of 10 m × 10 m, at an elevation between 200 and 300 m above sea level. At each plot all free-standing trees with diameter at breast height (dbh) ≥ 1 cm were measured. The AGB for all trees with dbh ≥ 10 cm was estimated by allometric models. In order to analyze changes in the diameter-dependent parameters used for estimating the AGB, different quadrat areas, ranging from 10 m × 10 m to 60 m × 60 m, were used across the study area, starting at the South-West end and moving towards the North-East end. The derived result was as follows: (a) Big trees (dbh ≥ 70 cm) with sparse distribution have remarkable contribution to the total AGB in Bruneian lowland MDF, and therefore, special consideration is required when estimating the AGB of big trees. Stem number of trees with dbh ≥ 70 cm comprised only 2.7% of all trees with dbh ≥ 10 cm, but 38.5% of the total AGB. (b) For estimating the AGB of big trees at the given acceptable limit of precision (p), it is more efficient to use large quadrats than to use small quadrats, because the total sampling area decreases with the former. Our result showed that 239 20 m × 20 m quadrats (9.6 ha in total) were required, while 15 60 m × 60 m quadrats (5.4 ha in total) were required when estimating the AGB of the trees

  16. Can above-ground ecosystem services compensate for reduced fertilizer input and soil organic matter in annual crops?

    van Gils, Stijn; van der Putten, Wim H; Kleijn, David

    2016-01-01

    1.Above-ground and below-ground environmental conditions influence crop yield by pollination, pest pressure, and resource supply. However, little is known about how interactions between these factors contribute to yield. Here, we used oilseed rape Brassica napus to test their effects on crop yield.2

  17. Effect of nitrogen addition and drought on above-ground biomass of expanding tall grasses Calamagrostis epigejos and Arrhenatherum elatius

    Fiala, Karel; Tůma, Ivan; Holub, Petr

    2011-01-01

    Roč. 66, č. 2 (2011), s. 275-281. ISSN 0006-3088 R&D Projects: GA ČR(CZ) GA526/06/0556 Institutional research plan: CEZ:AV0Z60050516 Keywords : nitrogen * drought * above-ground biomass Subject RIV: EF - Botanics Impact factor: 0.557, year: 2011

  18. Examining the potential of Sentinel-2 MSI spectral resolution in quantifying above ground biomass across different fertilizer treatments

    Sibanda, Mbulisi; Mutanga, Onisimo; Rouget, Mathieu

    2015-12-01

    The major constraint in understanding grass above ground biomass variations using remotely sensed data are the expenses associated with the data, as well as the limited number of techniques that can be applied to different management practices with minimal errors. New generation multispectral sensors such as Sentinel 2 Multispectral Imager (MSI) are promising for effective rangeland management due to their unique spectral bands and higher signal to noise ratio. This study resampled hyperspectral data to spectral resolutions of the newly launched Sentinel 2 MSI and the recently launched Landsat 8 OLI for comparison purposes. Using Sparse partial least squares regression, the resampled data was applied in estimating above ground biomass of grasses treated with different fertilizer combinations of ammonium sulfate, ammonium nitrate, phosphorus and lime as well as unfertilized experimental plots. Sentinel 2 MSI derived models satisfactorily performed (R2 = 0.81, RMSEP = 1.07 kg/m2, RMSEP_rel = 14.97) in estimating grass above ground biomass across different fertilizer treatments relative to Landsat 8 OLI (Landsat 8 OLI: R2 = 0.76, RMSEP = 1.15 kg/m2, RMSEP_rel = 16.04). In comparison, hyperspectral data derived models exhibited better grass above ground biomass estimation across complex fertilizer combinations (R2 = 0.92, RMSEP = 0.69 kg/m2, RMSEP_rel = 9.61). Although Sentinel 2 MSI bands and indices better predicted above ground biomass compared with Landsat 8 OLI bands and indices, there were no significant differences (α = 0.05) in the errors of prediction between the two new generational sensors across all fertilizer treatments. The findings of this study portrays Sentinel 2 MSI and Landsat 8 OLI as promising remotely sensed datasets for regional scale biomass estimation, particularly in resource scarce areas.

  19. The effect of cassava-based bioethanol production on above-ground carbon stocks: A case study from Southern Mali

    Increasing energy use and the need to mitigate climate change make production of liquid biofuels a high priority. Farmers respond worldwide to this increasing demand by converting forests and grassland into biofuel crops, but whether biofuels offer carbon savings depends on the carbon emissions that occur when land use is changed to biofuel crops. This paper reports the results of a study on cassava-based bioethanol production undertaken in the Sikasso region in Southern Mali. The paper outlines the estimated impacts on above-ground carbon stocks when land use is changed to increase cassava production. The results show that expansion of cassava production for bioethanol will most likely lead to the conversion of fallow areas to cassava. A land use change from fallow to cassava creates a reduction in the above-ground carbon stocks in the order of 4–13 Mg C ha−1, depending on (a) the age of the fallow, (b) the allometric equation used and (c) whether all trees are removed or the larger, useful trees are preserved. This ‘carbon debt’ associated with the above-ground biomass loss would take 8–25 years to repay if fossil fuels are replaced with cassava-based bioethanol. - Highlights: ► Demands for biofuels make production of cassava-based bioethanol a priority. ► Farmers in Southern Mali are likely to convert fallow areas to cassava production. ► Converting fallow to cassava creates reductions in above-ground carbon stocks. ► Estimates of carbon stock reductions include that farmers preserve useful trees. ► The carbon debt associated with above-ground biomass loss takes 8–25 years to repay.

  20. Above ground biomass estimation from lidar and hyperspectral airbone data in West African moist forests.

    Vaglio Laurin, Gaia; Chen, Qi; Lindsell, Jeremy; Coomes, David; Cazzolla-Gatti, Roberto; Grieco, Elisa; Valentini, Riccardo

    2013-04-01

    The development of sound methods for the estimation of forest parameters such as Above Ground Biomass (AGB) and the need of data for different world regions and ecosystems, are widely recognized issues due to their relevance for both carbon cycle modeling and conservation and policy initiatives, such as the UN REDD+ program (Gibbs et al., 2007). The moist forests of the Upper Guinean Belt are poorly studied ecosystems (Vaglio Laurin et al. 2013) but their role is important due to the drier condition expected along the West African coasts according to future climate change scenarios (Gonzales, 2001). Remote sensing has proven to be an effective tool for AGB retrieval when coupled with field data. Lidar, with its ability to penetrate the canopy provides 3D information and best results. Nevertheless very limited research has been conducted in Africa tropical forests with lidar and none to our knowledge in West Africa. Hyperspectral sensors also offer promising data, being able to evidence very fine radiometric differences in vegetation reflectance. Their usefulness in estimating forest parameters is still under evaluation with contrasting findings (Andersen et al. 2008, Latifi et al. 2012), and additional studies are especially relevant in view of forthcoming satellite hyperspectral missions. In the framework of the EU ERC Africa GHG grant #247349, an airborne campaign collecting lidar and hyperspectral data has been conducted in March 2012 over forests reserves in Sierra Leone and Ghana, characterized by different logging histories and rainfall patterns, and including Gola Rainforest National Park, Ankasa National Park, Bia and Boin Forest Reserves. An Optech Gemini sensor collected the lidar dataset, while an AISA Eagle sensor collected hyperspectral data over 244 VIS-NIR bands. The lidar dataset, with a point density >10 ppm was processed using the TIFFS software (Toolbox for LiDAR Data Filtering and Forest Studies)(Chen 2007). The hyperspectral dataset, geo

  1. Estimation of above ground biomass by using multispectral data for Evergreen Forest in Phu Hin Rong Kla National Park, Thailand

    Tropical forest is the most important and largest source for stocking CO2 from the atmosphere which might be one of the main sources of carbon emission, global warming and climate change in recent decades. There are two main objectives of this study. The first one is to establish a relationship between above ground biomass and vegetation indices and the other is to evaluate above ground biomass and carbon sequestration for evergreen forest areas in Phu Hin Rong Kla National park, Thailand. Random sampling design based was applied for calculating the above ground biomass at stand level in the selected area by using Brown and Tsutsumi allometric equations. Landsat 7 ETM+ data in February 2009 was used. Support Vector Machine (SVM) was applied for identifying evergreen forest area. Forty-three of vegetation indices and image transformations were used for finding the best correlation with forest stand biomass. Regression analysis was used to investigate the relationship between the biomass volume at stand level and digital data from the satellite image. TM51 which derived from Tsutsumi allometric equation was the highest correlation with stand biomass. Normalized Difference Vegetation Index (NDVI) was not the best correlation in this study. The best biomass estimation model was from TM51 and ND71 (R2 =0.658). The totals of above ground biomass and carbon sequestration were 112,062,010 ton and 56,031,005 ton respectively. The application of this study would be quite useful for understanding the terrestrial carbon dynamics and global climate change. (author)

  2. Forest Structure, Composition and Above Ground Biomass of Tree Community in Tropical Dry Forests of Eastern Ghats, India

    Sudam Charan SAHU

    2016-03-01

    Full Text Available The study of biomass, structure and composition of tropical forests implies also the investigation of forest productivity, protection of biodiversity and removal of CO2 from the atmosphere via C-stocks. The hereby study aimed at understanding the forest structure, composition and above ground biomass (AGB of tropical dry deciduous forests of Eastern Ghats, India, where as a total of 128 sample plots (20 x 20 meters were laid. The study showed the presence of 71 tree species belonging to 57 genera and 30 families. Dominant tree species was Shorea robusta with an importance value index (IVI of 40.72, while Combretaceae had the highest family importance value (FIV of 39.01. Mean stand density was 479 trees ha-1 and a basal area of 15.20 m2 ha-1. Shannon’s diversity index was 2.01 ± 0.22 and Simpson’s index was 0.85 ± 0.03. About 54% individuals were in the size between 10 and 20 cm DBH, indicating growing forests. Mean above ground biomass value was 98.87 ± 68.8 Mg ha-1. Some of the dominant species that contributed to above ground biomass were Shorea robusta (17.2%, Madhuca indica (7.9%, Mangifera indica (6.9%, Terminalia alata (6.9% and Diospyros melanoxylon (4.4%, warranting extra efforts for their conservation. The results suggested that C-stocks of tropical dry forests can be enhanced by in-situ conserving the high C-density species and also by selecting these species for afforestation and stand improvement programs. Correlations were computed to understand the relationship between above ground biomass, diversity indices, density and basal area, which may be helpful for implementation of REDD+ (reduce emissions from deforestation and forest degradation, and foster conservation, sustainable management of forests and enhancement of forest carbon stocks scheme.

  3. Forest Structure, Composition and Above Ground Biomass of Tree Community in Tropical Dry Forests of Eastern Ghats, India

    Sudam Charan SAHU; Ravindranath, N.H.; Suresh, H. S.

    2016-01-01

    The study of biomass, structure and composition of tropical forests implies also the investigation of forest productivity, protection of biodiversity and removal of CO2 from the atmosphere via C-stocks. The hereby study aimed at understanding the forest structure, composition and above ground biomass (AGB) of tropical dry deciduous forests of Eastern Ghats, India, where as a total of 128 sample plots (20 x 20 meters) were laid. The study showed the presence of 71 tree species belonging to 57 ...

  4. A Coevolutionary Arms Race: Understanding Plant-Herbivore Interactions

    Becklin, Katie M.

    2008-01-01

    Plants and insects share a long evolutionary history characterized by relationships that affect individual, population, and community dynamics. Plant-herbivore interactions are a prominent feature of this evolutionary history; it is by plant-herbivore interactions that energy is transferred from primary producers to the rest of the food web. Not…

  5. Transgenic cry1Ab/vip3H+epsps Rice with Insect and Herbicide Resistance Acted No Adverse Impacts on the Population Growth of a Non-Target Herbivore, the White-Backed Planthopper, Under Laboratory and Field Conditions

    LU Zeng-bin; HAN Nai-shun; TIAN Jun-ce; PENG Yu-fa; HU Cui; GUO Yu-yuan; SHEN Zhi-cheng; YE Gong-yin

    2014-01-01

    Numerous Bt rice lines expressing Cry protein derived from Bacillus thuringiensis Berliner (Bt) have been developed since 1989. However, the potential risks posed by Bt rice on non-target organisms still remain debate. The white-backed planthopper (WBPH), Sogatella furcifera (Horváth), is one of the most economically important insect pests of rice in Asian countries and also one of the main non-target herbivores of transgenic rice. In the current study, impacts of transgenic cry1Ab/vip3H+epsps rice (G6H1) with both insect and herbicide resistance on WBPH were evaluated to ascertain whether this transgenic rice line had potential risks for this sap-sucking pest under laboratory and ifeld conditions. The laboratory results showed that no signiifcant difference in egg developmental duration, nymphal survival rate and female fecundity was found for WBPH between G6H1 and its non-transgenic isoline (XS110). However, the development duration of nymphs was signiifcantly shorter and female longevity signiifcantly longer when WBPH fed on G6H1 by comparison with those on its control. To verify the results found in laboratory, a 3-yr ifeld trial was conducted to monitor WBPH population using both the vacuum-suction machine and beat plate methods. Although the seasonal density of WBPH nymphs and total density of nymphs and adults were not signiifcantly affected by transgenic rice regardless of the sampling methods, the seasonal density of WBPH adults in transgenic rice plots was slightly lower than that in the control when using the vacuum-suction machine. Based on these results both from laboratory and ifeld, it is clear that our tested transgenic rice line will not lead higher population of WBPH. However, long-term ifeld experiments to monitor the population dynamics of WPBH at large scale need to be conducted to conifrm the present conclusions in future.

  6. Transcriptional and metabolic signatures of Arabidopsis responses to chewing damage by an insect herbivore and bacterial infection and the consequences of their interaction

    Heidi M Appel

    2014-09-01

    Full Text Available Plants use multiple interacting signaling systems to identify and respond to biotic stresses. Although it is often assumed that there is specificity in signaling responses to specific pests, this is rarely examined outside of the gene-for-gene relationships of plant-pathogen interactions. In this study, we first compared early events in gene expression and later events in metabolite profiles of Arabidopsis thaliana following attack by either the caterpillar Spodoptera exigua or avirulent (DC3000 avrRpm1 Pseudomonas syringae pv. tomato at three time points. Transcriptional responses of the plant to caterpillar feeding were rapid, occurring within 1 h of feeding, and then decreased at 6 h and 24 h. In contrast, plant response to the pathogen was undetectable at 1 h but grew larger and more significant at 6 h and 24 h. There was a surprisingly large amount of overlap in jasmonate and salicylate signaling in responses to the insect and pathogen, including levels of gene expression and individual hormones. The caterpillar and pathogen treatments induced different patterns of expression of glucosinolate biosynthesis genes and levels of glucosinolates. This suggests that when specific responses develop, their regulation is complex and best understood by characterizing expression of many genes and metabolites. We then examined the effect of feeding by the caterpillar Spodoptera exigua on Arabidopsis susceptibility to virulent (DC3000 and avirulent (DC3000 avrRpm1 P. syringae pv. tomato, and found that caterpillar feeding enhanced Arabidopsis resistance to the avirulent pathogen and lowered resistance to the virulent strain. We conclude that efforts to improve plant resistance to bacterial pathogens are likely to influence resistance to insects and vice versa. Studies explicitly comparing plant responses to multiple stresses, including the role of elicitors at early time points, are critical to understanding how plants organize responses in natural

  7. Impact of Ground-Applied Termiticides on the Above-Ground Foraging Behavior of the Formosan Subterranean Termite.

    Henderson, Gregg; Gautam, Bal K; Wang, Cai

    2016-01-01

    We conducted a laboratory study to determine the impact of ground-applied termiticides on the above-ground foraging behavior of Coptotermes formosanus. Two concentrations (1 and 10 ppm) each of three termiticides, viz. fipronil, imidacloprid and chlorantraniliprole, were tested. After one month post-treatment (fipronil 10 ppm was run for 12 days only and all other treatments were run for one month), fipronil had the lowest percentage of survival (3%-4%) at both concentrations. Termite survival ranged from 31% to 40% in the case of imidacloprid treatments and 10 ppm chlorantraniliprole. However, 1 ppm chlorantraniliprole did not cause significant mortality compared to the controls. Foraging on the bottom substrate was evident in all replicates for all chemicals initially. However, a portion of the foraging population avoided the ground treatment toxicants after several days of bottom foraging. Only the slower-acting non-repellents created this repellent barrier, causing avoidance behavior that was most likely due to dead termites and fungus buildup on the treated bottom substrate. Fipronil appeared more toxic and faster acting at the concentrations tested, thus limiting this repellent effect. Suggestions by the pest control industry in Louisiana that some non-repellents can create a repellent barrier stranding live termites above ground are supported by this laboratory study. PMID:27571108

  8. Modeling the spatial distribution of above-ground carbon in Mexican coniferous forests using remote sensing and a geostatistical approach

    Galeana-Pizaña, J. Mauricio; López-Caloca, Alejandra; López-Quiroz, Penélope; Silván-Cárdenas, José Luis; Couturier, Stéphane

    2014-08-01

    Forest conservation is considered an option for mitigating the effect of greenhouse gases on global climate, hence monitoring forest carbon pools at global and local levels is important. The present study explores the capability of remote-sensing variables (vegetation indices and textures derived from SPOT-5; backscattering coefficient and interferometric coherence of ALOS PALSAR images) for modeling the spatial distribution of above-ground biomass in the Environmental Conservation Zone of Mexico City. Correlation and spatial autocorrelation coefficients were used to select significant explanatory variables in fir and pine forests. The correlation for interferometric coherence in HV polarization was negative, with correlations coefficients r = -0.83 for the fir and r = -0.75 for the pine forests. Regression-kriging showed the least root mean square error among the spatial interpolation methods used, with 37.75 tC/ha for fir forests and 29.15 tC/ha for pine forests. The results showed that a hybrid geospatial method, based on interferometric coherence data and a regression-kriging interpolator, has good potential for estimating above-ground biomass carbon.

  9. Statistical analysis of indoor radon concentrations in a reinforced concrete building with three stories above ground and one basement

    It is important to understand 222Rn concentrations in dwellings precisely for dose assessment. 222Rn concentrations were continuously measured in a reinforced-concrete house in Tokyo with three stories above ground and one basement for seven years, from October 1988 to September 1995. In the basement, temperature and humidity were also measured, which were used for analyzing the seasonal variation of the 222Rn concentration and its relationship with environmental factors. 222Rn concentrations on the 2nd and 3rd floors showed a statistically significant seasonal variation, i.e., higher in winter and lower in summer, but those on the 1st floor did not show any significant seasonal variation. The 222Rn concentration in the basement showed a reverse seasonal variation, i.e., higher in summer and lower in winter. The 222Rn concentrations on each floor showed a drastic decrease after the renewal of the dehumidifier in the basement, which suggests that the 222Rn concentration in the basement has an influence on that in the rooms above ground. A multiple regression analysis suggested that the 222Rn concentration in the basement and its seasonal variation can be expressed with statistical significance by the linear combination of temperature, humidity and atmospheric pressure. It was also revealed that the 222Rn concentration on the 1st floor can be expressed by the linear combination of the concentrations in the basement, 2nd and 3rd floors. (author)

  10. Above-ground Woody Biomass Production of Short-rotation Populus Plantations on Agricultural Land in Sweden

    Karacic, Almir; Verwijst, Theo; Weih, Martin [Swedish Univ. of Agricultural Sciences, Uppsala (Sweden). Dept. of Short Rotation Forestry

    2003-09-01

    Although poplars are widely grown in short-rotation forestry in many countries, little is known about poplar growth performance in Sweden. In this study, above-ground biomass production was estimated for several hybrid aspen and poplar clones planted at different initial density at five locations across Sweden. Biomass assessments were based on allometric relationships between total above-ground woody dry weight and the diameter at breast height. According to a common harvest practice, tree biomass was partitioned into pulpwood and biomass for energy purposes. The percentage of pulpwood was strongly determined by clone for DBH >10 cm. The mean annual increment ranged from 3.3 /ha/yr for balsam poplar in the north to 9.2 Mg/ha/yr for 9-yr-old 'Boelare' in southern Sweden. At the same age, hybrid aspen reached 7.9 Mg/ha/yr. The results suggest that poplars and hybrid aspen are superior as biomass producers compared with tree species commonly grown on agricultural land at these latitudes. The results are discussed in the light of future wood supply for pulpwood and energy purposes in Sweden.

  11. Development of Allometric Equations for Estimating Above-Ground Liana Biomass in Tropical Primary and Secondary Forests, Malaysia

    Patrick Addo-Fordjour

    2013-01-01

    Full Text Available The study developed allometric equations for estimating liana stem and total above-ground biomass in primary and secondary forests in the Penang National Park, Penang, Malaysia. Using biomass-diameter-length data of 60 liana individuals representing 15 species, allometric equations were developed for liana stem biomass and total above-ground biomass (TAGB. Three types of allometric equations were developed: models fitted to untransformed, weighted, and log-transformed (log10 data. There was a significant linear relationship between biomass and the predictors (diameter, length, and/or their combinations. The same set of models was developed for primary and secondary forests due to absence of differences in regression line slopes of the forests (ANCOVA: . The coefficients of determination values of the models were high (stem: 0.861 to 0.990; TAGB: 0.900 to 0.992. Generally, log-transformed models showed better fit (Furnival's index, FI 0.5. A comparison of the best TAGB model in this study (based on FI with previously published equations indicated that most of the equations significantly ( overestimated TAGB of lianas. However, a previous equation from Southeast Asia estimated TAGB similar to that of the current equation (. Therefore, regional or intracontinental equations should be preferred to intercontinental equations when estimating liana biomass.

  12. Molecular interactions between the specialist herbivore Manduca sexta (Lepidoptera, Sphingidae) and its natural host Nicotiana attenuata. II. Accumulation of plant mRNAs in response to insect-derived cues.

    Schittko, U; Hermsmeier, D; Baldwin, I T

    2001-02-01

    The transcriptional changes in Nicotiana attenuata Torr. ex Wats. elicited by attack from Manduca sexta larvae were previously characterized by mRNA differential display (D. Hermsmeier, U. Schittko, I.T. Baldwin [2001] Plant Physiol 125: 683-700). Because herbivore attack causes wounding, we disentangled wound-induced changes from those elicited by M. sexta oral secretions and regurgitant (R) with a northern analysis of a subset of the differentially expressed transcripts encoding threonine deaminase, pathogen-induced oxygenase, a photosystem II light-harvesting protein, a retrotransposon homolog, and three unknown genes. R extensively modified wound-induced responses by suppressing wound-induced transcripts (type I) or amplifying the wound-induced response (type II) further down-regulating wound-suppressed transcripts (type IIa) or up-regulating wound-induced transcripts (type IIb). It is interesting that although all seven genes displayed their R-specific patterns in the treated tissues largely independently of the leaf or plant developmental stage, only the type I genes displayed strong systemic induction. Ethylene was not responsible for any of the specific patterns of expression. R collected from different tobacco feeding insects, M. sexta, Manduca quinquemaculata, and Heliothis virescens, as well as from different instars of M. sexta were equally active. The active components of M. sexta R were heat stable and active in minute amounts, comparable with real transfer rates during larval feeding. Specific expression patterns may indicate that the plant is adjusting its wound response to efficiently fend off M. sexta, but may also be advantageous to the larvae, especially when R suppress wound-induced plant responses. PMID:11161027

  13. Long-term changes in above ground biomass after disturbance in a neotropical dry forest, Hellshire Hills, Jamaica

    Niño, Milena; McLaren, Kurt P.; Meilby, Henrik;

    2014-01-01

    We used data from experimental plots (control, partially cut and clear-cut) established in 1998, in a tropical dry forest (TDF) in Jamaica, to assess changes in above ground biomass (AGB) 10 years after disturbance. The treatments reduced AGB significantly in 1999 (partially cut: 37.6 %, clear-cu.......4 years for the clear-cut plots to recover pre-treatment AGB; this is significantly longer than AGB recovery time for some successional rainforests on abandoned pastures/farmland. Consequently, this TDF may not be as resilient as tropical rainforests.......-cut: 94.4 %) and after 10 years, AGB did not recover overall, nor did it recover in the clear-cut plots. Partially cut plots, however, recovered the lost AGB in 10 years via growth of uncut trees, which contributed significantly to biomass recovery, with only minor contributions from recruited trees and...

  14. A first map of tropical Africa's above-ground biomass derived from satellite imagery

    Baccini, A; Laporte, N; Goetz, S J; Sun, M [Woods Hole Research Center, 149 Woods Hole Road, Falmouth, MA 02540 (United States); Dong, H [Atmospheric Sciences Division, Brookhaven National Laboratory, Upton, NY 11973 (United States)], E-mail: abaccini@whrc.org

    2008-10-15

    Observations from the moderate resolution imaging spectroradiometer (MODIS) were used in combination with a large data set of field measurements to map woody above-ground biomass (AGB) across tropical Africa. We generated a best-quality cloud-free mosaic of MODIS satellite reflectance observations for the period 2000-2003 and used a regression tree model to predict AGB at 1 km resolution. Results based on a cross-validation approach show that the model explained 82% of the variance in AGB, with a root mean square error of 50.5 Mg ha{sup -1} for a range of biomass between 0 and 454 Mg ha{sup -1}. Analysis of lidar metrics from the Geoscience Laser Altimetry System (GLAS), which are sensitive to vegetation structure, indicate that the model successfully captured the regional distribution of AGB. The results showed a strong positive correlation (R{sup 2} = 0.90) between the GLAS height metrics and predicted AGB.

  15. Tree Species Composition, Diversity and Above Ground Biomass of Two Forest Types at Redang Island, Peninsula Malaysia

    Mahmud KHAIRIL

    2013-02-01

    Full Text Available A study was conducted to determine the tree species composition, diversity and above ground biomass at Redang Island, Terengganu. Two plots of 0.1 ha were established at the inland forest and coastal forest of the island. As the result, a total of 387 trees ≥ 5 diameters at breast height (DBH were recorded. The coastal forest recorded 167 individuals representing 48 species from 37 genera and 26 families while the inland forest had 220 individuals representing 50 species from 43 genera and 25 families. Shorea glauca (Dipterocarpaceae was the most important species at the coastal forest with a Species Importance Value Index (SIVi of 10.5 % while Dipterocarpus costulatus (Dipterocarpaceae was the most important species at the inland forest with 13.8 %. Dipterocarpaceae was the most important family in both forest plots with FIVi at 20.4 % in the coastal and 21.5 % in the inland forest. The Shannon-Weiner Diversity Index (H’ was considered high in both forest plots with 3.4 (H’max = 3.9 at the coastal forest and 3.5 (H’max = 4.0 at the inland forest. Sorenson’s Community Similarity Coefficient (CCs showed that tree species communities between the two forest plots had moderate similarity with CC = 0.5. The Shannon Evenness Index (J’ in the two forest plots was 0.89. The total above ground biomass at the coastal forest was 491 t/ha and at the inland forest it was 408 t/ha. From all the species recorded in this study, 11 species were listed as threatened species by IUCN Red Data Book, of which four were listed as endangered and critically endangered, six were listed as lower risk and one species was listed as vulnerable.

  16. Predictive modeling of hazardous waste landfill total above-ground biomass using passive optical and LIDAR remotely sensed data

    Hadley, Brian Christopher

    This dissertation assessed remotely sensed data and geospatial modeling technique(s) to map the spatial distribution of total above-ground biomass present on the surface of the Savannah River National Laboratory's (SRNL) Mixed Waste Management Facility (MWMF) hazardous waste landfill. Ordinary least squares (OLS) regression, regression kriging, and tree-structured regression were employed to model the empirical relationship between in-situ measured Bahia (Paspalum notatum Flugge) and Centipede [Eremochloa ophiuroides (Munro) Hack.] grass biomass against an assortment of explanatory variables extracted from fine spatial resolution passive optical and LIDAR remotely sensed data. Explanatory variables included: (1) discrete channels of visible, near-infrared (NIR), and short-wave infrared (SWIR) reflectance, (2) spectral vegetation indices (SVI), (3) spectral mixture analysis (SMA) modeled fractions, (4) narrow-band derivative-based vegetation indices, and (5) LIDAR derived topographic variables (i.e. elevation, slope, and aspect). Results showed that a linear combination of the first- (1DZ_DGVI), second- (2DZ_DGVI), and third-derivative of green vegetation indices (3DZ_DGVI) calculated from hyperspectral data recorded over the 400--960 nm wavelengths of the electromagnetic spectrum explained the largest percentage of statistical variation (R2 = 0.5184) in the total above-ground biomass measurements. In general, the topographic variables did not correlate well with the MWMF biomass data, accounting for less than five percent of the statistical variation. It was concluded that tree-structured regression represented the optimum geospatial modeling technique due to a combination of model performance and efficiency/flexibility factors.

  17. Chemical ecology of insects and tritrophic interactions

    This paper reviews the chemical ecology of insects to explain the role of semiochemicals in plant-herbivore, herbivore-carnivore and plant-carnivore interactions. The semiochemical, mediating tritrophic interactions may be produced by plants, herbivores or their natural enemies (carnivores). Some semiochemicals attract the herbivores and carnivores and mediate interaction among them, while on the other hand some repel them. The semiochemicals are used by heribivores, parasites and predators as cues to locate food, host or prey. The same chemicals are also used for defensive purpose by some herbivores against their natural enemies as they are sequestered through their bodies. (author)

  18. Emerging role of roots in plant responses to aboveground insect herbivory

    Vamsi J.Nalam; Jyoti Shah; Punya Nachappa

    2013-01-01

    Plants have evolved complex biochemical mechanisms to counter threats from insect herbivory.Recent research has revealed an important role of roots in plant responses to above ground herbivory (AGH).The involvement of roots is integral to plant resistance and tolerance mechanisms.Roots not only play an active role in plant defenses by acting as sites for biosynthesis of various toxins and but also contribute to tolerance by storing photoassimilates to enable future regrowth.The interaction of roots with beneficial soilborne microorganisms also influences the outcome of the interaction between plant and insect herbivores.Shoot-to-root communication signals are critical for plant response to AGH.A better understanding of the role of roots in plant response to AGH is essential in order to develop a comprehensive picture of plant-insect interactions.Here,we summarize the current status of research on the role of roots in plant response to AGH and also discuss possible signals involved in shoot-to-root communication.

  19. Ecology of herbivorous arthropods in urban landscapes.

    Raupp, Michael J; Shrewsbury, Paula M; Herms, Daniel A

    2010-01-01

    Urbanization affects communities of herbivorous arthropods and provides opportunities for dramatic changes in their abundance and richness. Underlying these changes are creation of impervious surfaces; variation in the density, diversity, and complexity of vegetation; and maintenance practices including pulsed inputs of fertilizers, water, and pesticides. A rich body of knowledge provides theoretical underpinnings for predicting and understanding impacts of urbanization on arthropods. However, relatively few studies have elucidated mechanisms that explain patterns of insect and mite abundance and diversity across urbanization gradients. Published accounts suggest that responses to urbanization are often taxon specific, highly variable, and linked to properties of urbanization that weaken top-down and/or bottom-up processes, thereby destabilizing populations of herbivores and their natural enemies. In addition to revealing patterns in diversity and abundance of herbivores across urbanization gradients, a primary objective of this review is to examine mechanisms underlying these patterns and to identify potential hypotheses for future testing. PMID:19961321

  20. Tree density on a vegetated uranium mill tailings site and associated estimates of Ra-226 in above ground biomass

    The transfer of Ra-226 to the terrestrial pathway will depend on the uptake by indigenous species which colonize dry areas of inactive or abandoned uranium mill tailings sites. The density of trembling aspen and white birch, their heights and biomass values, have been determined 10 to 15 years after revegetation. In addition the percentage composition of the ground cover for herbs, shrubs and grasses is evaluated. For aspens of less than 1 m in height, the density of 0.0536 trees/m2 was considerably higher than for birches of the same height with 0.0097 trees/m2. As tree heights increase the number of trees/m2 decrease to 0.0049 and 0.0010 respectively for 3 to 4 m tall trees. Trees taller than 4 m were rarely found. The ground cover biomass (approximately 125 g/m2) consisted generally of two types; either shrubs were dominant or herbs and grasses prevailed. From Ra-226 concentrations in different above-ground biomass components and the average composition of the vegetation on one square metre, transfer values were estimated. Annual transfer by herbal biomass (leaves, herbs and grasses) ranged from 330 to 760 pCi/m2. The standing crop of woody biomass was estimated to range from 450 to 1700 pCi/m2

  1. Above-ground biomass estimation of tuberous bulrush ( Bolboschoenus planiculmis) in mudflats using remotely sensed multispectral image

    Kim, Ji Yoon; Im, Ran-Young; Do, Yuno; Kim, Gu-Yeon; Joo, Gea-Jae

    2016-03-01

    We present a multivariate regression approach for mapping the spatial distribution of above-ground biomass (AGB) of B. planiculmis using field data and coincident moderate spatial resolution satellite imagery. A total of 232 ground sample plots were used to estimate the biomass distribution in the Nakdong River estuary. Field data were overlain and correlated with digital values from an atmospherically corrected multispectral image (Landsat 8). The AGB distribution was derived using empirical models trained with field-measured AGB data. The final regression model for AGB estimation was composed using the OLI3, OLI4, and OLI7 spectral bands. The Pearson correlation between the observed and predicted biomass was significant (R = 0.84, p coefficient value: 53.4%) and revealed a negative relationship with the AGB biomass. The total distribution area of B. planiculmis was 1,922,979 m2. Based on the model estimation, the total AGB had a dry weight (DW) of approximately 298.2 tons. The distribution of high biomass stands (> 200 kg DW/900 m2) constituted approximately 23.91% of the total vegetated area. Our findings suggest the expandability of remotely sensed products to understand the distribution pattern of estuarine plant productivity at the landscape level.

  2. Mapping Above-Ground Biomass in a Tropical Forest in Cambodia Using Canopy Textures Derived from Google Earth

    Minerva Singh

    2015-04-01

    Full Text Available This study develops a modelling framework for utilizing very high-resolution (VHR aerial imagery for monitoring stocks of above-ground biomass (AGB in a tropical forest in Southeast Asia. Three different texture-based methods (grey level co-occurrence metric (GLCM, Gabor wavelets and Fourier-based textural ordination (FOTO were used in conjunction with two different machine learning (ML-based regression techniques (support vector regression (SVR and random forest (RF regression. These methods were implemented on both 50-cm resolution Digital Globe data extracted from Google Earth™ (GE and 8-cm commercially obtained VHR imagery. This study further examines the role of forest biophysical parameters, such as ground-measured canopy cover and vertical canopy height, in explaining AGB distribution. Three models were developed using: (i horizontal canopy variables (i.e., canopy cover and texture variables plus vertical canopy height; (ii horizontal variables only; and (iii texture variables only. AGB was variable across the site, ranging from 51.02 Mg/ha to 356.34 Mg/ha. GE-based AGB estimates were comparable to those derived from commercial aerial imagery. The findings demonstrate that novel use of this array of texture-based techniques with GE imagery can help promote the wider use of freely available imagery for low-cost, fine-resolution monitoring of forests parameters at the landscape scale.

  3. Nitrogen mediates above-ground effects of ozone but not below-ground effects in a rhizomatous sedge

    Jones, M.L.M., E-mail: lj@ceh.ac.u [Centre for Ecology and Hydrology (CEH), Environment Centre Wales, Deiniol Road, Bangor, LL57 2UW Wales (United Kingdom); Hodges, G. [AMEC, Earth and Environmental UK Ltd, Unit 1, Trinity Place, Thames St, Weybridge, Surrey KT13 8JB (United Kingdom); Mills, G. [Centre for Ecology and Hydrology (CEH), Environment Centre Wales, Deiniol Road, Bangor, LL57 2UW Wales (United Kingdom)

    2010-02-15

    Ozone and atmospheric nitrogen are co-occurring pollutants with adverse effects on natural grassland vegetation. Plants of the rhizomatous sedge Carex arenaria were exposed to four ozone regimes representing increasing background concentrations (background-peak): 10-30, 35-55, 60-80 and 85-105 ppb ozone at two nitrogen levels: 12 and 100 kg N ha{sup -1} yr{sup -1}. Ozone increased the number and proportion of senesced leaves, but not overall leaf number. There was a clear nitrogen x ozone interaction with high nitrogen reducing proportional senescence in each treatment and increasing the ozone dose (AOT40) at which enhanced senescence occurred. Ozone reduced total biomass due to significant effects on root biomass. There were no interactive effects on shoot:root ratio. Rhizome tissue N content was increased by both nitrogen and ozone. Results suggest that nitrogen mediates above-ground impacts of ozone but not impacts on below-ground resource translocation. This may lead to complex interactive effects between the two pollutants on natural vegetation. - Nitrogen alters threshold of ozone-induced senescence, but not below-ground resource allocation.

  4. Above Ground Leafless Woody Biomass and Nutrient Content within Different Compartments of a P. maximowicii × P. trichocarpa Poplar Clone

    Heinrich Spiecker

    2013-06-01

    Full Text Available In this study the quantification of biomass within all relevant compartments of a three-year-old poplar clone (P. maximowicii × P. trichocarpa planted on abandoned agricultural land at a density of 5000 trees ha−1 is presented. A total of 30 trees within a diameter range of 1.8 cm to 8.9 cm, at breast height (dbh at 1.3 m, were destructively sampled. In order to analyze the biomass, the complete tree, stem, as well as all branches, were divided into 1 cm diameter classes and all buds from the trees were completely removed. Total yield was calculated as 11.7 odt ha−1 year−1 (oven dry tonnes per hectare and year. Branches constituted 22.2% of total dry leafless biomass and buds 2.0%. The analyses revealed a strong correlation of the dry weight for all the three compartments with diameter at breast height. Debarked sample discs were used to obtain a ratio between wood and bark. Derived from these results, a model was developed to calculate the biomass of bark with dbh as the predictor variable. Mean bark percentage was found to be 16.8% of above ground leafless biomass. The results concur that bark percentage decreases with increasing tree diameter, providing the conclusion that larger trees contain a lower bark proportion, and thus positively influence the quality of the end product while consequently reducing the export of nutrients from site.

  5. Above-ground biomass models for Seabuckthorn (Hippophae salicifolia) in Mustang District, Nepal

    Rajchal, Rajesh; Meilby, Henrik

    2013-01-01

    fresh weight of fruit and oven-dry weight of wood (stem and branches) and leaves were measured and used as a basis for developing biomass models. Diameters of the trees were measured at 30 cm above ground whereas the heights were measured in terms of the total tree height (m). Among several models...... tested, the models suggested for local use were: ln(woody biomass, oven-dry, kg) = -3.083 + 2.436 ln(diameter, cm), ln (fruit biomass, fresh, kg) = -3.237 + 1.346 ln(diameter, cm) and ln(leaf biomass, oven-dry, kg) = -4.013 + 1.403 ln(Diameter, cm) with adjusted coefficients of determination of 0.99, 0.......73 and 0.91 for wood, fruit, and leaves, respectively. The models suggested for a slightly broader range of environmental conditions were: ln (woody biomass, oven-dry, kg) = -3.277 + 0.924 ln(diameter2 × height), ln(Fruit biomass, fresh, kg) = -3.146 + 0.485 ln(diameter2 × height) and ln(leaf biomass...

  6. Phytohormone mediation of interactions between herbivores and plant pathogens.

    Lazebnik, Jenny; Frago, Enric; Dicke, Marcel; van Loon, Joop J A

    2014-07-01

    Induced plant defenses against either pathogens or herbivore attackers are regulated by phytohormones. These phytohormones are increasingly recognized as important mediators of interactions between organisms associated with plants. In this review, we discuss the role of plant defense hormones in sequential tri-partite interactions among plants, pathogenic microbes, and herbivorous insects, based on the most recent literature. We discuss the importance of pathogen trophic strategy in the interaction with herbivores that exhibit different feeding modes. Plant resistance mechanisms also affect plant quality in future interactions with attackers. We discuss exemplary evidence for the hypotheses that (i) biotrophic pathogens can facilitate chewing herbivores, unless plants exhibit effector-triggered immunity, but (ii) facilitate or inhibit phloem feeders. (iii) Necrotrophic pathogens, on the other hand, can inhibit both phloem feeders and chewers. We also propose herbivore feeding mode as predictor of effects on pathogens of different trophic strategies, providing evidence for the hypotheses that (iv) phloem feeders inhibit pathogen attack by increasing SA induction, whereas (v) chewing herbivores tend not to affect necrotrophic pathogens, while they may either inhibit or facilitate biotrophic pathogens. Putting these hypotheses to the test will increase our understanding of phytohormonal regulation of plant defense to sequential attack by plant pathogens and insect herbivores. This will provide valuable insight into plant-mediated ecological interactions among members of the plant-associated community. PMID:25059974

  7. Above-Ground Dimensions and Acclimation Explain Variation in Drought Mortality of Scots Pine Seedlings from Various Provenances

    Seidel, Hannes; Menzel, Annette

    2016-01-01

    Seedling establishment is a critical part of the life cycle, thus seedling survival might be even more important for forest persistence under recent and future climate change. Scots pine forests have been disproportionally more affected by climate change triggered forest-dieback. Nevertheless, some Scots pine provenances might prove resilient to future drought events because of the species’ large distributional range, genetic diversity, and adaptation potential. However, there is a lack of knowledge on provenance-specific survival under severe drought events and on how acclimation alters survival rates in Scots pine seedlings. We therefore conducted two drought-induced mortality experiments with potted Scots pine seedlings in a greenhouse. In the first experiment, 760 three-year-old seedlings from 12 different provenances of the south-western distribution range were subjected to the same treatment followed by the mortality experiment in 2014. In the second experiment, we addressed the question of whether acclimation to re-occurring drought stress events and to elevated temperature might decrease mortality rates. Thus, 139 four-year-old seedlings from France, Germany, and Poland were subjected to different temperature regimes (2012–2014) and drought treatments (2013–2014) before the mortality experiment in 2015. Provenances clearly differed in their hazard of drought-induced mortality, which was only partly related to the climate of their origin. Drought acclimation decreased the hazard of drought-induced mortality. Above-ground dry weight and height were the main determinants for the hazard of mortality, i.e., heavier and taller seedlings were more prone to mortality. Consequently, Scots pine seedlings exhibit a considerable provenance-specific acclimation potential against drought mortality and the selection of suitable provenances might thus facilitate seedling establishment and the persistence of Scots pine forest. PMID:27458477

  8. Sensitivity of Above-Ground Biomass Estimates to Height-Diameter Modelling in Mixed-Species West African Woodlands.

    Valbuena, Rubén; Heiskanen, Janne; Aynekulu, Ermias; Pitkänen, Sari; Packalen, Petteri

    2016-01-01

    It has been suggested that above-ground biomass (AGB) inventories should include tree height (H), in addition to diameter (D). As H is a difficult variable to measure, H-D models are commonly used to predict H. We tested a number of approaches for H-D modelling, including additive terms which increased the complexity of the model, and observed how differences in tree-level predictions of H propagated to plot-level AGB estimations. We were especially interested in detecting whether the choice of method can lead to bias. The compared approaches listed in the order of increasing complexity were: (B0) AGB estimations from D-only; (B1) involving also H obtained from a fixed-effects H-D model; (B2) involving also species; (B3) including also between-plot variability as random effects; and (B4) involving multilevel nested random effects for grouping plots in clusters. In light of the results, the modelling approach affected the AGB estimation significantly in some cases, although differences were negligible for some of the alternatives. The most important differences were found between including H or not in the AGB estimation. We observed that AGB predictions without H information were very sensitive to the environmental stress parameter (E), which can induce a critical bias. Regarding the H-D modelling, the most relevant effect was found when species was included as an additive term. We presented a two-step methodology, which succeeded in identifying the species for which the general H-D relation was relevant to modify. Based on the results, our final choice was the single-level mixed-effects model (B3), which accounts for the species but also for the plot random effects reflecting site-specific factors such as soil properties and degree of disturbance. PMID:27367857

  9. Structure and distribution of glandular and non-glandular trichomes on above-ground organs in Inula helenium L. (Asteraceae

    Aneta Sulborska

    2014-01-01

    Full Text Available Micromorphology and distribution of glandular and non-glandular trichomes on the above-ground organs of Inula helenium L. were investigated using light and scanning electron microscopy (SEM. Two types of biseriate glandular trichomes, i.e. sessile and stalk hairs, and non-glandular trichomes were recorded. Sessile glandular trichomes were found on all examined I. helenium organs (with their highest density on the abaxial surface of leaves and disk florets, and on stems, whereas stalk glandular trichomes were found on leaves and stems. Sessile trichomes were characterised by a slightly lower height (58–103 μm and width (32–35 μm than the stalk trichomes (62–111 μm x 31–36 μm. Glandular hairs were composed of 5–7 (sessile trichomes or 6–9 (stalk trichomes cell tiers. Apical trichome cell tiers exhibited features of secretory cells. Secretion was accumulated in subcuticular space, which expanded and ruptured at the top, and released its content. Histochemical assays showed the presence of lipids and polyphenols, whereas no starch was detected. Non-glandular trichomes were seen on involucral bracts, leaves and stems (more frequently on involucral bracts. Their structure comprised 2–9 cells; basal cells (1–6 were smaller and linearly arranged, while apical cells had a prozenchymatous shape. The apical cell was the longest and sharply pointed. Applied histochemical tests revealed orange-red (presence of lipids and brow colour (presence of polyphenols in the apical cells of the trichomes. This may suggest that beside their protective role, the trichomes may participate in secretion of secondary metabolites.

  10. Risk Assessment of Genetically Engineered Maize Resistant to Diabrotica spp.: Influence on Above-Ground Arthropods in the Czech Republic.

    Svobodová, Zdeňka; Skoková Habuštová, Oxana; Hutchison, William D; Hussein, Hany M; Sehnal, František

    2015-01-01

    Transgenic maize MON88017, expressing the Cry3Bb1 toxin from Bacillus thuringiensis (Bt maize), confers resistance to corn rootworms (Diabrotica spp.) and provides tolerance to the herbicide glyphosate. However, prior to commercialization, substantial assessment of potential effects on non-target organisms within agroecosystems is required. The MON88017 event was therefore evaluated under field conditions in Southern Bohemia in 2009-2011, to detect possible impacts on the above-ground arthropod species. The study compared MON88017, its near-isogenic non-Bt hybrid DK315 (treated or not treated with the soil insecticide Dursban 10G) and two non-Bt reference hybrids (KIPOUS and PR38N86). Each hybrid was grown on five 0.5 ha plots distributed in a 14-ha field with a Latin square design. Semiquantitative ELISA was used to verify Cry3Bb1 toxin levels in the Bt maize. The species spectrum of non-target invertebrates changed during seasons and was affected by weather conditions. The thrips Frankliniella occidentalis was the most abundant species in all three successive years. The next most common species were aphids Rhopalosiphum padi and Metopolophium dirhodum. Frequently observed predators included Orius spp. and several species within the Coccinellidae. Throughout the three-year study, analysis of variance indicated some significant differences (Pinsects was similar in maize with the same genetic background, for both Bt (MON88017) and non-Bt (DK315) untreated or insecticide treated. KIPOUS and PR38N86 showed some differences in species abundance relative to the Bt maize and its near-isogenic hybrid. However, the effect of management regime on arthropod community was insignificant and accounted only for a negligible portion of the variability. PMID:26083254

  11. Influence of landscape heterogeneity on spatial patterns of wood productivity, wood specific density and above ground biomass in Amazonia

    Anderson, L. O.; Malhi, Y.; Ladle, R. J.; Aragão, L. E. O. C.; Shimabukuro, Y.; Phillips, O. L.; Baker, T.; Costa, A. C. L.; Espejo, J. S.; Higuchi, N.; Laurance, W. F.; López-González, G.; Monteagudo, A.; Núñez-Vargas, P.; Peacock, J.; Quesada, C. A.; Almeida, S.

    2009-09-01

    Long-term studies using the RAINFOR network of forest plots have generated significant insights into the spatial and temporal dynamics of forest carbon cycling in Amazonia. In this work, we map and explore the landscape context of several major RAINFOR plot clusters using Landsat ETM+ satellite data. In particular, we explore how representative the plots are of their landscape context, and test whether bias in plot location within landscapes may be influencing the regional mean values obtained for important forest biophysical parameters. Specifically, we evaluate whether the regional variations in wood productivity, wood specific density and above ground biomass derived from the RAINFOR network could be driven by systematic and unintentional biases in plot location. Remote sensing data covering 45 field plots were aggregated to generate landscape maps to identify the specific physiognomy of the plots. In the Landsat ETM+ data, it was possible to spectrally differentiate three types of terra firme forest, three types of forests over Paleovarzea geomorphologycal formation, two types of bamboo-dominated forest, palm forest, Heliconia monodominant vegetation, swamp forest, disturbed forests and land use areas. Overall, the plots were generally representative of the forest physiognomies in the landscape in which they are located. Furthermore, the analysis supports the observed regional trends in those important forest parameters. This study demonstrates the utility of landscape scale analysis of forest physiognomies for validating and supporting the finds of plot based studies. Moreover, the more precise geolocation of many key RAINFOR plot clusters achieved during this research provides important contextual information for studies employing the RAINFOR database.

  12. Influence of landscape heterogeneity on spatial patterns of wood productivity, wood specific density and above ground biomass in Amazonia

    L. O. Anderson

    2009-09-01

    Full Text Available Long-term studies using the RAINFOR network of forest plots have generated significant insights into the spatial and temporal dynamics of forest carbon cycling in Amazonia. In this work, we map and explore the landscape context of several major RAINFOR plot clusters using Landsat ETM+ satellite data. In particular, we explore how representative the plots are of their landscape context, and test whether bias in plot location within landscapes may be influencing the regional mean values obtained for important forest biophysical parameters. Specifically, we evaluate whether the regional variations in wood productivity, wood specific density and above ground biomass derived from the RAINFOR network could be driven by systematic and unintentional biases in plot location. Remote sensing data covering 45 field plots were aggregated to generate landscape maps to identify the specific physiognomy of the plots. In the Landsat ETM+ data, it was possible to spectrally differentiate three types of terra firme forest, three types of forests over Paleovarzea geomorphologycal formation, two types of bamboo-dominated forest, palm forest, Heliconia monodominant vegetation, swamp forest, disturbed forests and land use areas. Overall, the plots were generally representative of the forest physiognomies in the landscape in which they are located. Furthermore, the analysis supports the observed regional trends in those important forest parameters. This study demonstrates the utility of landscape scale analysis of forest physiognomies for validating and supporting the finds of plot based studies. Moreover, the more precise geolocation of many key RAINFOR plot clusters achieved during this research provides important contextual information for studies employing the RAINFOR database.

  13. Influence of landscape heterogeneity on spatial patterns of wood productivity, wood specific density and above ground biomass in Amazonia

    L. O. Anderson

    2009-02-01

    Full Text Available Long-term studies using the RAINFOR network of forest plots have generated significant insights into the spatial and temporal dynamics of forest carbon cycling in Amazonia. In this work, we map and explore the landscape context of several major RAINFOR plot clusters using Landsat ETM+ satellite data. In particular, we explore how representative the plots are of their landscape context, and test whether bias in plot location within landscapes may be influencing the regional mean values obtained for important forest biophysical parameters. Specifically, we evaluate whether the regional variations in wood productivity, wood specific density and above ground biomass derived from the RAINFOR network could be driven by systematic and unintentional biases in plot location. Remote sensing data covering 45 field plots were aggregated to generate landscape maps to identify the specific physiognomy of the plots. In the Landsat ETM+ data, it was possible to spectrally differentiate three types of terra firme forest, three types of alluvial terrain forest, two types of bamboo-dominated forest, palm forest, Heliconia monodominant vegetation, swamp forest, disturbed forests and land use areas. Overall, the plots were generally representative of the forest physiognomies in the landscape in which they are located. Furthermore, the analysis supports the observed regional trends in those important forest parameters. This study demonstrates the utility of landscape scale analysis of forest physiognomies for validating and supporting the finds of plot based studies. Moreover, the more precise geolocation of many key RAINFOR plot clusters achieved during this research provides important contextual information for studies employing the RAINFOR database.

  14. Above-Ground Dimensions and Acclimation Explain Variation in Drought Mortality of Scots Pine Seedlings from Various Provenances.

    Seidel, Hannes; Menzel, Annette

    2016-01-01

    Seedling establishment is a critical part of the life cycle, thus seedling survival might be even more important for forest persistence under recent and future climate change. Scots pine forests have been disproportionally more affected by climate change triggered forest-dieback. Nevertheless, some Scots pine provenances might prove resilient to future drought events because of the species' large distributional range, genetic diversity, and adaptation potential. However, there is a lack of knowledge on provenance-specific survival under severe drought events and on how acclimation alters survival rates in Scots pine seedlings. We therefore conducted two drought-induced mortality experiments with potted Scots pine seedlings in a greenhouse. In the first experiment, 760 three-year-old seedlings from 12 different provenances of the south-western distribution range were subjected to the same treatment followed by the mortality experiment in 2014. In the second experiment, we addressed the question of whether acclimation to re-occurring drought stress events and to elevated temperature might decrease mortality rates. Thus, 139 four-year-old seedlings from France, Germany, and Poland were subjected to different temperature regimes (2012-2014) and drought treatments (2013-2014) before the mortality experiment in 2015. Provenances clearly differed in their hazard of drought-induced mortality, which was only partly related to the climate of their origin. Drought acclimation decreased the hazard of drought-induced mortality. Above-ground dry weight and height were the main determinants for the hazard of mortality, i.e., heavier and taller seedlings were more prone to mortality. Consequently, Scots pine seedlings exhibit a considerable provenance-specific acclimation potential against drought mortality and the selection of suitable provenances might thus facilitate seedling establishment and the persistence of Scots pine forest. PMID:27458477

  15. Detection of large above-ground biomass variability in lowland forest ecosystems by airborne LiDAR

    J. Jubanski

    2013-06-01

    Full Text Available Quantification of tropical forest above-ground biomass (AGB over large areas as input for Reduced Emissions from Deforestation and forest Degradation (REDD+ projects and climate change models is challenging. This is the first study which attempts to estimate AGB and its variability across large areas of tropical lowland forests in Central Kalimantan (Indonesia through correlating airborne light detection and ranging (LiDAR to forest inventory data. Two LiDAR height metrics were analysed, and regression models could be improved through the use of LiDAR point densities as input (R2 = 0.88; n = 52. Surveying with a LiDAR point density per square metre of about 4 resulted in the best cost / benefit ratio. We estimated AGB for 600 km of LiDAR tracks and showed that there exists a considerable variability of up to 140% within the same forest type due to varying environmental conditions. Impact from logging operations and the associated AGB losses dating back more than 10 yr could be assessed by LiDAR but not by multispectral satellite imagery. Comparison with a Landsat classification for a 1 million ha study area where AGB values were based on site-specific field inventory data, regional literature estimates, and default values by the Intergovernmental Panel on Climate Change (IPCC showed an overestimation of 43%, 102%, and 137%, respectively. The results show that AGB overestimation may lead to wrong greenhouse gas (GHG emission estimates due to deforestation in climate models. For REDD+ projects this leads to inaccurate carbon stock estimates and consequently to significantly wrong REDD+ based compensation payments.

  16. Lasting effects of climate disturbance on perennial grassland above-ground biomass production under two cutting frequencies.

    Zwicke, Marine; Alessio, Giorgio A; Thiery, Lionel; Falcimagne, Robert; Baumont, René; Rossignol, Nicolas; Soussana, Jean-François; Picon-Cochard, Catherine

    2013-11-01

    Climate extremes can ultimately reshape grassland services such as forage production and change plant functional type composition. This 3-year field research studied resistance to dehydration and recovery after rehydration of plant community and plant functional types in an upland perennial grassland subjected to climate and cutting frequency (Cut+, Cut-) disturbances by measuring green tissue percentage and above-ground biomass production (ANPP). In year 1, a climate disturbance gradient was applied by co-manipulating temperature and precipitation. Four treatments were considered: control and warming-drought climatic treatment, with or without extreme summer event. In year 2, control and warming-drought treatments were maintained without extreme. In year 3, all treatments received ambient climatic conditions. We found that the grassland community was very sensitive to dehydration during the summer extreme: aerial senescence reached 80% when cumulated climatic water balance fell to -156 mm and biomass declined by 78% at the end of summer. In autumn, canopy greenness and biomass totally recovered in control but not in the warming-drought treatment. However ANPP decreased under both climatic treatments, but the effect was stronger on Cut+ (-24%) than Cut- (-15%). This decline was not compensated by the presence of three functional types because they were negatively affected by the climatic treatments, suggesting an absence of buffering effect on grassland production. In the following 2 years, lasting effects of climate disturbance on ANPP were observable. The unexpected stressful conditions of year 3 induced a decline in grassland production in the Cut+ control treatment. The fact that this treatment cumulated higher (45%) N export over the 3 years suggests that N plays a key role in ANPP stability. As ANPP in this mesic perennial grassland did not show engineering resilience, long-term experimental manipulation is needed. Infrequent mowing appears more

  17. Testing the generality of above-ground biomass allometry across plant functional types at the continent scale.

    Paul, Keryn I; Roxburgh, Stephen H; Chave, Jerome; England, Jacqueline R; Zerihun, Ayalsew; Specht, Alison; Lewis, Tom; Bennett, Lauren T; Baker, Thomas G; Adams, Mark A; Huxtable, Dan; Montagu, Kelvin D; Falster, Daniel S; Feller, Mike; Sochacki, Stan; Ritson, Peter; Bastin, Gary; Bartle, John; Wildy, Dan; Hobbs, Trevor; Larmour, John; Waterworth, Rob; Stewart, Hugh T L; Jonson, Justin; Forrester, David I; Applegate, Grahame; Mendham, Daniel; Bradford, Matt; O'Grady, Anthony; Green, Daryl; Sudmeyer, Rob; Rance, Stan J; Turner, John; Barton, Craig; Wenk, Elizabeth H; Grove, Tim; Attiwill, Peter M; Pinkard, Elizabeth; Butler, Don; Brooksbank, Kim; Spencer, Beren; Snowdon, Peter; O'Brien, Nick; Battaglia, Michael; Cameron, David M; Hamilton, Steve; McAuthur, Geoff; Sinclair, Jenny

    2016-06-01

    Accurate ground-based estimation of the carbon stored in terrestrial ecosystems is critical to quantifying the global carbon budget. Allometric models provide cost-effective methods for biomass prediction. But do such models vary with ecoregion or plant functional type? We compiled 15 054 measurements of individual tree or shrub biomass from across Australia to examine the generality of allometric models for above-ground biomass prediction. This provided a robust case study because Australia includes ecoregions ranging from arid shrublands to tropical rainforests, and has a rich history of biomass research, particularly in planted forests. Regardless of ecoregion, for five broad categories of plant functional type (shrubs; multistemmed trees; trees of the genus Eucalyptus and closely related genera; other trees of high wood density; and other trees of low wood density), relationships between biomass and stem diameter were generic. Simple power-law models explained 84-95% of the variation in biomass, with little improvement in model performance when other plant variables (height, bole wood density), or site characteristics (climate, age, management) were included. Predictions of stand-based biomass from allometric models of varying levels of generalization (species-specific, plant functional type) were validated using whole-plot harvest data from 17 contrasting stands (range: 9-356 Mg ha(-1) ). Losses in efficiency of prediction were plant functional types. Development of new species-specific models is only warranted when gains in accuracy of stand-based predictions are relatively high (e.g. high-value monocultures). PMID:26683241

  18. Drought and root herbivory interact to alter the response of above-ground parasitoids to aphid infested plants and associated plant volatile signals

    Muhammad Tariq; Wright, Denis J.; Bruce, Toby J. A.; Staley, Joanna T.

    2013-01-01

    Multitrophic interactions are likely to be altered by climate change but there is little empirical evidence relating the responses of herbivores and parasitoids to abiotic factors. Here we investigated the effects of drought on an above/below-ground system comprising a generalist and a specialist aphid species (foliar herbivores), their parasitoids, and a dipteran species (root herbivore).We tested the hypotheses that: (1) high levels of drought stress and below-ground herbivory interact to r...

  19. Paleobiology of Herbivorous Dinosaurs

    Barrett, Paul M.

    2014-05-01

    Herbivorous dinosaurs were abundant, species-rich components of Late Triassic-Cretaceous terrestrial ecosystems. Obligate high-fiber herbivory evolved independently on several occasions within Dinosauria, through the intermediary step of omnivory. Anatomical character complexes associated with this diet exhibit high levels of convergence and morphological disparity, and may have evolved by correlated progression. Dinosaur faunas changed markedly during the Mesozoic, from early faunas dominated by taxa with simple, uniform feeding mechanics to Cretaceous biomes including diverse sophisticated sympatric herbivores; the environmental and biological drivers causing these changes remain unclear. Isotopic, taphonomic, and anatomical evidence implies that niche partitioning reduced competition between sympatric herbivores, via morphological differentiation, dietary preferences, and habitat selection. Large body size in dinosaur herbivores is associated with low plant productivity, and gave these animals prominent roles as ecosystem engineers. Although dinosaur herbivores lived through several major events in floral evolution, there is currently no evidence for plant-dinosaur coevolutionary interactions.

  20. Belowground induction by delia radicum or phytohormones affect aboveground herbivore communities on field-grown broccoli

    Pierre, S.P.; Dugravot, S.; Hervé, M. R.; Hassan, H M; Dam, N.M. van; Cortesero, A. M.

    2013-01-01

    Induced plant defence in response to phytophagous insects is a well described phenomenon. However, so far little is known about the effect of induced plant responses on subsequently colonizing herbivores in the field. Broccoli plants were induced in the belowground compartment using (i) infestation by the root-herbivore Delia radicum, (ii) root application of jasmonic acid (JA) or (iii) root application of salicylic acid (SA). The abundance of D. radicum and six aboveground herbivores display...

  1. Modelling above-ground carbon dynamics using multi-temporal airborne lidar: insights from a Mediterranean woodland

    Simonson, W.; Ruiz-Benito, P.; Valladares, F.; Coomes, D.

    2016-02-01

    Woodlands represent highly significant carbon sinks globally, though could lose this function under future climatic change. Effective large-scale monitoring of these woodlands has a critical role to play in mitigating for, and adapting to, climate change. Mediterranean woodlands have low carbon densities, but represent important global carbon stocks due to their extensiveness and are particularly vulnerable because the region is predicted to become much hotter and drier over the coming century. Airborne lidar is already recognized as an excellent approach for high-fidelity carbon mapping, but few studies have used multi-temporal lidar surveys to measure carbon fluxes in forests and none have worked with Mediterranean woodlands. We use a multi-temporal (5-year interval) airborne lidar data set for a region of central Spain to estimate above-ground biomass (AGB) and carbon dynamics in typical mixed broadleaved and/or coniferous Mediterranean woodlands. Field calibration of the lidar data enabled the generation of grid-based maps of AGB for 2006 and 2011, and the resulting AGB change was estimated. There was a close agreement between the lidar-based AGB growth estimate (1.22 Mg ha-1 yr-1) and those derived from two independent sources: the Spanish National Forest Inventory, and a tree-ring based analysis (1.19 and 1.13 Mg ha-1 yr-1, respectively). We parameterised a simple simulator of forest dynamics using the lidar carbon flux measurements, and used it to explore four scenarios of fire occurrence. Under undisturbed conditions (no fire) an accelerating accumulation of biomass and carbon is evident over the next 100 years with an average carbon sequestration rate of 1.95 Mg C ha-1 yr-1. This rate reduces by almost a third when fire probability is increased to 0.01 (fire return rate of 100 years), as has been predicted under climate change. Our work shows the power of multi-temporal lidar surveying to map woodland carbon fluxes and provide parameters for carbon

  2. Interactive effects of frequent burning and timber harvesting on above ground carbon biomass in temperate eucalypt forests

    Collins, Luke; Penman, Trent; Ximenes, Fabiano; Bradstock, Ross

    2015-04-01

    The sequestration of carbon has been identified as an important strategy to mitigate the effects of climate change. Fuel reduction burning and timber harvesting are two common co-occurring management practices within forests. Frequent burning and timber harvesting may alter forest carbon pools through the removal and redistribution of biomass and demographic and structural changes to tree communities. Synergistic and antagonistic interactions between frequent burning and harvesting are likely to occur, adding further complexity to the management of forest carbon stocks. Research aimed at understanding the interactive effects of frequent fire and timber harvesting on carbon biomass is lacking. This study utilised data from two long term (25 - 30 years) manipulative burning experiments conducted in southern Australia in temperate eucalypt forests dominated by resprouting canopy species. Specifically we examined the effect of fire frequency and harvesting on (i) total biomass of above ground carbon pools and (ii) demographic and structural characteristics of live trees. We also investigated some of the mechanisms driving these changes. Frequent burning reduced carbon biomass by up to 20% in the live tree carbon pool. Significant interactions occurred between fire and harvesting, whereby the reduction in biomass of trees >20 cm diameter breast height (DBH) was amplified by increased fire frequency. The biomass of trees DBH increased with harvesting intensity in frequently burnt areas, but was unaffected by harvesting intensity in areas experiencing low fire frequency. Biomass of standing and fallen coarse woody debris was relatively unaffected by logging and fire frequency. Fire and harvesting significantly altered stand structure over the study period. Comparison of pre-treatment conditions to current conditions revealed that logged sites had a significantly greater increase in the number of small trees (DBH) than unlogged sites. Logged sites showed a significant

  3. Modelling above-ground carbon dynamics using multi-temporal airborne lidar: insights from a Mediterranean woodland

    W. Simonson

    2015-09-01

    Full Text Available Woodlands represent highly significant carbon sinks globally, though could lose this function under future climatic change. Effective large-scale monitoring of these woodlands has a critical role to play in mitigating for, and adapting to, climate change. Mediterranean woodlands have low carbon densities, but represent important global carbon stocks due to their extensiveness and are particularly vulnerable because the region is predicted to become much hotter and drier over the coming century. Airborne lidar is already recognized as an excellent approach for high-fidelity carbon mapping, but few studies have used multi-temporal lidar surveys to measure carbon fluxes in forests and none have worked with Mediterranean woodlands. We use a multi-temporal (five year interval airborne lidar dataset for a region of central Spain to estimate above-ground biomass (AGB and carbon dynamics in typical mixed broadleaved/coniferous Mediterranean woodlands. Field calibration of the lidar data enabled the generation of grid-based maps of AGB for 2006 and 2011, and the resulting AGB change were estimated. There was a close agreement between the lidar-based AGB growth estimate (1.22 Mg ha−1 year−1 and those derived from two independent sources: the Spanish National Forest Inventory, and a~tree-ring based analysis (1.19 and 1.13 Mg ha−1 year−1, respectively. We parameterised a simple simulator of forest dynamics using the lidar carbon flux measurements, and used it to explore four scenarios of fire occurrence. Under undisturbed conditions (no fire occurrence an accelerating accumulation of biomass and carbon is evident over the next 100 years with an average carbon sequestration rate of 1.95 Mg C ha−1 year−1. This rate reduces by almost a third when fire probability is increased to 0.01, as has been predicted under climate change. Our work shows the power of multi-temporal lidar surveying to map woodland carbon fluxes and provide parameters for carbon

  4. EU-wide maps of growing stock and above-ground biomass in forests based on remote sensing and field measurements

    Gallaun, H.; Zanchi, G.; Nabuurs, G.J.; Hengeveld, G.M.; Schardt, M.; Verkerk, P.J.

    2010-01-01

    The overall objective of this study was to combine national forest inventory data and remotely sensed data to produce pan-European maps on growing stock and above-ground woody biomass for the two species groups " broadleaves" and " conifers" An automatic up-scaling approach making use of satellite r

  5. Phytochemical mimicry of reproductive hormones and modulation of herbivore fertility by phytoestrogens.

    Hughes, C. L.

    1988-01-01

    Plants have physical and chemical mechanisms for defense from attack by animals. Phytochemical defenses that protect plants from attack by insects include antifeedants, insecticides, and insect growth regulators. Phytochemical options exist by which plants can modulate the fertility of the other major group of plant predators, vertebrate herbivores, and thereby reduce cumulative attacks by those herbivores. The success of such a defense depends upon phytochemical mimicry of vertebrate reprodu...

  6. The key to success: host plant adaptations in the root herbivore 'Diabrotica virgifera virgifera'

    Robert, Christelle A.M; Turlings, Ted C.

    2012-01-01

    Antagonistic interactions between plants and insects are likely the drivers of a fascinating coevolutionary arms race between the two trophic levels. Plants- and plant breeders- are continuously developing traits that allow them to fend-off herbivores, while phytophagous insect keep inventing counter-adaptations to withstand plant defenses. Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae) is a specialist root herbivore of maize, Zea mays. Known as the billion dollar bug in ...

  7. Above-ground biomass production and allometric relations of Eucalyptus globulus Labill. coppice plantations along a chronosequence in the central highlands of Ethiopia

    Eucalyptus plantations are extensively managed for wood production in the central highlands of Ethiopia. Nevertheless, little is known about their biomass (dry matter) production, partitioning and dynamics over time. Data from 10 different Eucalyptus globulus stands, with a plantation age ranging from 11 to 60 years and with a coppice-shoot age ranging from 1 to 9 years were collected and analyzed. Above-ground tree biomass of 7-10 sampled trees per stand was determined destructively. Dry weights of tree components (Wc; leaves, twigs, branches, stembark, and stemwood) and total above-ground biomass (Wa) were estimated as a function of diameter above stump (D), tree height (H) and a combination of these. The best fits were obtained, using combinations of D and H. When only one explanatory variable was used, D performed better than H. Total above-ground biomass was linearly related to coppice-shoot age. In contrast a negative relation was observed between the above-ground biomass production and total plantation age (number of cutting cycles). Total above-ground biomass increased from 11 t ha-1 at a stand age of 1 year to 153 t ha-1 at 9 years. The highest dry weight was allocated to stemwood and decreased in the following order: stemwood > leaves > stembark > twigs > branches. The equations developed in this study to estimate biomass components can be applied to other Eucalyptus plantations under the assumption that the populations being studied are similar with regard to density and tree size to those for which the relationships were developed

  8. Herbivore-induced resistance against microbial pathogens in Arabidopsis

    Vos, de M.; Zaanen, van W.; Koornneef, A.; Korzelius, J.P.; Dicke, M.; Loon, van L.C.; Pieterse, C.M.J.

    2006-01-01

    Caterpillars of the herbivore Pieris rapae stimulate the production of jasmonic acid (JA) and ethylene (ET) in Arabidopsis (Arabidopsis thaliana) and trigger a defense response that affects insect performance on systemic tissues. To investigate the spectrum of effectiveness of P. rapae-induced resis

  9. Maintenance of genetic diversity through plant-herbivore interactions

    Gloss, Andrew D.; Dittrich, Anna C. Nelson; Goldman-Huertas, Benjamin; Whiteman, Noah K.

    2013-01-01

    Identifying the factors governing the maintenance of genetic variation is a central challenge in evolutionary biology. New genomic data, methods and conceptual advances provide increasing evidence that balancing selection, mediated by antagonistic species interactions, maintains functionally-important genetic variation within species and natural populations. Because diverse interactions between plants and herbivorous insects dominate terrestrial communities, they provide excellent systems to ...

  10. Variation in stem mortality rates determines patterns of above-ground biomass in Amazonian forests: implications for dynamic global vegetation models

    Johnson, Michelle; Galbraith, David; Gloor, Manuel; De Deaurwaerder, Hannes; Guimberteau, Mattieu; Rammig, Anja; Thonicke, Kristin; Verbeeck, Hans; von Randow, Celso; Monteagudo Mendoza, Abel; Phillips, Oliver L; Brienen, Roel; Feldpausch, Ted R.; Lopez Gonzales, Gabriela; Fauset, Sophie

    2016-01-01

    Understanding the processes that determine above-ground biomass (AGB) in Amazonian forests is important for predicting the sensitivity of these ecosystems to environmental change and for designing and evaluating dynamic global vegetation models (DGVMs). AGB is determined by inputs from woody productivity [woody net primary productivity (NPP)] and the rate at which carbon is lost through tree mortality. Here, we test whether two direct metrics of tree mortality (the absolute rate of woody biom...

  11. Diversity and above-ground biomass patterns of vascular flora induced by flooding in the drawdown area of China's Three Gorges Reservoir.

    Qiang Wang

    Full Text Available Hydrological alternation can dramatically influence riparian environments and shape riparian vegetation zonation. However, it was difficult to predict the status in the drawdown area of the Three Gorges Reservoir (TGR, because the hydrological regime created by the dam involves both short periods of summer flooding and long-term winter impoundment for half a year. In order to examine the effects of hydrological alternation on plant diversity and biomass in the drawdown area of TGR, twelve sites distributed along the length of the drawdown area of TGR were chosen to explore the lateral pattern of plant diversity and above-ground biomass at the ends of growing seasons in 2009 and 2010. We recorded 175 vascular plant species in 2009 and 127 in 2010, indicating that a significant loss of vascular flora in the drawdown area of TGR resulted from the new hydrological regimes. Cynodon dactylon and Cyperus rotundus had high tolerance to short periods of summer flooding and long-term winter flooding. Almost half of the remnant species were annuals. Species richness, Shannon-Wiener Index and above-ground biomass of vegetation exhibited an increasing pattern along the elevation gradient, being greater at higher elevations subjected to lower submergence stress. Plant diversity, above-ground biomass and species distribution were significantly influenced by the duration of submergence relative to elevation in both summer and previous winter. Several million tonnes of vegetation would be accumulated on the drawdown area of TGR in every summer and some adverse environmental problems may be introduced when it was submerged in winter. We conclude that vascular flora biodiversity in the drawdown area of TGR has dramatically declined after the impoundment to full capacity. The new hydrological condition, characterized by long-term winter flooding and short periods of summer flooding, determined vegetation biodiversity and above-ground biomass patterns along the

  12. Above-ground tree outside forest (TOF) phytomass and carbon estimation in the semiarid region of southern Haryana: A synthesis approach of remote sensing and field data

    Kuldeep Singh; Pritam Chand

    2012-12-01

    Trees outside forest (TOF) play an important role in global carbon cycling, since they are large pools of carbon as well as potential carbon sinks and sources to the atmosphere. In view of the importance of biomass estimates in the global carbon (C) cycle, the present study demonstrates the potential of the standwise tree outside forest inventory data and finer spatial resolution of IRS-P6 LISS-IV satellite data to classify TOF, to estimate above-ground TOF phytomass and the carbon content of TOF in a semiarid region of the southern Haryana, India. The study reports that above-ground TOF phytomass varied from 1.26 tons/ha in the scattered trees in the rural/urban area to 91.5 tons/ha in the dense linear TOF along the canal. The total above-ground TOF phytomass and carbon content was calculated as 367.04 and 174.34 tons/ha, respectively in the study area. The study results conclude that the classification of TOF and estimation of phytomass and carbon content in TOF can be successfully achieved through the combined approach of Remote Sensing and GIS based spatial technique with the supplement of field data. The present approach will help to find out the potential carbon sequestration zone in the semi-arid region of southern Haryana, India.

  13. Estimating above-ground biomass by fusion of LiDAR and multispectral data in subtropical woody plant communities in topographically complex terrain in North-eastern Australia

    Sisira Ediriweera; Sumith Pathirana; Tim Danaher; Doland Nichols

    2014-01-01

    We investigated a strategy to improve predicting capacity of plot-scale above-ground biomass (AGB) by fusion of LiDAR and Land-sat5 TM derived biophysical variables for subtropical rainforest and eucalypts dominated forest in topographically complex landscapes in North-eastern Australia. Investigation was carried out in two study areas separately and in combination. From each plot of both study areas, LiDAR derived structural parameters of vegetation and reflectance of all Landsat bands, vegetation indices were employed. The regression analysis was carried out separately for LiDAR and Landsat derived variables indi-vidually and in combination. Strong relationships were found with LiDAR alone for eucalypts dominated forest and combined sites compared to the accuracy of AGB estimates by Landsat data. Fusing LiDAR with Landsat5 TM derived variables increased overall performance for the eucalypt forest and combined sites data by describing extra variation (3% for eucalypt forest and 2% combined sites) of field estimated plot-scale above-ground biomass. In contrast, separate LiDAR and imagery data, and fusion of LiDAR and Landsat data performed poorly across structurally complex closed canopy subtropical rainforest. These findings reinforced that obtaining accurate estimates of above ground biomass using remotely sensed data is a function of the complexity of horizontal and vertical structural diversity of vegetation.

  14. An extreme case of plant-insect codiversification

    Cruaud, Astrid; Rønsted, Nina; Chanterasuwan, Bhanumas;

    2012-01-01

    It is thought that speciation in phytophagous insects is often due to colonization of novel host plants, because radiations of plant and insect lineages are typically asynchronous. Recent phylogenetic comparisons have supported this model of diversification for both insect herbivores and speciali...

  15. Plant responses to insect egg deposition.

    Hilker, Monika; Fatouros, Nina E

    2015-01-01

    Plants can respond to insect egg deposition and thus resist attack by herbivorous insects from the beginning of the attack, egg deposition. We review ecological effects of plant responses to insect eggs and differentiate between egg-induced plant defenses that directly harm the eggs and indirect defenses that involve egg parasitoids. Furthermore, we discuss the ability of plants to take insect eggs as warning signals; the eggs indicate future larval feeding damage and trigger plant changes that either directly impair larval performance or attract enemies of the larvae. We address the questions of how egg-associated cues elicit plant defenses, how the information that eggs have been laid is transmitted within a plant, and which molecular and chemical plant responses are induced by egg deposition. Finally, we highlight evolutionary aspects of the interactions between plants and insect eggs and ask how the herbivorous insect copes with egg-induced plant defenses and may avoid them by counteradaptations. PMID:25341089

  16. Herbivore defense responses and associated herbivore defense mechanism as revealed by comparing a resistant wild soybean with a susceptible cultivar

    Xiaoyi Wang

    2015-12-01

    Full Text Available Plants have evolved sophisticated defense mechanisms against herbivores to help them adapt to the environment. Understanding the defense mechanisms in plants can help us control insects in a more effective manner. In this study, we found that compared with Tianlong 2 (a cultivated soybean with insect susceptibility, ED059 (a wild soybean line with insect resistance contains sharper pubescence tips, as well as lower transcript levels of wound-induced protein kinase (WIPK and salicylic acid-induced protein kinase (SIPK, which are important mitogen-activated protein kinases involved in early defense response to herbivores. The observed lower transcript levels of WIPK and SIPK induced higher levels of jasmonic acid (JA, JA biosynthesis enzymes (AOC3 and some secondary metabolites in ED059. Functional analysis of the KTI1 gene via Agrobacterium-mediated transformation in Arabidopsis thaliana indicated that it plays an important role in herbivore defense in ED059. We further investigated the molecular response of third-instar Helicoverpa armigera (Hübner larvae to Tianlong 2 and ED059. We found apoptotic cells only in the midguts of larvae that fed on ED059. Compared with larvae reared on the susceptible cultivar Tianlong 2, transcript levels of catalase (CAT and glutathione S-transferase (GST were up-regulated, whereas those of CAR, CHSB, and TRY were down-regulated in larvae that fed on the highly resistant variety ED059. We propose that these differences underlie the different herbivore defense responses of ED059 and Tianlong 2.

  17. Modulation of plant defense responses to herbivores by simultaneous recognition of different herbivore-associated elicitors in rice.

    Shinya, Tomonori; Hojo, Yuko; Desaki, Yoshitake; Christeller, John T; Okada, Kazunori; Shibuya, Naoto; Galis, Ivan

    2016-01-01

    Induced plant defense responses against insect herbivores are triggered by wounding and/or perception of herbivore elicitors from their oral secretions (OS) and/or saliva. In this study, we analyzed OS isolated from two rice chewing herbivores, Mythimna loreyi and Parnara guttata. Both types of crude OS had substantial elicitor activity in rice cell system that allowed rapid detection of early and late defense responses, i.e. accumulation of reactive oxygen species (ROS) and defense secondary metabolites, respectively. While the OS from M. loreyi contained large amounts of previously reported insect elicitors, fatty acid-amino acid conjugates (FACs), the elicitor-active P. guttata's OS contained no detectable FACs. Subsequently, elicitor activity associated with the high molecular mass fraction in OS of both herbivores was identified, and shown to promote ROS and metabolite accumulations in rice cells. Notably, the application of N-linolenoyl-Gln (FAC) alone had only negligible elicitor activity in rice cells; however, the activity of isolated elicitor fraction was substantially promoted by this FAC. Our results reveal that plants integrate various independent signals associated with their insect attackers to modulate their defense responses and reach maximal fitness in nature. PMID:27581373

  18. The Root Herbivore History of the Soil Affects the Productivity of a Grassland Plant Community and Determines Plant Response to New Root Herbivore Attack

    Sonnemann, Ilja; Hempel, Stefan; Beutel, Maria; Hanauer, Nicola; Reidinger, Stefan; Wurst, Susanne

    2013-01-01

    Insect root herbivores can alter plant community structure by affecting the competitive ability of single plants. However, their effects can be modified by the soil environment. Root herbivory itself may induce changes in the soil biota community, and it has recently been shown that these changes can affect plant growth in a subsequent season or plant generation. However, so far it is not known whether these root herbivore history effects (i) are detectable at the plant community level and/or...

  19. A comparison of two above-ground biomass estimation techniques integrating satellite-based remotely sensed data and ground data for tropical and semiarid forests in Puerto Rico

    Iiames, J. S.; Riegel, J.; Lunetta, R.

    2013-12-01

    Two above-ground forest biomass estimation techniques were evaluated for the United States Territory of Puerto Rico using predictor variables acquired from satellite based remotely sensed data and ground data from the U.S. Department of Agriculture Forest Inventory Analysis (FIA) program. The U.S. Environmental Protection Agency (EPA) estimated above-ground forest biomass implementing methodology first posited by the Woods Hole Research Center developed for conterminous United States (National Biomass and Carbon Dataset [NBCD2000]). For EPA's effort, spatial predictor layers for above-ground biomass estimation included derived products from the U.S. Geologic Survey (USGS) National Land Cover Dataset 2001 (NLCD) (landcover and canopy density), the USGS Gap Analysis Program (forest type classification), the USGS National Elevation Dataset, and the NASA Shuttle Radar Topography Mission (tree heights). In contrast, the U.S. Forest Service (USFS) biomass product integrated FIA ground-based data with a suite of geospatial predictor variables including: (1) the Moderate Resolution Imaging Spectrometer (MODIS)-derived image composites and percent tree cover; (2) NLCD land cover proportions; (3) topographic variables; (4) monthly and annual climate parameters; and (5) other ancillary variables. Correlations between both data sets were made at variable watershed scales to test level of agreement. Notice: This work is done in support of EPA's Sustainable Healthy Communities Research Program. The U.S EPA funded and conducted the research described in this paper. Although this work was reviewed by the EPA and has been approved for publication, it may not necessarily reflect official Agency policy. Mention of any trade names or commercial products does not constitute endorsement or recommendation for use.

  20. The Effects of Plant Compensatory Regrowth and Induced Resistance on Herbivore Population Dynamics.

    Stieha, Christopher R; Abbott, Karen C; Poveda, Katja

    2016-02-01

    Outbreaks of herbivorous insects are detrimental to natural and agricultural systems, but the mechanisms driving outbreaks are not well understood. Plant responses to herbivory have the potential to produce outbreaks, but long-term effects of plant responses on herbivore dynamics are understudied. To quantify these effects, we analyze mathematical models of univoltine herbivores consuming annual plants with two responses: (1) compensatory regrowth, which affects herbivore survival in food-limited situations by increasing the amount of food available to the herbivore; and (2) induced resistance, which reduces herbivore survival proportional to the strength of the response. Compensatory regrowth includes tolerance, where plants replace some or all of the consumed biomass, and overcompensation, where plants produce more biomass than was consumed. We found that overcompensation can cause bounded fluctuations in the herbivore density (called outbreaks here) by itself, whereas neither tolerance nor induced resistance can cause an outbreak on its own. Food limitation and induced resistance can also drive outbreaks when they act simultaneously. Tolerance damps these outbreaks, but overcompensation, by contrast, qualitatively changes the conditions under which the outbreaks occur. Not properly accounting for these interactions may explain why it has been difficult to document plant-driven insect outbreaks and could undermine efforts to control herbivore populations in agricultural systems. PMID:26807745

  1. A test of the herbivore optimization hypothesis using muskoxen and a graminoid meadow plant community

    David L. Smith

    1996-01-01

    Full Text Available A prediction from the herbivore optimization hypothesis is that grazing by herbivores at moderate intensities will increase net above-ground primary productivity more than at lower or higher intensities. I tested this hypothesis in an area of high muskox {Ovibos moschatus density on north-central Banks Island, Northwest Territories, Canada (73°50'N, 119°53'W. Plots (1 m2 in graminoid meadows dominated by cottongrass (Eriophorum triste were either clipped, exposed to muskoxen, protected for part of one growing season, or permanently protected. This resulted in the removal of 22-44%, 10-39%, 0-39% or 0%, respectively, of shoot tissue during each growing season. Contrary to the predictions of the herbivore optimization hypothesis, productivity did not increase across this range of tissue removal. Productivity of plants clipped at 1.5 cm above ground once or twice per growing season, declined by 60+/-5% in 64% of the tests. The productivity of plants grazed by muskoxen declined by 56+/-7% in 25% of the tests. No significant change in productivity was observed in 36% and 75% of the tests in clipped and grazed treatments, respecrively. Clipping and grazing reduced below-ground standing crop except where removals were small. Grazing and clipping did not stimulate productivity of north-central Banks Island graminoid meadows.

  2. Impacts of Woody Invader Dillenia suffruticosa (Griff. Martelli on Physio-chemical Properties of Soil and, Below and Above Ground Flora

    B.A.K. Wickramathilake

    2014-01-01

    Full Text Available Dillenia suffruticosa (Griffith Martelli, that spreads fast in low-lying areas in wet zone of Sri Lanka is currently listed as a nationally important Invasive Alien Species that deserves attention in ecological studies. Thus, impact of this woody invader on physical, chemical properties of soil and below and above ground flora was investigated. Five sampling sites were identified along a distance of 46km from Avissawella to Ratnapura. At each site, two adjacent plots [1m x10m each for D. suffruticosa present (D+ and absent (D-] were outlined. Physical and chemical soil parameters, microbial biomass and number of bacterial colonies in soil were determined using standard procedures and compared between D+ and D- by ANOVA using SPSS. Rate of decomposition of D. suffruticosa leaves was also determined using the litter bag technique at 35% and 50% moisture levels. Above ground plant species richness in sample stands was compared using Jaccard and Sorenson diversity indices.  Decomposition of D. suffruticosa leaves was slow, but occurred at a more or less similar rate irrespective of moisture content of soil. Particle size distribution in D+ soil showed a much higher percentage of large soil particles.  Higher % porosity in D+ sites was a clear indication that the soil was aerated.  The pH was significantly lower for D+ than D- thus developing acidic soils whereas conductivity has been significantly high making soil further stressed. The significant drop in Cation Exchange Capacity (CEC in D+ soil was a remarkable finding to be concerned with as it correlated with fertility of soil. Significantly higher values of phosphates reported in D+ soil support the idea that plant invaders are capable to increase phosphates in soil. Higher biomass values recorded for D+ sites together with higher number of bacterial colonies could be related to the unexpectedly recorded higher Organic Carbon. Both  the  Jaccard  and  Sorenson   indices indicated  that

  3. Insect Counter-Adaptations to Plant Cyanogenic Glucosides

    Pentzold, Stefan

    toxic hydrogen cyanide. Such a binary system of components that are chemically inert when separated is also referred to as two-component plant defence. Since the co-evolution of cyanogenic plants and insect herbivores has continued for several hundred million years, some specialised herbivores have...... classes of two-component plant chemical defence [3]. The results obtained in this thesis provide unique insights into the co-evolution and adaptation of insect herbivores to cyanogenic plants. It raises several research questions regarding herbivory of cyanogenic plants that need to be examined in more......Cyanogenic glucosides are ancient and widespread defence compounds that are used by plants to fend off non-adapted insect herbivores. After insect herbivory and plant tissue damage, cyanogenic glucosides come into contact with compartmentalised plant β-glucosidases, resulting in the release of...

  4. Bottom-up and top-down herbivore regulation mediated by glucosinolates in Brassica oleracea var. acephala

    Santolamazza Carbone, Serena; Velasco Pazos, Pablo; Soengas Fernández, María del Pilar; Cartea González, María Elena

    2014-01-01

    Quantitative differences in plant defence metabolites, such as glucosinolates, may directly affect herbivore preference and performance, and indirectly affect natural enemy pressure. By assessing insect abundance and leaf damage rate, we studied the responses of insect herbivores to six genotypes of Brassica oleracea var. acephala, selected from the same cultivar for having high or low foliar content of sinigrin, glucoiberin and glucobrassicin. We also investigated whether the natural parasit...

  5. Above-ground woody carbon sequestration measured from tree rings is coherent with net ecosystem productivity at five eddy-covariance sites.

    Babst, Flurin; Bouriaud, Olivier; Papale, Dario; Gielen, Bert; Janssens, Ivan A; Nikinmaa, Eero; Ibrom, Andreas; Wu, Jian; Bernhofer, Christian; Köstner, Barbara; Grünwald, Thomas; Seufert, Günther; Ciais, Philippe; Frank, David

    2014-03-01

    • Attempts to combine biometric and eddy-covariance (EC) quantifications of carbon allocation to different storage pools in forests have been inconsistent and variably successful in the past. • We assessed above-ground biomass changes at five long-term EC forest stations based on tree-ring width and wood density measurements, together with multiple allometric models. Measurements were validated with site-specific biomass estimates and compared with the sum of monthly CO₂ fluxes between 1997 and 2009. • Biometric measurements and seasonal net ecosystem productivity (NEP) proved largely compatible and suggested that carbon sequestered between January and July is mainly used for volume increase, whereas that taken up between August and September supports a combination of cell wall thickening and storage. The inter-annual variability in above-ground woody carbon uptake was significantly linked with wood production at the sites, ranging between 110 and 370 g C m(-2) yr(-1) , thereby accounting for 10-25% of gross primary productivity (GPP), 15-32% of terrestrial ecosystem respiration (TER) and 25-80% of NEP. • The observed seasonal partitioning of carbon used to support different wood formation processes refines our knowledge on the dynamics and magnitude of carbon allocation in forests across the major European climatic zones. It may thus contribute, for example, to improved vegetation model parameterization and provides an enhanced framework to link tree-ring parameters with EC measurements. PMID:24206564

  6. Using multi-frequency radar and discrete-return LiDAR measurements to estimate above-ground biomass and biomass components in a coastal temperate forest

    Tsui, Olivier W.; Coops, Nicholas C.; Wulder, Michael A.; Marshall, Peter L.; McCardle, Adrian

    2012-04-01

    Height measurements from small-footprint discrete-return LiDAR and backscatter coefficients from C- and L-band radar were used independently and in combination to estimate above-ground component and total biomass for a coniferous temperate forest, located on Vancouver Island, British Columbia, Canada. Reference biomass data were obtained from plot-level data and used for comparison against the LiDAR and radar-based biomass models. For the LiDAR-only model, height metrics such as mean first return height and percentiles (e.g., 10th and 90th) of first returns correlated best to total above-ground and stem biomass. While percent of first returns above 2 m and percentiles (75th and 90th) of first returns height metrics correlated best to crown biomass. A comparison between above-ground components and total biomass indicate that stem biomass displayed the highest relationship with the LiDAR measurements while crown biomass showed the lowest relationship with relative root mean squared error ranging from 16% to 22%, respectively. Alternatively, the radar-only models indicated that for C-band radar, a combination of HH and VV backscatter demonstrated the most significant correlation with forest biomass compared to coherence based models with a relative root mean squared error of 53%. For L-band radar, a combination of HH and HV backscatter showed the most significant correlation compared to coherence based models with a relative root mean squared error of 44%. Exploring a mixture of C- and L-band backscatter and coherence based models revealed that a combination of C-HV and L-HV coherence magnitudes provided the best radar relationship with forest biomass with a relative root mean squared error of 35%. Also for all radar-based models, L- and C-band backscatter and coherence magnitudes were poorly correlated with individual biomass components when compared to total above-ground biomass. The addition of C- and L-band backscatter and coherence variables to the Li

  7. The effect of wildfire and clear-cutting on above-ground biomass, foliar C to N ratios and fiber content throughout succession: Implications for forage quality in woodland caribou (Rangifer tarandus caribou)

    Mallon, E. E.; Turetsky, M.; Thompson, I.; Noland, T. L.; Wiebe, P.

    2013-12-01

    Disturbance is known to play an important role in maintaining the productivity and biodiversity of boreal forest ecosystems. Moderate to low frequency disturbance is responsible for regeneration opportunities creating a mosaic of habitats and successional trajectories. However, large-scale deforestation and increasing wildfire frequencies exacerbate habitat loss and influence biogeochemical cycles. This has raised concern about the quality of the under-story vegetation post-disturbance and whether this may impact herbivores, especially those vulnerable to change. Forest-dwelling caribou (Rangifer tarandus caribou) are declining in several regions of Canada and are currently listed as a species at risk by COSEWIC. Predation and landscape alteration are viewed as the two main threats to woodland caribou. This has resulted in caribou utilizing low productivity peatlands as refuge and the impact of this habitat selection on their diet quality is not well understood. Therefore there are two themes in the study, 1) Forage quantity: above-ground biomass and productivity and 2) Forage quality: foliar N and C to N ratios and % fiber. The themes are addressed in three questions: 1) How does forage quantity and quality vary between upland forests and peatlands? 2) How does wildfire affect the availability and nutritional quality of forage items? 3) How does forage quality vary between sites recovering from wildfire versus timber harvest? Research sites were located in the Auden region north of Geraldton, ON. This landscape was chosen because it is known woodland caribou habitat and has thorough wildfire and silviculture data from the past 7 decades. Plant diversity, above-ground biomass, vascular green area and seasonal foliar fiber and C to N ratios were collected across a matrix of sites representing a chronosequence of time since disturbance in upland forests and peatlands. Preliminary findings revealed productivity peaked in early age stands (0-30 yrs) and biomass peaked

  8. Resistance to sap-sucking insects in modern-day agriculture

    Martin eDe Vos

    2013-06-01

    Full Text Available Plants and herbivores have co-evolved in their natural habitats for about 350 million years, but since the domestication of crops, plant resistance against insects has taken a different turn. With the onset of monoculture-driven modern agriculture, selective pressure on insects to overcome resistances has dramatically increased. Therefore plant breeders have resorted to high-tech tools to continuously create new insect-resistant crops. Efforts in the past 30 years have resulted in elucidation of mechanisms of many effective plant defenses against insect herbivores. Here, we critically appraise these efforts and - with a focus on sap-sucking insects - discuss how these findings have contributed to herbivore-resistant crops. Moreover, in this review we try to assess where future challenges and opportunities lay ahead. Of particular importance will be a mandatory reduction in systemic pesticide usage and thus a greater reliance on alternative methods, such as improved plant genetics for plant resistance to insect herbivores.

  9. Net Changes in Above Ground Woody Carbon Stock in Western Juniper Woodlands using Wavelet Techniques and Multi-temporal Aerial Photography

    Strand, E. K.; Bunting, S. C.; Smith, A. M.

    2006-12-01

    Expansion of woody plant cover in semi-arid ecosystems previously occupied primarily by grasses and forbs has been identified as an important land cover change process affecting the global carbon budget. Although woody encroachment occurs worldwide, quantifying changes in carbon pools and fluxes related to this phenomenon via remote sensing is challenging because large areas are affected at a fine spatial resolution (1- 10 m) and, in many cases, at slow temporal rates. Two-dimensional spatial wavelet analysis (SWA) represents a novel image processing technique that has been successful in automatically and objectively quantifying ecologically relevant features at multiple scales. We apply SWA to current and historic 1-m resolution black and white aerial photography to quantify changes in above ground woody biomass and carbon stock of western juniper (Juniperus occidentalis subsp. occidentalis) expanding into sagebrush (Artemisia spp.) steppe on the Owyhee Plateau in southwestern Idaho. Due to the large land area (330,000 ha) and variable availability of historical photography, we sampled forty-eight 100-ha blocks situated across the area, stratified using topographic, soil, and land stewardship variables. The average juniper plant cover increased one-fold (from 5.3% to 10.4% total cover) at the site during the time period of 1939-1946 to 1998-2004. Juniper plant density has increased by 128% with a higher percentage of the plant population in the smaller size classes compared to the size distribution 60 years ago. After image-based SWA delineation of tree crown sizes, we computed the change in above ground woody plant biomass and carbon stock between the two time periods using allometry. Areas where the shrub steppe is dominated by low sagebrush (Artemisia arbuscula) has experienced little to no expansion of western juniper. However, on deeper, more well drained soils capable of supporting mountain big sagebrush (Artemisia tridentata subsp. vaseyana), the above

  10. Euthanasia: above ground, below ground.

    Magnusson, R S

    2004-10-01

    The key to the euthanasia debate lies in how best to regulate what doctors do. Opponents of euthanasia frequently warn of the possible negative consequences of legalising physician assisted suicide and active euthanasia (PAS/AE) while ignoring the covert practice of PAS/AE by doctors and other health professionals. Against the background of survey studies suggesting that anything from 4% to 10% of doctors have intentionally assisted a patient to die, and interview evidence of the unregulated, idiosyncratic nature of underground PAS/AE, this paper assesses three alternatives to the current policy of prohibition. It argues that although legalisation may never succeed in making euthanasia perfectly safe, legalising PAS/AE may nevertheless be safer, and therefore a preferable policy alternative, to prohibition. At a minimum, debate about harm minimisation and the regulation of euthanasia needs to take account of PAS/AE wherever it is practised, both above and below ground. PMID:15467073

  11. Herbivore-induced resource sequestration in plants: why bother?

    Orians, Colin M; Thorn, Alexandra; Gómez, Sara

    2011-09-01

    Herbivores can cause numerous changes in primary plant metabolism. Recent studies using radioisotopes, for example, have found that insect herbivores and related cues can induce faster export from leaves and roots and greater partitioning into tissues inaccessible to foraging herbivores. This process, termed induced resource sequestration, is being proposed as an important response of plants to cope with herbivory. Here, we review the evidence for resource sequestration and suggest that associated allocation and ecological costs may limit the benefit of this response because resources allocated to storage are not immediately available to other plant functions or may be consumed by other enemies. We then present a conceptual model that describes the conditions under which benefits might outweigh costs of induced resource sequestration. Benefits and costs are discussed in the context of differences in plant life-history traits and biotic and abiotic conditions, and new testable hypotheses are presented to guide future research. We predict that intrinsic factors related to life history, ontogeny and phenology will alter patterns of induced sequestration. We also predict that induced sequestration will depend on certain external factors: abiotic conditions, types of herbivores, and trophic interactions. We hope the concepts presented here will stimulate more focused research on the ecological and evolutionary costs and benefits of herbivore-induced resource sequestration. PMID:21431939

  12. Variable effects of temperature on insect herbivory

    Nathan P. Lemoine

    2014-05-01

    Full Text Available Rising temperatures can influence the top-down control of plant biomass by increasing herbivore metabolic demands. Unfortunately, we know relatively little about the effects of temperature on herbivory rates for most insect herbivores in a given community. Evolutionary history, adaptation to local environments, and dietary factors may lead to variable thermal response curves across different species. Here we characterized the effect of temperature on herbivory rates for 21 herbivore-plant pairs, encompassing 14 herbivore and 12 plant species. We show that overall consumption rates increase with temperature between 20 and 30 °C but do not increase further with increasing temperature. However, there is substantial variation in thermal responses among individual herbivore-plant pairs at the highest temperatures. Over one third of the herbivore-plant pairs showed declining consumption rates at high temperatures, while an approximately equal number showed increasing consumption rates. Such variation existed even within herbivore species, as some species exhibited idiosyncratic thermal response curves on different host plants. Thus, rising temperatures, particularly with respect to climate change, may have highly variable effects on plant-herbivore interactions and, ultimately, top-down control of plant biomass.

  13. Insects, infestations and nutrient fluxes

    Michalzik, B.

    2012-04-01

    Forest ecosystems are characterized by a high temporal and spatial variability in the vertical transfer of energy and matter within the canopy and the soil compartment. The mechanisms and controlling factors behind canopy processes and system-internal transfer dynamics are imperfectly understood at the moment. Seasonal flux diversities and inhomogeneities in throughfall composition have been reported from coniferous and deciduous forests, and in most cases leaf leaching has been considered as principle driver for differences in the amount and quality of nutrients and organic compounds (Tukey and Morgan 1963). Since herbivorous insects and the processes they initiate received less attention in past times, ecologists now emphasize the need for linking biological processes occurring in different ecosystem strata to explain rates and variability of nutrient cycling (Bardgett et al. 1998, Wardle et al. 2004). Consequently, herbivore insects in the canopies of forests are increasingly identified to play an important role for the (re)cycling and availability of nutrients, or, more generally, for the functioning of ecosystems not only in outbreak situations but also at endemic (non-outbreak) density levels (Stadler et al. 2001, Hunter et al. 2003). Before, little attention was paid to insect herbivores when quantifying element and energy fluxes through ecosystems, although the numerous and different functions insects fulfill in ecosystems (e.g. as pollinators, herbivores or detritivores) were unanimously recognized (Schowalter 2000). Amongst the reasons for this restraint was the argument that the total biomass of insects tends to be relatively low compared to the biomass of trees or the pool of soil organic matter (Ohmart et al. 1983). A second argument which was put forward to justify the inferior role of insects in nutrient cycling were the supposed low defoliation losses between 5-10% of the annual leaf biomass, or net primary production, due to insect herbivory under

  14. Plant Defense against Herbivorous Pests: Exploiting Resistance and Tolerance Traits for Sustainable Crop Protection

    Mitchell, Carolyn; Brennan, Rex M.; Graham, Julie; Karley, Alison J.

    2016-01-01

    Interactions between plants and insect herbivores are important determinants of plant productivity in managed and natural vegetation. In response to attack, plants have evolved a range of defenses to reduce the threat of injury and loss of productivity. Crop losses from damage caused by arthropod pests can exceed 15% annually. Crop domestication and selection for improved yield and quality can alter the defensive capability of the crop, increasing reliance on artificial crop protection. Sustainable agriculture, however, depends on reduced chemical inputs. There is an urgent need, therefore, to identify plant defensive traits for crop improvement. Plant defense can be divided into resistance and tolerance strategies. Plant traits that confer herbivore resistance typically prevent or reduce herbivore damage through expression of traits that deter pests from settling, attaching to surfaces, feeding and reproducing, or that reduce palatability. Plant tolerance of herbivory involves expression of traits that limit the negative impact of herbivore damage on productivity and yield. Identifying the defensive traits expressed by plants to deter herbivores or limit herbivore damage, and understanding the underlying defense mechanisms, is crucial for crop scientists to exploit plant defensive traits in crop breeding. In this review, we assess the traits and mechanisms underpinning herbivore resistance and tolerance, and conclude that physical defense traits, plant vigor and herbivore-induced plant volatiles show considerable utility in pest control, along with mixed species crops. We highlight emerging approaches for accelerating the identification of plant defensive traits and facilitating their deployment to improve the future sustainability of crop protection. PMID:27524994

  15. Turnabout Is Fair Play: Herbivory-Induced Plant Chitinases Excreted in Fall Armyworm Frass Suppress Herbivore Defenses in Maize.

    Ray, Swayamjit; Alves, Patrick C M S; Ahmad, Imtiaz; Gaffoor, Iffa; Acevedo, Flor E; Peiffer, Michelle; Jin, Shan; Han, Yang; Shakeel, Samina; Felton, Gary W; Luthe, Dawn S

    2016-05-01

    The perception of herbivory by plants is known to be triggered by the deposition of insect-derived factors such as saliva and oral secretions, oviposition materials, and even feces. Such insect-derived materials harbor chemical cues that may elicit herbivore and/or pathogen-induced defenses in plants. Several insect-derived molecules that trigger herbivore-induced defenses in plants are known; however, insect-derived molecules suppressing them are largely unknown. In this study, we identified two plant chitinases from fall armyworm (Spodoptera frugiperda) larval frass that suppress herbivore defenses while simultaneously inducing pathogen defenses in maize (Zea mays). Fall armyworm larvae feed in enclosed whorls of maize plants, where frass accumulates over extended periods of time in close proximity to damaged leaf tissue. Our study shows that maize chitinases, Pr4 and Endochitinase A, are induced during herbivory and subsequently deposited on the host with the feces. These plant chitinases mediate the suppression of herbivore-induced defenses, thereby increasing the performance of the insect on the host. Pr4 and Endochitinase A also trigger the antagonistic pathogen defense pathway in maize and suppress fungal pathogen growth on maize leaves. Frass-induced suppression of herbivore defenses by deposition of the plant-derived chitinases Pr4 and Endochitinase A is a unique way an insect can co-opt the plant's defense proteins for its own benefit. It is also a phenomenon unlike the induction of herbivore defenses by insect oral secretions in most host-herbivore systems. PMID:26979328

  16. Structural, physiognomic and above-ground biomass variation in savanna–forest transition zones on three continents – how different are co-occurring savanna and forest formations?

    E. M. Veenendaal

    2015-05-01

    Full Text Available Through interpretations of remote-sensing data and/or theoretical propositions, the idea that forest and savanna represent "alternative stable states" is gaining increasing acceptance. Filling an observational gap, we present detailed stratified floristic and structural analyses for forest and savanna stands located mostly within zones of transition (where both vegetation types occur in close proximity in Africa, South America and Australia. Woody plant leaf area index variation was related to tree canopy cover in a similar way for both savanna and forest with substantial overlap between the two vegetation types. As total woody plant canopy cover increased, so did the relative contribution of middle and lower strata of woody vegetation. Herbaceous layer cover declined as woody cover increased. This pattern of understorey grasses and herbs progressively replaced by shrubs as the canopy closes over was found for both savanna and forests and on all continents. Thus, once subordinate woody canopy layers are taken into account, a less marked transition in woody plant cover across the savanna–forest-species discontinuum is observed compared to that inferred when trees of a basal diameter > 0.1 m are considered in isolation. This is especially the case for shrub-dominated savannas and in taller savannas approaching canopy closure. An increased contribution of forest species to the total subordinate cover is also observed as savanna stand canopy closure occurs. Despite similarities in canopy-cover characteristics, woody vegetation in Africa and Australia attained greater heights and stored a greater amount of above-ground biomass than in South America. Up to three times as much above-ground biomass is stored in forests compared to savannas under equivalent climatic conditions. Savanna–forest transition zones were also found to typically occur at higher precipitation regimes for South America than for Africa. Nevertheless, consistent across all three

  17. Distance and sex determine host plant choice by herbivorous beetles.

    Daniel J Ballhorn

    Full Text Available BACKGROUND: Plants respond to herbivore damage with the release of volatile organic compounds (VOCs. This indirect defense can cause ecological costs when herbivores themselves use VOCs as cues to localize suitable host plants. Can VOCs reliably indicate food plant quality to herbivores? METHODOLOGY: We determined the choice behavior of herbivorous beetles (Chrysomelidae: Gynandrobrotica guerreroensis and Cerotoma ruficornis when facing lima bean plants (Fabaceae: Phaseolus lunatus with different cyanogenic potential, which is an important constitutive direct defense. Expression of inducible indirect defenses was experimentally manipulated by jasmonic acid treatment at different concentrations. The long-distance responses of male and female beetles to the resulting induced plant volatiles were investigated in olfactometer and free-flight experiments and compared to the short-distance decisions of the same beetles in feeding trials. CONCLUSION: Female beetles of both species were repelled by VOCs released from all induced plants independent of the level of induction. In contrast, male beetles were repelled by strongly induced plants, showed no significant differences in choice behavior towards moderately induced plants, but responded positively to VOCs released from little induced plants. Thus, beetle sex and plant VOCs had a significant effect on host searching behavior. By contrast, feeding behavior of both sexes was strongly determined by the cyanogenic potential of leaves, although females again responded more sensitively than males. Apparently, VOCs mainly provide information to these beetles that are not directly related to food quality. Being induced by herbivory and involved in indirect plant defense, such VOCs might indicate the presence of competitors and predators to herbivores. We conclude that plant quality as a food source and finding a potentially enemy-free space is more important for female than for male insect herbivores

  18. Assessing the consequences of global change for forest disturbance from herbivores and pathogens

    Ayres, M.P.; Lombardero, M.J. [Department of Biological Sciences, Dartmouth College, NH 03755-3576 Hanover (United States)

    2000-11-15

    Herbivores and pathogens impact the species composition, ecosystem function, and socioeconomic value of forests. Herbivores and pathogens are an integral part of forests, but sometimes produce undesirable effects and a degradation of forest resources. In the United States, a few species of forest pests routinely have significant impacts on up to 20 million ha of forest with economic costs that probably exceed $1 billion/year. Climatic change could alter patterns of disturbance from herbivores and pathogens through: (1) direct effects on the development and survival of herbivores and pathogens; (2) physiological changes in tree defenses; and (3) indirect effects from changes in the abundance of natural enemies (e.g. parasitoids of insect herbivores), mutualists (e.g. insect vectors of tree pathogens), and competitors. Because of their short life cycles, mobility, reproductive potential, and physiological sensitivity to temperature, even modest climate change will have rapid impacts on the distribution and abundance of many forest insects and pathogens. We identify 32 syndromes of biotic disturbance in North American forests that should be carefully evaluated for their responses to climate change: 15 insect herbivores, browsing mammals; 12 pathogens; 1 plant parasite; and 3 undiagnosed patterns of forest decline. It is probable that climatic effects on some herbivores and pathogens will impact on biodiversity, recreation, property value, forest industry, and even water quality. Some scenarios are beneficial (e.g. decreased snow cover may increase winter mortality of some insect pests), but many are detrimental (e.g. warming tends to accelerate insect development rate and facilitate range expansions of pests and climate change tends to produce a mismatch between mature trees and their environment, which can increase vulnerability to herbivores and pathogens). Changes in forest disturbance can produce feedback to climate through affects on water and carbon flux in

  19. Ultraviolet-B Radiation and Nitrogen Affect Nutrient Concentrations and the Amount of Nutrients Acquired by Above-Ground Organs of Maize

    Carlos M. Correia

    2012-01-01

    Full Text Available UV-B radiation effects on nutrient concentrations in above-ground organs of maize were investigated at silking and maturity at different levels of applied nitrogen under field conditions. The experiment simulated a 20% stratospheric ozone depletion over Portugal. At silking, UV-B increased N, K, Ca, and Zn concentrations, whereas at maturity Ca, Mg, Zn, and Cu increased and N, P and Mn decreased in some plant organs. Generally, at maturity, N, Ca, Cu, and Mn were lower, while P, K, and Zn concentrations in stems and nitrogen-use efficiency (NUE were higher in N-starved plants. UV-B and N effects on shoot dry biomass were more pronounced than on nutrient concentrations. Nutrient uptake decreased under high UV-B and increased with increasing N application, mainly at maturity harvest. Significant interactions UV-B x N were observed for NUE and for concentration and mass of some elements. For instance, under enhanced UV-B, N, Cu, Zn, and Mn concentrations decreased in leaves, except on N-stressed plants, whereas they were less affected by N nutrition. In order to minimize nutritional, economical, and environmental negative consequences, fertiliser recommendations based on element concentration or yield goals may need to be adjusted.

  20. Evaluating Generic Pantropical Allometric Models for the Estimation of Above-Ground Biomass in the Teak Plantations of Southern Western Ghats, India

    S. Sandeep

    2015-09-01

    Full Text Available The use of suitable tree biomass allometric equations is crucial for making precise and non- destructive estimation of carbon storage and biomass energy values. The aim of this research was to evaluate the accuracy of the most commonly used pantropical allometric models and site-specific models to estimate the above-ground biomass (AGB in different aged teak plantations of Southern Western Ghats of India. For this purpose, the AGB data measured for 70 trees with diameter >10 cm from different aged teak plantations in Kerala part of Southern Western Ghats following destructive procedure was used. The results show that site specific models based on a single predictor variable diameter at breast height (dbh, though simple, may grossly increase the uncertainty across sites. Hence, a generic model encompassing dbh, height and wood specific gravity with sufficient calibration taking into account different forest types is advised for the tropical forest systems. The study also suggests that the commonly used pantropical models should be evaluated for different ecosystems prior to their application at national or regional scales.

  1. The Effect of Above-Ground Medium Voltage Power Lines on Displaying Site Selection of the Great Bustard (Otis Tarda in Central Hungary

    Lóránt Miklós

    2015-02-01

    Full Text Available Our study was conducted in the Upper-Kiskunság region, Central Hungary, which hosts the largest Pannonian population of the Great Bustard (Otis tarda. The influence of the presence of aboveground medium voltage power lines on displaying site selection of Great Bustard males was investigated. The results revealed that displaying males totally reject the sites located within 350-400 m or closer to medium voltage power lines as displaying sites and show relative rejection towards potential displaying sites located at a distance between 500 and 1000 m far from power lines. Surprisingly, the overall negative effects influence much larger part of the potential displaying grounds, up to the distance to 3500 m from power lines. It can be declared that power lines reduce the extent of suitable displaying sites of the Great Bustards in the Upper-Kiskunság region. Accordingly, installation of new above-ground power lines (and other kind of wires, such as high voltage power lines, optical cables etc. would further reduce the extent of suitable displaying sites.

  2. Reflectance of blue, green, red and near infrared radiation from wetland vegetation used in a model discriminating live and dead above ground biomass

    Field measurements of canopy reflectance of wetland vegetation in the blue (450 ran), green (548 nm), red (655 nm) and NIR (805 nm) wavebands were correlated with plant biomass variables. Negative relationships, asymptotic in nature, were observed between visible wavebands, canopy reflectance and total live biomass as well as green biomass, with correlation coefficients r between −0·52 and −0·93. Curvilinear relations were observed between NIR canopy reflectance and total live biomass as well as green biomass, with r between 0·39 and 0·88. Different normalization indices (NIR blue−1, NIR red−1, VI, PI and NIRlbio) were tested and positive relations between these indices and total live biomass and green biomass were observed, with r between 0·69 and 0·96. Inverse relations of an asymptotic nature were observed between dead biomass as a percentage of total biomass and of green biomass, with r between 0·90 and 0·91. A model discriminating live and dead above-ground biomass was developed to improve correlations between canopy reflectance and biomass variables. The model nearly doubled the correlation coefficient between reflectance and green biomass for a canopy containing large amounts of interfering dead biomass, but did not change this correlation for a canopy containing small amounts of dead biomass. (author)

  3. Above-ground biomass and carbon estimates of Shorea robusta and Tectona grandis forests using QuadPOL ALOS PALSAR data

    Behera, M. D.; Tripathi, P.; Mishra, B.; Kumar, Shashi; Chitale, V. S.; Behera, Soumit K.

    2016-01-01

    Mechanisms to mitigate climate change in tropical countries such as India require information on forest structural components i.e., biomass and carbon for conservation steps to be implemented successfully. The present study focuses on investigating the potential use of a one time, QuadPOL ALOS PALSAR L-band 25 m data to estimate above-ground biomass (AGB) using a water cloud model (WCM) in a wildlife sanctuary in India. A significant correlation was obtained between the SAR-derived backscatter coefficient (σ°) and the field measured AGB, with the maximum coefficient of determination for cross-polarized (HV) σ° for Shorea robusta, and the weakest correlation was observed with co-polarized (HH) σ° for Tectona grandis forests. The biomass of S. robusta and that of T. grandis were estimated on the basis of field-measured data at 444.7 ± 170.4 Mg/ha and 451 ± 179.4 Mg/ha respectively. The mean biomass values estimated using the WCM varied between 562 and 660 Mg/ha for S. robusta; between 590 and 710 Mg/ha for T. grandis using various polarized data. Our results highlighted the efficacy of one time, fully polarized PALSAR data for biomass and carbon estimate in a dense forest.

  4. Synergistic effects of three Piper amides on generalist and specialist herbivores.

    Dyer, L A; Dodson, C D; Stireman, J O; Tobler, M A; Smilanich, A M; Fincher, R M; Letourneau, D K

    2003-11-01

    The tropical rainforest shrub Piper cenocladum, which is normally defended against herbivores by a mutualistic ant, contains three amides that have various defensive functions. While the ants are effective primarily against specialist herbivores, we hypothesized that these secondary compounds would be effective against a wider range of insects, thus providing a broad array of defenses against herbivores. We also tested whether a mixture of amides would be more effective against herbivores than individual amides. Diets spiked with amides were offered to five herbivores: a naïve generalist caterpillar (Spodoptera frugiperda), two caterpillar species that are monophagous on P. cenocladum (Eois spp.), leaf-cutting ants (Atta cephalotes), and an omnivorous ant (Paraponera clavata). Amides had negative effects on all insects, whether they were naïve, experienced, generalized, or specialized feeders. For Spodoptera, amide mixtures caused decreased pupal weights and survivorship and increased development times. Eois pupal weights, larval mass gain, and development times were affected by additions of individual amides, but increased parasitism and lower survivorship were caused only by the amide mixture. Amide mixtures also deterred feeding by the two ant species, and crude plant extracts were strongly deterrent to P. clavata. The mixture of all three amides had the most dramatic deterrent and toxic effects across experiments, with the effects usually surpassing expected additive responses, indicating that these compounds can act synergistically against a wide array of herbivores. PMID:14682530

  5. Ant plant herbivore interactions in the neotropical cerrado savanna

    Oliveira, Paulo S.; Freitas, André V. L.

    2004-12-01

    The Brazilian cerrado savanna covers nearly 2 million km2 and has a high incidence on foliage of various liquid food sources such as extrafloral nectar and insect exudates. These liquid rewards generate intense ant activity on cerrado foliage, making ant plant herbivore interactions especially prevalent in this biome. We present data on the distribution and abundance of extrafloral nectaries in the woody flora of cerrado communities and in the flora of other habitats worldwide, and stress the relevance of liquid food sources (including hemipteran honeydew) for the ant fauna. Consumption by ants of plant and insect exudates significantly affects the activity of the associated herbivores of cerrado plant species, with varying impacts on the reproductive output of the plants. Experiments with an ant plant butterfly system unequivocally demonstrate that the behavior of both immature and adult lepidopterans is closely related to the use of a risky host plant, where intensive visitation by ants can have a severe impact on caterpillar survival. We discuss recent evidence suggesting that the occurrence of liquid rewards on leaves plays a key role in mediating the foraging ecology of foliage-dwelling ants, and that facultative ant plant mutualisms are important in structuring the community of canopy arthropods. Ant-mediated effects on cerrado herbivore communities can be revealed by experiments performed on wide spatial scales, including many environmental factors such as soil fertility and vegetation structure. We also present some research questions that could be rewarding to investigate in this major neotropical savanna.

  6. The influence of a neotropical herbivore (Lamponius portoricensis) on nutrient cycling and soil processes.

    Fonte, S J; Schowalter, T D

    2005-12-01

    The role of phytophagous insects in ecosystem nutrient cycling remains poorly understood. By altering the flow of litterfall nutrients from the canopy to the forest floor, herbivores may influence key ecosystem processes. We manipulated levels of herbivory in a lower montane tropical rainforest of Puerto Rico using the common herbivore, Lamponius portoricensis (Phasmatidea), on a prevalent understory plant, Piper glabrescens (Piperaceae), and measured the effects on nutrient input to the forest floor and on rates of litter decomposition. Four treatment levels of herbivory generated a full range of leaf area removal, from plants experiencing no herbivory to plants that were completely defoliated (>4,000 cm(2) leaf area removed during the 76-day study duration). A significant (Pfloor. These results suggest that insect herbivores can influence forest floor nutrient dynamics and thus merit further consideration in discussions on ecosystem nutrient dynamics. PMID:16175388

  7. Towards ground-truthing of spaceborne estimates of above-ground life biomass and leaf area index in tropical rain forests

    P. Köhler

    2010-08-01

    Full Text Available The canopy height h of forests is a key variable which can be obtained using air- or spaceborne remote sensing techniques such as radar interferometry or LIDAR. If new allometric relationships between canopy height and the biomass stored in the vegetation can be established this would offer the possibility for a global monitoring of the above-ground carbon content on land. In the absence of adequate field data we use simulation results of a tropical rain forest growth model to propose what degree of information might be generated from canopy height and thus to enable ground-truthing of potential future satellite observations. We here analyse the correlation between canopy height in a tropical rain forest with other structural characteristics, such as above-ground life biomass (AGB (and thus carbon content of vegetation and leaf area index (LAI and identify how correlation and uncertainty vary for two different spatial scales. The process-based forest growth model FORMIND2.0 was applied to simulate (a undisturbed forest growth and (b a wide range of possible disturbance regimes typically for local tree logging conditions for a tropical rain forest site on Borneo (Sabah, Malaysia in South-East Asia. In both undisturbed and disturbed forests AGB can be expressed as a power-law function of canopy height h (AGB = a · hb with an r2 ~ 60% if data are analysed in a spatial resolution of 20 m × 20 m (0.04 ha, also called plot size. The correlation coefficient of the regression is becoming significant better in the disturbed forest sites (r2 = 91% if data are analysed hectare wide. There seems to exist no functional dependency between LAI and canopy height, but there is also a linear correlation (r2 ~ 60% between AGB and the area fraction of gaps in which the canopy is highly disturbed. A reasonable agreement of our results with observations is obtained from a

  8. Modeling Water and Nutrient Transport through the Soil-Root-Canopy Continuum: Explicitly Linking the Below- and Above-Ground Processes

    Kumar, P.; Quijano, J. C.; Drewry, D.

    2010-12-01

    Vegetation roots provide a fundamental link between the below ground water and nutrient dynamics and above ground canopy processes such as photosynthesis, evapotranspiration and energy balance. The “hydraulic architecture” of roots, consisting of the structural organization of the root system and the flow properties of the conduits (xylem) as well as interfaces with the soil and the above ground canopy, affect stomatal conductance thereby directly linking them to the transpiration. Roots serve as preferential pathways for the movement of moisture from wet to dry soil layers during the night, both from upper soil layer to deeper layers during the wet season (‘hydraulic descent’) and vice-versa (‘hydraulic lift’) as determined by the moisture gradients. The conductivities of transport through the root system are significantly, often orders of magnitude, larger than that of the surrounding soil resulting in movement of soil-moisture at rates that are substantially larger than that through the soil. This phenomenon is called hydraulic redistribution (HR). The ability of the deep-rooted vegetation to “bank” the water through hydraulic descent during wet periods for utilization during dry periods provides them with a competitive advantage. However, during periods of hydraulic lift these deep-rooted trees may facilitate the growth of understory vegetation where the understory scavenges the hydraulically lifted soil water. In other words, understory vegetation with relatively shallow root systems have access to the banked deep-water reservoir. These inter-dependent root systems have a significant influence on water cycle and ecosystem productivity. HR induced available moisture may support rhizosphere microbial and mycorrhizal fungi activities and enable utilization of heterogeneously distributed water and nutrient resources To capture this complex inter-dependent nutrient and water transport through the soil-root-canopy continuum we present modeling

  9. Estimating the Above-Ground Biomass in Miombo Savanna Woodlands (Mozambique, East Africa Using L-Band Synthetic Aperture Radar Data

    Maria J. Vasconcelos

    2013-03-01

    Full Text Available The quantification of forest above-ground biomass (AGB is important for such broader applications as decision making, forest management, carbon (C stock change assessment and scientific applications, such as C cycle modeling. However, there is a great uncertainty related to the estimation of forest AGB, especially in the tropics. The main goal of this study was to test a combination of field data and Advanced Land Observing Satellite (ALOS Phased Array L-band Synthetic Aperture Radar (PALSAR backscatter intensity data to reduce the uncertainty in the estimation of forest AGB in the Miombo savanna woodlands of Mozambique (East Africa. A machine learning algorithm, based on bagging stochastic gradient boosting (BagSGB, was used to model forest AGB as a function of ALOS PALSAR Fine Beam Dual (FBD backscatter intensity metrics. The application of this method resulted in a coefficient of correlation (R between observed and predicted (10-fold cross-validation forest AGB values of 0.95 and a root mean square error of 5.03 Mg·ha−1. However, as a consequence of using bootstrap samples in combination with a cross validation procedure, some bias may have been introduced, and the reported cross validation statistics could be overoptimistic. Therefore and as a consequence of the BagSGB model, a measure of prediction variability (coefficient of variation on a pixel-by-pixel basis was also produced, with values ranging from 10 to 119% (mean = 25% across the study area. It provides additional and complementary information regarding the spatial distribution of the error resulting from the application of the fitted model to new observations.

  10. Optimizing the number of training areas for modeling above-ground biomass with ALS and multispectral remote sensing in subtropical Nepal

    Rana, Parvez; Gautam, Basanta; Tokola, Timo

    2016-07-01

    Remote sensing-based inventories of above-ground forest biomass (AGB) require a set of training plots representative of the area to be studied, the collection of which is the most expensive part of the analysis. These are time-consuming and costly because the large variety in forest conditions requires more plots to adequately capture this variability. A field campaign in general is challenging and is hampered by the complex topographic conditions, limited accessibility, steep mountainous terrains which increase labor efforts and costs. In addition it is also depend on the ratio between size of study area and number of training plots. In this study, we evaluate the number of training areas (sample size) required to estimate AGB for an area in the southern part of Nepal using airborne laser scanning (ALS), RapidEye and Landsat data. Three experiments were conducted: (i) AGB model performance, based on all the field training plots; (ii) reduction of the sample size, based on the ALS metrics and the AGB distribution; and (iii) prediction of the optimal number of training plots, based on the correlation between the remote sensing and field data. The AGB model was fitted using the sparse Bayesian method. AGB model performance was validated using an independent validation dataset. The effect of the strategies for reducing the sample size was readily apparent for the ALS-based AGB prediction, but the RapidEye and Landsat sensor data failed to capture any such effect. The results indicate that adequate coverage of the variability in tree height and density was an important condition for selecting the training plots. In addition, the ALS-based AGB prediction required the smallest number of training plots and was also quite stable with a small number of field plots.

  11. Heavy metal accumulation in the above-ground vegetation and soil around an iron smelting factory in Ile-Ife, southwestern Nigeria

    Emmanuel F. Isola; Olusanya A. Olatunji; Akinjide M. Afolabi; Ademayowa A. Omodara

    2015-01-01

    This study investigated the accumulation of heavy metals in the above-ground vegetation and soil around an iron smelting factory located at the Fashina Area, Ile-Ife, Osun State, southwestern Nigeria. This was with a view to establish baseline data which can be used for assessing the impact of the steel processing industry in the area. Samples of the two most common herbaceous species (Chromolaena odorataand Aspilia africana) around the factory were randomly collected at 10 m away from the wall of the factory, and soil samples were randomly collected at 0–15 cm depths in the same area. The plant species were oven-dried, put through a mixed acid digestion procedure, and, along with soil samples, were analyzed for N, P, K, C, Zn, Pb, Cd, Ni, and Cr using an atomic absorption spectrophotometer. The data obtained were subjected to appropriate descriptive and inferential statistical analyses. The results revealed that the soils were slightly acidic, with pH values of 6.23±0.24 in the dry season and 6.10±0.16 in the rainy season. There was a significant difference (P P > N in both Aspilia africana andChromolaena odorata. In the dry season, C percentage concentration was higher inAspilia africana, while the other elements followed the trend observed in the rainy season. The concentration of Zn was higher inAspilia af-ricana in both the polluted site and the control site in the rainy season, while the concentrations of the other heavy metals were higher inChromolaena odoratain the dry season. This study revealed that the heavy metal concentration varied with the plant species and also with the prevailing seasonal conditions. Also, the accumulation and concentration of heavy metals in both plant species and in the soil indicated a potential hazard of the factory to the local environment.

  12. Above-ground sulfur cycling in adjacent coniferous and deciduous forest and watershed sulfur retention in the Georgia Piedmont, U.S.A.

    Cappellato, R.; Peters, N.E.; Meyers, T.P.

    1998-01-01

    Atmospheric deposition and above-ground cycling of sulfur (S) were evaluated in adjacent deciduous and coniferous forests at the Panola Mountain Research Watershed (PMRW), Georgia U.S.A. Total atmospheric S deposition (wet plus dry) was 12.9 and 12.7 kg ha-1 yr-1 for the deciduous and coniferous forests, respectively, from October 1987 through November 1989. Dry deposition contributes more than 40% to the total atmospheric S deposition, and SO2 is the major source (~55%) of total dry S deposition. Dry deposition to these canopies is similar to regional estimates suggesting that 60-km proximity to emission sources does not noticeably impact dry deposition at PMRW. Below-canopy S fluxes (throughfall plus stemflow) in each forest are 37% higher annually in the deciduous forest than in the coniferous forest. An excess in below-canopy S flux in the deciduous forest is attributed to leaching and higher dry deposition than in the coniferous forest. Total S deposition to the forest floor by throughfall, stemflow and litterfall was 2.4 and 2.8 times higher in the deciduous and coniferous forests, respectively, than annual S growth requirement for foliage and wood. Although A deposition exceeds growth requirement, more than 95% of the total atmospheric S deposition was retained by the watershed in 1988 and 1989. The S retention at PMRW is primarily due to SO2+4 adsorption by iron oxides and hydroxides in watershed soils. The S content in while oak and loblolly pine boles have increased more than 200% in the last 20 yr, possibly reflecting increases in emissions.

  13. Assessment of Above-Ground Biomass of Borneo Forests through a New Data-Fusion Approach Combining Two Pan-Tropical Biomass Maps

    Andreas Langner

    2015-08-01

    Full Text Available This study investigates how two existing pan-tropical above-ground biomass (AGB maps (Saatchi 2011, Baccini 2012 can be combined to derive forest ecosystem specific carbon estimates. Several data-fusion models which combine these AGB maps according to their local correlations with independent datasets such as the spectral bands of SPOT VEGETATION imagery are analyzed. Indeed these spectral bands convey information about vegetation type and structure which can be related to biomass values. Our study area is the island of Borneo. The data-fusion models are evaluated against a reference AGB map available for two forest concessions in Sabah. The highest accuracy was achieved by a model which combines the AGB maps according to the mean of the local correlation coefficients calculated over different kernel sizes. Combining the resulting AGB map with a new Borneo land cover map (whose overall accuracy has been estimated at 86.5% leads to average AGB estimates of 279.8 t/ha and 233.1 t/ha for forests and degraded forests respectively. Lowland dipterocarp and mangrove forests have the highest and lowest AGB values (305.8 t/ha and 136.5 t/ha respectively. The AGB of all natural forests amounts to 10.8 Gt mainly stemming from lowland dipterocarp (66.4%, upper dipterocarp (10.9% and peat swamp forests (10.2%. Degraded forests account for another 2.1 Gt of AGB. One main advantage of our approach is that, once the best fitting data-fusion model is selected, no further AGB reference dataset is required for implementing the data-fusion process. Furthermore, the local harmonization of AGB datasets leads to more spatially precise maps. This approach can easily be extended to other areas in Southeast Asia which are dominated by lowland dipterocarp forest, and can be repeated when newer or more accurate AGB maps become available.

  14. Virus infection decreases the attractiveness of white clover plants for a non-vectoring herbivore

    van Mölken, Tamara; Caluwe, Hannie de; Hordijk, Cornelis A.;

    2012-01-01

    Plant pathogens and insect herbivores are prone to share hosts under natural conditions. Consequently, pathogen-induced changes in the host plant can affect herbivory, and vice versa. Even though plant viruses are ubiquitous in the field, little is known about plant-mediated interactions between...

  15. Complex odour from plants under attack: herbivore's enemies react to the whole, not its parts.

    M. van Wijk; P.J.A. de Bruijn; M.W. Sabelis

    2011-01-01

    Background Insect herbivory induces plant odors that attract herbivores' natural enemies. Assuming this attraction emerges from individual compounds, genetic control over odor emission of crops may provide a rationale for manipulating the distribution of predators used for pest control. However, stu

  16. Behavioral Ecology of Oviposition-Site Selection in Herbivorous True Bugs

    Martínez, G.; Soler, R.; Dicke, M.

    2013-01-01

    Optimal oviposition theory predicts that female herbivores will prefer to oviposit on those plants that maximize offspring performance, also known as the “mother knows best” paradigm. This is the general pattern within the insect order Lepidoptera with specialist diets and reduced larval mobility. I

  17. Behavioral Ecology of Oviposition-Site Selection in Herbivorous True Bugs

    Martinez, G.; Soler, R.; Dicke, M.; Brockmann, H.J.; Roper, T.J.; Naguib, M.; Mitani, J.C.; Simmons, L.W.; Barrett, L.

    2013-01-01

    Optimal oviposition theory predicts that female herbivores prefer to oviposit on those plants that maximize offspring performance, also known as the “mother knows best” paradigm. This is the general pattern within the insect order Lepidoptera with specialist diets and reduced larval mobility. In tha

  18. Potato tuber herbivory increases resistance to aboveground lepidopteran herbivores.

    Kumar, Pavan; Ortiz, Erandi Vargas; Garrido, Etzel; Poveda, Katja; Jander, Georg

    2016-09-01

    Plants mediate interactions between aboveground and belowground herbivores. Although effects of root herbivory on foliar herbivores have been documented in several plant species, interactions between tuber-feeding herbivores and foliar herbivores are rarely investigated. We report that localized tuber damage by Tecia solanivora (Guatemalan tuber moth) larvae reduced aboveground Spodoptera exigua (beet armyworm) and Spodoptera frugiperda (fall armyworm) performance on Solanum tuberosum (potato). Conversely, S. exigua leaf damage had no noticeable effect on belowground T. solanivora performance. Tuber infestation by T. solanivora induced systemic plant defenses and elevated resistance to aboveground herbivores. Lipoxygenase 3 (Lox3), which contributes to the synthesis of plant defense signaling molecules, had higher transcript abundance in T. solanivora-infested leaves and tubers than in equivalent control samples. Foliar expression of the hydroxycinnamoyl-CoA quinate hydroxycinnamoyl transferase (HQT) and 3-hydroxy-3-methylglutaryl CoA reductase I (HMGR1) genes, which are involved in chlorogenic acid and steroidal glycoalkaloid biosynthesis, respectively, also increased in response to tuber herbivory. Leaf metabolite profiling demonstrated the accumulation of unknown metabolites as well as the known potato defense compounds chlorogenic acid, α-solanine, and α-chaconine. When added to insect diet at concentrations similar to those found in potato leaves, chlorogenic acid, α-solanine, and α-chaconine all reduced S. exigua larval growth. Thus, despite the fact that tubers are a metabolic sink tissue, T. solanivora feeding elicits a systemic signal that induces aboveground resistance against S. exigua and S. frugiperda by increasing foliar abundance of defensive metabolites. PMID:27147449

  19. Insects as alternative hosts for phytopathogenic bacteria.

    Nadarasah, Geetanchaly; Stavrinides, John

    2011-05-01

    Phytopathogens have evolved specialized pathogenicity determinants that enable them to colonize their specific plant hosts and cause disease, but their intimate associations with plants also predispose them to frequent encounters with herbivorous insects, providing these phytopathogens with ample opportunity to colonize and eventually evolve alternative associations with insects. Decades of research have revealed that these associations have resulted in the formation of bacterial-vector relationships, in which the insect mediates dissemination of the plant pathogen. Emerging research, however, has highlighted the ability of plant pathogenic bacteria to use insects as alternative hosts, exploiting them as they would their primary plant host. The identification of specific bacterial genetic determinants that mediate the interaction between bacterium and insect suggests that these interactions are not incidental, but have likely arisen following the repeated association of microorganisms with particular insects over evolutionary time. This review will address the biology and ecology of phytopathogenic bacteria that interact with insects, including the traditional role of insects as vectors, as well as the newly emerging paradigm of insects serving as alternative primary hosts. Also discussed is one case where an insect serves as both host and vector, which may represent a transitionary stage in the evolution of insect-phytopathogen associations. PMID:21251027

  20. Sensitivity of Backscatter Intensity of ALOS/PALSAR to Above-ground Biomass and Other Biophysical Parameters of Boreal Forests in Alaska and Japan

    Suzuki, R.; Hayashi, M.; Kim, Y.; Ishii, R.; Kobayashi, H.; Shoyama, K.; Adachi, M.; Takahashi, A.; Saigusa, N.; Ito, A.

    2012-12-01

    For the better understanding of the carbon cycle in the global environment, investigations on the spatio-temporal variation of the carbon stock which is stored as vegetation biomass is important. The backscatter intensity of "Phased Array type L-band Synthetic Aperture Radar (PALSAR)" onboard the satellite "Advanced Land Observing Satellite (ALOS)" provides us the information which is applicable to estimate the forest above-ground biomass (AGB). This study examines the sensitivity of the backscatter intensity of ALOS/PALSAR to the forest AGB and other biophysical parameters (tree height, tree diameter at breast height (DBH), and tree stand density) for boreal forests in two geographical regions of Alaska and Kushiro, northern Japan, and compares the sensitivities in two regions. In Alaska, a forest survey was executed in the south-north transect (about 300 km long) along a trans-Alaska pipeline which profiles the ecotone from the boreal forest to tundra in 2007. Forest AGBs and other biophysical parameters at 29 forests along the transect were measured by Bitterlich method. In Kushiro, a forest survey was carried out at 42 forests in 2011 and those parameters were similarly obtained by Bitterlich method. 20 and 2 scenes of ALOS/PALSAR FBD Level 1.5 data that cover the regions in Alaska and Kushiro, respectively, were collected and mosaicked. Backscatter intensities of ALOS/PALSAR in HH (horizontally polarized transmitted and horizontally polarized received) and HV (horizontally polarized transmitted and vertically polarized received) modes were compared with the forest AGB and other biophysical parameters. The intensity generally increased with the increase of those biophysical parameters in both HV and HH modes, but the intensity in HV mode generally had a stronger correlation to those parameters than in HH mode in both Alaska and Kushiro. The HV intensity had strong correlation to the forest AGB and DBH, while weak correlation to the tree stand density in Alaska

  1. Estimation of the carbon pool in soil and above-ground biomass within mangrove forests in Southeast Mexico using allometric equations

    Jesús Jaime Guerra-Santos; Rosa María Cerón-Bretón; Julia Griselda Cerón-Bretón; Diana Lizett Damián-Hernández; Reyna Cristina Sánchez-Junco; Emma del Carmen Guevara Carrió

    2014-01-01

    We report the results of carbon stored in soil and aboveground biomass from the most important area of mangroves in Mexico, with dominant vegetation of Red mangrove (Rhizophora mangle L.), Black mangrove (Avicennia germinans L.), white mangrove (Laguncularia racemosa Gaertn.) and button mangrove (Conocarpus erectus L.). We sampled soils with high fertility during the dry season in 2009 and 2010 at three sites on Atasta Peninsula, Campeche. We used allometric equations to estimate above ground biomass (AGB) of trees. AGB was higher in C. erectus (253.18±32.17 t⋅ha-1), lower in A. germinans (161.93±12.63 t⋅ha-1), and intermediate in R. mangle (181.70±16.58 t⋅ha-1) and L. racemosa (206.07±19.12 t⋅ha-1). Of the three studied sites, the highest absolute value for AGB was 279.72 t⋅ha-1 in button mangrove forest at any single site. Carbon stored in soil at the three sites ranged from 36.80±10.27 to 235.77±66.11 t⋅ha-1. The Tukey test (p <0.05) made for AGB was higher for black mangrove showed significant differences in soil carbon content between black mangrove and button mangrove. C. erectus had higher AGB compared with the other species. A. germinans trees had lower AGB because they grew in hypersaline environments, which reduced their development. C. erectus grew on higher ground where soils were richer in nutrients. AGB tended to be low in areas near the sea and increased with distance from the coast. A. germinans usually grew on recently deposited sediments. We assumed that all sites have the same potential to store carbon in soil, and then we found that there were no significant differences in carbon content between the three samples sites: all sites had potential to store carbon for long periods. Carbon storage at the three sampling sites in the state of Campeche, Mexico, was higher than that reported for other locations.

  2. Water activities in Forsmark (Part II). The final disposal facility for spent fuel: water activities above ground; Vattenverksamhet i Forsmark (del II). Slutfoervarsanlaeggningen foer anvaent kaernbraensle: Vattenverksamheter ovan mark

    Werner, Kent (EmpTec (Sweden)); Hamren, Ulrika; Collinder, Per (Ekologigruppen AB (Sweden)); Ridderstolpe, Peter (WRS Uppsala AB (Sweden))

    2010-09-15

    The construction of the repository for spent nuclear fuel in Forsmark is associated with a number of measures above ground that constitute water operations according to Chapter 11 in the Swedish Environmental Code. This report, which is an appendix to the Environmental Impact Assessment, describes these water operations, their effects and consequences, and planned measures

  3. An Extreme Case of Plant-Insect Codiversification: Figs and Fig-Pollinating Wasps

    Cruaud, Astrid; Rønsted, Nina; Chanterasuwan, Bhanumas; Chou, Lien Siang; Clement, Wendy L.; Couloux, Arnaud; Cousins, Benjamin; Genson, Gwenaëlle; Harrison, Rhett D.; Hanson, Paul E.; Hossaert-McKey, Martine; Jabbour-Zahab, Roula; Jousselin, Emmanuelle; Kerdelhué, Carole; Kjellberg, Finn; Lopez-Vaamonde, Carlos; Peebles, John; Peng, Yan-Qiong; Pereira, Rodrigo A.S.; Schramm, Tselil; Ubaidillah, Rosichon; van Noort, Simon; Weiblen, George D.; Yang, Da-Rong; Yodpinyanee, Anak; Libeskind-Hadas, Ran; Cook, James M.; Rasplus, Jean-Yves; Savolainen, Vincent

    2012-01-01

    It is thought that speciation in phytophagous insects is often due to colonization of novel host plants, because radiations of plant and insect lineages are typically asynchronous. Recent phylogenetic comparisons have supported this model of diversification for both insect herbivores and speciali...... subsequent dispersal, rather than with Gondwanan vicariance. Overall, our findings indicate that the fig-pollinator mutualism represents an extreme case among plant-insect interactions of coordinated dispersal and long-term co-diversification.......It is thought that speciation in phytophagous insects is often due to colonization of novel host plants, because radiations of plant and insect lineages are typically asynchronous. Recent phylogenetic comparisons have supported this model of diversification for both insect herbivores and...... specialized pollinators. An exceptional case where contemporaneous plant-insect diversification might be expected is the obligate mutualism between fig trees (Ficus species, Moraceae) and their pollinating wasps (Agaonidae, Hymenoptera). The ubiquity and ecological significance of this mutualism in tropical...

  4. Avoiding incidental predation by mammalian herbivores: accurate detection and efficient response in aphids

    Gish, Moshe; Dafni, Amots; Inbar, Moshe

    2011-09-01

    Mammalian herbivores eat plants that may also provide food and shelter for insects. The direct trophic effect of the browsing and grazing of mammalian herbivory on insects, which is probably prevalent in terrestrial ecosystems, has been mostly neglected by ecologists. We examined how the aphid Uroleucon sonchi L. deals with the danger of incidental predation by mammalian herbivores. We found that most (76%) of the aphids in a colony survive the ingestion of the plant by a feeding herbivore. They do so by sensing the combination of heat and humidity in the herbivore's breath and immediately dropping off the plant in large numbers. Their ability to sense the herbivore's breath or their tendency to drop off the plant weakens as ambient temperature rises. This could indicate a limitation of the aphids' sensory system or an adaptation that enables them to avoid the hostile conditions on a hot ground. Once on the ground, U. sonchi is highly mobile and capable of locating a new host plant by advancing in a pattern that differs significantly from random movement. The accurate and efficient defense mechanism of U. sonchi emphasizes the significance of incidental predation as a danger to plant-dwelling invertebrates.

  5. Microbial detoxification in the gut of a specialist avian herbivore, the Greater Sage-Grouse.

    Kohl, Kevin D; Connelly, John W; Dearing, M Denise; Forbey, Jennifer Sorensen

    2016-07-01

    One function of the gut microbiota gaining recent attention, especially in herbivorous mammals and insects, is the metabolism of plant secondary metabolites (PSMs). We investigated whether this function exists within the gut communities of a specialist avian herbivore. We sequenced the cecal metagenome of the Greater Sage-Grouse (Centrocercus urophasianus), which specializes on chemically defended sagebrush (Artemisia spp.). We predicted that the cecal metagenome of the sage-grouse would be enriched in genes associated with the metabolism of PSMs when compared to the metagenome of the domestic chicken. We found that representation of microbial genes associated with 'xenobiotic degradation and metabolism' was 3-fold higher in the sage-grouse cecal metagenomes when compared to that of the domestic chicken. Further, we identified a complete metabolic pathway for the degradation of phenol to pyruvate, which was not detected in the metagenomes of the domestic chicken, bovine rumen or 14 species of mammalian herbivores. Evidence of monoterpene degradation (a major class of PSMs in sagebrush) was less definitive, although we did detect genes for several enzymes associated with this process. Overall, our results suggest that the gut microbiota of specialist avian herbivores plays a similar role to the microbiota of mammalian and insect herbivores in degrading PSMs. PMID:27242374

  6. Estimating Above-Ground Biomass Within the Footprint of an Eddy-Covariance Flux Tower: Continuous LiDAR Based Estimates Compared With Discrete Inventory and Disturbance History Based Stratification Boundaries

    Ferster, C. J.; Trofymow, J. A.; Coops, N. C.; Chen, B.; Black, T. A.

    2008-12-01

    Eddy-covariance (EC) flux towers provide data about carbon (C) exchange between land and the atmosphere at an ecosystem scale. However, important research questions need to be addressed when placing EC flux towers in complex heterogeneous forest landscapes, such as the coastal forests of Western Canada. Recently available footprint analysis, which describes the contribution function and catchment area where EC flux is being measured, can be used to relate EC flux tower measurements with the biological structure and carbon stock distributions of complex forest landscapes. In this study, above ground biomass is estimated near an EC flux tower using two approaches. In the first approach, a remote sensing based surface representing above ground biomass was estimated using small footprint, discrete return, light detection and ranging (LiDAR) data. Plot level LiDAR metrics were supplemented with metrics calculated using individual tree detection. A multiple regression model was developed to estimate above ground biomass using ground plot and LiDAR data, and then the model was applied across the EC flux footprint area to estimate the spatial distribution of above ground biomass. In the second approach, line boundaries from forest inventory, disturbance history, and site series were used to delineate discrete stratification units and the measured groundplot data assigned to the various strata. Within the heterogeneous tower footprint area, footprint weighting allows us to compare and contrast above ground biomass estimates from these two approaches. Using this methodology we then plan to compare, for the same period, ground-based measurements of ecosystem C stock changes with accumulative EC measured net ecosystem C flux.

  7. Herbivore-mediated material fluxes in a northern deciduous forest under elevated carbon dioxide and ozone concentrations.

    Meehan, Timothy D; Couture, John J; Bennett, Alison E; Lindroth, Richard L

    2014-10-01

    Anthropogenic changes in atmospheric carbon dioxide (CO2 ) and ozone (O3 ) are known to alter tree physiology and growth, but the cascading effects on herbivore communities and herbivore-mediated nutrient cycling are poorly understood. We sampled herbivore frass, herbivore-mediated greenfall, and leaf-litter deposition in temperate forest stands under elevated CO2 (c. 560 ppm) and O3 (c. 1.5× ambient), analyzed substrate chemical composition, and compared the quality and quantity of fluxes under multiple atmospheric treatments. Leaf-chewing herbivores fluxed 6.2 g m(-2)  yr(-1) of frass and greenfall from the canopy to the forest floor, with a carbon : nitrogen (C : N) ratio 32% lower than that of leaf litter. Herbivore fluxes of dry matter, C, condensed tannins, and N increased under elevated CO2 (35, 32, 63 and 39%, respectively), while fluxes of N decreased (18%) under elevated O3 . Herbivore-mediated dry matter inputs scaled across atmospheric treatments as a constant proportion of leaf-litter inputs. Increased fluxes under elevated CO2 were consistent with increased herbivore consumption and abundance, and with increased plant growth and soil respiration, previously reported for this experimental site. Results suggest that insect herbivory will reinforce other factors, such as photosynthetic rate and fine-root production, impacting C sequestration by forests in future environments. PMID:25078062

  8. Impacts of urbanization process on insect diversity

    Shuisong Ye

    2013-05-01

    Full Text Available Rapid worldwide urbanization during the last century has led to more than half the world’s population living in urban regions. Studies of how urbanization affects insect diversity have focused on the following: insect abundance, distribution, extinction, food habits and ecosystem services. Native insect populations have declined greatly in urban areas, where studies of their spatial distribution have revealed that abundance decreases along what is termed the rural–city center gradient (RCG, many native insects even extinct with urbanization process. Most specialist insect communities have declined in abundance due to urbanization, while some generalist species, such as aphids, cockroaches and termites, have increased slightly in abundance. It is also the case that herbivorous, parasitic, saprophagous and flower-visiting insects are much more negatively influenced by urbanization than predator insects. This has a significant effect on the ecosystem services of insects. The decline of many insects due to urbanization can be attributed to environmental pollution (including air pollution, water pollution, light pollution, and heat pollution, habitat fragmentation, road hardening, clustering of buildings, and occurrence of introduced invasive species. As urbanization continues, measures should be taken to protect insects in urban areas. This will entail improving basic scientific research on the problem, construction of suitable habitats, and informing the general public of the benefits of environmental protection.

  9. Turnabout Is Fair Play: Herbivory-Induced Plant Chitinases Excreted in Fall Armyworm Frass Suppress Herbivore Defenses in Maize1[OPEN

    Alves, Patrick C.M.S.; Gaffoor, Iffa; Acevedo, Flor E.; Peiffer, Michelle; Jin, Shan; Han, Yang; Shakeel, Samina; Felton, Gary W.

    2016-01-01

    The perception of herbivory by plants is known to be triggered by the deposition of insect-derived factors such as saliva and oral secretions, oviposition materials, and even feces. Such insect-derived materials harbor chemical cues that may elicit herbivore and/or pathogen-induced defenses in plants. Several insect-derived molecules that trigger herbivore-induced defenses in plants are known; however, insect-derived molecules suppressing them are largely unknown. In this study, we identified two plant chitinases from fall armyworm (Spodoptera frugiperda) larval frass that suppress herbivore defenses while simultaneously inducing pathogen defenses in maize (Zea mays). Fall armyworm larvae feed in enclosed whorls of maize plants, where frass accumulates over extended periods of time in close proximity to damaged leaf tissue. Our study shows that maize chitinases, Pr4 and Endochitinase A, are induced during herbivory and subsequently deposited on the host with the feces. These plant chitinases mediate the suppression of herbivore-induced defenses, thereby increasing the performance of the insect on the host. Pr4 and Endochitinase A also trigger the antagonistic pathogen defense pathway in maize and suppress fungal pathogen growth on maize leaves. Frass-induced suppression of herbivore defenses by deposition of the plant-derived chitinases Pr4 and Endochitinase A is a unique way an insect can co-opt the plant’s defense proteins for its own benefit. It is also a phenomenon unlike the induction of herbivore defenses by insect oral secretions in most host-herbivore systems. PMID:26979328

  10. Low beta diversity of herbivorous insects in tropical forests

    Novotný, Vojtěch; Miller, S. E.; Hulcr, Jiří; Drew, R. A. I.; Basset, Y.; Janda, Milan; Setliff, G. P.; Darrow, K.; Stewart, A. J. A.; Auga, J.; Isua, B.; Molem, K.; Manumbor, M.; Tamtiai, E.; Mogia, M.; Weiblen, G. D.

    2007-01-01

    Roč. 448, č. 7154 (2007), s. 692-695. ISSN 0028-0836 R&D Projects: GA AV ČR IAA600960712; GA ČR GD206/03/H034; GA MŠk LC06073; GA MŠk ME 916 Institutional research plan: CEZ:AV0Z50070508 Keywords : diversity Subject RIV: EH - Ecology, Behaviour Impact factor: 28.751, year: 2007

  11. The global distribution of diet breadth in insect herbivores

    Forister, M. J.; Novotný, Vojtěch; Panorska, A. K.; Baje, L.; Basset, Y.; Butterill, Philip T.; Čížek, Lukáš; Coley, P. D.; Dem, F.; Diniz, I. R.; Drozd, P.; Fox, M.; Glassmire, A. E.; Hazen, R.; Hrček, Jan; Jahner, J. P.; Kaman, Ondřej; Kozubowski, T. J.; Kursar, T. A.; Lewis, O. T.; Lill, J.; Marquis, R. J.; Miller, S. E.; Morais, H. C.; Murakami, M.; Nickel, H.; Pardikes, N. A.; Ricklefs, R. E.; Singer, M. S.; Smilanich, A. M.; Stireman, J. O.; Villamarín-Cortez, S.; Vodka, Štěpán; Volf, Martin; Wagner, D. L.; Walla, T.; Weiblen, G. D.; Dyer, L. A.

    2015-01-01

    Roč. 112, č. 2 (2015), s. 442-447. ISSN 0027-8424 Institutional support: RVO:60077344 Keywords : host range * latitudinal gradient * niche width Subject RIV: EH - Ecology, Behaviour Impact factor: 9.674, year: 2014 http://www.pnas.org/content/112/2/442.full.pdf+html

  12. Inter-varietal interactions among plants in genotypically diverse mixtures tend to decrease herbivore performance.

    Grettenberger, Ian M; Tooker, John F

    2016-09-01

    Much research has explored the effects of plant species diversity on herbivore populations, but far less has considered effects of plant genotypic diversity, or how abiotic stressors, like drought, can modify effects. Mechanisms by which plant genotypic diversity affects herbivore populations remain largely unresolved. We used greenhouse studies with a model system of wheat (Triticum aestivum L.) and bird cherry-oat aphid (Rhopalosiphum padi L.) to determine whether the genotypic diversity of a plant's neighborhood influences performance and fitness of herbivores on a focal plant and if drought changes the influence of neighborhood diversity. Taken across all varieties we tested, plant-plant interactions in diverse neighborhoods reduced aphid performance and generated associational resistance, although effects on aphids depended on variety identity. In diverse mixtures, drought stress greatly diminished the genotypic diversity-driven reduction in aphid performance. Neighborhood diversity influenced mother aphid size, and appeared to partially explain how plant-plant interactions reduced the number of offspring produced in mixtures. Plant size did not mediate effects on aphid performance, although neighborhood diversity reduced plant mass across varieties and watering treatments. Our results suggest inter-varietal interactions in genotypic mixtures can affect herbivore performance in the absence of herbivore movement and that abiotic stress may diminish any effects. Accounting for how neighborhood diversity influences resistance of an individual plant to herbivores will help aid development of mixtures of varieties for managing insect pests and clarify the role of plant genotypic diversity in ecosystems. PMID:27170329

  13. Genetic diversity increases insect herbivory on oak saplings.

    Castagneyrol, Bastien; Lagache, Lélia; Giffard, Brice; Kremer, Antoine; Jactel, Hervé

    2012-01-01

    A growing body of evidence from community genetics studies suggests that ecosystem functions supported by plant species richness can also be provided by genetic diversity within plant species. This is not yet true for the diversity-resistance relationship as it is still unclear whether damage by insect herbivores responds to genetic diversity in host plant populations. We developed a manipulative field experiment based on a synthetic community approach, with 15 mixtures of one to four oak (Quercus robur) half-sib families. We quantified genetic diversity at the plot level by genotyping all oak saplings and assessed overall damage caused by ectophagous and endophagous herbivores along a gradient of increasing genetic diversity. Damage due to ectophagous herbivores increased with the genetic diversity in oak sapling populations as a result of higher levels of damage in mixtures than in monocultures for all families (complementarity effect) rather than because of the presence of more susceptible oak genotypes in mixtures (selection effect). Assemblages of different oak genotypes would benefit polyphagous herbivores via improved host patch location, spill over among neighbouring saplings and diet mixing. By contrast, genetic diversity was a poor predictor of the abundance of endophagous herbivores, which increased with individual sapling apparency. Plant genetic diversity may not provide sufficient functional contrast to prevent tree sapling colonization by specialist herbivores while enhancing the foraging of generalist herbivores. Long term studies are nevertheless required to test whether the effect of genetic diversity on herbivory change with the ontogeny of trees and local adaptation of specialist herbivores. PMID:22937168

  14. Maize Plants Recognize Herbivore-Associated Cues from Caterpillar Frass.

    Ray, Swayamjit; Gaffor, Iffa; Acevedo, Flor E; Helms, Anjel; Chuang, Wen-Po; Tooker, John; Felton, Gary W; Luthe, Dawn S

    2015-09-01

    Caterpillar behaviors such as feeding, crawling, and oviposition are known to induce defenses in maize and other plant species. We examined plant defense responses to another important caterpillar behavior, their defecation. Fall armyworms (FAW, Spodoptera frugiperda), a major threat to maize (Zea mays), are voracious eaters and deposit copious amounts of frass in the enclosed whorl tissue surrounding their feeding site, where it remains for long periods of time. FAW frass is composed of molecules derived from the host plant, the insect itself, and associated microbes, and hence provides abundant cues that may alter plant defense responses. We observed that proteins from FAW frass initially induced wound-responsive defense genes in maize; however, a pathogenesis-related (pr) defense gene was induced as the time after application increased. Elicitation of pathogen defenses by frass proteins was correlated with increased herbivore performance and reduced fungal pathogen performance over time. These responses differ from the typical plant response to oral secretions of the FAW. The results pave the way for identification of protein molecule(s) from the excretion of an herbivore that elicits pathogen defense responses while attenuating herbivore defenses in plants. PMID:26306592

  15. Interacting effects of insects and flooding on wood decomposition.

    Michael D Ulyshen

    Full Text Available Saproxylic arthropods are thought to play an important role in wood decomposition but very few efforts have been made to quantify their contributions to the process and the factors controlling their activities are not well understood. In the current study, mesh exclusion bags were used to quantify how arthropods affect loblolly pine (Pinus taeda L. decomposition rates in both seasonally flooded and unflooded forests over a 31-month period in the southeastern United States. Wood specific gravity (based on initial wood volume was significantly lower in bolts placed in unflooded forests and for those unprotected from insects. Approximately 20.5% and 13.7% of specific gravity loss after 31 months was attributable to insect activity in flooded and unflooded forests, respectively. Importantly, minimal between-treatment differences in water content and the results from a novel test carried out separately suggest the mesh bags had no significant impact on wood mass loss beyond the exclusion of insects. Subterranean termites (Isoptera: Rhinotermitidae: Reticulitermes spp. were 5-6 times more active below-ground in unflooded forests compared to flooded forests based on wooden monitoring stakes. They were also slightly more active above-ground in unflooded forests but these differences were not statistically significant. Similarly, seasonal flooding had no detectable effect on above-ground beetle (Coleoptera richness or abundance. Although seasonal flooding strongly reduced Reticulitermes activity below-ground, it can be concluded from an insignificant interaction between forest type and exclusion treatment that reduced above-ground decomposition rates in seasonally flooded forests were due largely to suppressed microbial activity at those locations. The findings from this study indicate that southeastern U.S. arthropod communities accelerate above-ground wood decomposition significantly and to a similar extent in both flooded and unflooded forests

  16. Ecological Importance of Insects in Selenium Biogenic Cycling

    Nadezhda Golubkina

    2014-01-01

    Full Text Available Selenium is an essential trace element for animal and human beings. Despite the importance of insects in most ecosystems and their significant contribution to the biological cycling of trace elements due to high abundance, population productivity, and diverse ecosystem functions, surprisingly little information is available on selenium bioaccumulation by these arthropods. This review considers selenium essentiality and toxicity to insects as well as insects’ contribution to selenium trophic transfer through the food chains. Data on Se accumulation by insects of the Dniester River Valley with no anthropogenic Se loading reveal typically low Se content in necrophagous insects compared to predators and herbivores and seasonal variations in Se accumulation.

  17. A Latex Metabolite Benefits Plant Fitness under Root Herbivore Attack.

    Huber, Meret; Epping, Janina; Schulze Gronover, Christian; Fricke, Julia; Aziz, Zohra; Brillatz, Théo; Swyers, Michael; Köllner, Tobias G; Vogel, Heiko; Hammerbacher, Almuth; Triebwasser-Freese, Daniella; Robert, Christelle A M; Verhoeven, Koen; Preite, Veronica; Gershenzon, Jonathan; Erb, Matthias

    2016-01-01

    Plants produce large amounts of secondary metabolites in their shoots and roots and store them in specialized secretory structures. Although secondary metabolites and their secretory structures are commonly assumed to have a defensive function, evidence that they benefit plant fitness under herbivore attack is scarce, especially below ground. Here, we tested whether latex secondary metabolites produced by the common dandelion (Taraxacum officinale agg.) decrease the performance of its major native insect root herbivore, the larvae of the common cockchafer (Melolontha melolontha), and benefit plant vegetative and reproductive fitness under M. melolontha attack. Across 17 T. officinale genotypes screened by gas and liquid chromatography, latex concentrations of the sesquiterpene lactone taraxinic acid β-D-glucopyranosyl ester (TA-G) were negatively associated with M. melolontha larval growth. Adding purified TA-G to artificial diet at ecologically relevant concentrations reduced larval feeding. Silencing the germacrene A synthase ToGAS1, an enzyme that was identified to catalyze the first committed step of TA-G biosynthesis, resulted in a 90% reduction of TA-G levels and a pronounced increase in M. melolontha feeding. Transgenic, TA-G-deficient lines were preferred by M. melolontha and suffered three times more root biomass reduction than control lines. In a common garden experiment involving over 2,000 T. officinale individuals belonging to 17 different genotypes, high TA-G concentrations were associated with the maintenance of high vegetative and reproductive fitness under M. melolontha attack. Taken together, our study demonstrates that a latex secondary metabolite benefits plants under herbivore attack, a result that provides a mechanistic framework for root herbivore driven natural selection and evolution of plant defenses below ground. PMID:26731567

  18. Gut microbes may facilitate insect herbivory of chemically defended plants.

    Hammer, Tobin J; Bowers, M Deane

    2015-09-01

    The majority of insect species consume plants, many of which produce chemical toxins that defend their tissues from attack. How then are herbivorous insects able to develop on a potentially poisonous diet? While numerous studies have focused on the biochemical counter-adaptations to plant toxins rooted in the insect genome, a separate body of research has recently emphasized the role of microbial symbionts, particularly those inhabiting the gut, in plant-insect interactions. Here we outline the "gut microbial facilitation hypothesis," which proposes that variation among herbivores in their ability to consume chemically defended plants can be due, in part, to variation in their associated microbial communities. More specifically, different microbes may be differentially able to detoxify compounds toxic to the insect, or be differentially resistant to the potential antimicrobial effects of some compounds. Studies directly addressing this hypothesis are relatively few, but microbe-plant allelochemical interactions have been frequently documented from non-insect systems-such as soil and the human gut-and thus illustrate their potential importance for insect herbivory. We discuss the implications of this hypothesis for insect diversification and coevolution with plants; for example, evolutionary transitions to host plant groups with novel allelochemicals could be initiated by heritable changes to the insect microbiome. Furthermore, the ecological implications extend beyond the plant and insect herbivore to higher trophic levels. Although the hidden nature of microbes and plant allelochemicals make their interactions difficult to detect, recent molecular and experimental techniques should enable research on this neglected, but likely important, aspect of insect-plant biology. PMID:25936531

  19. Increase in toxicity of an invasive weed after reassociation with its coevolved herbivore.

    Zangerl, Arthur R; Berenbaum, May R

    2005-10-25

    The ability of weeds to proliferate into nonindigenous habitats has been attributed to escape from their native natural enemies, allowing reallocation of resources from chemical defense into growth and reproduction. Many invasive weeds, however, eventually encounter their native, coevolved enemies in areas of introduction. Examination of herbarium specimens of an invasive phototoxic European weed, Pastinaca sativa, through 152 years reveals phytochemical shifts coincident in time with the accidental introduction of a major herbivore, the parsnip webworm, Depressaria pastinacella. Plants collected before the introduction of webworms in North America and during the earliest stages of establishment (1850-1889) are lower in toxic furanocoumarins than all plants subsequently collected in North America and lower than European plant samples collected before 1889. Thus, introduction of a major specialist herbivore can increase noxiousness of a species in its area of introduction, illuminating a potential consequence of classical biocontrol programs involving insect herbivores and poisonous weeds. PMID:16230607

  20. Effects of root herbivory on pyrrolizidine alkaloid content and aboveground plant-herbivore-parasitoid interactions in Jacobaea vulgaris

    Kostenko, O.; Mulder, P.P.J.; Bezemer, T.M.

    2013-01-01

    The importance of root herbivory is increasingly recognized in ecological studies, and the effects of root herbivory on plant growth, chemistry, and performance of aboveground herbivores have been relatively well studied. However, how belowground herbivory by root feeding insects affects aboveground

  1. Effects of Root Herbivory on Pyrrolizidine Alkaloid Content and Aboveground Plant-Herbivore-Parasitoid Interactions in Jacobaea Vulgaris

    Kostenko, O.; Mulder, P.P.J.; Bezemer, T.M.

    2013-01-01

    The importance of root herbivory is increasingly recognized in ecological studies, and the effects of root herbivory on plant growth, chemistry, and performance of aboveground herbivores have been relatively well studied. However, how belowground herbivory by root feeding insects affects aboveground

  2. Elevated air temperature alters an old-field insect community in a multi-factor climate change experiment

    Villalpando, Sean [Appalachian State University; Williams, Ray [ORNL; Norby, Richard J [ORNL

    2009-01-01

    To address how multiple, interacting climate drivers may affect plant-insect community associations, we sampled the insect community from a constructed old-field plant community grown under simultaneous [CO2], temperature, and water manipulation. Insects were identified to morphospecies, assigned to feeding guilds and abundance, richness and evenness quantified. Warming significantly increased Order Thysanoptera abundance and reduced overall morphospecies richness and evenness. Non-metric multidimensional scaling clearly supported the effect of warming on insect community composition. Reductions in richness for herbivores and parasitoids suggest trophic-level effects within the insect community. Analysis of dominant insects demonstrated the effects of warming were limited to a relatively small number of morphospecies. Reported reductions in whole-community foliar N at elevated [CO2] unexpectedly did not result in any effects on herbivores. These results demonstrate climatic warming may alter certain insect communities via effects on insect species most responsive to higher temperature, contributing to a change in community structure.

  3. Insect Keepers

    Moore, Virginia J.; Chessin, Debby A.; Theobald, Becky

    2010-01-01

    Insects are fascinating creatures--especially when you and your students get up close and personal with them! To that end, the authors facilitated an inquiry-based investigation with an emphasis on identification of the different types of insects found in the school yard, their characteristics, their habitat, and what they eat, while engaging the…

  4. Experimental infection of plants with an herbivore-associated bacterial endosymbiont influences herbivore host selection behavior

    Although bacterial endosymbioses are common among phloeophagous herbivores, little is known regarding the effects of symbionts on herbivore host selection and population dynamics. We tested the hypothesis that plant selection and reproductive performance by a phloem-feeding herbivore (potato psyllid...

  5. Birds exploit herbivore-induced plant volatiles to locate herbivorous prey

    Amo, L.; Jansen, J.J.; Dam, van N.M.; Dicke, M.; Visser, M.E.

    2013-01-01

    Arthropod herbivory induces plant volatiles that can be used by natural enemies of the herbivores to find their prey. This has been studied mainly for arthropods that prey upon or parasitise herbivorous arthropods but rarely for insectivorous birds, one of the main groups of predators of herbivorous

  6. Plant-derived visual signals may protect beetle herbivores from bird predators

    Tamar Keasar; Miriam Kishinevsky; Avi Shmida; Yoram Gerchman; Nicka Chinkov; Avi Koplovich; Gadi Katzir

    2013-01-01

    Insect herbivores often use chemical signals obtained from their food plants to deter enemies and/or attract sexual partners. Do plant-based visual signals act similarly, i.e., repel consumers' enemies and appeal to potential mates? We explored this question using the pollen-feeding beetle Pygopleurus israelitus (Glaphyridae), a specialized pollinator of Anemone coronaria's chemically defended red-morph flowers. We presented dead beetles, which had fed either on anemones or on cat-food, to yo...

  7. Spatial and Temporal Potato Intensification Drives Insecticide Resistance in the Specialist Herbivore, Leptinotarsa decemlineata

    Huseth, Anders S.; Petersen, Jessica D.; Poveda, Katja; Szendrei, Zsofia; Nault, Brian A.; Kennedy, George G.; Groves, Russell L.

    2015-01-01

    Landscape-scale intensification of individual crops and pesticide use that is associated with this intensification is an emerging, environmental problem that is expected to have unequal effects on pests with different lifecycles, host ranges, and dispersal abilities. We investigate if intensification of a single crop in an agroecosystem has a direct effect on insecticide resistance in a specialist insect herbivore. Using a major potato pest, Leptinotarsa decemlineata, we measured imidacloprid...

  8. Herbivore-plant interactions: mixed-function oxidases and secondary plant substances.

    Brattsten, L B; Wilkinson, C F; Eisner, T

    1977-06-17

    The mixed-function oxidases of a polyphagous insect larva (the southern armyworm, Spodoptera eridania) were found to be induced by a diversity of secondary plant substances. The induction proceeds rapidly and in response to a small quantity of secondary substance. Following induction, the larva is less susceptible to dietary poisoning. It is argued that mixed-function oxidases play a major role in protecting herbivores against chemical stress from secondary plant substances. PMID:17831753

  9. Insect Data

    National Oceanic and Atmospheric Administration, Department of Commerce — Records of past temperature and environment derived from beetle and other insect fossils. Parameter keywords describe what was measured in this data set. Additional...

  10. The effect of nutrients on pyrrolizidine alkaloids in Senecio plants and their interactions with herbivores and pathogens.

    Hol, W H G

    2011-03-01

    The aim of this review is to combine the knowledge of studies on effects of nutrients on pyrrolizidine alkaloids (PAs) in Senecio with those studies of effects of PAs on herbivores and pathogens in order to predict the effects that nutrients may have on herbivores and pathogens via changes in PAs. We discuss whether these predictions match with the outcome of studies where the effect of nutrients on herbivores and insects were measured. PA concentrations in S. jacobaea, S. vulgaris and S. aquaticus were mostly reduced by NPK fertilization, with genotype-specific effects occurring. Plant organs varied in their response to increased fertilization; PA concentrations in flowers remained constant, while shoot and roots were mostly negatively affected. Biomass change is probably largely responsible for the change in concentrations. Nutrients affect both the variety and the levels of PAs in the plant. The reduced PA concentrations after NPK fertilization was expected to benefit herbivores, but no or negative responses from insect herbivores were observed. Apparently other changes in the plant after fertilization are overriding the effect of PAs. Pathogens do seem to benefit from the lower PA concentrations after fertilization; they were more detrimental to fertilized plants than to unfertilized control plants. Future studies should include the effect of each element of nutrients separately and in combinations in order to gain more insight in the effect of specific nutrients on PA content in Senecio plants. PMID:21475405

  11. Forests and climate change - lessons from insects

    Battisti A

    2004-01-01

    Full Text Available The climate change may indirectly affects the forest ecosystems through the activity of phytophagous insects. The climate change has been claimed to be responsible of the range expansion northward and upward of several insect species of northern temperate forests, as well as of changes in the seasonal phenology. Several papers have dealt with the prediction of the most likely consequences of the climate change on the phytophagous insects, including some of the most important forest pests. Increased levels of CO2 in the atmosphere involve an increase of the C/N balance of the plant tissues, which in turn results in a lower food quality for many defoliating insects. Some insects respond by increasing the level of leaf consumption and consequently the damage to the tree, whereas others show higher mortality and lower performance. The level of plant chemical defenses may also be affected by a change of CO2. The temperature is affecting either the survival of the insects which are active during the cold period, such as the pine processionary moth, or the synchronization mechanism between the host and the herbivores, as in the case of the larch bud moth. An increase of temperature may alter the mechanism by which the insects adjust their cycles to the local climate (diapause, resulting in faster development and higher feeding rate, as in the case of the spruce webspinning sawfly outbreaks in the Southern Alps.

  12. Forests and climate change - lessons from insects

    Battisti A

    2008-02-01

    Full Text Available The climate change may indirectly affects the forest ecosystems through the activity of phytophagous insects. The climate change has been claimed to be responsible of the range expansion northward and upward of several insect species of northern temperate forests, as well as of changes in the seasonal phenology. Several papers have dealt with the prediction of the most likely consequences of the climate change on the phytophagous insects, including some of the most important forest pests. Increased levels of CO2 in the atmosphere involve an increase of the C/N balance of the plant tissues, which in turn results in a lower food quality for many defoliating insects. Some insects respond by increasing the level of leaf consumption and consequently the damage to the tree, whereas others show higher mortality and lower performance. The level of plant chemical defences may also be affected by a change of CO2. The temperature is affecting either the survival of the insects which are active during the cold period, such as the pine processionary moth, or the synchronization mechanism between the host and the herbivores, as in the case of the larch bud moth. An increase of temperature may alter the mechanism by which the insects adjust their cycles to the local climate (diapause, resulting in faster development and higher feeding rate, as in the case of the spruce web-spinning sawfly outbreaks in the Southern Alps.

  13. Where do herbivore-induced plant volatiles go?

    Jarmo K. Holopainen

    2013-06-01

    Full Text Available Herbivore induced plant volatiles (HIPV are specific volatile organic compounds (VOC that a plant produces in response to herbivory. Some HIPVs are only produced after damage, while others are also produced by intact plants, but in lower quantities. Among the known functions of HIPVs are within plant volatile signalling to activate systemic plant defences, the priming and activation of defences in neighbouring plants and the attraction of natural enemies of herbivores. When released into the atmosphere a plant’s control over the produced compounds ends. However, many of the HIPVs are highly reactive with atmospheric oxidants and their atmospheric life times could be relatively short, often only a few minutes. We summarise the potential ecological and atmospheric processes that involve the reaction products of HIPVs in their gaseous, liquid and solid secondary organic aerosol (SOA forms, both in the atmosphere and after deposition on plant surfaces. A potential negative feedback loop, based on the reactions forming SOA from HIPV and the associated stimulation of sun screening cloud formation is presented. This hypothesis is based on recent field surveys in the geographical areas facing greatest degree of global warming and insect outbreaks. Furthermore, we discuss how these processes could benefit the individual plant or conspecifics that originally released the HIPVs into the atmosphere. Further ecological studies should aim to elucidate the possible reasons for biosynthesis of short-lived volatile compounds to have evolved as a response to external biotic damage to plants.

  14. Experimental infection of plants with an herbivore-associated bacterial endosymbiont influences herbivore host selection behavior.

    Thomas Seth Davis

    Full Text Available Although bacterial endosymbioses are common among phloeophagous herbivores, little is known regarding the effects of symbionts on herbivore host selection and population dynamics. We tested the hypothesis that plant selection and reproductive performance by a phloem-feeding herbivore (potato psyllid, Bactericera cockerelli is mediated by infection of plants with a bacterial endosymbiont. We controlled for the effects of herbivory and endosymbiont infection by exposing potato plants (Solanum tuberosum to psyllids infected with "Candidatus Liberibacter solanacearum" or to uninfected psyllids. We used these treatments as a basis to experimentally test plant volatile emissions, herbivore settling and oviposition preferences, and herbivore population growth. Three important findings emerged: (1 plant volatile profiles differed with respect to both herbivory and herbivory plus endosymbiont infection when compared to undamaged control plants; (2 herbivores initially settled on plants exposed to endosymbiont-infected psyllids but later defected and oviposited primarily on plants exposed only to uninfected psyllids; and (3 plant infection status had little effect on herbivore reproduction, though plant flowering was associated with a 39% reduction in herbivore density on average. Our experiments support the hypothesis that plant infection with endosymbionts alters plant volatile profiles, and infected plants initially recruited herbivores but later repelled them. Also, our findings suggest that the endosymbiont may not place negative selection pressure on its host herbivore in this system, but plant flowering phenology appears correlated with psyllid population performance.

  15. The developmental race between maturing host plants and their butterfly herbivore - the influence of phenological matching and temperature.

    Posledovich, Diana; Toftegaard, Tenna; Wiklund, Christer; Ehrlén, Johan; Gotthard, Karl

    2015-11-01

    Interactions between herbivorous insects and their host plants that are limited in time are widespread. Therefore, many insect-plant interactions result in a developmental race, where herbivores need to complete their development before plants become unsuitable, while plants strive to minimize damage from herbivores by outgrowing them. When spring phenologies of interacting species change asymmetrically in response to climate warming, there will be a change in the developmental state of host plants at the time of insect herbivore emergence. In combination with altered temperatures during the subsequent developmental period, this is likely to affect interaction strength as well as fitness of interacting species. Here, we experimentally explore whether the combined effect of phenological matching and thermal conditions influence the outcome of an insect-host interaction. We manipulated both developmental stages of the host plants at the start of the interaction and temperature during the subsequent developmental period in a model system of a herbivorous butterfly, Anthocharis cardamines, and five of its Brassicaceae host plant species. Larval performance characteristics were favoured by earlier stages of host plants at oviposition as well as by higher developmental temperatures on most of the host species. The probability of a larva needing a second host plant covered the full range from no influence of either phenological matching or temperature to strong effects of both factors, and complex interactions between them. The probability of a plant outgrowing a larva was dependent only on the species identity. This study demonstrates that climatic variation can influence the outcome of consumer-resource interactions in multiple ways and that its effects differ among host plant species. Therefore, climate warming is likely to change the temporal match between larval and plant development in some plant species, but not in the others. This is likely to have important

  16. Herbivore space use influences coral reef recovery.

    Eynaud, Yoan; McNamara, Dylan E; Sandin, Stuart A

    2016-06-01

    Herbivores play an important role in marine communities. On coral reefs, the diversity and unique feeding behaviours found within this functional group can have a comparably diverse set of impacts in structuring the benthic community. Here, using a spatially explicit model of herbivore foraging, we explore how the spatial pattern of grazing behaviours impacts the recovery of a reef ecosystem, considering movements at two temporal scales-short term (e.g. daily foraging patterns) and longer term (e.g. monthly movements across the landscape). Model simulations suggest that more spatially constrained herbivores are more effective at conferring recovery capability by providing a favourable environment to coral recruitment and growth. Results also show that the composition of food available to the herbivore community is linked directly to the pattern of space use by herbivores. To date, most studies of variability among the impacts of herbivore species have considered the diversity of feeding modes and mouthparts. Our work provides a complementary view of spatial patterns of foraging, revealing that variation in movement behaviours alone can affect patterns of benthic change, and thus broadens our view of realized links between herbivore diversity and reef recovery. PMID:27429784

  17. Young aphids avoid erroneous dropping when evading mammalian herbivores by combining input from two sensory modalities.

    Moshe Gish

    Full Text Available Mammalian herbivores may incidentally ingest plant-dwelling insects while foraging. Adult pea aphids (Acyrthosiphon pisum avoid this danger by dropping off their host plant after sensing the herbivore's warm and humid breath and the vibrations it causes while feeding. Aphid nymphs may also drop (to escape insect enemies, but because of their slow movement, have a lower chance of finding a new plant. We compared dropping rates of first-instar nymphs with those of adults, after exposing pea aphids to different combinations of simulated mammalian breath and vibrations. We hypothesized that nymphs would compensate for the greater risk they face on the ground by interpreting more conservatively the mammalian herbivore cues they perceive. Most adults dropped in response to breath alone, but nymphs rarely did so. Breath stimulus accompanied by one concurrent vibrational stimulus, caused a minor rise in adult dropping rates. Adding a second vibration during breath had no additional effect on adults. The nymphs, however, relied on a combination of the two types of stimuli, with a threefold increase in dropping rates when the breath was accompanied by one vibration, and a further doubling of dropping rates when the second vibration was added. The age-specificity of the aphids' herbivore detection mechanism is probably an adaptation to the different cost of dropping for the different age groups. Relying on a combination of stimuli from two sensory modalities enables the vulnerable nymphs to avoid costly mistakes. Our findings emphasize the importance of the direct trophic effect of mammalian herbivory for plant-dwelling insects.

  18. Molecular strategies of plant defense and insect counter-defense

    KEYANZHU-SALZMAN; JIAN-LONGBI; TONG-XIANLIU

    2005-01-01

    The prediction of human population growth worldwide indicates there will be a need to substantially increase food production in order to meet the demand on food supply.This can be achieved in part by the effective management of insect pests. Since plants have co-evolved with herbivorous insects for millions of years, they have developed an array of defense genes to protect themselves against a wide variety of chewing and sucking insects.Using these naturally-occurring genes via genetic engineering represents an environmentally friendly insect pest-control measure. Insects, however, have been actively evolving adaptive mechanisms to evade natural plant defenses. Such evolved adaptability undoubtedly has helped insects during the last century to rapidly overcome a great many humanimposed management practices and agents, including chemical insecticides and genetically engineered plants. Thus, better understanding of the molecular and genetic basis of plant defense and insect counter-defense mechanisms is imperative, not only from a basic science perspective, but also for biotechnology-based pest control practice. In this review, we emphasize the recent advance and understanding of molecular strategies of attack-counterattack and defense-counter-defense between plants and their herbivores.

  19. Effects of Genetic Variability and Habitat of Qualea parviflora (Vochysiaceae) on Herbivory by Free-feeding and Gall-forming Insects

    GONÇALVES-ALVIM, SILMARY J.; Collevatti, Rosane G.; Fernandes, G. Wilson

    2004-01-01

    • Background and Aims Differences in the chemical and physical traits of plants caused by both genetic and habitat characteristics may influence attack by herbivores. Leaves of Qualea parviflora (Vochysiaceae), a common tree of different habitats in the Brazilian Neotropical savannas (cerrado), are susceptible to severe attack by herbivorous free-living and gall-forming insects. Attack by free-living and gall-forming insects within and between populations of Q. parviflora were examined and it...

  20. Ants and their effects on an insect herbivore community associated with the inflorescences of Byrsonima crassifolia (Linnaeus) H.B.K. (Malpighiaceae) Formigas e seus efeitos em uma comunidade de insetos herbívoros associada com as inflorescências de Byrsonima crassifolia (Linnaeus) H.B.K. (Malpighiaceae)

    G. Wilson Fernandes; Marcílio Fagundes; Magda K. Barcelos Greco; Marcos Soares Barbeitos; Jean Carlos Santos

    2005-01-01

    The effects of ants on the insect community on inflorescences of Byrsonima crassifolia (Malpighiaceae) were tested in an ant exclusion experiment in a cerrado vegetation in southeastern Brazil. Forty-four species of insects (23 families) and nine species of ants (6 genera and 3 subfamilies) were found on the inflorescences of B. crassifolia. The exclusion of ants, primarily Camponotus sericeiventris and Camponotus spp., reduced the treehopper population to 20% of the original abundance. Ant e...

  1. Hyperparasitoids use herbivore-induced plant volatiles to locate their parasitoid host.

    Poelman, Erik H; Bruinsma, Maaike; Zhu, Feng; Weldegergis, Berhane T; Boursault, Aline E; Jongema, Yde; van Loon, Joop J A; Vet, Louise E M; Harvey, Jeffrey A; Dicke, Marcel

    2012-01-01

    Plants respond to herbivory with the emission of induced plant volatiles. These volatiles may attract parasitic wasps (parasitoids) that attack the herbivores. Although in this sense the emission of volatiles has been hypothesized to be beneficial to the plant, it is still debated whether this is also the case under natural conditions because other organisms such as herbivores also respond to the emitted volatiles. One important group of organisms, the enemies of parasitoids, hyperparasitoids, has not been included in this debate because little is known about their foraging behaviour. Here, we address whether hyperparasitoids use herbivore-induced plant volatiles to locate their host. We show that hyperparasitoids find their victims through herbivore-induced plant volatiles emitted in response to attack by caterpillars that in turn had been parasitized by primary parasitoids. Moreover, only one of two species of parasitoids affected herbivore-induced plant volatiles resulting in the attraction of more hyperparasitoids than volatiles from plants damaged by healthy caterpillars. This resulted in higher levels of hyperparasitism of the parasitoid that indirectly gave away its presence through its effect on plant odours induced by its caterpillar host. Here, we provide evidence for a role of compounds in the oral secretion of parasitized caterpillars that induce these changes in plant volatile emission. Our results demonstrate that the effects of herbivore-induced plant volatiles should be placed in a community-wide perspective that includes species in the fourth trophic level to improve our understanding of the ecological functions of volatile release by plants. Furthermore, these findings suggest that the impact of species in the fourth trophic level should also be considered when developing Integrated Pest Management strategies aimed at optimizing the control of insect pests using parasitoids. PMID:23209379

  2. Predator foraging altitudes reveal the structure of aerial insect communities.

    Helms, Jackson A; Godfrey, Aaron P; Ames, Tayna; Bridge, Eli S

    2016-01-01

    The atmosphere is populated by a diverse array of dispersing insects and their predators. We studied aerial insect communities by tracking the foraging altitudes of an avian insectivore, the Purple Martin (Progne subis). By attaching altitude loggers to nesting Purple Martins and collecting prey delivered to their nestlings, we determined the flight altitudes of ants and other insects. We then tested hypotheses relating ant body size and reproductive ecology to flight altitude. Purple Martins flew up to 1,889 meters above ground, and nestling provisioning trips ranged up to 922 meters. Insect communities were structured by body size such that species of all sizes flew near the ground but only light insects flew to the highest altitudes. Ant maximum flight altitudes decreased by 60% from the lightest to the heaviest species. Winged sexuals of social insects (ants, honey bees, and termites) dominated the Purple Martin diet, making up 88% of prey individuals and 45% of prey biomass. By transferring energy from terrestrial to aerial food webs, mating swarms of social insects play a substantial role in aerial ecosystems. Although we focus on Purple Martins and ants, our combined logger and diet method could be applied to a range of aerial organisms. PMID:27352817

  3. Ethylene contributes to mir1-mediated maize defense against the phloem-sap sucking insect Rhopalosiphum maidis.

    Signaling networks among multiple phytohormones fine-tune plant defense responses to insect herbivore attack. Previously, it was reported that the synergistic combination of ethylene (ET) and jasmonic acid (JA) was required for providing maize insect resistance1 (mir1), a key endogenous defense sign...

  4. Plant Size as Determinant of Species Richness of Herbivores, Natural Enemies and Pollinators across 21 Brassicaceae Species.

    Hella Schlinkert

    Full Text Available Large plants are often more conspicuous and more attractive for associated animals than small plants, e.g. due to their wider range of resources. Therefore, plant size can positively affect species richness of associated animals, as shown for single groups of herbivores, but studies usually consider intraspecific size differences of plants in unstandardised environments. As comprehensive tests of interspecific plant size differences under standardised conditions are missing so far, we investigated effects of plant size on species richness of all associated arthropods using a common garden experiment with 21 Brassicaceae species covering a broad interspecific plant size gradient from 10 to 130 cm height. We recorded plant associated ecto- and endophagous herbivores, their natural enemies and pollinators on and in each aboveground plant organ, i.e. flowers, fruits, leaves and stems. Plant size (measured as height from the ground, the number of different plant organ entities and their biomass were assessed. Increasing plant size led to increased species richness of associated herbivores, natural enemies and pollinating insects. This pattern was found for ectophagous and endophagous herbivores, their natural enemies, as well as for herbivores associated with leaves and fruits and their natural enemies, independently of the additional positive effects of resource availability (i.e. organ biomass or number of entities and, regarding natural enemies, herbivore species richness. We found a lower R2 for pollinators compared to herbivores and natural enemies, probably caused by the high importance of flower characteristics for pollinator species richness besides plant size. Overall, the increase in plant height from 10 to 130 cm led to a 2.7-fold increase in predicted total arthropod species richness. In conclusion, plant size is a comprehensive driver of species richness of the plant associated arthropods, including pollinators, herbivores and their

  5. Genetic diversity increases insect herbivory on oak saplings.

    Bastien Castagneyrol

    Full Text Available A growing body of evidence from community genetics studies suggests that ecosystem functions supported by plant species richness can also be provided by genetic diversity within plant species. This is not yet true for the diversity-resistance relationship as it is still unclear whether damage by insect herbivores responds to genetic diversity in host plant populations. We developed a manipulative field experiment based on a synthetic community approach, with 15 mixtures of one to four oak (Quercus robur half-sib families. We quantified genetic diversity at the plot level by genotyping all oak saplings and assessed overall damage caused by ectophagous and endophagous herbivores along a gradient of increasing genetic diversity. Damage due to ectophagous herbivores increased with the genetic diversity in oak sapling populations as a result of higher levels of damage in mixtures than in monocultures for all families (complementarity effect rather than because of the presence of more susceptible oak genotypes in mixtures (selection effect. Assemblages of different oak genotypes would benefit polyphagous herbivores via improved host patch location, spill over among neighbouring saplings and diet mixing. By contrast, genetic diversity was a poor predictor of the abundance of endophagous herbivores, which increased with individual sapling apparency. Plant genetic diversity may not provide sufficient functional contrast to prevent tree sapling colonization by specialist herbivores while enhancing the foraging of generalist herbivores. Long term studies are nevertheless required to test whether the effect of genetic diversity on herbivory change with the ontogeny of trees and local adaptation of specialist herbivores.

  6. Insect immunorecognition

    E Ottaviani

    2005-10-01

    Full Text Available The mechanisms of the innate immunity in the insects have been reviewed. In particular, thecellular component (phagocytosis, encapsulation, melanization, nodule formation, wound healing,hemolymph clotting and transplantation and the humoral component (lectins, cytokine-like moleculesand anti-microbial peptides of the hemolymph have been investigated.

  7. Stinging Insect Matching Game

    ... for Kids ▸ Stinging Insect Matching Game Share | Stinging Insect Matching Game Stinging insects can ruin summer fun for those who are ... the difference between the different kinds of stinging insects in order to keep your summer safe and ...

  8. Estimation of Above-Ground Tree Biomass Based on Probability Distribution of Allometric Parameters%基于异速参数概率分布的立木地上生物量估算

    黄兴召; 陈东升; 孙晓梅; 张守攻

    2014-01-01

    Allometric biomass equations are widely used to predict above-ground biomass in forest ecosystems. It found the distribution of the parameters a and b of the allometry between above-ground biomass ( M ) and diameter at breast height( D) ,lnM = a + blnD,well approximated by a bivariate normal from analysis a data of 304 functions of 80 papers. ANOVA was tested to parameters in seven genera. In contrast to the parameter a,there was significant difference in parameter b. There were negative correlation between the parameter a and b,the parameter b and latitude. From this negative correlation,simultaneous-equation was used to build general model for parameters which were changed by latitude . Three methods which include established general model,minimum-least-square regression and Bayesian approach were used to fitting the above-ground biomass of Larix kaempferi in sub-tropical alpine area. The result showed that general model was the lowest precise quantifications ( R2 =0. 892 ) ,but it could estimate the biomass where forest situated in latitude without samples. With sample size was more than 50,both Bayesian method and minimum-least-square regression was no significant difference in the mean absolute error. And it was less than 50,Bayesian method was better than minimum-least-square regression. Therefore,it was suggested that Bayesian method was used to estimate above-ground biomass when the sample size was less than 50 .%对收集的80篇文献中304个地上部分生物量( M)和胸径( D)的异速生物量模型 lnM =a+blnD数据集研究发现:模型参数a和b符合二元正态分布;参数a和b之间、参数b和纬度间呈负相关,并依此相关关系应用联立方程组建立参数a和b随纬度变化的通用模型。以实测的北亚热带高山区日本落叶松地上部分生物量数据对新建的通用模型、最小二乘法和贝叶斯方法拟合生物量的适用性进行研究,结果表明:虽然通用模型的拟合精度最低( R

  9. Host-Plant Specialization Mediates the Influence of Plant Abundance on Host Use by Flower Head-Feeding Insects.

    Nobre, Paola A F; Bergamini, Leonardo L; Lewinsohn, Thomas M; Jorge, Leonardo R; Almeida-Neto, Mário

    2016-02-01

    Among-population variation in host use is a common phenomenon in herbivorous insects. The simplest and most trivial explanation for such variation in host use is the among-site variation in plant species composition. Another aspect that can influence spatial variation in host use is the relative abundance of each host-plant species compared to all available hosts. Here, we used endophagous insects that develop in flower heads of Asteraceae species as a study system to investigate how plant abundance influences the pattern of host-plant use by herbivorous insects with distinct levels of host-range specialization. Only herbivores recorded on three or more host species were included in this study. In particular, we tested two related hypotheses: 1) plant abundance has a positive effect on the host-plant preference of herbivorous insects, and 2) the relative importance of plant abundance to host-plant preference is greater for herbivorous species that use a wider range of host-plant species. We analyzed 11 herbivore species in 20 remnants of Cerrado in Southeastern Brazil. For 8 out of 11 herbivore species, plant abundance had a positive influence on host use. In contrast to our expectation, both the most specialized and the most generalist herbivores showed a stronger positive effect of plant species abundance in host use. Thus, we found evidence that although the abundance of plant species is a major factor determining the preferential use of host plants, its relative importance is mediated by the host-range specialization of herbivores. PMID:26637546

  10. Cytokinin levels and signaling respond to wounding and the perception of herbivore elicitors in Nicotiana attenuata

    Martin Schfer; Ivan D Meza-Canales; Aura Navarro-Quezada; Christoph Brtting; Radomira Vankov; Ian T Baldwin; Stefan Meldau

    2015-01-01

    Nearly half a century ago insect herbivores were found to induce the formation of green islands by manipulating cytokinin (CK) levels. However, the response of the CK pathway to attack by chewing insect herbivores remains unclear. Here, we characterize the CK pathway of Nicotiana attenuata (Torr. ex S. Wats.) and its response to wounding and perception of herbivore‐associated molecular patterns (HAMPs). We identified 44 genes involved in CK biosynthesis, inactivation, degradation, and signaling. Leaf wounding rapidly induced transcriptional changes in multiple genes throughout the pathway, as wel as in the levels of CKs, including isopentenyladenosine and cis‐zeatin riboside;perception of HAMPs present in the oral secretions (OS) of the specialist herbivore Manduca sexta amplified these responses. The jasmonate pathway, which triggers many herbivore‐induced processes, was not required for these HAMP‐triggered changes, but rather suppressed the CK responses. Interestingly CK pathway changes were observed also in systemic leaves in response to wounding and OS application indicating a role of CKs in mediating long distance systemic processes in response to herbivory. Since wounding and grasshopper OS elicited similar accumulations of CKs in Arabidopsis thaliana L., we propose that CKs are integral components of wounding and HAMP‐triggered responses in many plant species.

  11. A Physiological and Behavioral Mechanism for Leaf Herbivore-Induced Systemic Root Resistance.

    Erb, Matthias; Robert, Christelle A M; Marti, Guillaume; Lu, Jing; Doyen, Gwladys R; Villard, Neil; Barrière, Yves; French, B Wade; Wolfender, Jean-Luc; Turlings, Ted C J; Gershenzon, Jonathan

    2015-12-01

    Indirect plant-mediated interactions between herbivores are important drivers of community composition in terrestrial ecosystems. Among the most striking examples are the strong indirect interactions between spatially separated leaf- and root-feeding insects sharing a host plant. Although leaf feeders generally reduce the performance of root herbivores, little is known about the underlying systemic changes in root physiology and the associated behavioral responses of the root feeders. We investigated the consequences of maize (Zea mays) leaf infestation by Spodoptera littoralis caterpillars for the root-feeding larvae of the beetle Diabrotica virgifera virgifera, a major pest of maize. D. virgifera strongly avoided leaf-infested plants by recognizing systemic changes in soluble root components. The avoidance response occurred within 12 h and was induced by real and mimicked herbivory, but not wounding alone. Roots of leaf-infested plants showed altered patterns in soluble free and soluble conjugated phenolic acids. Biochemical inhibition and genetic manipulation of phenolic acid biosynthesis led to a complete disappearance of the avoidance response of D. virgifera. Furthermore, bioactivity-guided fractionation revealed a direct link between the avoidance response of D. virgifera and changes in soluble conjugated phenolic acids in the roots of leaf-attacked plants. Our study provides a physiological mechanism for a behavioral pattern that explains the negative effect of leaf attack on a root-feeding insect. Furthermore, it opens up the possibility to control D. virgifera in the field by genetically mimicking leaf herbivore-induced changes in root phenylpropanoid patterns. PMID:26430225

  12. Insects: A nutritional alternative

    Dufour, P. A.

    1981-01-01

    Insects are considered as potential food sources in space. Types of insects consumed are discussed. Hazards of insect ingestion are considered. Insect reproduction, requirements, and raw materials conversion are discussed. Nutrition properties and composition of insects are considered. Preparation of insects as human food is discussed.

  13. Insect evolution.

    Engel, Michael S

    2015-10-01

    It goes without saying that insects epitomize diversity, and with over a million documented species they stand out as one of the most remarkable lineages in the 3.5-billion-year history of life on earth (Figure 1). This reality is passé to even the layperson and is taken for granted in the same way none of us think much of our breathing as we go about our day, and yet insects are just as vital to our existence. Insects are simultaneously familiar and foreign to us, and while a small fraction are beloved or reviled, most are simply ignored. These inexorable evolutionary overachievers outnumber us all, their segmented body plan is remarkably labile, they combine a capacity for high rates of speciation with low levels of natural extinction, and their history of successes eclipses those of the more familiar ages of dinosaurs and mammals alike. It is their evolution - persisting over vast expanses of geological time and inextricably implicated in the diversification of other lineages - that stands as one of the most expansive subjects in biology. PMID:26439349

  14. Transcriptional responses of Brassica nigra to feeding by specialist insects of different feeding guilds

    Colette Broekgaarden; Roeland E. Voorrips; Marcel Dicke; Ben Vosman

    2011-01-01

    Plants show phenotypic changes when challenged with herbivorous insects. The mechanisms underlying these changes include the activation of transcriptional responses, which are dependent on the attacking insect. Most transcriptomic studies on crucifer-insect interactions have focused on the model plant Arabidopsis thaliana, a species that faces low herbivore pressure in nature. Here, we study the transcriptional responses of plants from a wild black mustard (Brassica nigra) population to herbivores of different feeding guilds using an A. thaliana-bused whole-genome microarray that has previously been shown to be suitable for transcriptomic analyses in Brassica. Transcriptional responses of 5. nigra after infestation with either Pieris rapae caterpillars or Brevicoryne brassicae aphids are analyzed and compared. Additionally, the insect-induced expression changes of some individual genes are analyzed through quantitative real-time polymerase chain reaction. The results show that feeding by both insect species results in the accumulation of transcripts encoding proteins involved in the detoxification of reactive oxygen species, defensive proteins and glucosinolates and this is correlated with experimental evidence in the literature on such biochemical effects. Although genes encoding proteins involved in similar processes are regulated by both insects, there was little overlap in the induction or repression of individual genes. Furthermore, P. rapae and B. brassicae seem to affect different phytohormone signaling pathways. In conclusion, our results indicate that B. nigra activates several defense-related genes in response to P. rapae or B. brassicae feeding, but that the response is dependent on the attacking insect species.

  15. Habitats as complex odour environments: how does plant diversity affect herbivore and parasitoid orientation?

    Nicole Wäschke

    Full Text Available Plant diversity is known to affect success of host location by pest insects, but its effect on olfactory orientation of non-pest insect species has hardly been addressed. First, we tested in laboratory experiments the hypothesis that non-host plants, which increase odour complexity in habitats, affect the host location ability of herbivores and parasitoids. Furthermore, we recorded field data of plant diversity in addition to herbivore and parasitoid abundance at 77 grassland sites in three different regions in Germany in order to elucidate whether our laboratory results reflect the field situation. As a model system we used the herb Plantago lanceolata, the herbivorous weevil Mecinus pascuorum, and its larval parasitoid Mesopolobus incultus. The laboratory bioassays revealed that both the herbivorous weevil and its larval parasitoid can locate their host plant and host via olfactory cues even in the presence of non-host odour. In a newly established two-circle olfactometer, the weeviĺs capability to detect host plant odour was not affected by odours from non-host plants. However, addition of non-host plant odours to host plant odour enhanced the weeviĺs foraging activity. The parasitoid was attracted by a combination of host plant and host volatiles in both the absence and presence of non-host plant volatiles in a Y-tube olfactometer. In dual choice tests the parasitoid preferred the blend of host plant and host volatiles over its combination with non-host plant volatiles. In the field, no indication was found that high plant diversity disturbs host (plant location by the weevil and its parasitoid. In contrast, plant diversity was positively correlated with weevil abundance, whereas parasitoid abundance was independent of plant diversity. Therefore, we conclude that weevils and parasitoids showed the sensory capacity to successfully cope with complex vegetation odours when searching for hosts.

  16. Marine and terrestrial herbivores display convergent chemical ecology despite 400 million years of independent evolution.

    Rasher, Douglas B; Stout, E Paige; Engel, Sebastian; Shearer, Tonya L; Kubanek, Julia; Hay, Mark E

    2015-09-29

    Chemical cues regulate key ecological interactions in marine and terrestrial ecosystems. They are particularly important in terrestrial plant-herbivore interactions, where they mediate both herbivore foraging and plant defense. Although well described for terrestrial interactions, the identity and ecological importance of herbivore foraging cues in marine ecosystems remain unknown. Here we show that the specialist gastropod Elysia tuca hunts its seaweed prey, Halimeda incrassata, by tracking 4-hydroxybenzoic acid to find vegetative prey and the defensive metabolite halimedatetraacetate to find reproductive prey. Foraging cues were predicted to be polar compounds but instead were nonpolar secondary metabolites similar to those used by specialist terrestrial insects. Tracking halimedatetraacetate enables Elysia to increase in abundance by 12- to 18-fold on reproductive Halimeda, despite reproduction in Halimeda being rare and lasting for only ∼36 h. Elysia swarm to reproductive Halimeda where they consume the alga's gametes, which are resource rich but are chemically defended from most consumers. Elysia sequester functional chloroplasts and halimedatetraacetate from Halimeda to become photosynthetic and chemically defended. Feeding by Elysia suppresses the growth of vegetative Halimeda by ∼50%. Halimeda responds by dropping branches occupied by Elysia, apparently to prevent fungal infection associated with Elysia feeding. Elysia is remarkably similar to some terrestrial insects, not only in its hunting strategy, but also its feeding method, defense tactics, and effects on prey behavior and performance. Such striking parallels indicate that specialist herbivores in marine and terrestrial systems can evolve convergent ecological strategies despite 400 million years of independent evolution in vastly different habitats. PMID:26324909

  17. Elevated atmospheric CO2 triggers compensatory feeding by root herbivores on a C3 but not a C4 grass.

    Scott N Johnson

    Full Text Available Predicted increases in atmospheric carbon dioxide (CO2 concentrations often reduce nutritional quality for herbivores by increasing the C:N ratio of plant tissue. This frequently triggers compensatory feeding by aboveground herbivores, whereby they consume more shoot material in an attempt to meet their nutritional needs. Little, however, is known about how root herbivores respond to such changes. Grasslands are particularly vulnerable to root herbivores, which can collectively exceed the mass of mammals grazing aboveground. Here we provide novel evidence for compensatory feeding by a grass root herbivore, Sericesthis nigrolineata, under elevated atmospheric CO2 (600 µmol mol(-1 on a C3 (Microlaena stipoides but not a C4 (Cymbopogon refractus grass species. At ambient CO2 (400 µmol mol(-1 M. stipoides roots were 44% higher in nitrogen (N and 7% lower in carbon (C concentrations than C. refractus, with insects performing better on M. stipoides. Elevated CO2 decreased N and increased C:N in M. stipoides roots, but had no impact on C. refractus roots. Root-feeders displayed compensatory feeding on M. stipoides at elevated CO2, consuming 118% more tissue than at ambient atmospheric CO2. Despite this, root feeder biomass remained depressed by 24%. These results suggest that compensatory feeding under elevated atmospheric CO2 may make some grass species particularly vulnerable to attack, potentially leading to future shifts in the community composition of grasslands.

  18. Contribution of insectivorous avifauna to top down control of Lindera benzoin herbivores at forest edge and interior habitats

    Skoczylas, Daniel R.; Muth, Norris Z.; Niesenbaum, Richard A.

    2007-11-01

    Predation of herbivorous Lepidoptera larvae by insectivorous avifauna was estimated on Lindera benzoin in edge and interior habitats at two sites in eastern Pennsylvania (USA). Clay baits modeled after Epimecis hortaria (Geometridae) larvae, the primary herbivore of L. benzoin at our study sites, were used to estimate predation by birds. In both habitat types, models were placed on uninjured L. benzoin leaves as well as on leaves that had prior insect herbivore damage. Rates of model attack were greater, and model longevity reduced, in forest edge plots compared to interiors. Naturally occurring herbivore damage on L. benzoin was greater in forest interiors. However, model attack was not significantly greater on leaves with prior herbivory damage, suggesting that birds do not effectively use this type of leaf damage as a cue in their foraging. Our findings are consistent with a contribution of bird predation towards top-down control of herbivory in this system. We further discuss these results in a broader context considering the possible effects of habitat type on leaf quality, leaf defense, and herbivore performance.

  19. Effects of root herbivory on pyrrolizidine alkaloid content and aboveground plant-herbivore-parasitoid interactions in Jacobaea vulgaris

    O. Kostenko; Mulder, P.P.J.; Bezemer, T.M.

    2013-01-01

    The importance of root herbivory is increasingly recognized in ecological studies, and the effects of root herbivory on plant growth, chemistry, and performance of aboveground herbivores have been relatively well studied. However, how belowground herbivory by root feeding insects affects aboveground parasitoid development is largely unknown. In this study, we examined the effects of root herbivory by wireworms (Agriotes lineatus) on the expression of primary and secondary compounds in the lea...

  20. Sapling herbivory, invertebrate herbivores and predators across a natural tree diversity gradient in Germany’s largest connected deciduous forest

    Sobek, Stephanie; Scherber, Christoph; Steffan-Dewenter, Ingolf; Tscharntke, Teja

    2009-01-01

    Tree species-rich forests are hypothesised to be less susceptible to insect herbivores, but so far herbivory–diversity relationships have rarely been tested for tree saplings, and no such study has been published for deciduous forests in Central Europe. We expected that diverse tree communities reduce the probability of detection of host plants and increase abundance of predators, thereby reducing herbivory. We examined levels of herbivory suffered by beech (Fagus sylvatica L.) and maple sapl...

  1. Physiological function and ecological aspects of fatty acid-amino acid conjugates in insects.

    Yoshinaga, Naoko

    2016-07-01

    In tritrophic interactions, plants recognize herbivore-produced elicitors and release a blend of volatile compounds (VOCs), which work as chemical cues for parasitoids or predators to locate their hosts. From detection of elicitors to VOC emissions, plants utilize sophisticated systems that resemble the plant-microbe interaction system. Fatty acid-amino acid conjugates (FACs), a class of insect elicitors, resemble compounds synthesized by microbes in nature. Recent evidence suggests that the recognition of insect elicitors by an ancestral microbe-associated defense system may be the origin of tritrophic interactions mediated by FACs. Here we discuss our findings in light of how plants have customized this defense to be effective against insect herbivores, and how some insects have successfully adapted to these defenses. PMID:26940831

  2. Insects had it first: surfactants as a defence against predators

    Rostás, Michael; Blassmann, Katrin

    2010-01-01

    Insects have evolved an astonishing array of defences to ward off enemies. Well-known and widespread is the regurgitation of oral secretions (OS), fluids that repel attacking predators. In herbivores, the effectiveness of OS has been ascribed so far to the presence of deterrent secondary metabolites sequestered from the host plant. This notion implies, however, that generalists experience less protection on plants with low amounts of secondary metabolites or with compounds ineffective against...

  3. Insects had it first: surfactants as a defence against predators

    Rostás, Michael; Blassmann, Katrin

    2008-01-01

    Insects have evolved an astonishing array of defences to ward off enemies. Well known and widespread is the regurgitation of oral secretion (OS), fluid that repels attacking predators. In herbivores, the effectiveness of OS has been ascribed so far to the presence of deterrent secondary metabolites sequestered from the host plant. This notion implies, however, that generalists experience less protection on plants with low amounts of secondary metabolites or with compounds ineffective against ...

  4. Insects had it first: surfactants as a defence against predators

    Rostás, Michael; Blassmann, Katrin

    2010-01-01

    Insects have evolved an astonishing array of defences to ward off enemies. Well known and widespread is the regurgitation of oral secretion (OS), fluid that repels attacking predators. In herbivores, the effectiveness of OS has been ascribed so far to the presence of deterrent secondary metabolites sequestered from the host plant. This notion implies, however, that generalists experience less protection on plants with low amounts of secondary metabolites or with compounds ineffective against ...

  5. Plant defense against herbivores: chemical aspects.

    Mithöfer, Axel; Boland, Wilhelm

    2012-01-01

    Plants have evolved a plethora of different chemical defenses covering nearly all classes of (secondary) metabolites that represent a major barrier to herbivory: Some are constitutive; others are induced after attack. Many compounds act directly on the herbivore, whereas others act indirectly via the attraction of organisms from other trophic levels that, in turn, protect the plant. An enormous diversity of plant (bio)chemicals are toxic, repellent, or antinutritive for herbivores of all types. Examples include cyanogenic glycosides, glucosinolates, alkaloids, and terpenoids; others are macromolecules and comprise latex or proteinase inhibitors. Their modes of action include membrane disruption, inhibition of nutrient and ion transport, inhibition of signal transduction processes, inhibition of metabolism, or disruption of the hormonal control of physiological processes. Recognizing the herbivore challenge and precise timing of plant activities as well as the adaptive modulation of the plants' metabolism is important so that metabolites and energy may be efficiently allocated to defensive activities. PMID:22404468

  6. Uncertainty analysis for regional-level above-ground biomass estimates based on individual tree biomass model%单木生物量模型估计区域尺度生物量的不确定性

    傅煜; 雷渊才; 曾伟生

    2015-01-01

    采用系统抽样体系江西省固定样地杉木连续观测数据和生物量数据,通过Monte Carlo法反复模拟由单木生物量模型推算区域尺度地上生物量的过程,估计了江西省杉木地上总生物量。基于不同水平建模样本量n及不同决定系数R2的设计,分别研究了单木生物量模型参数变异性及模型残差变异性对区域尺度生物量估计不确定性的影响。研究结果表明:2009年江西省杉木地上生物量估计值为(19.84±1.27) t/hm2,不确定性占生物量估计值约6.41%。生物量估计值和不确定性值达到平稳状态所需的运算时间随建模样本量及决定系数R2的增大而减小;相对于模型参数变异性,残差变异性对不确定性的影响更小。%Above-ground forest biomass at regional-level is typically estimated by adding model predictions of biomass from individual trees in a plot, and subsequently aggregating predictions from plots to large areas. There are multiple sources of uncertainties in model predictions during this aggregated process. These uncertainties always affect the precision of large area biomass estimates, and the effects are generally overlooked; however, failure to account for these uncertainties will cause erroneously optimistic precision estimates. Monte Carlo simulation is an effective method for estimating large-scale biomass and assessing the uncertainty associated with multiple sources of errors and complex models. In this paper, we applied the Monte Carlo approach to simulate regional-level above-ground biomass and to assess uncertainties related to the variability from model residuals and parameters separately. A nonlinear model form was used. Data were obtained from permanent sample plots and biomass observation of Cunninghamia lanceolata in JiangXi Province, China. Overall, 70 individual trees were destructively sampled for biomass estimation from June to September, 2009. Based on the commonly used allometric model

  7. The Role of Insect-Derived Cues in Eliciting Indirect Plant Defenses in Tobacco, Nicotiana tabacum

    Delphia, Casey M.; Mark C. Mescher; Felton, Gary W.; De Moraes, Consuelo M

    2006-01-01

    In response to insect feeding, plants release complex volatile blends that are important host-location cues for natural enemies of herbivores. These induced volatile responses are mediated by insect-derived cues and differ significantly from responses to mechanical wounding. To improve understanding of the cues that elicit plant volatile responses, we explored the effects of Heliothis virescens saliva on volatile induction in tobacco, Nicotiana tabacum, using an ablation technique that preven...

  8. Aboveground insect herbivory increases plant competitive asymmetry, while belowground herbivory mitigates the effect

    Borgström, Pernilla; Strengbom, Joachim; Viketoft, Maria; Bommarco, Riccardo

    2016-01-01

    Insect herbivores can shift the composition of a plant community, but the mechanism underlying such shifts remains largely unexplored. A possibility is that insects alter the competitive symmetry between plant species. The effect of herbivory on competition likely depends on whether the plants are subjected to aboveground or belowground herbivory or both, and also depends on soil nitrogen levels. It is unclear how these biotic and abiotic factors interactively affect competition. In a greenho...

  9. Distribution of aquatic insects in phumdis (floating island) of Loktak Lake, Manipur, northeastern India

    K. Takhelmayum; Gupta, S.

    2011-01-01

    A study was made on the temporal fluctuations of distribution of aquatic insects around Phumdi Live (PL), Phumdi Mixed (PM) and Phumdi Dry (PD) areas of Loktak Lake. Phumdis are a heterogeneous mass of soil, vegetation and organic matter. The study revealed the presence of predators, and the absence of herbivores and detritivores in both PL and PM, the PD area was totally devoid of insects. Although both the habitats supported the same predator groups hemiptera and odonata, diversity and ...

  10. Impact of the terminal Cretaceous event on plant–insect associations

    Labandeira, Conrad C.; Johnson, Kirk R; Wilf, Peter

    2002-01-01

    Evidence for a major extinction of insect herbivores is provided by presence–absence data for 51 plant–insect associations on 13,441 fossil plant specimens, spanning the Cretaceous/Paleogene boundary in southwestern North Dakota. The most specialized associations, which were diverse and abundant during the latest Cretaceous, almost disappeared at the boundary and failed to recover in younger strata even while generalized associations regained their Cretaceous abundances. These results are con...

  11. Responses of community-level plant-insect interactions to climate warming in a meadow steppe.

    Zhu, Hui; Zou, Xuehui; Wang, Deli; Wan, Shiqiang; Wang, Ling; Guo, Jixun

    2015-01-01

    Climate warming may disrupt trophic interactions, consequently influencing ecosystem functioning. Most studies have concentrated on the temperature-effects on plant-insect interactions at individual and population levels, with a particular emphasis on changes in phenology and distribution. Nevertheless, the available evidence from the community level is limited. A 3-year field manipulative experiment was performed to test potential responses of plant and insect communities, and plant-insect interactions, to elevated temperature in a meadow steppe. Warming increased the biomass of plant community and forbs, and decreased grass biomass, indicating a shift from grass-dominant to grass-forb mixed plant community. Reduced abundance of the insect community under warming, particularly the herbivorous insects, was attributed to lower abundance of Euchorthippus unicolor and a Cicadellidae species resulting from lower food availability and higher defensive herbivory. Lower herbivore abundance caused lower predator species richness because of reduced prey resources and contributed to an overall decrease in insect species richness. Interestingly, warming enhanced the positive relationship between insect and plant species richness, implying that the strength of the plant-insect interactions was altered by warming. Our results suggest that alterations to plant-insect interactions at a community level under climate warming in grasslands may be more important and complex than previously thought. PMID:26686758

  12. Allergies to Insect Venom

    ... attracts these insects.  Use insect repellents and keep insecticide available. Treatment tips:  Venom immunotherapy (allergy shots to insect venom(s) is highly effective in preventing subsequent sting ...

  13. Molecular interactions between the specialist herbivore Manduca sexta (lepidoptera, sphingidae) and its natural host Nicotiana attenuata. VI. Microarray analysis reveals that most herbivore-specific transcriptional changes are mediated by fatty acid-amino acid conjugates.

    Halitschke, Rayko; Gase, Klaus; Hui, Dequan; Schmidt, Dominik D; Baldwin, Ian T

    2003-04-01

    Evidence is accumulating that insect-specific plant responses are mediated by constituents in the oral secretions and regurgitants (R) of herbivores, however the relative importance of the different potentially active constituents remains unclear. Fatty acid-amino acid conjugates (FACs) are found in the R of many insect herbivores and have been shown to be necessary and sufficient to elicit a set of herbivore-specific responses when the native tobacco plant Nicotiana attenuata is attacked by the tobacco hornworm, Manduca sexta. Attack by this specialist herbivore results in a large transcriptional reorganization in N. attenuata, and 161 genes have been cloned from previous cDNA differential display-polymerase chain reaction and subtractive hybridization with magnetic beads analysis. cDNAs of these genes, in addition to those of 73 new R-responsive genes identified by cDNA-amplified fragment-length polymorphism display of R-elicited plants, were spotted on polyepoxide coated glass slides to create microarrays highly enriched in Manduca spp.- and R-induced genes. With these microarrays, we compare transcriptional responses in N. attenuata treated with R from the two most damaging lepidopteran herbivores of this plant in nature, M. sexta and Manduca quinquemaculata, which have very similar FAC compositions in their R, and with the two most abundant FACs in Manduca spp. R. More than 68% of the genes up- and down-regulated by M. sexta R were similarly regulated by M. quinquemaculata R. A majority of genes up-regulated (64%) and down-regulated (49%) by M. sexta R were similarly regulated by treatment with the two FACs. In contrast, few genes showed similar transcriptional changes after H(2)O(2)- and R-treatment. These results demonstrate that the two most abundant FACs in Manduca spp. R can account for the majority of Manduca spp.-induced alterations of the wound response of N. attenuata. PMID:12692348

  14. Insect Growth Regulators for Insect Pest Control*

    TUNAZ, Hasan

    2004-01-01

    Insecticides with growth regulating properties (IGR) may adversely affect insects by regulating or inhibiting specific biochemical pathways or processes essential for insect growth and development. Some insects exposed to such compounds may die due to abnormal regulation of hormone-mediated cell or organ development. Other insects may die either from a prolonged exposure at the developmental stage to other mortality factors (susceptibility to natural enemies, environmental conditions etc) or ...

  15. Warming strengthens an herbivore-plant interaction.

    O'Connor, Mary I

    2009-02-01

    Temperature has strong, predictable effects on metabolism. Through this mechanism, environmental temperature affects individuals and populations of poikilotherms by determining rates of resource use, growth, reproduction, and mortality. Predictable variation in metabolic processes such as growth and reproduction could affect the strength of species interactions, but the community-level consequences of metabolic temperature dependence are virtually unexplored. I experimentally tested the hypothesis that plant-herbivore interaction strength increases with temperature using a common species of marine macroalga (Sargassum filipendula) and the grazing amphipod Ampithoe longimana. Increasing temperature increased per capita interaction strength in two independent experiments and reversed a positive effect of temperature on plant growth. Temperature did not alter palatability of plant tissue to herbivores or average herbivore feeding rate. A predictable effect of temperature on herbivore-plant interaction strength could provide key information toward understanding local food web responses to changing temperatures at different spatial and temporal scales. Efforts to extend the effects of physiological mechanisms to larger scale patterns, including projections of the ecological effects of climate change, must be expanded to include the effects of changing conditions on trophic interactions. PMID:19323223

  16. Experimental support of the stress-gradient hypothesis in herbivore-herbivore interactions

    Dangles, Olivier; Herrera, M; Anthelme, Fabien

    2013-01-01

    The stress-gradient hypothesis (SGH) postulates an increase in the frequency of positive species interactions at increasing amounts of stress. While the SGH has been extensively tested in plant-plant interactions along abiotic stresses, it remains unclear whether this hypothesis could apply to higher trophic levels, such as herbivores, along biotic stress gradients. To address this issue, we investigated how the interaction between two potato herbivores may change along a stress gradient crea...

  17. Costs and benefits of plant allelochemicals in herbivore diet in a multi enemy world.

    Reudler, J H; Lindstedt, C; Pakkanen, H; Lehtinen, I; Mappes, J

    2015-12-01

    Sequestration of plant defensive chemicals by herbivorous insects is a way of defending themselves against their natural enemies. Such herbivores have repeatedly evolved bright colours to advertise their unpalatability to predators, i.e. they are aposematic. This often comes with a cost. In this study, we examined the costs and benefits of sequestration of iridoid glycosides (IGs) by the generalist aposematic herbivore, the wood tiger moth, Parasemia plantaginis. We also asked whether the defence against one enemy (a predator) is also effective against another (a parasitoid). We found that the larvae excrete most of the IGs and only small amounts are found in the larvae. Nevertheless, the amounts present in the larvae are sufficient to deter ant predators and also play a role in defence against parasitoids. However, excreting and handling these defensive plant compounds is costly, leading to longer development time and lower pupal mass. Interestingly, the warning signal efficiency and the amount of IGs in the larvae of P. plantaginis are negatively correlated; larvae with less efficient warning signals contain higher levels of chemical defence compounds. Our results may imply that there is a trade-off between production and maintenance of coloration and chemical defence. Although feeding on a diet containing IGs can have life-history costs, it offers multiple benefits in the defence against predators and parasitoids. PMID:26296333

  18. Water Activities in Laxemar Simpevarp. The final disposal facility for spent nuclear fuel - removal of groundwater and water activities above ground; Vattenverksamhet i Laxemar-Simpevarp. Slutfoervarsanlaeggning foer anvaent kaernbraensle - bortledande av grundvatten samt vattenverksamheter ovan mark

    Werner, Kent (EmpTec (Sweden)); Hamren, Ulrika; Collinder, Per (Ekologigruppen AB (Sweden))

    2010-12-15

    This report concerns water operations (Chapter 11 in the Environmental Code) below and above ground associated with construction, operation, and decommissioning of a repository for spent nuclear fuel in Laxemar in the municipality of Oskarshamn. SKB has chosen Forsmark in the municipality of Oesthammar as site for the repository, and the report hence describes a non-chosen alternative. The report provides a comprehensive description of how the water operations would be executed, their hydrogeological and hydrological effects and the resulting consequences. The description is a background material for comparisons between the two sites in terms of water operations. The underground part of a repository in Laxemar would, among other things, consist of an access ramp and a repository area at a depth of approximately 500 metres. The construction, operation, and decommissioning phases would in total comprise a time period of 60-70 years. Inflowing groundwater would be diverted during construction and operation. The modelling tool MIKE SHE has been used to assess the effects of the groundwater diversion, for instance in terms of groundwater levels and stream discharges. According to MIKE SHE calculations for a hypothetical case with a fully open repository, the total groundwater inflow would be in the order of 55-90 litres per second depending on the permeability of the grouted zone around ramp, shafts and tunnels. In reality, the whole repository would not be open simultaneously, and the inflow would therefore be less. The groundwater diversion would cause groundwater- level drawdown in the rock, which in turn would lead to drawdown of the groundwater table in relatively large areas above and around the repository. According to model calculations, there would be an insignificant drawdown of the water level in Lake Frisksjoen, the largest lake in the area. The discharge in the most important stream of the area (Laxemaraan) would be reduced by less than ten percent

  19. Is the Performance of a Specialist Herbivore Affected by Female Choices and the Adaptability of the Offspring?

    Galdino, Tarcísio Visintin da Silva; Picanço, Marcelo Coutinho; Ferreira, Dalton Oliveira; Silva, Geverson Aelton Resende; de Souza, Thadeu Carlos; Silva, Gerson Adriano

    2015-01-01

    The performance of herbivorous insects is related to the locations of defenses and nutrients found in the different plant organs on which they feed. In this context, the females of herbivorous insect species select certain parts of the plant where their offspring can develop well. In addition, their offspring can adapt to plant defenses. A system where these ecological relationships can be studied occurs in the specialist herbivore, Tuta absoluta, on tomato plants. In our experiments we evaluated: (i) the performance of the herbivore T. absoluta in relation to the tomato plant parts on which their offspring had fed, (ii) the spatial distribution of the insect stages on the plant canopy and (iii) the larval resistance to starvation and their walking speed at different instar stages. We found that the T. absoluta females preferred to lay their eggs in the tomato plant parts where their offspring had greater chances of success. We verified that the T. absoluta females laid their eggs on both sides of the leaves to better exploit resources. We also observed that the older larvae (3rd and 4th instars) moved to the most nutritious parts of the plant, thus increasing their performance. The T. absoluta females and offspring (larvae) were capable of identifying plant sites where their chances of better performance were higher. Additionally, their offspring (larvae) spread across the plant to better exploit the available plant nutrients. These behavioral strategies of T. absoluta facilitate improvement in their performance after acquiring better resources, which help reduce their mortality by preventing the stimulation of plant defense compounds and the action of natural enemies. PMID:26600074

  20. Is the Performance of a Specialist Herbivore Affected by Female Choices and the Adaptability of the Offspring?

    Tarcísio Visintin da Silva Galdino

    Full Text Available The performance of herbivorous insects is related to the locations of defenses and nutrients found in the different plant organs on which they feed. In this context, the females of herbivorous insect species select certain parts of the plant where their offspring can develop well. In addition, their offspring can adapt to plant defenses. A system where these ecological relationships can be studied occurs in the specialist herbivore, Tuta absoluta, on tomato plants. In our experiments we evaluated: (i the performance of the herbivore T. absoluta in relation to the tomato plant parts on which their offspring had fed, (ii the spatial distribution of the insect stages on the plant canopy and (iii the larval resistance to starvation and their walking speed at different instar stages. We found that the T. absoluta females preferred to lay their eggs in the tomato plant parts where their offspring had greater chances of success. We verified that the T. absoluta females laid their eggs on both sides of the leaves to better exploit resources. We also observed that the older larvae (3rd and 4th instars moved to the most nutritious parts of the plant, thus increasing their performance. The T. absoluta females and offspring (larvae were capable of identifying plant sites where their chances of better performance were higher. Additionally, their offspring (larvae spread across the plant to better exploit the available plant nutrients. These behavioral strategies of T. absoluta facilitate improvement in their performance after acquiring better resources, which help reduce their mortality by preventing the stimulation of plant defense compounds and the action of natural enemies.

  1. Measuring Asymmetry in Insect-Plant Networks

    Cruz, Cláudia P. T.; de Almeida, Adriana M.; Corso, Gilberto

    2011-03-01

    In this work we focus on interaction networks between insects and plants and in the characterization of insect plant asymmetry, an important issue in coevolution and evolutionary biology. We analyze in particular the asymmetry in the interaction matrix of animals (herbivorous insects) and plants (food resource for the insects). Instead of driving our attention to the interaction matrix itself we derive two networks associated to the bipartite network: the animal network, D1, and the plant network, D2. These networks are constructed according to the following recipe: two animal species are linked once if they interact with the same plant. In a similar way, in the plant network, two plants are linked if they interact with the same animal. To explore the asymmetry between D2 and D1 we test for a set of 23 networks from the ecologic literature networks: the difference in size, ΔL, clustering coefficient difference, ΔC, and mean connectivity difference, Δ. We used a nonparametric statistical test to check the differences in ΔL, ΔC and Δ. Our results indicate that ΔL and Δ show a significative asymmetry.

  2. Measuring Asymmetry in Insect-Plant Networks

    In this work we focus on interaction networks between insects and plants and in the characterization of insect plant asymmetry, an important issue in coevolution and evolutionary biology. We analyze in particular the asymmetry in the interaction matrix of animals (herbivorous insects) and plants (food resource for the insects). Instead of driving our attention to the interaction matrix itself we derive two networks associated to the bipartite network: the animal network, D1, and the plant network, D2. These networks are constructed according to the following recipe: two animal species are linked once if they interact with the same plant. In a similar way, in the plant network, two plants are linked if they interact with the same animal. To explore the asymmetry between D2 and D1 we test for a set of 23 networks from the ecologic literature networks: the difference in size, ΔL, clustering coefficient difference, ΔC, and mean connectivity difference, Δ. We used a nonparametric statistical test to check the differences in ΔL, ΔC and Δ. Our results indicate that ΔL and Δ show a significative asymmetry.

  3. Measuring Asymmetry in Insect-Plant Networks

    Cruz, Claudia P T [Programa de Pos-Graduacao em Fisica, Universidade Federal do Rio Grande do Norte, UFRN - Campus Universitario, Lagoa Nova, CEP 59078 972, Natal, RN (Brazil); De Almeida, Adriana M [Departamento de Botanica, Ecologia e Zoologia, Centro de Biociencias, Universidade Federal do Rio Grande do Norte, UFRN - Campus Universitario, Lagoa Nova, CEP 59078 972, Natal, RN (Brazil); Corso, Gilberto, E-mail: claudia@dfte.ufrn.br, E-mail: adrianam@ufrn.br, E-mail: corso@cb.ufrn.br [Departamento de Biofisica e Farmacologia, Centro de Biociencias, Universidade Federal do Rio Grande do Norte, UFRN - Campus Universitario, Lagoa Nova, CEP 59078 972, Natal, RN (Brazil)

    2011-03-01

    In this work we focus on interaction networks between insects and plants and in the characterization of insect plant asymmetry, an important issue in coevolution and evolutionary biology. We analyze in particular the asymmetry in the interaction matrix of animals (herbivorous insects) and plants (food resource for the insects). Instead of driving our attention to the interaction matrix itself we derive two networks associated to the bipartite network: the animal network, D{sub 1}, and the plant network, D{sub 2}. These networks are constructed according to the following recipe: two animal species are linked once if they interact with the same plant. In a similar way, in the plant network, two plants are linked if they interact with the same animal. To explore the asymmetry between D{sub 2} and D{sub 1} we test for a set of 23 networks from the ecologic literature networks: the difference in size, {Delta}L, clustering coefficient difference, {Delta}C, and mean connectivity difference, {Delta}. We used a nonparametric statistical test to check the differences in {Delta}L, {Delta}C and {Delta}. Our results indicate that {Delta}L and {Delta} show a significative asymmetry.

  4. Reciprocal diversification in a complex plant-herbivore-parasitoid food web

    Bokma Folmer

    2007-11-01

    Full Text Available Abstract Background Plants, plant-feeding insects, and insect parasitoids form some of the most complex and species-rich food webs. According to the classic escape-and-radiate (EAR hypothesis, these hyperdiverse communities result from coevolutionary arms races consisting of successive cycles of enemy escape, radiation, and colonization by new enemy lineages. It has also been suggested that "enemy-free space" provided by novel host plants could promote host shifts by herbivores, and that parasitoids could similarly drive diversification of gall form in insects that induce galls on plants. Because these central coevolutionary hypotheses have never been tested in a phylogenetic framework, we combined phylogenetic information on willow-galling sawflies with data on their host plants, gall types, and enemy communities. Results We found that evolutionary shifts in host plant use and habitat have led to dramatic prunings of parasitoid communities, and that changes in gall phenotype can provide "enemy-free morphospace" for millions of years even in the absence of host plant shifts. Some parasites have nevertheless managed to colonize recently-evolved gall types, and this has apparently led to adaptive speciation in several enemy groups. However, having fewer enemies does not in itself increase speciation probabilities in individual sawfly lineages, partly because the high diversity of the enemy community facilitates compensatory attack by remaining parasite taxa. Conclusion Taken together, our results indicate that niche-dependent parasitism is a major force promoting ecological divergence in herbivorous insects, and that prey divergence can cause speciation in parasite lineages. However, the results also show that the EAR hypothesis is too simplistic for species-rich food webs: instead, diversification seems to be spurred by a continuous stepwise process, in which ecological and phenotypic shifts in prey lineages are followed by a lagged evolutionary

  5. Insect-induced effects on plants and possible effectors used by galling and leaf-mining insects to manipulate their host-plant.

    Giron, David; Huguet, Elisabeth; Stone, Graham N; Body, Mélanie

    2016-01-01

    Gall-inducing insects are iconic examples in the manipulation and reprogramming of plant development, inducing spectacular morphological and physiological changes of host-plant tissues within which the insect feeds and grows. Despite decades of research, effectors involved in gall induction and basic mechanisms of gall formation remain unknown. Recent research suggests that some aspects of the plant manipulation shown by gall-inducers may be shared with other insect herbivorous life histories. Here, we illustrate similarities and contrasts by reviewing current knowledge of metabolic and morphological effects induced on plants by gall-inducing and leaf-mining insects, and ask whether leaf-miners can also be considered to be plant reprogrammers. We review key plant functions targeted by various plant reprogrammers, including plant-manipulating insects and nematodes, and functionally characterize insect herbivore-derived effectors to provide a broader understanding of possible mechanisms used in host-plant manipulation. Consequences of plant reprogramming in terms of ecology, coevolution and diversification of plant-manipulating insects are also discussed. PMID:26723843

  6. Plant–insect interactions from Middle Triassic (late Ladinian) of Monte Agnello (Dolomites, N-Italy)—initial pattern and response to abiotic environmental perturbations

    Torsten Wappler; Evelyn Kustatscher; Elio Dellantonio

    2015-01-01

    The Paleozoic–Mesozoic transition is characterized by the most massive extinction of the Phanerozoic. Nevertheless, an impressive adaptive radiation of herbivorous insects occurred on gymnosperm-dominated floras not earlier than during the Middle to Late Triassic, penecontemporaneous with similar events worldwide, all which exhibit parallel expansions of generalized and mostly specialized insect herbivory on plants, expressed as insect damage on a various plant organs and tissues. The flora f...

  7. Differential effects of indole and aliphatic glucosinolates on lepidopteran herbivores.

    Müller, René; de Vos, Martin; Sun, Joel Y; Sønderby, Ida E; Halkier, Barbara A; Wittstock, Ute; Jander, Georg

    2010-08-01

    Glucosinolates are a diverse group of defensive secondary metabolites that is characteristic of the Brassicales. Arabidopsis thaliana (L.) Heynh. (Brassicaceae) lines with mutations that greatly reduce abundance of indole glucosinolates (cyp79B2 cyp79B3), aliphatic glucosinolates (myb28 myb29), or both (cyp79B2 cyp79B3 myb28 myb29) make it possible to test the in vivo defensive function of these two major glucosinolate classes. In experiments with Lepidoptera that are not crucifer-feeding specialists, aliphatic and indole glucosinolates had an additive effect on Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae) larval growth, whereas Trichoplusia ni (Hübner) (Lepidoptera: Noctuidae) and Manduca sexta (L.) (Lepidoptera: Sphingidae) were affected only by the absence of aliphatic glucosinolates. In the case of two crucifer-feeding specialists, Pieris rapae (L.) (Lepidoptera: Pieridae) and Plutella xylostella (L.) (Lepidoptera: Plutellidae), there were no major changes in larval performance due to decreased aliphatic and/or indole glucosinolate content. Nevertheless, choice tests show that aliphatic and indole glucosinolates act in an additive manner to promote larval feeding of both species and P. rapae oviposition. Together, these results support the hypothesis that a diversity of glucosinolates is required to limit the growth of multiple insect herbivores. PMID:20617455

  8. Insect-resistant transgenic plants in a multi-trophic context.

    Groot, Astrid T; Dicke, Marcel

    2002-08-01

    So far, genetic engineering of plants in the context of insect pest control has involved insertion of genes that code for toxins, and may be characterized as the incorporation of biopesticides into classical plant breeding. In the context of pesticide usage in pest control, natural enemies of herbivores have received increasing attention, because carnivorous arthropods are an important component of insect pest control. However, in plant breeding programmes, natural enemies of herbivores have largely been ignored, although there are many examples that show that plant breeding affects the effectiveness of biological control. Negative influences of modified plant characteristics on carnivorous arthropods may induce population growth of new, even more harmful pest species that had no pest status prior to the pesticide treatment. Sustainable pest management will only be possible when negative effects on non-target, beneficial arthropods are minimized. In this review, we summarize the effects of insect-resistant crops and insect-resistant transgenic crops, especially Bt crops, from a food web perspective. As food web components, we distinguish target herbivores, non-target herbivores, pollinators, parasitoids and predators. Below-ground organisms such as Collembola, nematodes and earthworms should also be included in risk assessment studies, but have received little attention. The toxins produced in Bt plants retain their toxicity when bound to the soil, so accumulation of these toxins is likely to occur. Earthworms ingest the bound toxins but are not affected by them. However, earthworms may function as intermediaries through which the toxins are passed on to other trophic levels. In studies where effects of insect-resistant (Bt) plants on natural enemies were considered, positive, negative and no effects have been found. So far, most studies have concentrated on natural enemies of target herbivores. However, Bt toxins are structurally rearranged when they bind to

  9. Book Review: Insect Virology

    Viruses that infect insects have long been of interest both as a means for controlling insect pest populations in an environmentally safe manner, and also as significant threats to beneficial insects of great value, such as honey bees and silkworms. Insect viruses also have been of intrinsic intere...

  10. Ozone impedes the ability of a herbivore to find its host

    Plant-emitted hydrocarbons mediate several key interactions between plants and insects. They enhance the ability of pollinators and herbivores to locate suitable host plants, and parasitoids to locate herbivores. While plant volatiles provide strong chemical signals, these signals are potentially degraded by exposure to pollutants such as ozone, which has increased in the troposphere and is projected to continue to increase over the coming decades. Despite the potential broad ecological significance of reduced plant signaling effectiveness, few studies have examined behavioral responses of insects to their hosts in polluted environments. Here, we use a laboratory study to test the effect of ozone concentration gradients on the ability of the striped cucumber beetle (Acalymma vittatum) to locate flowers of its host plant, Cucurbita foetidissima. Y-tube experiments showed that ozone mixing ratios below 80 parts per billion (ppb) resulted in beetles moving toward their host plant, but levels above 80 ppb resulted in beetles moving randomly with respect to host location. There was no evidence that beetles avoided polluted air directly. The results show that ozone pollution has great potential to perniciously alter key interactions between plants and animals. (letter)

  11. Ozone impedes the ability of a herbivore to find its host

    Fuentes, Jose D.; Roulston, T.'ai H.; Zenker, John

    2013-03-01

    Plant-emitted hydrocarbons mediate several key interactions between plants and insects. They enhance the ability of pollinators and herbivores to locate suitable host plants, and parasitoids to locate herbivores. While plant volatiles provide strong chemical signals, these signals are potentially degraded by exposure to pollutants such as ozone, which has increased in the troposphere and is projected to continue to increase over the coming decades. Despite the potential broad ecological significance of reduced plant signaling effectiveness, few studies have examined behavioral responses of insects to their hosts in polluted environments. Here, we use a laboratory study to test the effect of ozone concentration gradients on the ability of the striped cucumber beetle (Acalymma vittatum) to locate flowers of its host plant, Cucurbita foetidissima. Y-tube experiments showed that ozone mixing ratios below 80 parts per billion (ppb) resulted in beetles moving toward their host plant, but levels above 80 ppb resulted in beetles moving randomly with respect to host location. There was no evidence that beetles avoided polluted air directly. The results show that ozone pollution has great potential to perniciously alter key interactions between plants and animals.

  12. Drought stress affects plant metabolites and herbivore preference but not host location by its parasitoids.

    Weldegergis, Berhane T; Zhu, Feng; Poelman, Erik H; Dicke, Marcel

    2015-03-01

    One of the main abiotic stresses that strongly affects plant survival and the primary cause of crop loss around the world is drought. Drought stress leads to sequential morphological, physiological, biochemical and molecular changes that can have severe effects on plant growth, development and productivity. As a consequence of these changes, the interaction between plants and insects can be altered. Using cultivated Brassica oleracea plants, the parasitoid Microplitis mediator and its herbivorous host Mamestra brassicae, we studied the effect of drought stress on (1) the emission of plant volatile organic compounds (VOCs), (2) plant hormone titres, (3) preference and performance of the herbivore, and (4) preference of the parasitoid. Higher levels of jasmonic acid (JA) and abscisic acid (ABA) were recorded in response to herbivory, but no significant differences were observed for salicylic acid (SA) and indole-3-acetic acid (IAA). Drought significantly impacted SA level and showed a significant interactive effect with herbivory for IAA levels. A total of 55 VOCs were recorded and the difference among the treatments was influenced largely by herbivory, where the emission rate of fatty acid-derived volatiles, nitriles and (E)-4,8-dimethylnona-1,3,7-triene [(E)-DMNT] was enhanced. Mamestra brassicae moths preferred to lay eggs on drought-stressed over control plants; their offspring performed similarly on plants of both treatments. VOCs due to drought did not affect the choice of M. mediator parasitoids. Overall, our study reveals an influence of drought on plant chemistry and insect-plant interactions. PMID:25370387

  13. Cascading effects of early-season herbivory on late-season herbivores and their parasitoids.

    Hernandez-Cumplido, Johnattran; Glauser, Gaetan; Benrey, Betty

    2016-05-01

    There is an increasing awareness that herbivory by one insect species induces changes in a plant that affect the performance of other herbivore species that feed on the same plant. However, previous studies of interspecies interactions mediated by plant defense responses have rarely taken into account different insect guilds or the third trophic level. Using a combination of field and laboratory experiments, we examined how early-season herbivory in lima bean plants (Phaseolus lunatus) by the leaf-chewing herbivore Cerotoma ruficornis and the bean pod weevil Apion godmani affects the abundance and performance of the seed beetle Zabrotes subfasciatus and that of its parasitoid Stenocorse bruchivora, which occurs on the plants at the end of the growing season. In addition, we determined the consequences of early-season herbivore-induced defenses on plant performance. We hypothesized that early-season induction would affect plant reproduction and, hence, would alter the suitability of seeds for late-season seed-eating beetles, and that this would in turn alter the vulnerability of these seed beetles to parasitoids. We found strong support for these hypotheses. In the field, early-season herbivory negatively affected plant reproduction and seeds of these plants suffered lower levels of infestation by seed-eating beetles, which in turn suffered less parasitism. Laboratory assays with field-collected seeds confirmed that the performance of beetles and parasitoids was lower on seeds from plants that had been subjected to early-season herbivory. Further analyses revealed that seeds produced by control plants were larger, heavier, and had a higher concentration of cyanogenic glycosides and total protein content than seeds from plants subjected to herbivory. Our results provide insight into how direct and indirect interactions between and within different trophic levels affect the dynamics and structure of complex communities. PMID:27349104

  14. Rapid incorporation of glucosinolates as a strategy used by a herbivore to prevent activation by myrosinases.

    Abdalsamee, Mohamed K; Giampà, Marco; Niehaus, Karsten; Müller, Caroline

    2014-09-01

    Various plants have a binary defence system that consists of a substrate and a glucosidase, which is activated upon tissue disruption thereby forming reactive hydrolysis products. Insects feeding on such plants have to overcome this binary defence system or prevent the activation. In this study, we investigated the strategy used by a herbivore to deal with such binary defence. We studied, how the larvae of the sawfly Athalia rosae (Hymenoptera: Tenthredinidae) circumvent the activation of glucosinolates by myrosinase enzymes, which are found in their Brassicaceae host plants. Myrosinase activities were low in the front part of the larval gut but activities increased over the gut passage. In contrast, the glucosinolates were only highly concentrated in the first gut part and were rapidly incorporated into the haemolymph before the food reached the second half of the gut. Thus, the uptake and concentration of glucosinolates, i.e., sequestration, must occur in the front part of the gut. Using Matrix Assisted Laser Desorption Ionization-Mass Spectrometry Imaging (MALDI-MSI), we could demonstrate that the incorporated glucosinolate sinalbin circulates in the haemolymph where it accumulates around the Malpighian tubules. This study highlights the pivotal role of the gut of an adapted herbivore as a regulatory functional organ to cope with plant toxins. MALDI-MSI turned out as a highly useful technique to visualise glucosinolates in a herbivore, which has to deal with plants exhibiting a binary defence system, and may be applied to follow the fate of plant metabolites in other insect species in the future. PMID:25017143

  15. The effect of nitrogen additions on oak foliage and herbivore communities at sites with high and low atmospheric pollution

    To evaluate plant and herbivore responses to nitrogen we conducted a fertilization study at a low and high pollution site in the mixed conifer forests surrounding Los Angeles, California. Contrary to expectations, discriminant function analysis of oak herbivore communities showed significant response to N fertilization when atmospheric deposition was high, but not when atmospheric deposition was low. We hypothesize that longer-term fertilization treatments are needed at the low pollution site before foliar N nutrition increases sufficiently to affect herbivore communities. At the high pollution site, fertilization was also associated with increased catkin production and higher densities of a byturid beetle that feeds on the catkins of oak. Leaf nitrogen and nitrate were significantly higher at the high pollution site compared to the low pollution site. Foliar nitrate concentrations were positively correlated with abundance of sucking insects, leafrollers and plutellids in all three years of the study. - Nitrogen additions at sites impacted by air pollution were associated with altered foliar herbivore communities and increased densities of a catkin-feeding beetle on Quercus kellogii

  16. Water Holding Function of Above-ground Structure of Plant Community in Upper Reaches of Chishui River%赤水河上游植物群落地上结构持水功能评价

    肖卫平; 喻阳华; 严令斌; 喻理飞

    2015-01-01

    The upstream plant community in Chishui River was chosen as research object to build the evaluation in-dex system of plant community water-holding function by using PCA and RDA sort-based analysis for screening water holding function index of above-ground structure of plant communities.Based on the assessment of water holding a-bility of 27 samples by the index weighted product , the results showed that differences in the structure of plant com-munity was the major cause for different water holding levels.In all analyzed plant communities, only croton, with combination of cypress presented higher water-holding ability, and then were the community of shrub, climax and timber forest, while the shrub-grass, brush stage, as well as bamboo standing in tree layer were the lowest.%以赤水河上游森林群落为研究对象,采用PCA和RDA排序分析,筛选植物群落地上部分组成及结构的持水功能指标,构建了植物群落持水功能评价指标体系,并采用指标加权乘积法评价赤水河上游27块森林群落样地的持水能力。结果表明,灌草、灌木、灌丛阶段群落及乔林阶段中竹林为低持水群落,次顶极群落和多数乔林群落为中持水群落,仅乔林阶段中巴豆+柏木群落中2块样地为高持水群落。导致群落持水功能差异的主因是持水结构组成不同。

  17. Molecular interactions between the specialist herbivore Manduca sexta (Lepidoptera, Sphingidae) and its natural host Nicotiana attenuata. III. Fatty acid-amino acid conjugates in herbivore oral secretions are necessary and sufficient for herbivore-specific plant responses.

    Halitschke, R; Schittko, U; Pohnert, G; Boland, W; Baldwin, I T

    2001-02-01

    Feeding by the tobacco specialist Manduca sexta (Lepidoptera, Sphingidae) and application of larval oral secretions and regurgitant (R) to mechanical wounds are known to elicit: (a) a systemic release of mono- and sesquiterpenes, (b) a jasmonate burst, and (c) R-specific changes in transcript accumulation of putatively growth- and defense-related mRNAs in Nicotiana attenuata Torr. ex Wats. We identified several fatty acid-amino acid conjugates (FACs) in the R of M. sexta and the closely related species Manduca quinquemaculata which, when synthesized and applied to mechanical wounds at concentrations comparable with those found in R, elicited all three R-specific responses. Ion-exchange treatment of R, which removed all detectable FACs and free fatty acids (FAs), also removed all detectable activity. The biological activity of ion-exchanged R could be completely restored by the addition of synthetic FACs at R-equivalent concentrations, whereas the addition of FAs did not restore the biological activity of R. We conclude that the biological activity of R is not related to the supply of FAs to the octadecanoid cascade for endogenous jasmonate biosynthesis, but that FACs elicit the herbivore-specific responses by another mechanism and that the insect-produced modification of plant-derived FAs is necessary for the plant's recognition of this specialized herbivore. PMID:11161028

  18. Reglucosylation of the benzoxazinoid DIMBOA with inversion of stereochemical configuration is a detoxification strategy in lepidopteran herbivores.

    Wouters, Felipe C; Reichelt, Michael; Glauser, Gaétan; Bauer, Eugen; Erb, Matthias; Gershenzon, Jonathan; Vassão, Daniel G

    2014-10-13

    Benzoxazinoids are chemical defenses against herbivores and are produced by many members of the grass family. These compounds are stored as stable glucosides in plant cells and require the activity of glucosidases to release the corresponding toxic aglucones. In maize leaves, the most abundant benzoxazinoid is (2R)-DIMBOA-Glc, which is converted into the toxic DIMBOA upon herbivory. The ways in which three Spodoptera species metabolize this toxin were investigated. (2S)-DIMBOA-Glc, an epimer of the initial plant compound, was observed in the insect frass, and the associated glucosyltransferase activity was detected in the insect gut tissue. The epimeric glucoside produced by the insect was found to be no longer reactive towards plant glucosidases and thus cannot be converted into a toxin. Stereoselective reglucosylation thus represents a detoxification strategy in Spodoptera species that might help to explain their success as agricultural pests on benzoxazinoid-containing crops. PMID:25196135

  19. Ants and their effects on an insect herbivore community associated with the inflorescences of Byrsonima crassifolia (Linnaeus H.B.K. (Malpighiaceae Formigas e seus efeitos em uma comunidade de insetos herbívoros associada com as inflorescências de Byrsonima crassifolia (Linnaeus H.B.K. (Malpighiaceae

    G. Wilson Fernandes

    2005-06-01

    Full Text Available The effects of ants on the insect community on inflorescences of Byrsonima crassifolia (Malpighiaceae were tested in an ant exclusion experiment in a cerrado vegetation in southeastern Brazil. Forty-four species of insects (23 families and nine species of ants (6 genera and 3 subfamilies were found on the inflorescences of B. crassifolia. The exclusion of ants, primarily Camponotus sericeiventris and Camponotus spp., reduced the treehopper population to 20% of the original abundance. Ant exclusion and time influenced the abundance of chewing (Exclusion, POs efeitos de formigas na comunidade de insetos em inflorescências de Byrsonima crassifolia (Malpighiaceae foram testados em um experimento de exclusão em uma vegetação de cerrado no Sudeste do Brasil. Quarenta e quatro espécies de insetos (23 famílias e nove espécies de formigas (seis gêneros e três subfamílias foram encontradas nas inflorescências de B. crassifolia. A exclusão das formigas, principalmente de Camponotus sericeiventris e de Camponotus spp. reduziu a população de membracídeos para 20% da abundância original. Exclusão das formigas e o tempo influenciaram a abundância de insetos mastigadores (exclusão, P<0,001; tempo, P<0,002 e sugadores (exclusão, P<0,02; tempo, P<0,01. Insetos mastigadores e sugadores foram encontrados duas vezes mais em inflorescências com formigas excluídas quando comparados com inflorescências controle (P<0,001. Insetos sugadores foram encontrados 1,5 vezes mais em inflorescências com formigas excluídas do que no controle. Apenas o tempo influenciou significativamente a riqueza de insetos mastigadores e sugadores associados com as inflorescências de B. crassifolia. Inflorescências em ramos controle foram significativamente menos atacadas por herbívoros do que inflorescências em ramos com formigas excluídas (P<0,001. Portanto, estes resultados sugerem que a presença das formigas influencia a estrutura da comunidade de insetos herb

  20. Condensed tannins increase nitrogen recovery by trees following insect defoliation.

    Madritch, Michael D; Lindroth, Richard L

    2015-10-01

    While the importance of plant secondary metabolites to belowground functioning is gaining recognition, the perception remains that secondary metabolites are produced for herbivore defense, whereas their belowground impacts are ecological by-products, or 'afterlife' effects. However, plants invest a significant amount of resources into production of secondary metabolites that have minimal effects on herbivore resistance (e.g. condensed tannins and insect herbivores). We show that genetically mediated variation in condensed tannin concentration is correlated with plant nitrogen recovery following a severe defoliation event. We used single-tree mesocosms labeled with (15) N to track nitrogen through both the frass and litter cycling pathways. High concentrations of leaf tannins in Populus tremuloides were correlated with (15) N recovery from frass within the same growing season and in the following growing season. Likewise, leaf tannin concentrations were also correlated with (15) N recovery from the litter of defoliated trees in the growing season following the defoliation event. Conversely, tannins were not well correlated with nitrogen uptake under conditions of nominal herbivory. Our results suggest that tannins may confer benefits in response to herbivore pressure through conserved belowground nitrogen cycling, rather than via defensive properties. Consequently, tannins may be considered as chemical mediators of tolerance rather than resistance. PMID:25952793

  1. Can inducible resistance in plants cause herbivore aggregations? Spatial patterns in an inducible plant/herbivore model.

    Anderson, Kurt E; Inouye, Brian D; Underwood, Nora

    2015-10-01

    Many theories regarding the evolution of inducible resistance in plants have an implicit spatial component, but most relevant population dynamic studies ignore spatial dynamics. We examined a spatially explicit model of plant inducible resistance and herbivore population dynamics to explore how realistic features of resistance and herbivore responses influence spatial patterning. Both transient and persistent spatial patterns developed in all models examined, where patterns manifested as wave-like aggregations of herbivores and variation in induction levels. Patterns arose when herbivores moved away from highly induced plants, there was a lag between damage and deployment of induced resistance, and the relationship between herbivore density and strength of the induction response had a sigmoid shape. These mechanisms influenced pattern formation regardless of the assumed functional relationship between resistance and herbivore recruitment and mortality. However, in models where induction affected herbivore mortality, large-scale herbivore population cycles driven by the mortality response often co-occurred with smaller scale spatial patterns driven by herbivore movement. When the mortality effect dominated, however, spatial pattern formation was completely replaced by spatially synchronized herbivore population cycles. Our results present a new type of ecological pattern formation driven by induced trait variation, consumer behavior, and time delays that has broad implications for the community and evolutionary ecology of plant defenses. PMID:26649396

  2. A nuclear insect appears

    This book is dairy of a nuclear insect in A. F. era. It consists of 6 parts, which have fun pictures and titles. The contents are the letter that is sent the Homo sapiens by insect, exodus of nuclear insect F 100 years latter. The time that a nuclear insect is attacked in F 101, the time that a nuclear dinosaur is beat in AF 102, the time that a nuclear insect struggles in AF 104 and the time that a nuclear insect drifts in AF 104.

  3. Interactive impacts of a herbivore and a pathogen on two resistance types of Barbarea vulgaris (Brassicaceae)

    Heimes, Christine; Thiele, Jan; van Mölken, Tamara;

    2015-01-01

    It is well known that pathogens and arthropod herbivores attacking the same host plant may affect each other. Little is known, however, about their combined impact on plant fitness, which may differ from simple additive expectations. In a 2-year common garden field experiment, we tested whether...... by interactive impacts of the antagonists. Most of the insect-resistant G-plants were severely affected by white rust, which reduced biomass and reproductive potential compared to the controls. However, when also exposed to flea beetles, biomass loss was mitigated in G-plants, even though apparent disease...... the pathogen Albugo sp. (white blister rust) and the herbivorous flea beetle Phyllotreta nemorum affected each other's performance on two resistance types (G-type and P-type) of the crucifer Barbarea vulgaris ssp. arcuata, and whether biomass, reproduction and survival of the plants were affected...

  4. Availability and temporal heterogeneity of water supply affect the vertical distribution and mortality of a belowground herbivore and consequently plant growth.

    Tomonori Tsunoda

    Full Text Available We examined how the volume and temporal heterogeneity of water supply changed the vertical distribution and mortality of a belowground herbivore, and consequently affected plant biomass. Plantago lanceolata (Plantaginaceae seedlings were grown at one per pot under different combinations of water volume (large or small volume and heterogeneity (homogeneous water conditions, watered every day; heterogeneous conditions, watered every 4 days in the presence or absence of a larva of the belowground herbivorous insect, Anomala cuprea (Coleoptera: Scarabaeidae. The larva was confined in different vertical distributions to top feeding zone (top treatment, middle feeding zone (middle treatment, or bottom feeding zone (bottom treatment; alternatively no larva was introduced (control treatment or larval movement was not confined (free treatment. Three-way interaction between water volume, heterogeneity, and the herbivore significantly affected plant biomass. With a large water volume, plant biomass was lower in free treatment than in control treatment regardless of heterogeneity. Plant biomass in free treatment was as low as in top treatment. With a small water volume and in free treatment, plant biomass was low (similar to that under top treatment under homogeneous water conditions but high under heterogeneous ones (similar to that under middle or bottom treatment. Therefore, there was little effect of belowground herbivory on plant growth under heterogeneous water conditions. In other watering regimes, herbivores would be distributed in the shallow soil and reduced root biomass. Herbivore mortality was high with homogeneous application of a large volume or heterogeneous application of a small water volume. Under the large water volume, plant biomass was high in pots in which the herbivore had died. Thus, the combinations of water volume and heterogeneity affected plant growth via the change of a belowground herbivore.

  5. Insect Bites and Stings

    Most insect bites are harmless, though they sometimes cause discomfort. Bee, wasp, and hornet stings and fire ant bites usually hurt. Mosquito and flea bites usually itch. Insects can also spread diseases. In the United States, ...

  6. Insects: An Interdisciplinary Unit

    Leger, Heather

    2007-01-01

    The author talks about an interdisciplinary unit on insects, and presents activities that can help students practice communication skills (interpersonal, interpretive, and presentational) and learn about insects with hands-on activities.

  7. Flying insects and robots

    Ellington, Charlie

    2009-01-01

    Understanding flight mechanics of insects can aid engineers in developing intelligent flying robots. In this seminal book, biologists and engineers detail the mechanics, technology, and intelligence of insects then discuss potential benefits of their research.

  8. Quinoa, Chenopodium quinoa, Provides a New Host for Native Herbivores in Northern Europe: Case Studies of the Moth, Scrobipalpa atriplicella, and the Tortoise Beetle, Cassida nebulosa

    Sigsgaard, Lene; Jacobsen, Sven Erik; Christiansen, Jørgen Lindskrog

    2008-01-01

    The Andean grain, quinoa, Chenopodium quinoa Willd. (Caryophyllales: Amaranthaceae), is gaining increasing attention as a future food and fodder crop in Denmark and other parts of Europe. Prior to 2005, pest problems in the crop were negligible in Denmark, however native insects may become adapted to this new host. Herbivores feeding on the closely related and very common weed in arable crops Chenopodium album L. present a special risk. In 2006 there was a heavy attack of Scrobipalpa atriplic...

  9. Effects of manipulated herbivore inputs on nutrient flux and decomposition in a tropical rainforest in Puerto Rico.

    Schowalter, T D; Fonte, S J; Geaghan, J; Wang, J

    2011-12-01

    Forest canopy herbivores are known to increase rates of nutrient fluxes to the forest floor in a number of temperate and boreal forests, but few studies have measured effects of herbivore-enhanced nutrient fluxes in tropical forests. We simulated herbivore-induced fluxes in a tropical rainforest in Puerto Rico by augmenting greenfall (fresh foliage fragments), frassfall (insect feces), and throughfall (precipitation enriched with foliar leachates) in replicated experimental plots on the forest floor. Background rates of greenfall and frassfall were measured monthly using litterfall collectors and augmented by adding 10× greenfall or 10× frassfall to designated plots. Throughfall fluxes of NH(4), NO(3) and PO(4) (but not water) were doubled in treatment plots, based on published rates of fluxes of these nutrients in throughfall. Control plots received only background flux rates for these compounds but the same minimum amount of distilled water. We evaluated treatment effects as changes in flux rates for NO(3), NH(4) and PO(4), measured as decomposition rate of leaf litter in litterbags and as adsorption in ion-exchange resin bags at the litter-soil interface. Frass addition significantly increased NO(3) and NH(4) fluxes, and frass and throughfall additions significantly reduced decay rate, compared to controls. Reduced decay rate suggests that nitrogen flux was sufficient to inhibit microbial decomposition activity. Our treatments represented fluxes expected from low-moderate herbivore outbreaks and demonstrated that herbivores, at these outbreak levels, increase ecosystem-level N and P fluxes by >30% in this tropical rainforest. PMID:21713416

  10. Insect Barcode Information System

    Pratheepa, Maria; Jalali, Sushil Kumar; Arokiaraj, Robinson Silvester; Venkatesan, Thiruvengadam; Nagesh, Mandadi; Panda, Madhusmita; Pattar, Sharath

    2014-01-01

    Insect Barcode Information System called as Insect Barcode Informática (IBIn) is an online database resource developed by the National Bureau of Agriculturally Important Insects, Bangalore. This database provides acquisition, storage, analysis and publication of DNA barcode records of agriculturally important insects, for researchers specifically in India and other countries. It bridges a gap in bioinformatics by integrating molecular, morphological and distribution details of agriculturally ...

  11. Sunflower insect pests

    Like other annual crops, sunflowers are fed upon by a variety of insect pests capable of reducing yields. Though there are a few insects which are considered consistent or severe (e.g., sunflower moth, banded sunflower moth, red sunflower seed weevil), many more insects are capable of causing proble...

  12. Exploring Sound with Insects

    Robertson, Laura; Meyer, John R.

    2010-01-01

    Differences in insect morphology and movement during singing provide a fascinating opportunity for students to investigate insects while learning about the characteristics of sound. In the activities described here, students use a free online computer software program to explore the songs of the major singing insects and experiment with making…

  13. Effect of herbivore damage on broad leaf motion in wind

    Burnett, Nicholas; Kothari, Adit

    2015-11-01

    Terrestrial plants regularly experience wind that imposes aerodynamic forces on the plants' leaves. Passive leaf motion (e.g. fluttering) and reconfiguration (e.g. rolling into a cone shape) in wind can affect the drag on the leaf. In the study of passive leaf motion in wind, little attention has been given to the effect of herbivory. Herbivores may alter leaf motion in wind by making holes in the leaf. Also, a small herbivore (e.g. snail) on a leaf can act as a point mass, thereby affecting the leaf's motion in wind. Conversely, accelerations imposed on an herbivore sitting on a leaf by the moving leaf may serve as a defense by dislodging the herbivore. In the present study, we investigated how point masses (>1 g) and holes in leaves of the tuliptree affected passive leaf motion in turbulent winds of 1 and 5 m s-1. Leaf motion was unaffected by holes in the leaf surface (about 10% of leaf area), but an herbivore's mass significantly damped the accelerations of fluttering leaves. These results suggest that an herbivore's mass, but not the damage it inflicts, can affect leaf motion in the wind. Furthermore, the damping of leaf fluttering from an herbivore's mass may prevent passive leaf motions from being an effective herbivore defense.

  14. Onset of herbivore-induced resistance in systemic tissue primed for jasmonate-dependent defenses is activated by abscisic acid

    Irene A. Vos

    2013-12-01

    Full Text Available In Arabidopsis, the MYC2 transcription factor on the one hand and the AP2/ERF transcription factors ORA59 and ERF1 on the other hand regulate distinct branches of the jasmonic acid (JA signaling pathway in an antagonistic fashion, co-regulated by abscisic acid (ABA and ethylene, respectively. Feeding by larvae of the specialist herbivorous insect Pieris rapae (small cabbage white butterfly results in activation of the MYC-branch and concomitant suppression of the ERF-branch in insect-damaged leaves. Here we investigated differential JA signaling activation in undamaged systemic leaves of P. rapae-infested plants. We found that the MYC2 transcription factor gene was induced both in the local insect-damaged leaves and the systemic undamaged leaves of P. rapae-infested Arabidopsis plants. However, in contrast to the insect-damaged leaves, the undamaged tissue did not show activation of the MYC-branch marker gene VSP1. Comparison of the hormone signal signature revealed that the levels of JA and (+-7-iso-jasmonoyl-L-isoleucine (JA-Ile raised to similar extents in locally damaged and systemically undamaged leaves, but the production of ABA and the JA precursor 12-oxo-phytodienoic acid (OPDA was enhanced only in the local herbivore-damaged leaves, and not in the distal undamaged leaves. Challenge of undamaged leaves of pre-infested plants with either P. rapae larvae or exogenously applied ABA led to potentiated expression levels of MYC2 and VSP1, with the latter reaching extremely high expression levels. Moreover, P. rapae-induced resistance, as measured by reduction of caterpillar growth on pre-infested plants, was blocked in the ABA biosynthesis mutant aba2-1, that was also impaired in P. rapae-induced expression of VSP1. Together, these results suggest that ABA is a crucial regulator of herbivore-induced resistance by activating primed JA-regulated defense responses upon secondary herbivore attack in Arabidopsis.

  15. Integrating Insect Life History and Food Plant Phenology: Flexible Maternal Choice Is Adaptive

    Minghui Fei

    2016-08-01

    Full Text Available Experience of insect herbivores and their natural enemies in the natal habitat is considered to affect their likelihood of accepting a similar habitat or plant/host during dispersal. Growing phenology of food plants and the number of generations in the insects further determines lability of insect behavioural responses at eclosion. We studied the effect of rearing history on oviposition preference in a multivoltine herbivore (Pieris brassicae, and foraging behaviour in the endoparasitoid wasp (Cotesia glomerata a specialist enemy of P. brassicae. Different generations of the insects are obligatorily associated with different plants in the Brassicaceae, e.g., Brassica rapa, Brassica nigra and Sinapis arvensis, exhibiting different seasonal phenologies in The Netherlands. Food plant preference of adults was examined when the insects had been reared on each of the three plant species for one generation. Rearing history only marginally affected oviposition preference of P. brassicae butterflies, but they never preferred the plant on which they had been reared. C. glomerata had a clear preference for host-infested B. rapa plants, irrespective of rearing history. Higher levels of the glucosinolate breakdown product 3-butenyl isothiocyanate in the headspace of B. rapa plants could explain enhanced attractiveness. Our results reveal the potential importance of flexible plant choice for female multivoltine insects in nature.

  16. Integrating Insect Life History and Food Plant Phenology: Flexible Maternal Choice Is Adaptive.

    Fei, Minghui; Harvey, Jeffrey A; Weldegergis, Berhane T; Huang, Tzeyi; Reijngoudt, Kimmy; Vet, Louise M; Gols, Rieta

    2016-01-01

    Experience of insect herbivores and their natural enemies in the natal habitat is considered to affect their likelihood of accepting a similar habitat or plant/host during dispersal. Growing phenology of food plants and the number of generations in the insects further determines lability of insect behavioural responses at eclosion. We studied the effect of rearing history on oviposition preference in a multivoltine herbivore (Pieris brassicae), and foraging behaviour in the endoparasitoid wasp (Cotesia glomerata) a specialist enemy of P. brassicae. Different generations of the insects are obligatorily associated with different plants in the Brassicaceae, e.g., Brassica rapa, Brassica nigra and Sinapis arvensis, exhibiting different seasonal phenologies in The Netherlands. Food plant preference of adults was examined when the insects had been reared on each of the three plant species for one generation. Rearing history only marginally affected oviposition preference of P. brassicae butterflies, but they never preferred the plant on which they had been reared. C. glomerata had a clear preference for host-infested B. rapa plants, irrespective of rearing history. Higher levels of the glucosinolate breakdown product 3-butenyl isothiocyanate in the headspace of B. rapa plants could explain enhanced attractiveness. Our results reveal the potential importance of flexible plant choice for female multivoltine insects in nature. PMID:27527153

  17. Insect Barcode Information System

    Pratheepa, Maria; Jalali, Sushil Kumar; Arokiaraj, Robinson Silvester; Venkatesan, Thiruvengadam; Nagesh, Mandadi; Panda, Madhusmita; Pattar, Sharath

    2014-01-01

    Insect Barcode Information System called as Insect Barcode Informática (IBIn) is an online database resource developed by the National Bureau of Agriculturally Important Insects, Bangalore. This database provides acquisition, storage, analysis and publication of DNA barcode records of agriculturally important insects, for researchers specifically in India and other countries. It bridges a gap in bioinformatics by integrating molecular, morphological and distribution details of agriculturally important insects. IBIn was developed using PHP/My SQL by using relational database management concept. This database is based on the client– server architecture, where many clients can access data simultaneously. IBIn is freely available on-line and is user-friendly. IBIn allows the registered users to input new information, search and view information related to DNA barcode of agriculturally important insects.This paper provides a current status of insect barcode in India and brief introduction about the database IBIn. Availability http://www.nabg-nbaii.res.in/barcode PMID:24616562

  18. Drought and flooding have distinct effects on herbivore-induced responses and resistance in Solanum dulcamara.

    Nguyen, Duy; D'Agostino, Nunzio; Tytgat, Tom O G; Sun, Pulu; Lortzing, Tobias; Visser, Eric J W; Cristescu, Simona M; Steppuhn, Anke; Mariani, Celestina; van Dam, Nicole M; Rieu, Ivo

    2016-07-01

    In the field, biotic and abiotic stresses frequently co-occur. As a consequence, common molecular signalling pathways governing adaptive responses to individual stresses can interact, resulting in compromised phenotypes. How plant signalling pathways interact under combined stresses is poorly understood. To assess this, we studied the consequence of drought and soil flooding on resistance of Solanum dulcamara to Spodoptera exigua and their effects on hormonal and transcriptomic profiles. The results showed that S. exigua larvae performed less well on drought-stressed plants than on well-watered and flooded plants. Both drought and insect feeding increased abscisic acid and jasmonic acid (JA) levels, whereas flooding did not induce JA accumulation. RNA sequencing analyses corroborated this pattern: drought and herbivory induced many biological processes that were repressed by flooding. When applied in combination, drought and herbivory had an additive effect on specific processes involved in secondary metabolism and defence responses, including protease inhibitor activity. In conclusion, drought and flooding have distinct effects on herbivore-induced responses and resistance. Especially, the interaction between abscisic acid and JA signalling may be important to optimize plant responses to combined drought and insect herbivory, making drought-stressed plants more resistant to insects than well-watered and flooded plants. PMID:26759219

  19. Do cities simulate climate change? A comparison of herbivore response to urban and global warming

    Youngsteadt, Elsa; Dale, Adam G.; Terando, Adam; Dunn, Robert R.; Frank, Steven D.

    2014-01-01

    Cities experience elevated temperature, CO2, and nitrogen deposition decades ahead of the global average, such that biological response to urbanization may predict response to future climate change. This hypothesis remains untested due to a lack of complementary urban and long-term observations. Here, we examine the response of an herbivore, the scale insect Melanaspis tenebricosa, to temperature in the context of an urban heat island, a series of historical temperature fluctuations, and recent climate warming. We survey M. tenebricosa on 55 urban street trees in Raleigh, NC, 342 herbarium specimens collected in the rural southeastern United States from 1895 to 2011, and at 20 rural forest sites represented by both modern (2013) and historical samples. We relate scale insect abundance to August temperatures and find that M. tenebricosa is most common in the hottest parts of the city, on historical specimens collected during warm time periods, and in present-day rural forests compared to the same sites when they were cooler. Scale insects reached their highest densities in the city, but abundance peaked at similar temperatures in urban and historical datasets and tracked temperature on a decadal scale. Although urban habitats are highly modified, species response to a key abiotic factor, temperature, was consistent across urban and rural-forest ecosystems. Cities may be an appropriate but underused system for developing and testing hypotheses about biological effects of climate change. Future work should test the applicability of this model to other groups of organisms.

  20. Successful herbivore attack due to metabolic diversion of a plant chemical defense.

    Wittstock, Ute; Agerbirk, Niels; Stauber, Einar J; Olsen, Carl Erik; Hippler, Michael; Mitchell-Olds, Thomas; Gershenzon, Jonathan; Vogel, Heiko

    2004-04-01

    Plants protect themselves against herbivory with a diverse array of repellent or toxic secondary metabolites. However, many herbivorous insects have developed counteradaptations that enable them to feed on chemically defended plants without apparent negative effects. Here, we present evidence that larvae of the specialist insect, Pieris rapae (cabbage white butterfly, Lepidoptera: Pieridae), are biochemically adapted to the glucosinolate-myrosinase system, the major chemical defense of their host plants. The defensive function of the glucosinolate-myrosinase system results from the toxic isothiocyanates that are released when glucosinolates are hydrolyzed by myrosinases on tissue disruption. We show that the hydrolysis reaction is redirected toward the formation of nitriles instead of isothiocyanates if plant material is ingested by P. rapae larvae, and that the nitriles are excreted with the feces. The ability to form nitriles is due to a larval gut protein, designated nitrile-specifier protein, that by itself has no hydrolytic activity on glucosinolates and that is unrelated to any functionally characterized protein. Nitrile-specifier protein appears to be the key biochemical counteradaptation that allows P. rapae to feed with impunity on plants containing glucosinolates and myrosinases. This finding sheds light on the ecology and evolution of plant-insect interactions and suggests novel highly selective pest management strategies. PMID:15051878

  1. Glucosinolate Desulfation by the Phloem-Feeding Insect Bemisia tabaci.

    Malka, Osnat; Shekhov, Anton; Reichelt, Michael; Gershenzon, Jonathan; Vassão, Daniel Giddings; Morin, Shai

    2016-03-01

    Glucosinolates are plant secondary defense metabolites confined nearly exclusively to the order Brassicales. Upon tissue rupture, glucosinolates are hydrolyzed to various bioactive breakdown products by the endogenous plant enzyme myrosinase. As the feeding of chewing insect herbivores is associated with plant tissue damage, these insects have developed several independent strategies for coping with the glucosinolate-myrosinase defense system. On the other hand, our knowledge of how phloem-feeding insects interact with the glucosinolate-myrosinase system is much more limited. In fact, phloem feeders might avoid contact with myrosinase altogether so their susceptibility to intoxication by glucosinolate hydrolysis products is unclear. Previous studies utilizing Arabidopsis thaliana plants accumulating high levels of aliphatic- or indolic-glucosinolates indicated that both glucosinolate groups have moderate negative effects on the reproductive performance of Bemisia tabaci, a generalist phloem-feeding insect. To get a deeper understanding of the interaction between B. tabaci and glucosinolate-defended plants, adults were allowed to feed on artificial diet containing intact glucosinolates or on Brussels sprout and A. thaliana plants, and their honeydew was analyzed for the presence of possible metabolites. We found that B. tabaci is capable of cleaving off the sulfate group of intact glucosinolates, producing desulfoglucosinolates that cannot be activated by myrosinases, a mechanism described to date only in several chewing insect herbivores. The presence of desulfated glucosinolates in the honeydew of a generalist phloem-feeder may indicate the necessity to detoxify glucosinolates, likely due to some level of cellular damage during feeding, which results in glucosinolate activation, or as a mechanism to circumvent the non-enzymatic breakdown of indolic glucosinolates. PMID:26961756

  2. High-nickel insects and nickel hyperaccumulator plants:A review

    Robert S.Boyd

    2009-01-01

    Insects can vary greatly in whole-body elemental concentrations.Recent investigations ofinsects associated with Ni hyperaecumulator plants have identified insects with relatively elevated whole.body N.leveis.Evaluation of the limited data available indicates that a whole-body Ni concentration of 500 μg Ni/g is exceptional:I propose that an insect species with a mean value of 500 μg Ni/g or greater,in either larval/nymphal or of high.Ni insects have been identified to date from studies in Mpurnalanga(South Africa),New Caledonia and California(USA).The highest mean Ni concentration reported is 3 500μg Ni/g for nymphs of a South African Stenoscepa species(Orthoptera:Pyrgomorphidae).The majority of high-Niinsects(66%)are heteropteran herbivores.Studies of high-Ni insect host prefefence indicate they are monophagous(or nearly so)on a particular Nihyperaccurnulator plant species.Much ofthe Ni in bodies of these insects is in their guts(upto 66%-75%),but elevated levels have also been found in Maipighian tubules,suggesting efficient elimination as one strategy for dealing with a high-Ni diet.Tissue levels of Ni are generally much lower than gut concentrations.butupto 1 200μg Ni/g has been reported from exuviae,suggesting that molting may be another pathway of Ni elimination.One ecological function of the high Ni concentration of these insects may be todefend them against natuml enemies.but to date only one experimental test has supported this"elemental defense"hypothesis.Community-level studies indicate that high-Ni insects mobilize Ni into food webs but that bioaccumulation of Ni does not occur at either plant-herbivore or herbivore-predator steps.Unsurprisingly,Ni bioaccumulation indices are greater for high-Ni insects compared to other insect species that feed on Ni hyperaccumulator plants.There is some evidence of Nimobilization into food webs by insect visitors to flowers of Nihyperaccumulator plants.but no high-Ni insect floral visitors have been reported.

  3. Estimation of above-ground biomass of grassland based on multi-source remote sensing data%基于多元遥感数据的草地生物量估算方法

    王新云; 郭艺歌; 何杰

    2014-01-01

    Radar (SAR) C-band data was utilized to develop a biomass regression model and estimate the aboveground biomass (AGB) of the Caragana microphylla shrubbery in the desert steppe region in the northwest of China. The research area was located at Yangzhaizi Village in Ningxia Autonomous region. Grassland inventory was carried out in 45 randomly distributed plots (30 m × 30 m), and the data was used for either model development or validation. An allometric regression model was established to estimate its biomass for every Caragana microphylla shrub with CH (crown width multiple plant height) variable. The local allometric regression equation was applied to calculate AGB per plot. Furthermore, the correlation between the aboveground biomass of Caragana microphylla shrubbery and the radar backscatter coefficient was analyzed. The AGB regression model was developed by integrating field measurements of 25 sample plots with RADARSAT-2 backscatter remotely sensed data. The multiple stepwise regressions algorithm was applied to develop the AGB model and estimate the grassland above-ground biomass from RADARSAT-2 backscatter data. The developed model was validated by using 20 independent sample plots. Simultaneously, RADARSAT-2 images were fused with the optical HJ1B data by using a discrete wavelet transform for the land cover classification. The image classification based on the objects was performed by using the empirical-statistical machine learning techniques, such as a classification and regression trees (CART) algorithm. The overall accuracy and Kappa value of the proposed method was 90.2% and 0.88, respectively. It indicated that the proposed method performed well for the land use and land cover (LULC) classification. An AGB biomass distribution map was produced by RADARSAT-2 backscatter data in combination with the land cover classification image and AGB regression model. As a comparison, the AGB from RADARSAT-2 estimates were compared with the results from the HJ1B

  4. Spatial and Temporal Potato Intensification Drives Insecticide Resistance in the Specialist Herbivore, Leptinotarsa decemlineata.

    Anders S Huseth

    Full Text Available Landscape-scale intensification of individual crops and pesticide use that is associated with this intensification is an emerging, environmental problem that is expected to have unequal effects on pests with different lifecycles, host ranges, and dispersal abilities. We investigate if intensification of a single crop in an agroecosystem has a direct effect on insecticide resistance in a specialist insect herbivore. Using a major potato pest, Leptinotarsa decemlineata, we measured imidacloprid (neonicotinoid resistance in populations across a spatiotemporal crop production gradient where potato production has increased in Michigan and Wisconsin, USA. We found that concurrent estimates of area and temporal frequency of potato production better described patterns of imidacloprid resistance among L. decemlineata populations than general measures of agricultural production (% cropland, landscape diversity. This study defines the effects individual crop rotation patterns can have on specialist herbivore insecticide resistance in an agroecosystem context, and how impacts of intensive production can be estimated with general estimates of insecticide use. Our results provide empirical evidence that variation in the intensity of neonicotinoid-treated potato in an agricultural landscape can have unequal impacts on L. decemlineata insecticide insensitivity, a process that can lead to resistance and locally intensive insecticide use. Our study provides a novel approach applicable in other agricultural systems to estimate impacts of crop rotation, increased pesticide dependence, insecticide resistance, and external costs of pest management practices on ecosystem health.

  5. Spatial and Temporal Potato Intensification Drives Insecticide Resistance in the Specialist Herbivore, Leptinotarsa decemlineata.

    Huseth, Anders S; Petersen, Jessica D; Poveda, Katja; Szendrei, Zsofia; Nault, Brian A; Kennedy, George G; Groves, Russell L

    2015-01-01

    Landscape-scale intensification of individual crops and pesticide use that is associated with this intensification is an emerging, environmental problem that is expected to have unequal effects on pests with different lifecycles, host ranges, and dispersal abilities. We investigate if intensification of a single crop in an agroecosystem has a direct effect on insecticide resistance in a specialist insect herbivore. Using a major potato pest, Leptinotarsa decemlineata, we measured imidacloprid (neonicotinoid) resistance in populations across a spatiotemporal crop production gradient where potato production has increased in Michigan and Wisconsin, USA. We found that concurrent estimates of area and temporal frequency of potato production better described patterns of imidacloprid resistance among L. decemlineata populations than general measures of agricultural production (% cropland, landscape diversity). This study defines the effects individual crop rotation patterns can have on specialist herbivore insecticide resistance in an agroecosystem context, and how impacts of intensive production can be estimated with general estimates of insecticide use. Our results provide empirical evidence that variation in the intensity of neonicotinoid-treated potato in an agricultural landscape can have unequal impacts on L. decemlineata insecticide insensitivity, a process that can lead to resistance and locally intensive insecticide use. Our study provides a novel approach applicable in other agricultural systems to estimate impacts of crop rotation, increased pesticide dependence, insecticide resistance, and external costs of pest management practices on ecosystem health. PMID:26030877

  6. Indirect plant-parasitoid interactions mediated by changes in herbivore physiology.

    Kaplan, Ian; Carrillo, Juli; Garvey, Michael; Ode, Paul J

    2016-04-01

    In occupying an intermediate trophic position, herbivorous insects serve a vital link between plants at the base of the food chain and parasitoids at the top. Although these herbivore-mediated indirect plant-parasitoid interactions are well-documented, new studies have uncovered previously undescribed mechanisms that are fundamentally changing how we view tri-trophic relationships. In this review we highlight recent advances in this field focusing on both plant-driven and parasitoid-driven outcomes that flow up and down the trophic web, respectively. From the bottom-up, plant metabolites can impact parasitoid success by altering host immune function; however, few have considered the potential effects of other plant defense strategies such as tolerance on parasitoid ecology and behavior. From the top-down, parasitoids have long been considered plant bodyguards, but in reality the consequences of parasitism for herbivory rates and induction of plant defensive chemistry are far more complicated with cascading effects on community-level interactions. PMID:27436656

  7. Effects of pollutants on bottom-up and top-down processes in insect-plant interactions

    Bottom-up (host plant quality) and top-down (natural enemies) forces both influence the fitness and population dynamics of herbivores. However, the impact of pollutants acting on these forces has not been examined, which prompted us to review the literature to test hypotheses regarding this area of research. A comprehensive literature search found 126 references which examined fitness components and population dynamics of 203 insect herbivores. One hundred and fifty-three of the 203 herbivores (75.4%) had fitness impacted due to bottom-up factors in polluted environments. In contrast, only 20 of the 203 (9.9%) had fitness significantly impacted due to top-down factors in polluted environments. The paucity of results for top-down factors impacting fitness does not necessarily mean that top-down factors are less important, but rather that fewer studies include natural enemies. We provide a synthesis of available data by pollution type and herbivore guild, and suggest future research to address this issue. - Pollutants can affect insect herbivores through bottom-up and, possibly, top-down processes

  8. Reduction of herbivore density as a tool for reduction of herbivore browsing on palatable tree species

    Kamler, Jiří; Homolka, Miloslav; Barančeková, Miroslava; Krojerová-Prokešová, Jarmila

    2010-01-01

    Roč. 129, č. 2 (2010), s. 155-162. ISSN 1612-4669 R&D Projects: GA ČR GP206/03/P134; GA MŠk LC06073 Institutional research plan: CEZ:AV0Z60930519 Keywords : herbivore impact * habitat use * forest regeneration * spruce * beech * rowan Subject RIV: EH - Ecology, Behaviour Impact factor: 1.942, year: 2010

  9. Mediation of herbivore attack and induced resistance by plant vigor and ontogeny

    Santos, Jean Carlos; Fernandes, G. Wilson

    2010-11-01

    A large number of insect galls induced by Contarinia sp. (Cecidomyiidae) on cashew plants, Anacardium occidentale L. (Anacardiaceae), and induced resistance (hypersensitivity) against galling were observed in five restored different-aged stands in the Amazonian tropical rain forest. We tested three hypotheses: (1) the effect of age-dependent changes on the attack by Contarinia sp. and on induced resistance of A. occidentale to herbivory (plant ontogeny - herbivory hypothesis); (2) the effect of leaf size on the oviposition preference by the gall-midge (plant vigor hypothesis), and (3) whether past attack could influence future attack and induced resistance (attack prediction hypothesis). Tree age positively influenced attack levels and gall density. The leaves of older trees experienced four-fold greater attack and supported two-fold more galls. Hypersensitive response was also positively affected by tree age. This induced resistance was six-fold higher on older trees. Therefore, we suggest that induced resistance in A. occidentale was age-dependent, hence supporting the plant ontogeny - herbivory hypothesis. Higher preference of Contarinia sp. on larger sized leaves of A. occidentale was only observed in old stands, hence providing support for the plant vigor hypothesis. The same trend was observed in hypersensitive response. Only two older plots (5-7-year-old) were better predictors of current attack and resistance of A. occidentale, hence supporting the attack prediction hypothesis. Our results suggest that plant development is an important factor that contributes to the structuring of interactions between host plant and insect herbivores. However, more information about ontogenetic changes and regeneration processes is needed to understand plant-herbivore interactions in the Amazonian forest.

  10. Proteomics and insect immunity

    L Shi

    2006-01-01

    Full Text Available Insect innate immunity is both a model for vertebrate immunity as well as a key system that impactsmedically important pathogens that are transmitted by insects. Recent developments in proteomics andprotein identification techniques combined with the completion of genome sequences for Anophelesgambiae and Drosophila melanogaster provided the tools for examining insect immunity at a new level ofmolecular detail. Application of proteomics to insect immunity resulted in predictions of new roles inimmunity for proteins already known in other contexts (e.g. ferritin, transferrin, Chi-lectins and helped totarget specific members of multi-gene families that respond to different pathogens (e.g. serine proteases,thioester proteins. In addition, proteomics studies verify that post-translational modifications play a keyrole in insect immunity since many of the identified proteins are modified in some way. These studiescomplement recent work on insect transcriptomes and provide new directions for further investigation ofinnate immunity.

  11. Herbivore handling of a plant's trichome: the case of Heliconius charithonia (L.) (Lepidoptera: Nymphalidae) and Passiflora lobata (Killip) Hutch. (Passifloraceae)

    Trichomes reduce herbivore attack on plants by physically and/or chemically inhibiting movement or other activities. Despite evidence that herbivores are negatively affected by trichomes there also reports of insect counter-adaptations that circumvent the plant's defense. This paper reports on a study that investigated the likely mechanisms employed by larvae of the nymphalid butterfly, Heliconius charithonia (L.), that allow it to feed on a host that is presumably protected by hooked trichomes (Passiflora lobata (Killip) Hutch). Evidence were gathered using data from direct observations of larval movement and behavior, faeces analysis, scanning electron microscopy of plant surface and experimental analysis of larval movement on plants with and without trichomes (manually removed). The latter involved a comparison with a non specialist congener, Heliconius pachinus Salvin. Observations showed that H. charithonia larvae are capable of freeing themselves from entrapment on trichome tips by physical force. Moreover, wandering larvae lay silk mats on the trichomes and remove their tips by biting. In fact, trichome tips were found in the faeces. Experimental removal of trichomes aided in the movement of the non specialist but had no noticeable effect on the specialist larvae. These results support the suggestion that trichomes are capable of deterring a non specialist herbivore (H. pachinus). The precise mechanisms that allow the success of H. charithonia are not known, but I suggest that a blend of behavioral as well as physical resistance mechanisms is involved. Future studies should ascertain whether larval integument provides physical resistance to trichomes. (author)

  12. Insects, isotopes and radiation

    The sterile insect technique (SIT), which uses radiation to sexually sterilize insects and prevent reproduction, is particularly effective in eradicating harmful insects. The Joint Division of the IAEA/FAO has been involved in the use of isotopes and radiation in insect control since 1964. Efforts by the IAEA and FAO to transfer the SIT technology to developing countries are continuing by providing valuable research and development support for field projects. The cooperative SIT project against the tse tse fly was very successful in eradicating this harmful pest from the north-central Nigeria. A similar SIT project is actually underway to eradicate the Mediteranean fruit fly in Mexico

  13. Impact of herbivores on nitrogen cycling: contrasting effects of small and large species

    Bakker, E.S.; Olff, H.; Boekhoff, M.; Gleichman, J.M.; Berendse, F.

    2004-01-01

    Herbivores are reported to slow down as well as enhance nutrient cycling in grasslands. These conflicting results may be explained by differences in herbivore type. In this study we focus on herbivore body size as a factor that causes differences in herbivore effects on N cycling. We used an exclosu

  14. Impact of herbivores on nitrogen cycling : contrasting effects of small and large species

    Bakker, ES; Olff, H; Boekhoff, M; Gleichman, JM; Berendse, F

    2004-01-01

    Herbivores are reported to slow down as well as enhance nutrient cycling in grasslands. These conflicting results may be explained by differences in herbivore type. In this study we focus on herbivore body size as a factor that causes differences in herbivore effects on N cycling. We used an exclosu

  15. Context-dependency of arbuscular mycorrhizal fungi on plant-insect interactions in an agroecosystem

    Nicholas A Barber

    2013-09-01

    Full Text Available Plants interact with a variety of other community members that have the potential to indirectly influence each other through a shared host plant. Arbuscular mycorrhizal fungi (AMF are generally considered plant mutualists because of their generally positive effects on plant nutrient status and growth. AMF may also have important indirect effects on plants by altering interactions with other community members. By influencing plant traits, AMF can modify aboveground interactions with both mutualists, such as pollinators, and antagonists, such as herbivores. Because herbivory and pollination can dramatically influence plant fitness, comprehensive assessment of plant-AMF interactions should include these indirect effects. To determine how AMF affect plant-insect interactions, we grew Cucumis sativus (Cucurbitaceae under five AMF inoculum treatments and control. We measured plant growth, floral production, flower size, and foliar nutrient content of half the plants, and transferred the other half to a field setting to measure pollinator and herbivore preference of wild insects. Mycorrhizal treatment had no effect on plant biomass or floral traits but significantly affected leaf nutrients, pollinator behavior, and herbivore attack. Although total pollinator visitation did not vary with AMF treatment, pollinators exhibited taxon-specific responses, with honey bees, bumble bees, and Lepidoptera all responding differently to AMF treatments. Flower number and size were unaffected by treatments, suggesting that differences in pollinator preference were driven by other floral traits. Mycorrhizae influenced leaf K and Na, but these differences in leaf nutrients did not correspond to variation in herbivore attack. Overall, we found that AMF indirectly influence both antagonistic and mutualistic insects, but impacts depend on the identity of both the fungal partner and the interacting insect, underscoring the context dependency of plant-AMF interactions.

  16. Native birds and alien insects: spatial density dependence in songbird predation of invading oak gallwasps

    Karsten Schönrogge; Tracey Begg; Stone, Graham N.

    2013-01-01

    Revealing the interactions between alien species and native communities is central to understanding the ecological consequences of range expansion. Much has been learned through study of the communities developing around invading herbivorous insects. Much less, however, is known about the significance of such aliens for native vertebrate predators for which invaders may represent a novel food source. We quantified spatial patterns in native bird predation of invading gall-inducing Andricus wa...

  17. Rewiring of the jasmonic acid signaling pathway during insect herbivory on Arabidopsis

    A. Verhage

    2011-01-01

    Plants are attacked by a plethora of potentially devastating pathogens and pests. To protect themselves, plants have evolved a sophisticated immune system in which phytohormones play pivotal regulatory roles. Jasmonic acid (JA) emerged as an important hormonal regulator of defense responses that are triggered by insect herbivores and microbial pathogens with a necrotrophic life style. Although JA accumulates in response to invasion by both types of attackers, JA-dependent defenses against her...

  18. Context-dependency of arbuscular mycorrhizal fungi on plant-insect interactions in an agroecosystem.

    Barber, Nicholas A; Kiers, E Toby; Hazzard, Ruth V; Adler, Lynn S

    2013-01-01

    Plants interact with a variety of other community members that have the potential to indirectly influence each other through a shared host plant. Arbuscular mycorrhizal fungi (AMF) are generally considered plant mutualists because of their generally positive effects on plant nutrient status and growth. AMF may also have important indirect effects on plants by altering interactions with other community members. By influencing plant traits, AMF can modify aboveground interactions with both mutualists, such as pollinators, and antagonists, such as herbivores. Because herbivory and pollination can dramatically influence plant fitness, comprehensive assessment of plant-AMF interactions should include these indirect effects. To determine how AMF affect plant-insect interactions, we grew Cucumis sativus (Cucurbitaceae) under five AMF inoculum treatments and control. We measured plant growth, floral production, flower size, and foliar nutrient content of half the plants, and transferred the other half to a field setting to measure pollinator and herbivore preference of wild insects. Mycorrhizal treatment had no effect on plant biomass or floral traits but significantly affected leaf nutrients, pollinator behavior, and herbivore attack. Although total pollinator visitation did not vary with AMF treatment, pollinators exhibited taxon-specific responses, with honey bees, bumble bees, and Lepidoptera all responding differently to AMF treatments. Flower number and size were unaffected by treatments, suggesting that differences in pollinator preference were driven by other floral traits. Mycorrhizae influenced leaf K and Na, but these differences in leaf nutrients did not correspond to variation in herbivore attack. Overall, we found that AMF indirectly influence both antagonistic and mutualistic insects, but impacts depend on the identity of both the fungal partner and the interacting insect, underscoring the context-dependency of plant-AMF interactions. PMID:24046771

  19. Mercury, Cadmium and Lead Biogeochemistry in the Soil–Plant–Insect System in Huludao City

    Zhang, Zhong-Sheng; Lu, Xian-Guo; Wang, Qi-Chao; Zheng, Dong-Mei

    2009-01-01

    Mercury, cadmium, and lead concentrations of ashed plants and insects samples were investigated and compared with those of soil to reveal their biogeochemical processes along food chains in Huludao City, Liaoning Province, China. Concentration factors of each fragments of the soil–plant–the herbivorous insect–the carnivorous insect food chain were 0.18, 6.57, and 7.88 for mercury; 6.82, 2.01, and 0.48 for cadmium; 1.47, 2.24, and 0.57 for lead, respectively. On the whole, mercury was the most...

  20. Insect Repellents: Protect Your Child from Insect Bites

    ... Text Size Email Print Share Choosing an Insect Repellent for Your Child Page Content Article Body Mosquitoes , ... protect your child from insect bites. Types of Repellents Insect repellents come in many forms, including aerosols, ...

  1. Pre-exposure of Arabidopsis to the abiotic or biotic environmental stimuli “chilling” or “insect eggs” exhibits different transcriptomic responses to herbivory

    Vivien Firtzlaff; Jana Oberländer; Sven Geiselhardt; Monika Hilker; Reinhard Kunze

    2016-01-01

    Plants can retain information about environmental stress and thus, prepare themselves for impending stress. In nature, it happens that environmental stimuli like ‘cold’ and ‘insect egg deposition’ precede insect herbivory. Both these stimuli are known to elicit transcriptomic changes in Arabidposis thaliana. It is unknown, however, whether they affect the plant’s anti-herbivore defence and feeding-induced transcriptome when they end prior to herbivory. Here we investigated the transcriptomic ...

  2. Taxonomic and Functional Structure of Phytophagous Insect Communities Associated with Grain Amaranth.

    Niveyro, S; Salvo, A

    2014-12-01

    Amaranthus are worldwide attacked mainly by leaf chewers and sucker insects. Stem borers and leaf miners follow in importance, while minor herbivores are leaf rollers, folders, and rasping-sucking insects. The herbivorous community observed on Amaranthus spp. in Argentina was consistent with the information reported worldwide both in guild composition and order proportion. Amaranth plants had a higher number of phytophagous species in their native rather than in its introduced range. Occurrence of insect guilds differed in space and time. The highest density of leaf chewers was observed shortly after the emergence of plants, while higher density of borer and sucker insects coincided with reproductive stages of the crop. The sucking guild was observed mainly at panicles, while the insects within the leaf chewer group were registered in both leaves (92.6%, n = 746 adults) and inflorescences (7.4%). The borer guild was also recorded in stems and inflorescences; however, the density of larvae in stems was about four times as high as the density observed in panicles (n = 137 larvae). PMID:27194061

  3. How plants handle multiple stresses: hormonal interactions underlying responses to abiotic stress and insect herbivory.

    Nguyen, Duy; Rieu, Ivo; Mariani, Celestina; van Dam, Nicole M

    2016-08-01

    Adaptive plant responses to specific abiotic stresses or biotic agents are fine-tuned by a network of hormonal signaling cascades, including abscisic acid (ABA), ethylene, jasmonic acid (JA) and salicylic acid. Moreover, hormonal cross-talk modulates plant responses to abiotic stresses and defenses against insect herbivores when they occur simultaneously. How such interactions affect plant responses under multiple stresses, however, is less understood, even though this may frequently occur in natural environments. Here, we review our current knowledge on how hormonal signaling regulates abiotic stress responses and defenses against insects, and discuss the few recent studies that attempted to dissect hormonal interactions occurring under simultaneous abiotic stress and herbivory. Based on this we hypothesize that drought stress enhances insect resistance due to synergistic interactions between JA and ABA signaling. Responses to flooding or waterlogging involve ethylene signaling, which likely reduces plant resistance to chewing herbivores due to its negative cross-talk with JA. However, the outcome of interactions between biotic and abiotic stress signaling is often plant and/or insect species-dependent and cannot simply be predicted based on general knowledge on the involvement of signaling pathways in single stress responses. More experimental data on non-model plant and insect species are needed to reveal general patterns and better understand the molecular mechanisms allowing plants to optimize their responses in complex environments. PMID:27095445

  4. De novo biosynthesis of volatiles induced by insect herbivory in cotton plants

    In response to insect feeding on the leaves, cotton (Gossypium hirsutum L.) plants release elevated levels of volatiles, which can serve as a chemical signal that attracts natural enemies of the herbivore to the damaged plant. Pulse-labeling experiments with [13C]CO2 demonstrated that many of the volatiles released, including the acyclic terpenes (E,E)-alpha-farnesene, (E)-beta-farnesene, (E)-beta-ocimene, linalool,(E)-4,8-dimethyl-1,3,7-nonatriene, and (E,E)-4,8,12-trimethyl-1,3,7,11-tridecatetrane, as well as the shikimate pathway product indole, are biosynthesized de novo following insect damage. However, other volatile constituents, including several cyclic terpenes, butyrates, and green leaf volatiles of the lipoxygenase pathway are released from storage or synthesized from stored intermediates. Analysis of volatiles from artificially damaged plants, with and without beet armyworm (Spodoptera exigua Hubner) oral secretions exogenously applied to the leaves, as well as volatiles from beet armyworm-damaged and -undamaged control plants, demonstrated that the application of caterpillar oral secretions increased both the production and release of several volatiles that are synthesized de novo in response to insect feeding. These results establish that the plant plays an active and dynamic role in mediating the interaction between herbivores and natural enemies of herbivores

  5. Tissue specific diurnal rhythms of metabolites and their regulation during herbivore attack in a native tobacco, Nicotiana attenuata.

    Sang-Gyu Kim

    Full Text Available Ecological performance is all about timing and the endogenous clock that allows the entrainment of rhythms and anticipation of fitness-determining events is being rapidly characterized. How plants anticipate daily abiotic stresses, such as cold in early mornings and drought at noon, as well as biotic stresses, such as the timing of pathogen infections, is being explored, but little is known about the clock's role in regulating responses to insect herbivores and mutualists, whose behaviors are known to be strongly diurnally regulated and whose attack is known to reconfigure plant metabolomes. We developed a liquid chromatography-mass spectrometry procedure and analyzed its output with model-based peak picking algorithms to identify metabolites with diurnal accumulation patterns in sink/source leaves and roots in an unbiased manner. The response of metabolites with strong diurnal patterns to simulated attack from the specialist herbivore, Manduca sexta larvae was analyzed and annotated with in-house and public databases. Roots and leaves had largely different rhythms and only 10 ions of 182 oscillating ions in leaves and 179 oscillating ions in roots were rhythmic in both tissues: root metabolites mainly peaked at dusk or night, while leaf metabolites peaked during the day. Many oscillating metabolites showed tissue-specific regulation by simulated herbivory of which systemic responses in unattacked tissues were particularly pronounced. Diurnal and herbivory-elicited accumulation patterns of disaccharide, phenylalanine, tyrosine, lyciumoside I, coumaroyl tyramine, 12-oxophytodienoic acid and jasmonic acid and those of their related biosynthetic transcripts were examined in detail. We conclude that oscillating metabolites of N. attenuata accumulate in a highly tissue-specific manner and the patterns reveal pronounced diurnal rhythms in the generalized and specialized metabolism that mediates the plant's responses to herbivores and mutualists. We

  6. Sapling herbivory, invertebrate herbivores and predators across a natural tree diversity gradient in Germany's largest connected deciduous forest.

    Sobek, Stephanie; Scherber, Christoph; Steffan-Dewenter, Ingolf; Tscharntke, Teja

    2009-05-01

    Tree species-rich forests are hypothesised to be less susceptible to insect herbivores, but so far herbivory-diversity relationships have rarely been tested for tree saplings, and no such study has been published for deciduous forests in Central Europe. We expected that diverse tree communities reduce the probability of detection of host plants and increase abundance of predators, thereby reducing herbivory. We examined levels of herbivory suffered by beech (Fagus sylvatica L.) and maple saplings (Acer pseudoplatanus L. and Acer platanoides L.) across a tree species diversity gradient within Germany's largest remaining deciduous forest area, and investigated whether simple beech or mixed stands were less prone to damage caused by herbivorous insects. Leaf area loss and the frequency of galls and mines were recorded for 1,040 saplings (>13,000 leaves) in June and August 2006. In addition, relative abundance of predators was assessed to test for potential top-down control. Leaf area loss was generally higher in the two species of maple compared to beech saplings, while only beech showed a decline in damage caused by leaf-chewing herbivores across the tree diversity gradient. No significant patterns were found for galls and mines. Relative abundance of predators on beech showed a seasonal response and increased on species-rich plots in June, suggesting higher biological control. We conclude that, in temperate deciduous forests, herbivory-tree diversity relationships are significant, but are tree species-dependent with bottom-up and top-down control as possible mechanisms. In contrast to maple, beech profits from growing in a neighbourhood of higher tree richness, which implies that species identity effects may be of greater importance than tree diversity effects per se. Hence, herbivory on beech appeared to be mediated bottom-up by resource concentration in the sampled forest stands, as well as regulated top-down through biocontrol by natural enemies. PMID:19238448

  7. Phytophagous insects of giant hogweed Heracleum mantegazzianum (Apiaceae) in invaded areas of Europe and in its native area of the Caucasus

    Hansen, Steen Ole; Hattendorf, Jan; Wittenberg, Ruediger;

    2006-01-01

    studies show a higher proportion of specialist herbivores in the native habitats compared to the invaded areas, supporting the "enemy release hypothesis" (ERH). When analysing the relative size of the niches (measured as plant organ biomass), we found less herbivore species per biomass oil the stem and......Giant hogweed, Heracleum mantegazzianum (Apiaceae), was introduced from the Caucasus into Western Europe more than 150 years ago and later became all invasive weed which created major problems for European authorities. Phytophagous insects were collected in the native range of the giant hogweed...... (Caucasus) and were compared to those found oil plants in the invaded parts of Europe. The list of herbivores was compiled from surveys of 27 localities in nine countries during two seasons. In addition, literature records for herbivores were analysed for a total of 16 Heracleum species. We recorded a total...

  8. Insects: Bugged Out!

    Piehl, Kathy

    2011-01-01

    Insects really need no introduction. They have lived on earth much longer than humans and vastly outnumber people and all other animal species combined. People encounter them daily in their houses and yards. Yet, when children want to investigate insects, books can help them start their explorations. "Paleo Bugs" carries readers back to the time…

  9. Insects and Bugs

    Sutherland, Karen

    2009-01-01

    They have been around for centuries. They sting, they bite. They cause intense itching or painful sores. They even cause allergic reactions and sometimes death. There are two types of insects that are pests to humans--those that sting and those that bite. The insects that bite do so with their mouths and include mosquitoes, chiggers, and ticks.…

  10. Reversing insect pollinator decline

    Potts, Simon; Wentworth, Jonathan

    2013-01-01

    Pollination by insects enables the reproduction of flowering plants and is critical to UK agriculture.1 Insect pollinators have declined globally, with implications for food security and wild habitats. This POSTnote summarises the causes for the recent trends, gaps in knowledge and possible strategies for reversing pollinator decline.

  11. Herbivores and nutrients control grassland plant diversity via light limitation.

    Borer, Elizabeth T; Seabloom, Eric W; Gruner, Daniel S; Harpole, W Stanley; Hillebrand, Helmut; Lind, Eric M; Adler, Peter B; Alberti, Juan; Anderson, T Michael; Bakker, Jonathan D; Biederman, Lori; Blumenthal, Dana; Brown, Cynthia S; Brudvig, Lars A; Buckley, Yvonne M; Cadotte, Marc; Chu, Chengjin; Cleland, Elsa E; Crawley, Michael J; Daleo, Pedro; Damschen, Ellen I; Davies, Kendi F; DeCrappeo, Nicole M; Du, Guozhen; Firn, Jennifer; Hautier, Yann; Heckman, Robert W; Hector, Andy; HilleRisLambers, Janneke; Iribarne, Oscar; Klein, Julia A; Knops, Johannes M H; La Pierre, Kimberly J; Leakey, Andrew D B; Li, Wei; MacDougall, Andrew S; McCulley, Rebecca L; Melbourne, Brett A; Mitchell, Charles E; Moore, Joslin L; Mortensen, Brent; O'Halloran, Lydia R; Orrock, John L; Pascual, Jesús; Prober, Suzanne M; Pyke, David A; Risch, Anita C; Schuetz, Martin; Smith, Melinda D; Stevens, Carly J; Sullivan, Lauren L; Williams, Ryan J; Wragg, Peter D; Wright, Justin P; Yang, Louie H

    2014-04-24

    Human alterations to nutrient cycles and herbivore communities are affecting global biodiversity dramatically. Ecological theory predicts these changes should be strongly counteractive: nutrient addition drives plant species loss through intensified competition for light, whereas herbivores prevent competitive exclusion by increasing ground-level light, particularly in productive systems. Here we use experimental data spanning a globally relevant range of conditions to test the hypothesis that herbaceous plant species losses caused by eutrophication may be offset by increased light availability due to herbivory. This experiment, replicated in 40 grasslands on 6 continents, demonstrates that nutrients and herbivores can serve as counteracting forces to control local plant diversity through light limitation, independent of site productivity, soil nitrogen, herbivore type and climate. Nutrient addition consistently reduced local diversity through light limitation, and herbivory rescued diversity at sites where it alleviated light limitation. Thus, species loss from anthropogenic eutrophication can be ameliorated in grasslands where herbivory increases ground-level light. PMID:24670649

  12. Non-native grass invasion associated with increases in insect diversity in temperate forest understory

    Metcalf, Judith L.; Emery, Sarah M.

    2015-11-01

    Invasive plants can alter the structure and function of plant communities to such a degree that they can also have significant impacts on the insect communities. Because insects play an important role in many ecosystems, changes in these communities could have important implications, beyond their biodiversity value, for ecosystem function and diversity at other trophic levels. Microstegium vimineum is an annual C4 grass that is invasive in many eastern North American deciduous forests. Because this grass plays an important role in determining the plant community structure in the understory of these forests, it also has the potential to significantly alter understory insect communities. In this study we evaluated the relationship between M. vimineum and understory insect communities in a forest reserve in Kentucky, USA. Total insect abundance, richness and diversity showed a positive association with M. vimineum presence. Trophic analysis showed significantly higher abundances of herbivores where M. vimineum was present. Forb abundance, which serves as the primary food source for herbivorous insects in this system, was lower in sites invaded with M. vimineum. Invasion by this non-native was also associated with significant increases in aboveground plant biomass which was nearly 50% greater in invaded sites. These results indicate that the understory insect community may be responding to increased biomass rather than the loss of native forb food resources, which contradicts other studies that have examined relationships between M. vimineum invasion and insects. Our results provide evidence that invasive plants can provide benefits for other trophic levels, even when native plant biodiversity is lost.

  13. Birds and bats reduce insect biomass and leaf damage in tropical forest restoration sites.

    Morrison, Emily B; Lindell, Catherine A

    2012-07-01

    Both birds and bats are important insect predators in tropical systems. However, the relative influence of birds and bats on insect populations and their indirect effects on leaf damage have not previously been investigated in tropical forest restoration sites. Leaf damage by herbivorous insects can negatively affect the growth and survival of tropical plants and thus can influence the success of tropical forest restoration efforts. We used an exclosure experiment to examine the top-down effects of birds and bats on insects and leaf damage in a large-scale forest restoration experiment. Given the potential influence of tree planting design on bird and bat abundances, we also investigated planting design effects on bird and bat insectivory and leaf damage. The experiment included two planting treatment plots: islands, where trees were planted in patches, and plantations, where trees were planted in rows to create continuous cover. In both types of plots, insect biomass was highest on tree branches where both birds and bats were excluded from foraging and lowest on branches without exclosures where both birds and bats were present. In the island plots, birds and bats had approximately equal impacts on insect populations, while in plantations bats appeared to have a slightly stronger effect on insects than did birds. In plantations, the levels of leaf damage were higher on branches where birds and bats were excluded than on branches where both had access. In island plots, no significant differences in leaf damage were found between exclosure treatments although potential patterns were in the same direction as in the plantations. Our results suggest that both birds and bats play important roles as top predators in restoration systems by reducing herbivorous insects and their damage to planted trees. Tropical restoration projects should include efforts to attract and provide suitable habitat for birds and bats, given their demonstrated ecological importance. PMID

  14. ‘Fungicide application method’ and the interpretation of mycorrhizal fungus insect indirect effects

    Laird, Robert A.; Addicott, John F.

    2008-09-01

    Mycorrhizal fungi, by altering their host plant's physiology, can have indirect effects on insect herbivores. The 'fungicide application method' is a common approach used to investigate the indirect effects of mycorrhizal fungi on insects. This approach works by using initially mycorrhizal plants, and then generating a subset of these plants that are free of mycorrhizal fungi by applying fungicide to their roots. When insect feeding-bioassays are conducted using the resulting mycorrhizal and non-mycorrhizal plants, differences in insect performance are typically attributed to differences in mycorrhizal colonization per se, rather than the application of the fungicide. Thus, the fungicide application method relies on the assumption that there is no direct toxicity of the fungicide on the focal insect species, and no indirect effects on the focal insect resulting from effects of the fungicide on the host plant or on non-target soil micro-organisms. We tested this critical assumption by feeding Zygogramma exclamationis (Chrysomelidae) larvae on non-mycorrhizal Helianthus annuus (Asteraceae) plants whose roots were treated with a solution of the fungicide benomyl or with a distilled water control. Larvae fed on benomyl-treated plants had reduced survival, lower relative growth rate, and lower food conversion efficiency, compared to larvae fed on control plants. Hence, fungicides applied to roots can affect herbivorous insect performance even in the absence of the possibility of mycorrhizal fungi-mediated effects. We recommend caution when using fungicide application and suggest that selective inoculation is a preferable method of generating mycorrhizal and non-mycorrhizal plants when studying mycorrhizal fungi-insect indirect effects.

  15. Sterile insect quality

    The sterile insect technique (SIT) depends greatly on the production of good quality sterile male insects that are released into target wild populations. Quality is assured through a system of bioassays of quality parameters that reflect the insect's ability to survive, interact with its environment, and locate, mate and fertilize females of the target population. The system was developed by compartmentalizing the essential survival and mating behaviours of the species involved, and then developing a series of tests to confirm that these behavioural traits are present in the mass-reared insects. The system also has a feedback loop to correct problems in the production portion of the system before they become evident. Nevertheless, regular implementation of field or field-cage tests under semi-natural conditions, where sterile males have to compete with wild males for wild females, is required to provide the ultimate assurance that the sterile insects have the ability to fulfil their mission after release. (author)

  16. Avoidance and tolerance to avian herbivores in aquatic plants

    Hidding, A.

    2009-01-01

    Tolerance and avoidance are the two contrasting strategies that plants may adopt to cope with herbivores. Tolerance traits define the degree to which communities remain unaffected by herbivory. Trade-offs between herbivore avoidance and competitive strength and between avoidance and colonization ability may shape population traits and communities under herbivory. In this thesis I present comparative and experimental studies on populations and communities of aquatic plants and how they deal wi...

  17. Masticatory Motor Patterns in Six Herbivorous Australian Marsupials

    Crompton, Alfred; Skinner, John; Lieberman, Daniel; Owerkovicz, Tomasz

    2007-01-01

    Electomyograms of the adductor muscles of the hairy-nosed wombat (Lasiorhinus latifrons), red kangaroo (Macropus rufus), Tammar wallaby (M. eugenii), koala (Phascolarctos cinereus), potoroo (Potorous tridactylus) and the brush-tailed possum (Trichosurus vulpecula) were analyzed and compared with those of placental herbivores. Marsupials have developed several different and distinct masticatory motor patterns that are all fundamentally different from those of placental herbivores where jaw mov...

  18. Hindgut Fermentation in Three Species of Marine Herbivorous Fish

    Mountfort, Douglas O.; Campbell, Jane; Clements, Kendall D.

    2002-01-01

    Symbioses with gut microorganisms provides a means by which terrestrial herbivores are able to obtain energy. These microorganisms ferment cell wall materials of plants to short-chain fatty acids (SCFA), which are then absorbed and used by the host animal. Many marine herbivorous fishes contain SCFA (predominantly acetate) in their hindgut, indicative of gut microbial activity, but rates of SCFA production have not been measured. Such information is an important prerequisite to understanding ...

  19. Insect gut bacterial diversity determined by environmental habitat, diet, developmental stage, and phylogeny of host.

    Yun, Ji-Hyun; Roh, Seong Woon; Whon, Tae Woong; Jung, Mi-Ja; Kim, Min-Soo; Park, Doo-Sang; Yoon, Changmann; Nam, Young-Do; Kim, Yun-Ji; Choi, Jung-Hye; Kim, Joon-Yong; Shin, Na-Ri; Kim, Sung-Hee; Lee, Won-Jae; Bae, Jin-Woo

    2014-09-01

    Insects are the most abundant animals on Earth, and the microbiota within their guts play important roles by engaging in beneficial and pathological interactions with these hosts. In this study, we comprehensively characterized insect-associated gut bacteria of 305 individuals belonging to 218 species in 21 taxonomic orders, using 454 pyrosequencing of 16S rRNA genes. In total, 174,374 sequence reads were obtained, identifying 9,301 bacterial operational taxonomic units (OTUs) at the 3% distance level from all samples, with an average of 84.3 (± 97.7) OTUs per sample. The insect gut microbiota were dominated by Proteobacteria (62.1% of the total reads, including 14.1% Wolbachia sequences) and Firmicutes (20.7%). Significant differences were found in the relative abundances of anaerobes in insects and were classified according to the criteria of host environmental habitat, diet, developmental stage, and phylogeny. Gut bacterial diversity was significantly higher in omnivorous insects than in stenophagous (carnivorous and herbivorous) insects. This insect-order-spanning investigation of the gut microbiota provides insights into the relationships between insects and their gut bacterial communities. PMID:24928884

  20. Small herbivores suppress algal accumulation on Agatti atoll, Indian Ocean

    Cernohorsky, Nicole H.; McClanahan, Timothy R.; Babu, Idrees; Horsák, Michal

    2015-12-01

    Despite large herbivorous fish being generally accepted as the main group responsible for preventing algal accumulation on coral reefs, few studies have experimentally examined the relative importance of herbivore size on algal communities. This study used exclusion cages with two different mesh sizes (1 × 1 cm and 6 × 6 cm) to investigate the impact of different-sized herbivores on algal accumulation rates on the shallow (8 cm body depth) while allowing smaller fishes to access the plots. In contrast to the conclusions of most previous studies, the exclusion of large herbivores had no significant effect on the accumulation of benthic algae and the amount of algae present within the coarse-mesh cages was relatively consistent throughout the experimental period (around 50 % coverage and 1-2 mm height). The difference in algal accumulation between the fine-mesh and coarse-mesh cages appears to be related to the actions of small individuals from 12 herbivorous fish species (0.17 ind. m-2 and 7.7 g m-2) that were able to enter through the coarse mesh. Although restricted to a single habitat, these results suggest that when present in sufficient densities and diversity, small herbivorous fishes can prevent the accumulation of algal biomass on coral reefs.

  1. Resistances to an Insect Herbivore and a Phytopathogenin Barbarea vulgaris

    Christensen, Stina

    pubescence; one has glabrous leaves and is therefore called G-type while the other has pubescent leaves and is called the P-type. The G-type is resistant to most genotypes of the flea beetle Phyllotreta nemorum as well as some other Brassicales specialists, and this resistance is conferred by saponins. The P...

  2. Complementarity effects through dietary mixing enhance the performance of a generalist insect herbivore

    Unsicker, Sybille B; Oswald, Anett; Köhler, Günter; Weisser, Wolfgang W.

    2008-01-01

    The ontogenetic niche concept predicts that resource use depends on an organism’s developmental stage. This concept has been investigated primarily in animals that show differing resource use strategies as juveniles and as adults, such as amphibians. We studied resource use and performance in the grasshopper Chorthippus parallelus (Orthoptera, Acrididae) provided with food plant mixtures of either one, three or eight plant species throughout their development. C. parallelus survival and fecun...

  3. Insect herbivores drive the loss of unique chemical defense in willows

    Volf, Martin; Julkunen-Titto, R.; Hrček, Jan; Novotný, Vojtěch

    2015-01-01

    Roč. 156, č. 1 (2015), s. 88-98. ISSN 0013-8703 R&D Projects: GA ČR(CZ) GA14-04258S Grant ostatní: GA JU(CZ) 153/2013/P; European Social Fund(CZ) CZ.1.07/2.3.00/20.0064 Institutional support: RVO:60077344 Keywords : coevolution * defensive traits * herbivory Subject RIV: EH - Ecology, Behaviour Impact factor: 1.616, year: 2014 http://onlinelibrary.wiley.com/doi/10.1111/eea.12312/epdf

  4. Insects on plants: explaining the paradox of low diversity within specialist herbivore guilds

    Novotný, Vojtěch; Miller, S. E.; Hrček, Jan; Baje, L.; Basset, Y.; Lewis, O. T.; Stewart, A. J. A.; Weiblen, G. D.

    2012-01-01

    Roč. 179, č. 3 (2012), s. 351-362. ISSN 0003-0147 R&D Projects: GA ČR GA206/09/0115; GA ČR GD206/08/H044; GA ČR GAP505/10/0673; GA AV ČR IAA600960712; GA MŠk LC06073; GA MŠk(CZ) LH11008; GA MŠk ME09082 Grant ostatní: National Science Foundation(US) DEB 9628840; National Science Foundation(US) DEB 9707928; National Science Foundation(US) DEB 0211591; National Science Foundation(US) DEB 0515678 Institutional research plan: CEZ:AV0Z50070508 Keywords : rainforest * New Guinea * host specialization Subject RIV: EH - Ecology, Behaviour Impact factor: 4.552, year: 2012 http://www.entu.cas.cz/png/NovotnyEtAlAMNAT2012.pdf

  5. Why are there so many species of herbivorous insects in tropical rainforests?

    Novotný, Vojtěch; Drozd, P.; Miller, S. E.; Kulfan, M.; Janda, Milan; Basset, Y.; Weiblen, G. D.

    2006-01-01

    Roč. 313, č. 5790 (2006), s. 1115-1118. ISSN 0036-8075 R&D Projects: GA ČR(CZ) GA206/04/0725; GA ČR(CZ) GD206/03/H034; GA AV ČR(CZ) IAA6007106; GA MŠk(CZ) ME 646; GA MŠk(CZ) 1P05ME744 Institutional research plan: CEZ:AV0Z50070508 Keywords : tropical rainforests Subject RIV: EH - Ecology, Behaviour Impact factor: 30.028, year: 2006

  6. Recalibrated tree of leaf beetles (Chrysomelidae indicates independent diversification of angiosperms and their insect herbivores.

    Jesús Gómez-Zurita

    Full Text Available BACKGROUND: The great diversity of the "Phytophaga" (weevils, longhorn beetles and leaf beetles has been attributed to their co-radiation with the angiosperms based on matching age estimates for both groups, but phylogenetic information and molecular clock calibrations remain insufficient for this conclusion. METHODOLOGY: A phylogenetic analysis of the leaf beetles (Chrysomelidae was conducted based on three partial ribosomal gene markers (mitochondrial rrnL, nuclear small and large subunit rRNA including over 3000 bp for 167 taxa representing most major chrysomelid lineages and outgroups. Molecular clock calibrations and confidence intervals were based on paleontological data from the oldest (K-T boundary leaf beetle fossil, ancient feeding traces ascribed to hispoid Cassidinae, and the vicariant split of Nearctic and Palearctic members of the Timarchini. PRINCIPAL FINDINGS: The origin of the Chrysomelidae was dated to 73-79 Mya (confidence interval 63-86 Mya, and most subfamilies were post-Cretaceous, consistent with the ages of all confirmed body fossils. Two major monocot feeding chrysomelid lineages formed widely separated clades, demonstrating independent colonization of this ancient (early Cretaceous angiosperm lineage. CONCLUSIONS: Previous calibrations proposing a much older origin of Chrysomelidae were not supported. Therefore, chrysomelid beetles likely radiated long after the origin of their host lineages and their diversification was driven by repeated radiaton on a pre-existing diverse resource, rather than ancient host associations.

  7. Predicting tropical insect herbivore abundance from host plant traits and phylogeny

    Whitfeld, T. J. S.; Novotný, Vojtěch; Miller, S. E.; Hrček, Jan; Klimeš, Petr; Weiblen, G. D.

    2012-01-01

    Roč. 93, č. 8 (2012), S211-S222. ISSN 0012-9658 R&D Projects: GA ČR GAP505/10/0673; GA ČR GA206/09/0115 Grant ostatní: National Science Foundation(US) DEB 0515678 Institutional research plan: CEZ:AV0Z50070508 Keywords : comparative methods * food webs * herbivory Subject RIV: EH - Ecology, Behaviour Impact factor: 5.175, year: 2012 http://geo.cbs.umn.edu/WhitfeldEtAl2012b.pdf

  8. Influence of phenolglucosides and trichome density on the distribution of insects herbivores on willows

    Soetens, Ph.; Rowell-Rahier, Martine; Pasteels, Jacques M.

    2009-01-01

    The effects of both trichome density and phenolglucoside content of leaves of 76 willow hybrids (Salix alba x fragilis) were measured to estimate their influence on the distribution of Phratora vitellinae (L.), Plagiodera versicolora Baly (Coleoptera: Chrysomelidae) and Pontania proxima (Lepeletier 1823) (Hymenoptera: Tenthredinidae) in a nursery at Gramont, Belgium. The willows showed differences in their phenolglucoside content and pilosity of leaves and are classified on these basis into ...

  9. Phylogenetic dispersion of host use in a tropical insect herbivore community

    Weiblen, G. D.; Webb, C. O.; Novotný, Vojtěch; Basset, Y.; Miller, S. E.

    2006-01-01

    Roč. 87, č. 7 (2006), s. 62-75. ISSN 0012-9658 R&D Projects: GA ČR(CZ) GA206/04/0725; GA MŠk(CZ) ME 646 Grant ostatní: National Science Foundation(US) 9407297; National Science Foundation(US) 9628840; National Science Foundation(US) 9707928; National Science Foundation(US) 0212873; National Science Foundation(US) 0211591 Institutional research plan: CEZ:AV0Z50070508 Keywords : community ecology * community phylogenetics * herbivory Subject RIV: EH - Ecology, Behaviour Impact factor: 4.782, year: 2006

  10. An anti-herbivore defense mutualism under elevated CO2 levels

    Marks, S.; Lincoln, D.E. (Winthrop Univ., Rock Hill, SC (United States))

    1994-06-01

    Previous studies have shown that insects typically consume more when fed leaf tissue grown under CO2 enrichment, but with few negative effects on growth. On the other hand, Lepidopteran larvae fed tissue infected with Balansiae fungal endophytes (which produce toxic alkaloids) typically eat less but suffer negative effects on growth and survival. This study was carried out to see how these two factors would interact to affect consumption and growth of Fall Armyworm larvae (Spodoptera frugiperda). Infected and uninfected ramets of a single genotype of tall fescue (Festuca arundinacea) were grown under CO2 concentrations of 400 and 700 ul/L. Larvae had increased relative growth in the high CO2 treatment, but decreased growth when fed infected tissue. Relative consumption of leaf tissue was greater in the high CO2 treatment, but was not effected by infection. CO2 level, infection, and their interaction all significantly reduced the efficiency of conversion of food ingested (ECI). It appears that tall fescue may not be as well defended against herbivores under CO2 enrichment, although insects may still avoid and be negatively effected by endophyte infected plants.

  11. Incompatibility between plant-derived defensive chemistry and immune response of two sphingid herbivores.

    Lampert, Evan C; Bowers, M Deane

    2015-01-01

    Herbivorous insects use several different defenses against predators and parasites, and tradeoffs among defensive traits may occur if these traits are energetically demanding. Chemical defense and immune response potentially can interact, and both can be influenced by host plant chemistry. Two closely related caterpillars in the lepidopteran family Sphingidae are both attacked by the same specialist endoparasitoid species but have mostly non-overlapping host plant ranges that differ in secondary chemistry. Ceratomia catalpae is a specialist on Catalpa and also will feed on Chilopsis, which both produce iridoid glycosides. Ceratomia undulosa consumes members of the Oleaceae, which produce seco-iridoid glycosides. Immune response of the two species on a typical host plant species (Catalpa bignonioides for C. catalpa; Fraxinus americana for C. undulosa) was compared using a melanization assay, and did not differ. In a second experiment, the iridoid glycoside catalpol was added to the diets of both insects, and growth rate, mass, chemical defense, and immune response were evaluated. Increased dietary catalpol weakened the immune response of C. undulosa and altered the development rate of C. catalpae by prolonging the third instar and accelerating the fourth instar. Catalpol sequestration was negatively correlated with immune response of C. catalpae, while C. undulosa was unable to sequester catalpol. These results show that immune response can be negatively influenced by increasing concentrations of sequestered defensive compounds. PMID:25516226

  12. Molecular interrogation of the feeding behaviour of field captured individual insects for interpretation of multiple host plant use.

    James P Hereward

    Full Text Available The way in which herbivorous insect individuals use multiple host species is difficult to quantify under field conditions, but critical to understanding the evolutionary processes underpinning insect-host plant relationships. In this study we developed a novel approach to understanding the host plant interactions of the green mirid, Creontiades dilutus, a highly motile heteropteran bug that has been associated with many plant species. We combine quantified sampling of the insect across its various host plant species within particular sites and a molecular comparison between the insects' gut contents and available host plants. This approach allows inferences to be made as to the plants fed upon by individual insects in the field. Quantified sampling shows that this "generalist" species is consistently more abundant on two species in the genus Cullen (Fabaceae, its primary host species, than on any other of its numerous listed hosts. The chloroplast intergenic sequences reveal that C. dilutus frequently feeds on plants additional to the one from which it was collected, even when individuals were sampled from the primary host species. These data may be reconciled by viewing multiple host use in this species as an adaptation to survive spatiotemporally ephemeral habitats. The methodological framework developed here provides a basis from which new insights into the feeding behaviour and host plant relationships of herbivorous insects can be derived, which will benefit not only ecological interpretation but also our understanding of the evolution of these relationships.

  13. A perspective on the importance of within-tree variation in mortality risk for a leaf-mining insect

    C. Low

    2012-05-01

    Full Text Available Within-tree variation in abiotic conditions can create a mosaic of fitness gradients for herbivorous insects. To explore these effects, we quantified the patterns of mortality of the solitary oak leafminer, Cameraria hamadryadella (Lepidoptera: Gracillariidae, which lives within leaves of white oak, Quercus alba. We found differential patterns of survival and larval feeding rate within the tree and in association with several abiotic factors: light levels, leaf nitrogen content, and canopy height. We suggest that the leaf scale microhabitat conditions are fundamental to plant-herbivore-enemy interactions because of the differential fitness effects on herbivores. Such effects would be missed by studies that average effects by whole plants. Our study population of C. hamadryadella is located within the Orland E. White State Arboretum of Virginia in Boyce, Virginia, USA.

  14. Evaluating herbivore management outcomes and associated vegetation impacts

    Rina C.C. Grant

    2011-05-01

    Full Text Available African savannas are characterised by temporal and spatial fluxes that are linked to fluxes in herbivore populations and vegetation structure and composition. We need to be concerned about these fluxes only when management actions cause the system to shift towards a less desired state. Large herbivores are a key attribute of African savannas and are important for tourism and biodiversity. Large protected areas such as the Kruger National Park (KNP manage for high biodiversity as the desired state, whilst private protected areas, such as those adjacent to the KNP, generally manage for high income. Biodiversity, sustainability and economic indicators are thus required to flag thresholds of potential concern (TPCs that may result in a particular set of objectives not being achieved. In large conservation areas such as the KNP, vegetation changes that result from herbivore impact, or lack thereof, affect biodiversity and TPCs are used to indicate unacceptable change leading to a possible loss of biodiversity; in private protected areas the loss of large herbivores is seen as an important indicator of economic loss. Therefore, the first-level indicators aim to evaluate the forage available to sustain grazers without deleteriously affecting the vegetation composition, structure and basal cover. Various approaches to monitoring for these indicators were considered and the importance of the selection of sites that are representative of the intensity of herbivore use is emphasised. The most crucial step in the adaptive management process is the feedback of information to inform management decisions and enable learning. Feedback loops tend to be more efficient where the organisation’s vision is focused on, for example, economic gain, than in larger protected areas, such as the KNP, where the vision to conserve biodiversity is broader and more complex.Conservation implications: In rangeland, optimising herbivore numbers to achieve the management

  15. Potential effects of elevated carbon dioxide on leaf-feeding forest insects

    2008-01-01

    The elevated concentration of atmospheric CO2 may result in a decline of leaf nutritional quality (especially N) and an increase in some kinds of defensive secondary components (such as phenolics). The changes in the phytochemistry of trees, combined with the effect of elevated CO2 per se, have a potential negative influence on insect herbivores. Here, we review the effect of elevated CO2 on the performance of leaf-feeding forest insects at individual-level and commu-nity-level. The elevated CO2 per se have little influence on the metabolism of insects. Over half of the tree-insect experimental systems show that the performance of individual insect become poorer under high-CO2 grown trees; but the others show that the insects have just little or no response to the treatments. The direction and magnitude of the changes in the performance of insects could be mediated by various factors. The effects of treatment are strongly species-dependent. The magni-tude of changes in the phytochemistry, the sensitivity and adaptive capacity of insects to the poorer leaf quality, the differences in plant growth conditions and experimental methods, and the mediated effects of other environmental factors (such as soil nutrient availability, light, temperature, O3) were all closely related to the final performance of insects. However, the larvae's consumption usually increased under enriched CO2 treatment, which was widely thought to be a compensa-tory response to poorer plant quality. The experiments on forest community-level found identically a reduction in herbivory, which was contrary to the results from small-scale experiments. The changes in insect popula-tion and the actual response of consumption by leaf-feeding forest insects under CO2 enrichment remain unclear, and more field-based experiments need to be conducted.

  16. Important Insect Pests of Fruit - Important Insect Pests of Nuts - Field Crop Insect Pests - Insect Pests of Vegetable Crops.

    Gesell, Stanley G.; And Others

    This document consists of four agriculture extension service publications from Pennsylvania State University. The titles are: (1) Important Insect Pests of Fruit; (2) Important Insect Pests of Nuts; (3) Field Crop Insect Pests; and (4) Insect Pests of Vegetable Crops. The first publication gives the hosts, injury, and description of 22 insect…

  17. Evolution of the Insects

    Grimaldi, David; Engel, Michael S.

    2005-05-01

    This book chronicles the complete evolutionary history of insects--their living diversity and relationships as well as 400 million years of fossils. Introductory sections cover the living species diversity of insects, methods of reconstructing evolutionary relationships, basic insect structure, and the diverse modes of insect fossilization and major fossil deposits. Major sections then explore the relationships and evolution of each order of hexapods. The volume also chronicles major episodes in the evolutionary history of insects from their modest beginnings in the Devonian and the origin of wings hundreds of millions of years before pterosaurs and birds to the impact of mass extinctions and the explosive radiation of angiosperms on insects, and how they evolved into the most complex societies in nature. Whereas other volumes focus on either living species or fossils, this is the first comprehensive synthesis of all aspects of insect evolution. Illustrated with 955 photo- and electron- micrographs, drawings, diagrams, and field photos, many in full color and virtually all of them original, this reference will appeal to anyone engaged with insect diversity--professional entomologists and students, insect and fossil collectors, and naturalists. David Grimaldi and Michael S. Engel have collectively published over 200 scientific articles and monographs on the relationships and fossil record of insects, including 10 articles in the journals Science, Nature, and Proceedings of the National Academy of Sciences. David Grimaldi is curator in the Division of Invertebrate Zoology, American Museum of Natural History and adjunct professor at Cornell University, Columbia University, and the City University of New York. David Grimaldi has traveled in 40 countries on 6 continents, collecting and studying recent species of insects and conducting fossil excavations. He is the author of Amber: Window to the Past (Abrams, 2003). Michael S. Engel is an assistant professor in the

  18. INSECT FLIGHT - BIOACOUSTICAL APPROACH

    Gopala Krishna, G.; Krishna Shankar, B.; Ahmad, A.

    1990-01-01

    Insect aerodynamics is drawing the attention of a number of researchers belonging to different disciplines with a view to understand its aerodynamic capabilities so as to revolutionise the aircraft technology. It is possible to understand, to some extent, the insect aerodynamics by experimentally determining the frequency of wing beat in its fethered state of flight by using flight sound technique and computing rate of mass flow, velocity, acceleration and mass of air induced in downward dire...

  19. Odours, potato and insects

    Karlsson, Miriam Frida

    2010-01-01

    Plant odours can give important information about the specie and these emitted chemical messengers mediate host-finding behaviour, to the insects living on potato. During the development of the potato crop, lasting approximately tree months, the insects described in this paper, has to find the crop. They then chose a part of the potato; leaves, tubers or flowers, where they feed, hide, mate or oviposit. Host plant selection or host preference is not only governed by nutritional quality but al...

  20. Insect immunology and hematopoiesis.

    Hillyer, Julián F

    2016-05-01

    Insects combat infection by mounting powerful immune responses that are mediated by hemocytes, the fat body, the midgut, the salivary glands and other tissues. Foreign organisms that have entered the body of an insect are recognized by the immune system when pathogen-associated molecular patterns bind host-derived pattern recognition receptors. This, in turn, activates immune signaling pathways that amplify the immune response, induce the production of factors with antimicrobial activity, and activate effector pathways. Among the immune signaling pathways are the Toll, Imd, Jak/Stat, JNK, and insulin pathways. Activation of these and other pathways leads to pathogen killing via phagocytosis, melanization, cellular encapsulation, nodulation, lysis, RNAi-mediated virus destruction, autophagy and apoptosis. This review details these and other aspects of immunity in insects, and discusses how the immune and circulatory systems have co-adapted to combat infection, how hemocyte replication and differentiation takes place (hematopoiesis), how an infection prepares an insect for a subsequent infection (immune priming), how environmental factors such as temperature and the age of the insect impact the immune response, and how social immunity protects entire groups. Finally, this review highlights some underexplored areas in the field of insect immunobiology. PMID:26695127

  1. Coping with toxic plant compounds--the insect's perspective on iridoid glycosides and cardenolides.

    Dobler, Susanne; Petschenka, Georg; Pankoke, Helga

    2011-09-01

    Specializing on host plants with toxic secondary compounds enforces specific adaptation in insect herbivores. In this review, we focus on two compound classes, iridoid glycosides and cardenolides, which can be found in the food plants of a large number of insect species that display various degrees of adaptation to them. These secondary compounds have very different modes of action: Iridoid glycosides are usually activated in the gut of the herbivores by β-glucosidases that may either stem from the food plant or be present in the gut as standard digestive enzymes. Upon cleaving, the unstable aglycone is released that unspecifically acts by crosslinking proteins and inhibiting enzymes. Cardenolides, on the other hand, are highly specific inhibitors of an essential ion carrier, the sodium pump. In insects exposed to both kinds of toxins, carriers either enabling the safe storage of the compounds away from the activating enzymes or excluding the toxins from sensitive tissues, play an important role that deserves further analysis. To avoid toxicity of iridoid glycosides, repression of activating enzymes emerges as a possible alternative strategy. Cardenolides, on the other hand, may lose their toxicity if their target site is modified and this strategy has evolved multiple times independently in cardenolide-adapted insects. PMID:21620425

  2. Effects of plant genotype and insect dispersal rate on the population dynamics of a forest pest.

    Moran, Emily V; Bewick, Sharon; Cobbold, Christina A

    2013-12-01

    It has been shown that plant genotype can strongly affect not only individual herbivore performance, but also community composition and ecosystem function. Few studies, however, have addressed how plant genotype affects herbivore population dynamics. In this paper, we used a simulation modeling approach to ask how the genetic composition of a forest influences pest outbreak dynamics, using the example of aspen (Populus tremuloides) and forest tent caterpillars (FTC; Malacosoma disstria). Specifically, we examined how plant genotype, the relative size of genotypic patches, and the rate of insect dispersal between them, affect the frequency, amplitude, and duration of outbreaks. We found that coupling two different genotypes does not necessarily result in an averaging of insect dynamics. Instead, depending on the ratio of patch sizes, when dispersal rates are moderate, outbreaks in the two-genotype case may be more or less severe than in forests of either genotype alone. Thresholds for different dynamic behaviors were similar for all genotypic combinations. Thus, the qualitative behavior of a stand of two different genotypes can be predicted based on the response of the insect to each genotype, the relative sizes of the two patches, and the scale of insect dispersal. PMID:24597225

  3. ScaleNet: a literature-based model of scale insect biology and systematics.

    García Morales, Mayrolin; Denno, Barbara D; Miller, Douglass R; Miller, Gary L; Ben-Dov, Yair; Hardy, Nate B

    2016-01-01

    Scale insects (Hemiptera: Coccoidea) are small herbivorous insects found on all continents except Antarctica. They are extremely invasive, and many species are serious agricultural pests. They are also emerging models for studies of the evolution of genetic systems, endosymbiosis and plant-insect interactions. ScaleNet was launched in 1995 to provide insect identifiers, pest managers, insect systematists, evolutionary biologists and ecologists efficient access to information about scale insect biological diversity. It provides comprehensive information on scale insects taken directly from the primary literature. Currently, it draws from 23,477 articles and describes the systematics and biology of 8194 valid species. For 20 years, ScaleNet ran on the same software platform. That platform is no longer viable. Here, we present a new, open-source implementation of ScaleNet. We have normalized the data model, begun the process of correcting invalid data, upgraded the user interface, and added online administrative tools. These improvements make ScaleNet easier to use and maintain and make the ScaleNet data more accurate and extendable. Database URL: http://scalenet.info. PMID:26861659

  4. Are edible insects really green?

    Caparros Megido, Rudy; Alabi, Taofic; Haubruge, Eric; Francis, Frédéric

    2015-01-01

    Edible insects are considered as one of the future and sustainable sources of animal protein. Insects for food or feed could have several origins. In Asia, Africa, South America or Oceania, the diversity of edible insects is very high (approximately 2000 species) and these insects are principally collected from the wild or semi-cultivated. However, in Western countries, entomophagy promoters rely on a few numbers of insect species (approximately 10 species) and on the development of industria...

  5. Genetic variation in primary metabolites of Pastinaca sativa; can herbivores act as selective agents?

    Zangerl, Arthur R; Berenbaum, May R

    2004-10-01

    Although insect herbivory has been shown to act as a selective agent on plant secondary metabolism, whether primary metabolites contribute to resistance and can respond to selection by herbivores remains untested. In the wild parsnip (Pastinaca sativa), its principal herbivore, Depressaria pastinacella, acts as a selective agent on furanocoumarin resistance factors. In this study, we determined whether webworms can, by causing differential reductions in fitness, act as selective agents on parsnip primary metabolites. Estimates of narrow-sense heritabilities were significantly different from zero for C18 fatty acids in buds and developing fruits, fructose and sorbitol in buds, fructose, myo-inositol, bergapten, and psoralen in fruits. Wild parsnips protected from webworms by insecticide produced 2.5 times as much seed biomass as unsprayed plants; that webworms accounted for this difference in plant fitness was indicated by a significant negative relationship between reproductive effort and an index of webworm damage. Only a handful of metabolites influenced resistance to webworms; these included osthol, sorbitol, and protein in developing fruits as well as previously documented furanocoumarins. Osthol, a coumarinic compound, enhanced resistance, as did protein content, while sorbitol lowered resistance. Other primary metabolites may affect resistance to webworms, but their effect was context-dependent, that is, their effect depended on concentrations of other metabolites (epistasis). Susceptible plant phenotypes were found to have average chemical compositions. Although there was genetic variation in some of the primary metabolites in parsnips, the epistatic nature of their involvement in resistance and the lack of genetic variation in some suggest that selection on them from webworms will be either inconsistent or ineffective. PMID:15609832

  6. Insect bite reactions

    Sanjay Singh

    2013-01-01

    Full Text Available Insects are a class of living creatures within the arthropods. Insect bite reactions are commonly seen in clinical practice. The present review touches upon the medically important insects and their places in the classification, the sparse literature on the epidemiology of insect bites in India, and different variables influencing the susceptibility of an individual to insect bites. Clinical features of mosquito bites, hypersensitivity to mosquito bites Epstein-Barr virus NK (HMB-EBV-NK disease, eruptive pseudoangiomatosis, Skeeter syndrome, papular pruritic eruption of HIV/AIDS, and clinical features produced by bed bugs, Mexican chicken bugs, assassin bugs, kissing bugs, fleas, black flies, Blandford flies, louse flies, tsetse flies, midges, and thrips are discussed. Brief account is presented of the immunogenic components of mosquito and bed bug saliva. Papular urticaria is discussed including its epidemiology, the 5 stages of skin reaction, the SCRATCH principle as an aid in diagnosis, and the recent evidence supporting participation of types I, III, and IV hypersensitivity reactions in its causation is summarized. Recent developments in the treatment of pediculosis capitis including spinosad 0.9% suspension, benzyl alcohol 5% lotion, dimethicone 4% lotion, isopropyl myristate 50% rinse, and other suffocants are discussed within the context of evidence derived from randomized controlled trials and key findings of a recent systematic review. We also touch upon a non-chemical treatment of head lice and the ineffectiveness of egg-loosening products. Knockdown resistance (kdr as the genetic mechanism making the lice nerves insensitive to permethrin is discussed along with the surprising contrary clinical evidence from Europe about efficacy of permethrin in children with head lice carrying kdr-like gene. The review also presents a brief account of insects as vectors of diseases and ends with discussion of prevention of insect bites and some

  7. Riqueza e abundância de herbívoros em flores de Vellozia nivea (Velloziaceae Richness and abundance of herbivores on Vellozia nivea (Velloziaceae flowers

    Elena Charlotte Landau

    1998-01-01

    Full Text Available Vellozia nivea (Velloziaceae é planta de porte herbáceo que ocorre em solos rochosos, nos campos rupestres da Serra do Cipó, MG. Suas flores hermafroditas são extremamente macias, representando fonte tenra de alimento para os insetos que predam suas tépalas e estruturas reprodutivas. Este trabalho teve como objetivo observar a influência da altura e do número de flores da planta hospedeira na abundância e riqueza de insetos herbívoros. Foram encontradas o total de 21 morfoespécies de insetos (nove famílias e três ordens associadas às flores de V. nivea. A altura e o número de flores da planta não apresentaram correlações significativas com a riqueza de herbívoros por planta (r² = 0,17; P > 0,05. Entretanto, estes dois fatores juntos explicaram 39% da variação observada na abundância dos insetos herbívoros por planta (P Vellozia nivea (Velloziaceae is a herbaceous plant that occurs on rocky soils in the rupestrian fields of the "Serra do Cipó", Minas Gerais State, Brazil. Its hermaphrodite flowers are extremely soft, representing a source of tender food for the insects that prey on its tepals and reproductive structures. The aim of this study was to observe the effect of the height and number of flowers of the host plant on the abundance and richness of herbivorous insects. We found 21 morphospecies of insects (nine families and three orders associated to flowers of V. nivea. No significant correlation between the number of flowers and plant height and the variety of herbivorous insects per plant was observed (r² = 0.17, P > 0.05. However, these two factors together explained 39% of the variation of insect abundance (P < 0.05. Thus, only the abundance of herbivorous insects was influenced by the number of flowers and the height of host plant.

  8. Vegetation factors influencing density and distribution of wild large herbivores in a southern African savannah

    Gandiwa, E.

    2014-01-01

    Understanding factors influencing large herbivore densities and distribution in terrestrial ecosystems is a fundamental goal of ecology. This study examined environmental factors influencing the density and distribution of wild large herbivores in Gonarezhou National Park, Zimbabwe. Vegetation and s

  9. Fish, Benthic and Urchin Survey Data from Kahekili Herbivore Fisheries Management Area (HFMA), Maui since 2008

    National Oceanic and Atmospheric Administration, Department of Commerce — In 2009, the state of Hawaii established the Kahekili Herbivore Fisheries Management Area (KHFMA) in West Maui. Fishing for herbivores (parrotfishes, surgeonfishes,...

  10. New approaches to forest above-ground biomass assessment

    Brovkina, Olga; Novotný, Jan; Zemek, František

    Volume 1. 1. Brno: Global Change Research Centre, Academy of Sciences of the Czech Republic, v. v. i, 2015 - (Urban, O.; Klem, K.), s. 186-196 ISBN 978-80-87902-14-1 R&D Projects: GA MŠk(CZ) LO1415 Institutional support: RVO:67179843 Keywords : CO2 * soil * stem * branches * leaves * respiration Subject RIV: EH - Ecology, Behaviour

  11. Measurement protocol for radon measurements in workplaces above ground

    The Swedish Radiation Protection Authority, SSI, has established a measurement protocol for measurements of radon in workplaces. The result from a measurement according to the protocol can be compared to the limit for indoor radon at workplaces, 400 Bq/m3 issued by the Swedish Work Environment Authority and also to the action level for schools, preschools and public buildings, 400 Bq/m3, issued by the National Board of Health and Welfare. The protocol recommends measurements to be done in two steps. The first measurement, called the preliminary measurement, will be done with an integrating measurement method over a period of at least two months. Track etch detectors or electret devices can be used. Since the preliminary measurements often overestimates the radon levels the workers are actually exposed to during working hours, a follow-up measurement has to be done if the preliminary measurement gives a result that exceeds 400 Bq/m3. In case there is need for an annual mean for comparison to the action level for schools a long-term measurement has to be done. Otherwise a method for follow-up measurements can be used at once. The follow-up measurement has to show the radon level during working hours. Two measurement strategies can be used depending on the function of the ventilation system. With the ventilation system running constantly, measurements can be done with track etch detectors for ten days or electret devices for five days. If the ventilation system is closed down at night electrets can be used for five days if the devise is open only during working hours or a continuous measurement device can be used for two days. Measurements have to be performed during the heating season, i.e. when the 24-hour average temperature is below +10 deg C, usually between October 1 and April 31. Most importantly the difference between interior and exterior temperatures must be big enough to allow natural draught ventilation system to activate. The result from a measurement made during the warmer part of the year is likely to show radon levels that are not representative for the whole year. Measurements have to cover at least 20 % of the rooms used for work places situated on the ground floor, in upper floors one measurement per floor has to be made and at least one per 500 m2. More measurements are recommended for buildings constructed from material with enhanced uranium and radium levels, such as blue lightweight concrete. Rooms in upper floors with vertical piping or other vertical openings through the building or rooms adjacent to rooms with piping should be measured. The detectors should not be moved during the measurement period and they should be placed so that the result is representative for the work place. Measurement devises must be calibrated every 12 months. This can be done at SSI or another laboratory recommended by SSI. Laboratories, consulting firms etc responsible for radon measurements have to guarantee that the results are correct. A quality system is required in order to perform measurements. The measurement protocol describes every method that can be used for radon measurements in detail as far as calibration and control systems are concerned. (author)

  12. Inoculation of tomato plants with rhizobacteria enhances the performance of the phloem-feeding insect Bemisia tabaci

    Shavit, Roee; Ofek-Lalzar, Maya; Burdman, Saul; Morin, Shai

    2013-01-01

    In their natural environment, plants experience multiple biotic interactions and respond to this complexity in an integrated manner. Therefore, plant responses to herbivory are flexible and depend on the context and complexity in which they occur. For example, plant growth promoting rhizobacteria (PGPR) can enhance plant growth and induce resistance against microbial pathogens and herbivorous insects by a phenomenon termed induced systemic resistance (ISR). In the present study, we investigat...

  13. Selenium hyperaccumulation offers protection from cell disruptor herbivores

    Quinn Colin F

    2010-08-01

    Full Text Available Abstract Background Hyperaccumulation, the rare capacity of certain plant species to accumulate toxic trace elements to levels several orders of magnitude higher than other species growing on the same site, is thought to be an elemental defense mechanism against herbivores and pathogens. Previous research has shown that selenium (Se hyperaccumulation protects plants from a variety of herbivores and pathogens. Selenium hyperaccumulating plants sequester Se in discrete locations in the leaf periphery, making them potentially more susceptible to some herbivore feeding modes than others. In this study we investigate the protective function of Se in the Se hyperaccumulators Stanleya pinnata and Astragalus bisulcatus against two cell disrupting herbivores, the western flower thrips (Frankliniella occidentalis and the two-spotted spider mite (Tetranychus urticae. Results Astragalus bisulcatus and S. pinnata with high Se concentrations (greater than 650 mg Se kg-1 were less subject to thrips herbivory than plants with low Se levels (less than 150 mg Se kg-1. Furthermore, in plants containing elevated Se levels, leaves with higher concentrations of Se suffered less herbivory than leaves with less Se. Spider mites also preferred to feed on low-Se A. bisulcatus and S. pinnata plants rather than high-Se plants. Spider mite populations on A. bisulcatus decreased after plants were given a higher concentration of Se. Interestingly, spider mites could colonize A. bisulcatus plants containing up to 200 mg Se kg-1 dry weight, concentrations which are toxic to many other herbivores. Selenium distribution and speciation studies using micro-focused X-ray fluorescence (μXRF mapping and Se K-edge X-ray absorption spectroscopy revealed that the spider mites accumulated primarily methylselenocysteine, the relatively non-toxic form of Se that is also the predominant form of Se in hyperaccumulators. Conclusions This is the first reported study investigating the

  14. Niche Segregation between Wild and Domestic Herbivores in Chilean Patagonia

    Esperanza C Iranzo; Juan Traba; Pablo Acebes; Benito A González; Cristina Mata; Estades, Cristián F.; Malo, Juan E.

    2013-01-01

    Competition arises when two co-occuring species share a limiting resource. Potential for competition is higher when species have coexisted for a short time, as it is the case for herbivores and livestock introduced in natural systems. Sheep, introduced in the late 19(th) century in Patagonia, bear a great resemblance in size and diet to the guanaco, the main native herbivore in Patagonia. In such circumstances, it could be expected that the two species compete and one of them could be displac...

  15. The Sterile Insect Technique

    Insect pests have caused an increasing problem in agriculture and human health through crop losses and disease transmission to man and livestock. Intervention to ensure food security and human health has relied on Integrated Pest Management (IPM) strategies to keep the pests population below economic injury levels. IPM integrate a variety of methods, but there has been over-reliance on chemical control following the discovery of insecticidal properties of DDT. It is now realized that, maintaining pest populations at controlled levels is unsustainable and eradication options is now being considered. Although the Sterile Insect Technique(SIT) could be used for insect suppression, it is gaining favour in the elimination (eradication) of the target pest population through Areawide-based IPM (Author)

  16. Behavioral Immunity in Insects

    Thierry Lefèvre

    2012-08-01

    Full Text Available Parasites can dramatically reduce the fitness of their hosts, and natural selection should favor defense mechanisms that can protect hosts against disease. Much work has focused on understanding genetic and physiological immunity against parasites, but hosts can also use behaviors to avoid infection, reduce parasite growth or alleviate disease symptoms. It is increasingly recognized that such behaviors are common in insects, providing strong protection against parasites and parasitoids. We review the current evidence for behavioral immunity in insects, present a framework for investigating such behavior, and emphasize that behavioral immunity may act through indirect rather than direct fitness benefits. We also discuss the implications for host-parasite co-evolution, local adaptation, and the evolution of non-behavioral physiological immune systems. Finally, we argue that the study of behavioral immunity in insects has much to offer for investigations in vertebrates, in which this topic has traditionally been studied.

  17. Effects of terrestrial pollutants on insect parasitoids.

    Butler, Casey D; Beckage, Nancy E; Trumble, John T

    2009-06-01

    Parasitoids are important organisms in the regulation of insect herbivores in natural, urban, and agricultural ecosystems. The impact of pollutants acting on parasitoids has not been extensively reviewed. This prompted us to propose a falsifiable null hypothesis (pollutants have no effects on parasitoids) and two alternative hypotheses (pollution negatively or positively affects parasitoids) to assess in the available literature the effects of pollutants acting on parasitoids. We found 26 studies examining 39 biological systems that met our criteria for inclusion. Of these studies, 18 of the 39 biological systems (46.2%) supported the null hypothesis while 18 (46.2%) supported the first alternative hypothesis in which pollutants exhibited negative effects on parasitoids. Only a small percentage of the studies (7.6%, 3 of 39) supported the second alternative hypothesis suggesting that pollutants had positive effects on parasitoids. We provide a synthesis of the available data by pollution type, summarize trends for different pollutants, and suggest future areas of research. PMID:19132813

  18. Aversion and attraction to harmful plant secondary compounds jointly shape the foraging ecology of a specialist herbivore.

    Humphrey, Parris T; Gloss, Andrew D; Alexandre, Nicolas M; Villalobos, Martha M; Fremgen, Marcella R; Groen, Simon C; Meihls, Lisa N; Jander, Georg; Whiteman, Noah K

    2016-05-01

    Most herbivorous insect species are restricted to a narrow taxonomic range of host plant species. Herbivore species that feed on mustard plants and their relatives in the Brassicales have evolved highly efficient detoxification mechanisms that actually prevent toxic mustard oils from forming in the bodies of the animals. However, these mechanisms likely were not present during the initial stages of specialization on mustard plants ~100 million years ago. The herbivorous fly Scaptomyza nigrita (Drosophilidae) is a specialist on a single mustard species, bittercress (Cardamine cordifolia; Brassicaceae) and is in a fly lineage that evolved to feed on mustards only in the past 10-20 million years. In contrast to many mustard specialists, S. nigrita does not prevent formation of toxic breakdown products (mustard oils) arising from glucosinolates (GLS), the primary defensive compounds in mustard plants. Therefore, it is an appealing model for dissecting the early stages of host specialization. Because mustard oils actually form in the bodies of S. nigrita, we hypothesized that in lieu of a specialized detoxification mechanism, S. nigrita may mitigate exposure to high GLS levels within plant tissues using behavioral avoidance. Here, we report that jasmonic acid (JA) treatment increased GLS biosynthesis in bittercress, repelled adult female flies, and reduced larval growth. S. nigrita larval damage also induced foliar GLS, especially in apical leaves, which correspondingly displayed the least S. nigrita damage in controlled feeding trials and field surveys. Paradoxically, flies preferred to feed and oviposit on GLS-producing Arabidopsis thaliana despite larvae performing worse in these plants versus non-GLS-producing mutants. GLS may be feeding cues for S. nigrita despite their deterrent and defensive properties, which underscores the diverse relationship a mustard specialist has with its host when lacking a specialized means of mustard oil detoxification. PMID

  19. Sterile insect technique and radiation in insect control

    Out of 39 papers and 6 summaries of the poster presentations published in this proceeding series, 23 respectively fall within the INIS subject scope. Four main topics were covered: a review of the sterile insect technique against various insect pests; its application to tsetse flies in eradication programmes; quality control of mass-reared insects for release; and the development of genetic approaches to insect mass rearing and control. Other topics emphasized integrated pest management, computer models and radioisotope labelling

  20. Insect GPCRs and TRP channels: putative targets for insect repellents

    Sang Hoon Kim

    2013-01-01

    Many insects such as mosquitoes cause life-threatening diseases such as malaria, yellow fever and West Nile virus. Malaria alone infects 500 million people annually and causes 1~3 million death per year. Volatile insect repellents, which are detected through the sense of smell, have long been used to protect humans against insect pests. Antifeedants are non-volatile aversive compounds that are detected through the sense of taste and prevent insects from feeding on plants. The molecular target...

  1. Floral ecology and insect visitation in riparian Tamarix sp. (saltcedar)

    Andersen, D.C.; Nelson, S.M.

    2013-01-01

    Climate change projections for semiarid and arid North America include reductions in stream discharge that could adversely affect riparian plant species dependent on stream-derived ground water. In order to better understand this potential impact, we used a space-for-time substitution to test the hypotheses that increasing depth-to-groundwater (DGW) is inversely related to Tamarix sp. (saltcedar) flower abundance (F) and nectar production per flower (N). We also assessed whether DGW affected the richness or abundance of insects visiting flowers. We examined Tamarix floral attributes and insect visitation patterns during 2010 and 2011 at three locations along a deep DWG gradient (3.2–4.1 m) on a floodplain terrace adjacent to Las Vegas Wash, an effluent-dominated Mojave Desert stream. Flower abundance and insect visitation patterns differed between years, but no effect from DGW on either F or N was detected. An eruption of a novel non-native herbivore, the splendid tamarisk weevil (Coniatus splendidulus), likely reduced flower production in 2011.

  2. INFLUENCE OF ELEVATED OZONE AND CARBON DIOXIDE ON INSECT DENSITIES.

    DELUCIA, E.; DERMODY, O.; O' NEILL, B.; ALDEA, M.; HAMILTON, J.; ZANGERL, A.; ROGER, A.; BERENBAUM, M.

    2005-01-05

    The combustion of fossil fuels is profoundly altering the chemical composition of the atmosphere. Beginning with the Industrial Revolution, the concentration of carbon dioxide in the atmosphere has increased from approximately 280 to 370 {micro}l l{sup -1} in 2004, and it is expected to exceed 550 {micro}l l{sup -1} by 2050. Tropospheric ozone has risen even more rapidly than CO{sub 2} and average summer concentrations in the Northern Hemisphere are expected to continue to increase by 0.5-2.5% per year over the next 30 years. Although elevated CO{sub 2} stimulates photosynthesis and productivity of terrestrial ecosystems, ozone (O{sub 3}) is deleterious. In addition to directly affecting the physiology and productivity of crops, increased concentrations of tropospheric CO{sub 2} and O{sub 3} are predicted to lower the nutritional quality of leaves, which has the potential to increase herbivory as insects eat more to meet their nutritional demands. We tested the hypothesis that changes in tropospheric chemistry affect the relationship between plants and insect herbivores by changing leaf quality. The susceptibility to herbivory of soybean grown in elevated CO{sub 2} or O{sub 3} was examined using free air gas concentration enrichment (SoyFACE). FACE technology has the advantage that plants are cultivated under realistic field conditions with no unwanted alteration of microclimate or artificial constraints on the insect community.

  3. Know your ABCs: Characterization and gene expression dynamics of ABC transporters in the polyphagous herbivore Helicoverpa armigera.

    Bretschneider, Anne; Heckel, David G; Vogel, Heiko

    2016-05-01

    Polyphagous insect herbivores are adapted to many different secondary metabolites of their host plants. However, little is known about the role of ATP-binding cassette (ABC) transporters, a multigene family involved in detoxification processes. To study the larval response of the generalist Helicoverpa armigera (Lepidoptera) and the putative role of ABC transporters, we performed developmental assays on artificial diet supplemented with secondary metabolites from host plants (atropine-scopolamine, nicotine and tomatine) and non-host plants (taxol) in combination with a replicated RNAseq experiment. A maximum likelihood phylogeny identified the subfamily affiliations of the ABC transporter sequences. Larval performance was equal on the atropine-scopolamine diet and the tomatine diet. For the latter we could identify a treatment-specific upregulation of five ABC transporters in the gut. No significant developmental difference was detected between larvae fed on nicotine or taxol. This was also mirrored in the upregulation of five ABC transporters when fed on either of the two diets. The highest number of differentially expressed genes was recorded in the gut samples in response to feeding on secondary metabolites. Our results are consistent with the expectation of a general detoxification response in a polyphagous herbivore. This is the first study to characterize the multigene family of ABC transporters and identify gene expression changes across different developmental stages and tissues, as well as the impact of secondary metabolites in the agricultural pest H. armigera. PMID:26951878

  4. Resilience in plant-herbivore networks during secondary succession.

    Edith Villa-Galaviz

    Full Text Available Extensive land-use change in the tropics has produced a mosaic of successional forests within an agricultural and cattle-pasture matrix. Post-disturbance biodiversity assessments have found that regeneration speed depends upon propagule availability and the intensity and duration of disturbance. However, reestablishment of species interactions is still poorly understood and this limits our understanding of the anthropogenic impacts upon ecosystem resilience. This is the first investigation that evaluates plant-herbivore interaction networks during secondary succession. In particular we investigated succession in a Mexican tropical dry forest using data of caterpillar associations with plants during 2007-2010. Plant-herbivore networks showed high resilience. We found no differences in most network descriptors between secondary and mature forest and only recently abandoned fields were found to be different. No significant nestedness or modularity network structure was found. Plant-herbivore network properties appear to quickly reestablish after perturbation, despite differences in species richness and composition. This study provides some valuable guidelines for the implement of restoration efforts that can enhance ecological processes such as the interaction between plants and their herbivores.

  5. Aquatic herbivores facilitate the emission of methane from wetlands

    Dingemans, B.J.J.; Bakker, E.S.; Bodelier, P.L.E.

    2011-01-01

    Wetlands are significant sources of atmospheric methane. Methane produced by microbes enters roots and escapes to the atmosphere through the shoots of emergent wetland plants. Herbivorous birds graze on helophytes, but their effect on methane emission remains unknown. We hypothesized that grazing on

  6. Herbivores and nutrients control grassland plant diversity via light limitation.

    Borer, Elizabeth T. [Department of Ecology, Evolution, and Behavior, University of Minnesota; et al, et al

    2014-01-01

    Human alterations to nutrient cycles1,2 and herbivore communities3–7 are affecting global biodiversity dramatically2. Ecological theory predicts these changes should be strongly counteractive: nutrient addition drives plant species loss through intensified competition for light, whereas herbivores prevent competitive exclusion by increasing ground-level light, particularly in productive systems8,9. Here we use experimental data spanning a globally relevant range of conditions to test the hypothesis that herbaceous plant species losses caused by eutrophication may be offset by increased light availability due to herbivory. This experiment, replicated in 40 grasslands on 6 continents, demonstrates that nutrients and herbivores can serve as counteracting forces to control local plant diversity through light limitation, independent of site productivity, soil nitrogen, herbivore type and climate. Nutrient addition consistently reduced local diversity through light limitation, and herbivory rescued diversity at sites where it alleviated light limitation. Thus, species loss from anthropogenic eutrophication can be ameliorated in grasslands where herbivory increases ground-level light.

  7. Arthropod (Insect) Bite or Sting

    ... or Sting Information for adults A A A Insect (arthropod) bites are typically pink or red and ... round in shape. Overview Bites or stings from insects (arthropods) are very common. Most reactions are mild ...

  8. Targeted predation of extrafloral nectaries by insects despite localized chemical defences.

    Gish, Moshe; Mescher, Mark C; De Moraes, Consuelo M

    2015-10-01

    Extrafloral (EF) nectaries recruit carnivorous arthropods that protect plants from herbivory, but they can also be exploited by nectar thieves. We studied the opportunistic, targeted predation (and destruction) of EF nectaries by insects, and the localized chemical defences that plants presumably use to minimize this effect. In field and laboratory experiments, we identified insects that were possibly responsible for EF nectary predation in Vicia faba (fava bean) and determined the extent and accuracy of the feeding damage done to the EF nectaries by these insects. We also performed biochemical analyses of plant tissue samples in order to detect microscale distribution patterns of chemical defences in the area of the EF nectary. We observed selective, targeted feeding on EF nectaries by several insect species, including some that are otherwise not primarily herbivorous. Biochemical analyses revealed high concentrations of l-3,4-dihydroxyphenylalanine, a non-protein amino acid that is toxic to insects, near and within the EF nectaries. These results suggest that plants allocate defences to the protection of EF nectaries from predation, consistent with expectations of optimal defence theory, and that this may not be entirely effective, as insects limit their exposure to these defences by consuming only the secreting tissue of the nectary. PMID:26446809

  9. Broadening insect gastronomy

    Halloran, Afton Marina Szasz; Münke, Christopher; Vantomme, Paul;

    2015-01-01

    In recent years there has been a trend among chefs to diversify their ingredients and techniques, drawing inspiration from other cultures and creating new foods by blending this knowledge with the flavours of their local region. Edible insects, with their plethora of taste, aromatic, textural and...

  10. Insects, isotopes and radiations

    The IAEA activity on coordinating the IAEA member-state efforts in the field of pest control is considered. A complex program of agricultural pest control (IPM), applied in many parts of the world is developed. The program provides for the use of natural means of control and cases of critical pest numbers-the use of insecticides. When controlling certain types of insects it is advisable to apply the 'large area control' methods which provide for the insect destruction in places of their concentration prior to migration. Methods of pest control over large areas also include radiation sexual sterilization method (SSM), application of insect phoromons (sexual attractants) to prevent mating, other types of chemical attractants, traps, mass cultivation and reproduction of parasite plants and animals, destroying insects, as well as improvement of host-plant resistance. A great attention is paid to isotope and radiation application in pest control (labelling, sexual sterilization using ionising radiation, radiation application in genetic engineering, mutant plant cultivation)

  11. Dispersal of forest insects

    Mcmanus, M. L.

    1979-01-01

    Dispersal flights of selected species of forest insects which are associated with periodic outbreaks of pests that occur over large contiguous forested areas are discussed. Gypsy moths, spruce budworms, and forest tent caterpillars were studied for their massive migrations in forested areas. Results indicate that large dispersals into forested areas are due to the females, except in the case of the gypsy moth.

  12. Recycled Insect Models

    Rule, Audrey C.; Meyer, Mary Ann

    2007-01-01

    This article presents an engaging activity in which high school students use a dichotomous key to guide the creation and classification of model insects from recycled plastic lids and containers. Besides teaching the use of a dichotomous key and the effect of evolutionary descent upon groupings of organisms, this activity focuses on an…

  13. Flying insects and Campylobacter

    Hald, Birthe; Sommer, Helle Mølgaard; Skovgård, Henrik

    Campylobacter in flies Flies of the Muscidae family forage on all kind of faeces – various fly species have different preferences. M domestica prefer pigs, horses and cattle faeces, animals which are all known to frequently excrete Campylobacter. As a result, the insects pick up pathogenic micro...

  14. Insect Resistant Maize 5307

    Directorate, Issued by Health Canada's Food

    2014-01-01

    Health Canada has notified Syngenta Seeds Canada Inc. that it has no objection to the sale of food derived from Insect Resistant Maize 5307. The Department conducted a comprehensive assessment of this corn event according to its Guidelines for the Safety Assessment of Novel Foods. These Guidelines are based upon internationally accepted principles for establishing the safety of foods with novel traits.

  15. Oenocytes in insects

    GF Martins

    2012-08-01

    Full Text Available Oenocytes are insect cells responsible for lipid processing and detoxification. Of ectodermic origin, they are found in close association with the insect epidermis, or fat body cells, or both depending on the insect species and developmental stage. They are easily distinguishable either by staining or by their ability to form cell clusters lined by a basal lamina, which makes it possible to isolate them from other cells. The most noticeable characteristic of the oenocytes ultrastructure is the presence of a well-developed smooth endoplasmic reticulum that can fill almost entire cell cytoplasm that for a long time was suggestive of lipid processing capacity. This capacity was confirmed lately through the usage of genetic, molecular and biochemistry approaches and other functions are also addressed to these cells, such as cuticular hydrocarbons and pheromones synthesis and detoxification. Additionally, oenocytes are considered analogous to mammalian hepatocytes based on their gene expression profiles and cell functions. In spite of the current knowledge about oenocytes, much about their protein expression profile remains unknown. In this review we provide a general overview of the state of the art related to oenocytes studies and certain morphological and biochemical aspects of such cells crucial for insect survival.

  16. Sterol metabolism of insects

    Ritter, F.J.; Wientjens, W.H.J.M.

    1967-01-01

    This article surveys the present knowledge of the sterol metabolism of insects. It is emphasized that a high degree of purity of the dietary sterols and the climination of the influence of symbionts are essential to present ambiguity in interpreting results. It is pointed out that a sharp distinctio

  17. Culture of insect tissues

    Several aspects are discussed related to the behavior of politenic chromosomes from Rhyncosciara salivary glands kept in culture during different periods of time, without interference of insect hormones. Nucleic acid-and protein synthesis in isolated nuclei and chromosomes are also investigated. Autoradiographic techniques and radioactive precursors for nucleic acids and proteins are used in the research. (M.A.)

  18. Colour constancy in insects.

    Chittka, Lars; Faruq, Samia; Skorupski, Peter; Werner, Annette

    2014-06-01

    Colour constancy is the perceptual phenomenon that the colour of an object appears largely unchanged, even if the spectral composition of the illuminating light changes. Colour constancy has been found in all insect species so far tested. Especially the pollinating insects offer a remarkable opportunity to study the ecological significance of colour constancy since they spend much of their adult lives identifying and choosing between colour targets (flowers) under continuously changing ambient lighting conditions. In bees, whose colour vision is best studied among the insects, the compensation provided by colour constancy is only partial and its efficiency depends on the area of colour space. There is no evidence for complete 'discounting' of the illuminant in bees, and the spectral composition of the light can itself be used as adaptive information. In patchy illumination, bees adjust their spatial foraging to minimise transitions between variously illuminated zones. Modelling allows the quantification of the adaptive benefits of various colour constancy mechanisms in the economy of nature. We also discuss the neural mechanisms and cognitive operations that might underpin colour constancy in insects. PMID:24647930

  19. Resistance to Insecticides in Insects

    ÇAKIR, Şükran; Şengül YAMANEL

    2005-01-01

    In recent years, the frequent usage of insecticides in struggle aganist insects, has caused development of resistance to those chemicals in insects. The increase in dosage of insecticide used due to development of resistance in insects, causes important problems in terms of environment and human health. This study includes topics such as insecticides which are used frequently in insect struggle, insecticide resistant types, genetic changes posing resistance, enzymes of resistance and resistan...

  20. The costs of anti-herbivore defense traits in agricultural crop plants: a case study involving leafhoppers and trichomes.

    Kaplan, Ian; Dively, Galen P; Denno, Robert F

    2009-06-01

    The expression of plant defenses is thought to entail costs (e.g., the allocation of resources away from growth or reproduction) that constrain the evolution of plant genotypes maximally defended against herbivores. Although central to the ecological theory underlying plant-insect interactions at large, the concept of defense costs is particularly evident in agricultural crops where plants may be under simultaneous selection for enhanced growth and/or reproduction (i.e., yield) and anti-herbivore resistance traits that deter pests. In this study we investigate the role of trichomes as a resistance mechanism against a sap-feeding insect (the leafhopper, Empoasca fabae) on potato. Natural variation in trichome density among 17 potato cultivars was used to test for the role of trichomes as a putative defense against leafhoppers, and evidence of costs in trichome expression. Two different types of costs were explored: (1) allocation costs (i.e., the relationship between trichomes and yield), and (2) costs involving trade-offs with alternative defense strategies (e.g., tolerance). Although leafhopper abundance did not decrease as trichome density increased, leafhopper injury to potato plants (foliar necrosis) was negatively correlated with trichome density. As a result, the per capita effect of leafhopper adults and nymphs on foliar damage was lower on plants with high trichome densities. We found no evidence, however, for costs of expressing this resistance trait; trichomes were not correlated with either potato yield or tolerance to herbivory. Thus, selection for multiple plant defenses to alleviate the impact of pests in agronomic crops may indeed be possible without inherent losses in plant yield. PMID:19544730

  1. Herbivore handling of a plant's trichome: the case of Heliconius charithonia (L.) (Lepidoptera: Nymphalidae) and Passiflora lobata (Killip) Hutch. (Passifloraceae)

    Cardoso, Marcio Z. [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil). Centro de Biociencias. Dept. de Botanica, Ecologia e Zoologia]. E-mail: mzc@cb.ufrn.br

    2008-05-15

    Trichomes reduce herbivore attack on plants by physically and/or chemically inhibiting movement or other activities. Despite evidence that herbivores are negatively affected by trichomes there also reports of insect counter-adaptations that circumvent the plant's defense. This paper reports on a study that investigated the likely mechanisms employed by larvae of the nymphalid butterfly, Heliconius charithonia (L.), that allow it to feed on a host that is presumably protected by hooked trichomes (Passiflora lobata (Killip) Hutch). Evidence were gathered using data from direct observations of larval movement and behavior, faeces analysis, scanning electron microscopy of plant surface and experimental analysis of larval movement on plants with and without trichomes (manually removed). The latter involved a comparison with a non specialist congener, Heliconius pachinus Salvin. Observations showed that H. charithonia larvae are capable of freeing themselves from entrapment on trichome tips by physical force. Moreover, wandering larvae lay silk mats on the trichomes and remove their tips by biting. In fact, trichome tips were found in the faeces. Experimental removal of trichomes aided in the movement of the non specialist but had no noticeable effect on the specialist larvae. These results support the suggestion that trichomes are capable of deterring a non specialist herbivore (H. pachinus). The precise mechanisms that allow the success of H. charithonia are not known, but I suggest that a blend of behavioral as well as physical resistance mechanisms is involved. Future studies should ascertain whether larval integument provides physical resistance to trichomes. (author)

  2. Protecting Yourself from Stinging Insects

    ... from St ing in g In sect s Flying Insects Outdoor workers are at risk of being stung by flying insects (bees, wasps, and hornets) and fire ants. While ... If a worker is stung by a stinging insect: ■■ Have someone stay with the worker to be ...

  3. The promise of insect genomics

    Grimmelikhuijzen, Cornelis J P; Cazzamali, Giuseppe; Williamson, Michael;

    2007-01-01

    Insects are the largest animal group in the world and are ecologically and economically extremely important. This importance of insects is reflected by the existence of currently 24 insect genome projects. Our perspective discusses the state-of-the-art of these genome projects and the impacts that...

  4. Defensive insect symbiont leads to cascading extinctions and community collapse.

    Sanders, Dirk; Kehoe, Rachel; van Veen, Fj Frank; McLean, Ailsa; Godfray, H Charles J; Dicke, Marcel; Gols, Rieta; Frago, Enric

    2016-07-01

    Animals often engage in mutualistic associations with microorganisms that protect them from predation, parasitism or pathogen infection. Studies of these interactions in insects have mostly focussed on the direct effects of symbiont infection on natural enemies without studying community-wide effects. Here, we explore the effect of a defensive symbiont on population dynamics and species extinctions in an experimental community composed of three aphid species and their associated specialist parasitoids. We found that introducing a bacterial symbiont with a protective (but not a non-protective) phenotype into one aphid species led to it being able to escape from its natural enemy and increase in density. This changed the relative density of the three aphid species which resulted in the extinction of the two other parasitoid species. Our results show that defensive symbionts can cause extinction cascades in experimental communities and so may play a significant role in the stability of consumer-herbivore communities in the field. PMID:27282315

  5. Responses of Herbivorous Fishes and Benthos to 6 Years of Protection at the Kahekili Herbivore Fisheries Management Area, Maui.

    Williams, Ivor D; White, Darla J; Sparks, Russell T; Lino, Kevin C; Zamzow, Jill P; Kelly, Emily L A; Ramey, Hailey L

    2016-01-01

    In response to concerns about declining coral cover and recurring macroalgal blooms, in 2009 the State of Hawaii established the Kahekili Herbivore Fisheries Management Area (KHFMA). Within the KHFMA, herbivorous fishes and sea urchins are protected, but other fishing is allowed. As part of a multi-agency monitoring effort, we conducted surveys at KHFMA and comparison sites around Maui starting 19 months before closure, and over the six years since implementation of herbivore protection. Mean parrotfish and surgeonfish biomass both increased within the KHFMA (by 139% [95%QR (quantile range): 98-181%] and 28% [95%QR: 3-52%] respectively). Most of those gains were of small-to-medium sized species, whereas large-bodied species have not recovered, likely due to low levels of poaching on what are preferred fishery targets in Hawaii. Nevertheless, coincident with greater biomass of herbivores within the KHFMA, cover of crustose coralline algae (CCA) has increased from ~2% before closure to ~ 15% in 2015, and macroalgal cover has remained low throughout the monitoring period. Strong evidence that changes in the KHFMA were a consequence of herbivore management are that (i) there were no changes in biomass of unprotected fish families within the KHFMA; and that (ii) there were no similar changes in parrotfish or CCA at comparison sites around Maui. It is not yet clear how effective herbivore protection might eventually be for the KHFMA's ultimate goal of coral recovery. Coral cover declined over the first few years of surveys-from 39.6% (SE 1.4%) in 2008, to 32.9% (SE 0.8%) in 2012, with almost all of that loss occurring by 2010 (1 year after closure), i.e. before meaningful herbivore recovery had occurred. Coral cover subsequently stabilized and may have slightly increased from 2012 through early 2015. However, a region-wide bleaching event in 2015 had already led to some coral mortality by the time surveys were conducted in late 2015, at which time cover had dropped back

  6. Responses of Herbivorous Fishes and Benthos to 6 Years of Protection at the Kahekili Herbivore Fisheries Management Area, Maui.

    Ivor D Williams

    Full Text Available In response to concerns about declining coral cover and recurring macroalgal blooms, in 2009 the State of Hawaii established the Kahekili Herbivore Fisheries Management Area (KHFMA. Within the KHFMA, herbivorous fishes and sea urchins are protected, but other fishing is allowed. As part of a multi-agency monitoring effort, we conducted surveys at KHFMA and comparison sites around Maui starting 19 months before closure, and over the six years since implementation of herbivore protection. Mean parrotfish and surgeonfish biomass both increased within the KHFMA (by 139% [95%QR (quantile range: 98-181%] and 28% [95%QR: 3-52%] respectively. Most of those gains were of small-to-medium sized species, whereas large-bodied species have not recovered, likely due to low levels of poaching on what are preferred fishery targets in Hawaii. Nevertheless, coincident with greater biomass of herbivores within the KHFMA, cover of crustose coralline algae (CCA has increased from ~2% before closure to ~ 15% in 2015, and macroalgal cover has remained low throughout the monitoring period. Strong evidence that changes in the KHFMA were a consequence of herbivore management are that (i there were no changes in biomass of unprotected fish families within the KHFMA; and that (ii there were no similar changes in parrotfish or CCA at comparison sites around Maui. It is not yet clear how effective herbivore protection might eventually be for the KHFMA's ultimate goal of coral recovery. Coral cover declined over the first few years of surveys-from 39.6% (SE 1.4% in 2008, to 32.9% (SE 0.8% in 2012, with almost all of that loss occurring by 2010 (1 year after closure, i.e. before meaningful herbivore recovery had occurred. Coral cover subsequently stabilized and may have slightly increased from 2012 through early 2015. However, a region-wide bleaching event in 2015 had already led to some coral mortality by the time surveys were conducted in late 2015, at which time cover had

  7. Augmenting Sulfur Metabolism and Herbivore Defense in Arabidopsis by Bacterial Volatile Signaling

    Mina eAziz

    2016-04-01

    Full Text Available Sulfur is an element necessary for the life cycle of higher plants. Its assimilation and reduction into essential biomolecules are pivotal factors determining a plant’s growth and vigor as well as resistance to environmental stress. While certain soil microbes can enhance ion solubility via chelating agents or oxidation, microbial regulation of plant-sulfur assimilation has not been reported. With an increasing understanding that soil microbes can activate growth and stress tolerance in plants via chemical signaling, the question arises as to whether such beneficial bacteria also regulate sulfur assimilation. Here we report a previously unidentified mechanism by which the growth-promoting rhizobacterium Bacillus amyloliquefaciens (GB03 transcriptionally activates genes responsible for sulfur assimilation, increasing sulfur uptake and accumulation in Arabidopsis. Transcripts encoding for sulfur-rich aliphatic and indolic glucosinolates are also GB03 induced. As a result, GB03-exposed plants with elevated glucosinolates exhibit greater protection against the generalist herbivore, Spodoptera exigua (beet armyworm. In contrast, a previously-characterized glucosinolate mutant compromised in the production of both aliphatic and indolic glucosinolates is also compromised in terms of GB03-induced protection against insect herbivory. As with in vitro studies, soil-grown plants show enhanced glucosinolate accumulation and protection against beet armyworm feeding with GB03 exposure. These results demonstrate the potential of microbes to enhance plant sulfur assimilation and emphasize the sophisticated integration of microbial signaling in plant defense.

  8. Augmenting Sulfur Metabolism and Herbivore Defense in Arabidopsis by Bacterial Volatile Signaling

    Aziz, Mina; Nadipalli, Ranjith K.; Xie, Xitao; Sun, Yan; Surowiec, Kazimierz; Zhang, Jin-Lin; Paré, Paul W.

    2016-01-01

    Sulfur is an element necessary for the life cycle of higher plants. Its assimilation and reduction into essential biomolecules are pivotal factors determining a plant’s growth and vigor as well as resistance to environmental stress. While certain soil microbes can enhance ion solubility via chelating agents or oxidation, microbial regulation of plant-sulfur assimilation has not been reported. With an increasing understanding that soil microbes can activate growth and stress tolerance in plants via chemical signaling, the question arises as to whether such beneficial bacteria also regulate sulfur assimilation. Here we report a previously unidentified mechanism by which the growth-promoting rhizobacterium Bacillus amyloliquefaciens (GB03) transcriptionally activates genes responsible for sulfur assimilation, increasing sulfur uptake and accumulation in Arabidopsis. Transcripts encoding for sulfur-rich aliphatic and indolic glucosinolates are also GB03 induced. As a result, GB03-exposed plants with elevated glucosinolates exhibit greater protection against the generalist herbivore, Spodoptera exigua (beet armyworm, BAW). In contrast, a previously characterized glucosinolate mutant compromised in the production of both aliphatic and indolic glucosinolates is also compromised in terms of GB03-induced protection against insect herbivory. As with in vitro studies, soil-grown plants show enhanced glucosinolate accumulation and protection against BAW feeding with GB03 exposure. These results demonstrate the potential of microbes to enhance plant sulfur assimilation and emphasize the sophisticated integration of microbial signaling in plant defense. PMID:27092166

  9. Augmenting Sulfur Metabolism and Herbivore Defense in Arabidopsis by Bacterial Volatile Signaling.

    Aziz, Mina; Nadipalli, Ranjith K; Xie, Xitao; Sun, Yan; Surowiec, Kazimierz; Zhang, Jin-Lin; Paré, Paul W

    2016-01-01

    Sulfur is an element necessary for the life cycle of higher plants. Its assimilation and reduction into essential biomolecules are pivotal factors determining a plant's growth and vigor as well as resistance to environmental stress. While certain soil microbes can enhance ion solubility via chelating agents or oxidation, microbial regulation of plant-sulfur assimilation has not been reported. With an increasing understanding that soil microbes can activate growth and stress tolerance in plants via chemical signaling, the question arises as to whether such beneficial bacteria also regulate sulfur assimilation. Here we report a previously unidentified mechanism by which the growth-promoting rhizobacterium Bacillus amyloliquefaciens (GB03) transcriptionally activates genes responsible for sulfur assimilation, increasing sulfur uptake and accumulation in Arabidopsis. Transcripts encoding for sulfur-rich aliphatic and indolic glucosinolates are also GB03 induced. As a result, GB03-exposed plants with elevated glucosinolates exhibit greater protection against the generalist herbivore, Spodoptera exigua (beet armyworm, BAW). In contrast, a previously characterized glucosinolate mutant compromised in the production of both aliphatic and indolic glucosinolates is also compromised in terms of GB03-induced protection against insect herbivory. As with in vitro studies, soil-grown plants show enhanced glucosinolate accumulation and protection against BAW feeding with GB03 exposure. These results demonstrate the potential of microbes to enhance plant sulfur assimilation and emphasize the sophisticated integration of microbial signaling in plant defense. PMID:27092166

  10. Effect of Drought on Herbivore-Induced Plant Gene Expression: Population Comparison for Range Limit Inferences.

    Gill, Gunbharpur Singh; Haugen, Riston; Matzner, Steven L; Barakat, Abdelali; Siemens, David H

    2016-01-01

    Low elevation "trailing edge" range margin populations typically face increases in both abiotic and biotic stressors that may contribute to range limit development. We hypothesize that selection may act on ABA and JA signaling pathways for more stable expression needed for range expansion, but that antagonistic crosstalk prevents their simultaneous co-option. To test this hypothesis, we compared high and low elevation populations of Boechera stricta that have diverged with respect to constitutive levels of glucosinolate defenses and root:shoot ratios; neither population has high levels of both traits. If constraints imposed by antagonistic signaling underlie this divergence, one would predict that high constitutive levels of traits would coincide with lower plasticity. To test this prediction, we compared the genetically diverged populations in a double challenge drought-herbivory growth chamber experiment. Although a glucosinolate defense response to the generalist insect herbivore Spodoptera exigua was attenuated under drought conditions, the plastic defense response did not differ significantly between populations. Similarly, although several potential drought tolerance traits were measured, only stomatal aperture behavior, as measured by carbon isotope ratios, was less plastic as predicted in the high elevation population. However, RNAseq results on a small subset of plants indicated differential expression of relevant genes between populations as predicted. We suggest that the ambiguity in our results stems from a weaker link between the pathways and the functional traits compared to transcripts. PMID:27135233

  11. The fungal endophyte Chaetomium globosum negatively affects both above- and belowground herbivores in cotton.

    Zhou, Wenqing; Starr, James L; Krumm, Janice L; Sword, Gregory A

    2016-10-01

    Mutualistic plant-endophyte symbioses can benefit plants by increasing host fitness through reductions in herbivory. The fungus, Chaetomium globosum strain TAMU 520, was previously isolated as an endophyte from cotton (Gossypium hirsutum) and can be re-inoculated to systemically colonize cotton plants via seed treatment. We evaluated the potential impacts of the endophyte in cotton on plant parasitic nematodes belowground, along with piercing-sucking and chewing insects aboveground. Endophytic C. globosum inhibited root-knot nematode (Meloidogyne incognita) infection and reduced female reproduction belowground. To confirm the endophytic effect of C. globosum on root-knot nematode, a contact fungicide was applied to remove soil-borne and epiphytic C. globosum Consistent inhibition of nematode activity was observed post-fungicide treatment, with positive C. globosum colonization confirmed within plant tissues. Aboveground, endophytic C. globosum also negatively affected the fecundity of both cotton aphids (Aphis gossypii) and beet armyworms (Spodoptera exigua). Faster development rates and smaller head capsule of beet armyworm larvae were observed when fed Chaetomium-colonized plants. However, no larval weight difference was found between Chaetomium-colonized and control plants. No consistent effect on plant performance was found across experiments. Our findings illustrate how a single facultative fungal endophyte can increase plant systemic resistance against a range of invertebrate herbivores in a major crop. PMID:27451418

  12. Effect of Drought on Herbivore-Induced Plant Gene Expression: Population Comparison for Range Limit Inferences

    Gunbharpur Singh Gill

    2016-03-01

    Full Text Available Low elevation “trailing edge” range margin populations typically face increases in both abiotic and biotic stressors that may contribute to range limit development. We hypothesize that selection may act on ABA and JA signaling pathways for more stable expression needed for range expansion, but that antagonistic crosstalk prevents their simultaneous co-option. To test this hypothesis, we compared high and low elevation populations of Boechera stricta that have diverged with respect to constitutive levels of glucosinolate defenses and root:shoot ratios; neither population has high levels of both traits. If constraints imposed by antagonistic signaling underlie this divergence, one would predict that high constitutive levels of traits would coincide with lower plasticity. To test this prediction, we compared the genetically diverged populations in a double challenge drought-herbivory growth chamber experiment. Although a glucosinolate defense response to the generalist insect herbivore Spodoptera exigua was attenuated under drought conditions, the plastic defense response did not differ significantly between populations. Similarly, although several potential drought tolerance traits were measured, only stomatal aperture behavior, as measured by carbon isotope ratios, was less plastic as predicted in the high elevation population. However, RNAseq results on a small subset of plants indicated differential expression of relevant genes between populations as predicted. We suggest that the ambiguity in our results stems from a weaker link between the pathways and the functional traits compared to transcripts.

  13. Repellent and Attractive Effects of α-, β-, and Dihydro-β- Ionone to Generalist and Specialist Herbivores.

    Cáceres, L A; Lakshminarayan, S; Yeung, K K-C; McGarvey, B D; Hannoufa, A; Sumarah, M W; Benitez, X; Scott, I M

    2016-02-01

    properties, especially to the crucifer flea beetle, while α-ionone did not show any significant activity. These findings demonstrate how regulating genes of the carotenoid pathway can increase herbivore deterrent volatiles, a novel tool for insect pest management. PMID:26852133

  14. The Many Dimensions of Diet Breadth: Phytochemical, Genetic, Behavioral, and Physiological Perspectives on the Interaction between a Native Herbivore and an Exotic Host.

    Harrison, Joshua G; Gompert, Zachariah; Fordyce, James A; Buerkle, C Alex; Grinstead, Rachel; Jahner, Joshua P; Mikel, Scott; Nice, Christopher C; Santamaria, Aldrin; Forister, Matthew L

    2016-01-01

    From the perspective of an herbivorous insect, conspecific host plants are not identical, and intraspecific variation in host nutritional quality or defensive capacity might mediate spatially variable outcomes in plant-insect interactions. Here we explore this possibility in the context of an ongoing host breadth expansion of a native butterfly (the Melissa blue, Lycaeides melissa) onto an exotic host plant (alfalfa, Medicago sativa). We examine variation among seven alfalfa populations that differed in terms of colonization by L. melissa; specifically, we examined variation in phytochemistry, foliar protein, and plant population genetic structure, as well as responses of caterpillars and adult butterflies to foliage from the same populations. Regional patterns of alfalfa colonization by L. melissa were well predicted by phytochemical variation, and colonized patches of alfalfa showed a similar level of inter-individual phytochemical diversity. However, phytochemical variation was a poor predictor of larval performance, despite the fact that survival and weight gain differed dramatically among caterpillars reared on plants from different alfalfa populations. Moreover, we observed a mismatch between alfalfa supporting the best larval performance and alfalfa favored by ovipositing females. Thus, the axes of plant variation that mediate interactions with L. melissa depend upon herbivore life history stage, which raises important issues for our understanding of adaptation to novel resources by an organism with a complex life history. PMID:26836490

  15. The subtilisin-like protease SBT3 contributes to insect resistance in tomato.

    Meyer, Michael; Huttenlocher, Franziska; Cedzich, Anna; Procopio, Susanne; Stroeder, Jasper; Pau-Roblot, Corinne; Lequart-Pillon, Michelle; Pelloux, Jérôme; Stintzi, Annick; Schaller, Andreas

    2016-07-01

    Subtilisin-like proteases (SBTs) constitute a large family of extracellular plant proteases, the function of which is still largely unknown. In tomato plants, the expression of SBT3 was found to be induced in response to wounding and insect attack in injured leaves but not in healthy systemic tissues. The time course of SBT3 induction resembled that of proteinase inhibitor II and other late wound response genes suggesting a role for SBT3 in herbivore defense. Consistent with such a role, larvae of the specialist herbivore Manduca sexta performed better on transgenic plants silenced for SBT3 expression (SBT3-SI). Supporting a contribution of SBT3 to systemic wound signaling, systemic induction of late wound response genes was attenuated in SBT3-SI plants. The partial loss of insect resistance may thus be explained by a reduction in systemic defense gene expression. Alternatively, SBT3 may play a post-ingestive role in plant defense. Similar to other anti-nutritive proteins, SBT3 was found to be stable and active in the insect's digestive system, where it may act on unidentified proteins of insect or plant origin. Finally, a reduction in the level of pectin methylesterification that was observed in transgenic plants with altered levels of SBT3 expression suggested an involvement of SBT3 in the regulation of pectin methylesterases (PMEs). While such a role has been described in other systems, PME activity and the degree of pectin methylesterification did not correlate with the level of insect resistance in SBT3-SI and SBT3 overexpressing plants and are thus unrelated to the observed resistance phenotype. PMID:27259555

  16. Herbivore-induced and floral homoterpene volatiles are biosynthesized by a single P450 enzyme (CYP82G1) in Arabidopsis.

    Lee, Sungbeom; Badieyan, Somayesadat; Bevan, David R; Herde, Marco; Gatz, Christiane; Tholl, Dorothea

    2010-12-01

    Terpene volatiles play important roles in plant-organism interactions as attractants of pollinators or as defense compounds against herbivores. Among the most common plant volatiles are homoterpenes, which are often emitted from night-scented flowers and from aerial tissues upon herbivore attack. Homoterpene volatiles released from herbivore-damaged tissue are thought to contribute to indirect plant defense by attracting natural enemies of pests. Moreover, homoterpenes have been demonstrated to induce defensive responses in plant-plant interaction. Although early steps in the biosynthesis of homoterpenes have been elucidated, the identity of the enzyme responsible for the direct formation of these volatiles has remained unknown. Here, we demonstrate that CYP82G1 (At3g25180), a cytochrome P450 monooxygenase of the Arabidopsis CYP82 family, is responsible for the breakdown of the C(20)-precursor (E,E)-geranyllinalool to the insect-induced C(16)-homoterpene (E,E)-4,8,12-trimethyltrideca-1,3,7,11-tetraene (TMTT). Recombinant CYP82G1 shows narrow substrate specificity for (E,E)-geranyllinalool and its C(15)-analog (E)-nerolidol, which is converted to the respective C(11)-homoterpene (E)-4,8-dimethyl-1,3,7-nonatriene (DMNT). Homology-based modeling and substrate docking support an oxidative bond cleavage of the alcohol substrate via syn-elimination of the polar head, together with an allylic C-5 hydrogen atom. CYP82G1 is constitutively expressed in Arabidopsis stems and inflorescences and shows highly coordinated herbivore-induced expression with geranyllinalool synthase in leaves depending on the F-box protein COI-1. CYP82G1 represents a unique characterized enzyme in the plant CYP82 family with a function as a DMNT/TMTT homoterpene synthase. PMID:21088219

  17. Undergraduates' mental models about insect anatomy and insect life cycles

    Diaz, Arlene Edith

    Educational studies focused on students' alternative conceptions have shown the importance of developing strategies to correct understanding. Identifying and comprehending student mental models are important since they may reflect alternate conceptions about scientific concepts. Mental models have been identified in various science education studies, but little is known about mental models undergraduates hold about insects. This research is significant because it identified mental models undergraduates have about insect anatomy and insect life cycles, exposed students to cognitive conflict by having them complete an online insect tutorial, and analyzed the effectiveness of this insect tutorial in correcting student understanding. An insect assessment was developed and administered pre- and post-instruction to probe students' mental models about insects. Different numbers of undergraduate students participated in different parts of the assessment; 276, 249, 166, and 58 students participated in the listing, drawing. definition, and life cycle parts of the assessment, respectively. The tutorial contained a variety of manipulated insect and non-insect images that challenged the students' understanding and generated cognitive conflict. This intervention guided students in replacing alternate conceptions with correct understanding. It was hypothesized that the tutorial would have a positive impact on student learning about insects. The results suggest that the tutorial had a positive impact on learning.

  18. [Protection against insects].

    Rudin, W

    2005-11-01

    Successful protection against haematophagous insects and ticks, especially in areas where transmission of diseases occurs, requires a consistent application of a combination of appropriate measures. However, this can never substitute a chemoprophylaxis. Which measures have to be used depends on the circumstances under which they have to work. Indoor, physical means such as mosquito-screens on doors and windows, air-conditioners, and bed nets can be used to keep the insects away. These measures can be supplemented or supported by insecticides used as knock-down sprays, by electrical evaporation or for the treatment of screens and bed nets. In the field, if it is not possible to avoid mosquito-areas during phases of activity, appropriate clothing and repellents must provide the protection. Bright, wide pants and shirts of dense weaving covering as much skin as bearable should be preferred. Repellents are sprays, lotions, milks or creams which are evenly applied to the skin to prevent insects from biting. They contain synthetic or natural active substances of substantially varying effectiveness. The gold standard since about 60 years is diethylbenzamine (DEET). There are a few other active substances with a lower risk of side effects, however, combined with a lower effectiveness mainly on people with a high attractiveness for mosquitoes. Products containing an extract of Eucalyptus citriodora provide the best protection amongst those with natural active substances. Wearing bracelets or necklaces treated with repellents, acoustic devices (buzzers), electrocuters, topical or systemic Vitamin B1 or eating garlic are useless measures to prevent insects from biting. PMID:16350532

  19. Stick insects in kindergarten

    Vodeb, Špela

    2014-01-01

    In the graduate thesis, the way of cultivating animals in the kindergarten is presented, the importance of preparation and maintenance of living corner, also the fundamental characteristics of stick insects are listed. In the empirical part, there are results of the questionnaire, which had been answered by 100 kindergarten teachers, mainly about the prevalence of use of living corner in kindergartens; do the teachers choose to use them and why, which animals are most commonly cultivated, and...

  20. Escape behaviors in insects.

    Card, Gwyneth M

    2012-04-01

    Escape behaviors are, by necessity, fast and robust, making them excellent systems with which to study the neural basis of behavior. This is especially true in insects, which have comparatively tractable nervous systems and members who are amenable to manipulation with genetic tools. Recent technical developments in high-speed video reveal that, despite their short duration, insect escape behaviors are more complex than previously appreciated. For example, before initiating an escape jump, a fly performs sophisticated posture and stimulus-dependent preparatory leg movements that enable it to jump away from a looming threat. This newfound flexibility raises the question of how the nervous system generates a behavior that is both rapid and flexible. Recordings from the cricket nervous system suggest that synchrony between the activity of specific interneuron pairs may provide a rapid cue for the cricket to detect the direction of an approaching predator and thus which direction it should run. Technical advances make possible wireless recording from neurons while locusts escape from a looming threat, enabling, for the first time, a direct correlation between the activity of multiple neurons and the time-course of an insect escape behavior. PMID:22226514

  1. Cleptobiosis in Social Insects

    Michael D. Breed

    2012-01-01

    Full Text Available In this review of cleptobiosis, we not only focus on social insects, but also consider broader issues and concepts relating to the theft of food among animals. Cleptobiosis occurs when members of a species steal food, or sometimes nesting materials or other items of value, either from members of the same or a different species. This simple definition is not universally used, and there is some terminological confusion among cleptobiosis, cleptoparasitism, brood parasitism, and inquilinism. We first discuss the definitions of these terms and the confusion that arises from varying usage of the words. We consider that cleptobiosis usually is derived evolutionarily from established foraging behaviors. Cleptobionts can succeed by deception or by force, and we review the literature on cleptobiosis by deception or force in social insects. We focus on the best known examples of cleptobiosis, the ectatommine ant Ectatomma ruidum, the harvester ant Messor capitatus, and the stingless bee Lestrimellita limão. Cleptobiosis is facilitated either by deception or physical force, and we discuss both mechanisms. Part of this discussion is an analysis of the ecological implications (competition by interference and the evolutionary effects of cleptobiosis. We conclude with a comment on how cleptobiosis can increase the risk of disease or parasite spread among colonies of social insects.

  2. Species- and site-specific impacts of an invasive herbivore on tree survival in mixed forests.

    Holland, E Penelope; Gormley, Andrew M; Pech, Roger P

    2016-04-01

    Invasive herbivores are often managed to limit their negative impact on plant populations, but herbivore density - plant damage relationships are notoriously spatially and temporally variable. Site and species characteristics (both plant and herbivore) must be considered when assessing the potential for herbivore damage, making it difficult to set thresholds for efficient management. Using the invasive brushtail possum Trichosurus vulpecula in New Zealand as a case study, we parameterized a generic model to predict annual probability of browse-induced mortality of five tree species at 12 sites. We compared predicted and observed tree mortality for each species + site combination to establish herbivore abundance - tree mortality thresholds for each site on a single and combined tree species basis. Model results indicated it is likely that possum browse was the primary cause of all tree mortality at nine of the 12 species-site combinations, allowing us to estimate site-specific thresholds below which possum population numbers should be reduced and maintained to keep tree mortality under a predetermined level, for example 0.5% per year. The browse model can be used to set site- and species-specific management action thresholds, and can be adapted easily for other plant or herbivore species. Results for multiple plant or herbivore species at a single site can be combined to create conservative, site-wide management strategies, and used to: determine which sites will be affected most by changes in herbivore abundance; quantify thresholds for herbivore management; and justify expenditure on herbivore control. PMID:27066221

  3. Distribution, behavior, and condition of herbivorous fishes on coral reefs track algal resources.

    Tootell, Jesse S; Steele, Mark A

    2016-05-01

    Herbivore distribution can impact community structure and ecosystem function. On coral reefs, herbivores are thought to play an important role in promoting coral dominance, but how they are distributed relative to algae is not well known. Here, we evaluated whether the distribution, behavior, and condition of herbivorous fishes correlated with algal resource availability at six sites in the back reef environment of Moorea, French Polynesia. Specifically, we tested the hypotheses that increased algal turf availability would coincide with (1) increased biomass, (2) altered foraging behavior, and (3) increased energy reserves of herbivorous fishes. Fish biomass and algal cover were visually estimated along underwater transects; behavior of herbivorous fishes was quantified by observations of focal individuals; fish were collected to assess their condition; and algal turf production rates were measured on standardized tiles. The best predictor of herbivorous fish biomass was algal turf production, with fish biomass increasing with algal production. Biomass of herbivorous fishes was also negatively related to sea urchin density, suggesting competition for limited resources. Regression models including both algal turf production and urchin density explained 94 % of the variation in herbivorous fish biomass among sites spread over ~20 km. Behavioral observations of the parrotfish Chlorurus sordidus revealed that foraging area increased as algal turf cover decreased. Additionally, energy reserves increased with algal turf production, but declined with herbivorous fish density, implying that algal turf is a limited resource for this species. Our findings support the hypothesis that herbivorous fishes can spatially track algal resources on coral reefs. PMID:26271287

  4. Metal concentrations of insects associated with the South African Ni hyperaccumulator Berkheya coddii (Asteraceae)

    ROBERT S. BOYD; MICHEAL A. DAVIS; MICHAEL A. WALL; KEVIN BALKWILL

    2006-01-01

    The high levels of some metals in metal hyperaccumulator plants may be transferred to insect associates. We surveyed insects collected from the South African Ni hyperaccumulator Berkheya coddii to document whole-body metal concentrations (Co, Cr, Cu, Mg, Mn, Ni, Pb, Zn). We also documented the concentrations of these metals in leaves, stems and inflorescences, finding extremely elevated levels of Ni (4 700-16 000 μg/g) and high values (5-34 μg/g) for Co, Cr, and Pb. Of 26 insect morphotypes collected from B. coddii, seven heteropterans, one coleopteran, and one orthopteran contained relatively high concentrations of Ni (> 500 μg/g). The large number of high-Ni heteropterans adds to discoveries of others (from California USA and New Caledonia) and suggests that members of this insect order may be particularly Ni tolerant. Nymphs of the orthopteran (Stenoscepa) contained 3 500 μg Ni/g, the greatest Ni concentration yet reported for an insect. We also found two beetles with elevated levels of Mg (> 2 800 μg/g), one beetle with elevated Cu (> 70 μg/g) and one heteropteran with an elevated level of Mn (> 200 μg/g). Our results show that insects feeding on a Ni hyperaccumulator can mobilize Ni into food webs, although we found no evidence of Ni biomagnification in either herbivore or carnivore insect taxa. We also conclude that some insects associated with hyperaccumulators can contain Ni levels that are high enough to be toxic to vertebrates.

  5. High-Arctic Plant-Herbivore Interactions under Climate Influence

    Berg, Thomas B.; Schmidt, Niels M.; Høye, Toke Thomas; Aastrup, Peter J.; Hendrichsen, Ditte Katrine; Forchhammer, Mads C.; Klein, David R.

    production of plants indirectly, influenced the spatial distribution of herbivores. Additionally, snow distribution directly affected the distribution of herbivores, and hence, in turn, affected the plant community by selective feeding and locally reducing the standing biomass of forage plants. Although only...... by influencing their access to forage in winter. During winter, musk oxen prefer areas with a thin snow-cover, where food is most easily accessible. In contrast, lemmings seek areas with thick snow-cover, which provide protection from the cold and some predators. Therefore, lemmings may be affected...... few moth larvae were observed at Zackenberg, these had in some cases important local effects owing to their foraging on up to 60% of the flower stands on individual mountain avens. UV-B radiation induces plants to produce secondary plant metabolites, which protects tissues against UV-B damage. This...

  6. Combined effects of arthropod herbivores and phytopathogens on plant performance

    Hauser, Thure Pavlo; Christensen, Stina; Heimes, Christine;

    2013-01-01

    1. Many plants are simultaneously attacked by arthropod herbivores and phytopathogens. These may affect each other directly and indirectly, enhancing or reducing the amount of plant resources they each consume. Ultimately, this may reduce or enhance plant performance relative to what should be ex....... However, as interactive impacts also differed among environments and parasite manipulation methods, this suggests that the ability of plants to compensate such losses may depend on environmental conditions and probably also overall infection load....... patterns we found were related to plant traits and experimental conditions. 5. Our results suggest that immediate loss of resources from interactions between arthropod herbivores and pathogens is generally moderated by compensation to an extent where there are no interactive effects on plant performance...

  7. Edible insects are the future?

    van Huis, Arnold

    2016-08-01

    The global increase in demand for meat and the limited land area available prompt the search for alternative protein sources. Also the sustainability of meat production has been questioned. Edible insects as an alternative protein source for human food and animal feed are interesting in terms of low greenhouse gas emissions, high feed conversion efficiency, low land use, and their ability to transform low value organic side streams into high value protein products. More than 2000 insect species are eaten mainly in tropical regions. The role of edible insects in the livelihoods and nutrition of people in tropical countries is discussed, but this food source is threatened. In the Western world, there is an increasing interest in edible insects, and examples are given. Insects as feed, in particular as aquafeed, have a large potential. Edible insects have about the same protein content as conventional meat and more PUFA. They may also have some beneficial health effects. Edible insects need to be processed and turned into palatable dishes. Food safety may be affected by toxicity of insects, contamination with pathogens, spoilage during conservation and allergies. Consumer attitude is a major issue in the Western world and a number of strategies are proposed to encourage insect consumption. We discuss research pathways to make insects a viable sector in food and agriculture: an appropriate disciplinary focus, quantifying its importance, comparing its nutritional value to conventional protein sources, environmental benefits, safeguarding food safety, optimising farming, consumer acceptance and gastronomy. PMID:26908196

  8. Aquatic herbivores facilitate the emission of methane from wetlands

    Dingemans, B.J.J.; Bakker, E.S.; Bodelier, P.L.E.

    2011-01-01

    Wetlands are significant sources of atmospheric methane. Methane produced by microbes enters roots and escapes to the atmosphere through the shoots of emergent wetland plants. Herbivorous birds graze on helophytes, but their effect on methane emission remains unknown. We hypothesized that grazing on shoots of wetland plants can modulate methane emission from wetlands. Diffusive methane emission was monitored inside and outside bird exclosures, using static flux chambers placed over whole vege...

  9. Contrasting Effects of Different Mammalian Herbivores on Sagebrush Plant Communities

    Kari E Veblen; Nehring, Kyle C.; McGlone, Christopher M.; Ritchie, Mark E.

    2015-01-01

    Herbivory by both grazing and browsing ungulates shapes the structure and functioning of terrestrial ecosystems worldwide, and both types of herbivory have been implicated in major ecosystem state changes. Despite the ecological consequences of differences in diets and feeding habits among herbivores, studies that experimentally distinguish effects of grazing from spatially co-occurring, but temporally segregated browsing are extremely rare. Here we use a set of long-term exclosures in northe...

  10. Contrasting effects of different mammalian herbivores on sagebrush plant communities.

    Kari E Veblen

    Full Text Available Herbivory by both grazing and browsing ungulates shapes the structure and functioning of terrestrial ecosystems worldwide, and both types of herbivory have been implicated in major ecosystem state changes. Despite the ecological consequences of differences in diets and feeding habits among herbivores, studies that experimentally distinguish effects of grazing from spatially co-occurring, but temporally segregated browsing are extremely rare. Here we use a set of long-term exclosures in northern Utah, USA, to determine how domestic grazers vs. wild ungulate herbivores (including browsers and mixed feeders affect sagebrush-dominated plant communities that historically covered ~62 million ha in North America. We sampled plant community properties and found that after 22 years grazing and browsing elicited perceptible changes in overall plant community composition and distinct responses by individual plant species. In the woody layer of the plant community, release from winter and spring wild ungulate herbivory increased densities of larger Wyoming big sagebrush (Artemisia tridentata, ssp. wyomingensis at the expense of small sagebrush, while disturbance associated with either cattle or wild ungulate activity alone was sufficient to increase bare ground and reduce cover of biological soil crusts. The perennial bunchgrass, bottlebrush squirretail (Elymus elymoides, responded positively to release from summer cattle grazing, and in turn appeared to competitively suppress another more grazing tolerant perennial grass, Sandberg's blue grass (Poa secunda. Grazing by domestic cattle also was associated with increased non-native species biomass. Together, these results illustrate that ungulate herbivory has not caused sagebrush plant communities to undergo dramatic state shifts; however clear, herbivore-driven shifts are evident. In a dry, perennial-dominated system where plant community changes can occur very slowly, our results provide insights into

  11. Chemically rich seaweeds poison corals when not controlled by herbivores

    Rasher, Douglas B; Hay, Mark E.

    2010-01-01

    Coral reefs are in dramatic global decline, with seaweeds commonly replacing corals. It is unclear, however, whether seaweeds harm corals directly or colonize opportunistically following their decline and then suppress coral recruitment. In the Caribbean and tropical Pacific, we show that, when protected from herbivores, ~40 to 70% of common seaweeds cause bleaching and death of coral tissue when in direct contact. For seaweeds that harmed coral tissues, their lipid-soluble extracts also prod...

  12. Herbivorous ecomorphology and specialization patterns in theropod dinosaur evolution.

    Zanno, Lindsay E; Makovicky, Peter J

    2011-01-01

    Interpreting key ecological parameters, such as diet, of extinct organisms without the benefit of direct observation or explicit fossil evidence poses a formidable challenge for paleobiological studies. To date, dietary categorizations of extinct taxa are largely generated by means of modern analogs; however, for many species the method is subject to considerable ambiguity. Here we present a refined approach for assessing trophic habits in fossil taxa and apply the method to coelurosaurian dinosaurs--a clade for which diet is particularly controversial. Our findings detect 21 morphological features that exhibit statistically significant correlations with extrinsic fossil evidence of coelurosaurian herbivory, such as stomach contents and a gastric mill. These traits represent quantitative, extrinsically founded proxies for identifying herbivorous ecomorphology in fossils and are robust despite uncertainty in phylogenetic relationships among major coelurosaurian subclades. The distribution of these features suggests that herbivory was widespread among coelurosaurians, with six major subclades displaying morphological evidence of the diet, and that contrary to previous thought, hypercarnivory was relatively rare and potentially secondarily derived. Given the potential for repeated, independent evolution of herbivory in Coelurosauria, we also test for repetitive patterns in the appearance of herbivorous traits within sublineages using rank concordance analysis. We find evidence for a common succession of increasing specialization to herbivory in the subclades Ornithomimosauria and Oviraptorosauria, perhaps underlain by intrinsic functional and/or developmental constraints, as well as evidence indicating that the early evolution of a beak in coelurosaurians correlates with an herbivorous diet. PMID:21173263

  13. Light, nutrients, and herbivore growth in oligotrophic streams

    Hill, Walter R [ORNL; Smith, John G [ORNL; Stewart, Arthur J [ORNL

    2010-02-01

    The light : nutrient hypothesis posits that herbivore growth is increasingly constrained by low food quality as the ratio of light to nutrients increases in aquatic ecosystems. We tested predictions of this hypothesis by examining the effects of large seasonal cycles in light and nutrients on the mineral content of periphyton and the growth rate of a dominant herbivore (the snail Elimia clavaeformis) in two oligotrophic streams. Streambed irradiances in White Oak Creek and Walker Branch (eastern Tennessee, USA) varied dramatically on a seasonal basis due to leaf phenology in the surrounding deciduous forests and seasonal changes in sun angle. Concentrations of dissolved nutrients varied inversely with light, causing light : nitrate and light : phosphate to range almost 100-fold over the course of any individual year. Periphyton nitrogen and phosphorus concentrations were much lower than the concentrations of these elements in snails, and they bottomed out in early spring when streambed irradiances were highest. Snail growth, however, peaked in early spring when light:nutrient ratios were highest and periphyton nutrient concentrations were lowest, Growth was linearly related to primary production (accounting for up to 85% of growth variance in individual years), which in turn was driven by seasonal variation in light. Conceptual models of herbivore growth indicate that growth should initially increase as increasing light levels stimulate primary production, but then level off, and then decrease as the negative effects of decreasing algal nutrient content override the positive effects of increased food production. Our results showed no evidence of an inflection point where increasing ratios of light to nutrients negatively affected growth. Snail growth in these intensively grazed streams is probably unaffected by periphyton nutrient content because exploitative competition for food reduces growth rates to levels where the demand for nitrogen and phosphorus is small

  14. Termites, vertebrate herbivores, and the fruiting success of Acacia drepanolobium.

    Brody, Alison K; Palmer, Todd M; Fox-Dobbs, Kena; Doak, Dan F

    2010-02-01

    In African savannas, vertebrate herbivores are often identified as key determinants of plant growth, survivorship, and reproduction. However, plant reproduction is likely to be the product of responses to a suite of abiotic and biotic factors, including nutrient availability and interactions with antagonists and mutualists. In a relatively simple system, we examined the role of termites (which act as ecosystem engineers--modifying physical habitat and creating islands of high soil fertility), vertebrate herbivores, and symbiotic ants, on the fruiting success of a dominant plant, Acacia drepanolobium, in East African savannas. Using observational data, large-scale experimental manipulations, and analysis of foliar N, we found that Acacia drepanolobium trees growing at the edge of termite mounds were more likely to reproduce than those growing farther away, in off-mound soils. Although vertebrate herbivores preferentially used termite mounds as demonstrated by dung deposits, long-term exclusion of mammalian grazers did not significantly reduce A. drepanolobium fruit production. Leaf N was significantly greater in trees growing next to mounds than in those growing farther away, and this pattern was unaffected by exclusion of vertebrates. Thus, soil enrichment by termites, rather than through dung and urine deposition by large herbivores, is of primary importance to fruit production near mounds. Across all mound-herbivore treatment combinations, trees that harbored Crematogaster sjostedti were more likely to fruit than those that harbored one of the other three ant species. Although C. sjostedti is less aggressive than the other ants, it tends to inhabit large, old trees near termite mounds which are more likely to fruit than smaller ones. Termites play a key role in generating patches of nutrient-rich habitat important to the reproductive success of A. drepanolobium in East African savannas. Enhanced nutrient acquisition from termite mounds appears to allow plants to

  15. Climatic change and insect outbreaks

    Insects represent the dominant natural disturbance factor in Canada's forests. Host trees are often killed over extensive areas. This paper examines how climate change may influence insect outbreak regimes in Canada's forests, primarily focusing on temperature, as the potential rate of increase of many insects is dependent on temperature. The extent and frequency of temperature extremes can have major impacts on insect populations. Temperature increases will accelerate development, activity and movement as well as influence reduced mortality from climatic factors. In addition, higher temperatures are likely to facilitate extended periods of activity at both ends of the season. It was concluded that a number of complex factors will likely determine the direct effect of increasing temperatures on insects. Changes in the abiotic environment, changes in species interactions, and changes in the regimes of natural selection will influence future insect activity. For example, increases in carbon:nitrogen ratios are expected to cause insects to eat more in order to maintain dietary nitrogen. The effects of climate change is expected to differ quantitatively among species in the complex food chains where most insect species are embedded. It is also assumed that if geographic distribution of insects shifts in response to climate change, their impact should basically remain static. Most published scenarios suggest that outbreaks of insects in Canada will last longer and occur more frequently where the climate will become warmer. However, climate warming may also allow certain insects to extend their ranges into regions of vulnerable host species. It was suggested that further research is necessary, as no data has been collected on how insects might respond to predicted, concurrent changes in atmospheric chemistry and climate. 19 refs

  16. A Moveable Feast: Insects Moving at the Forest-Crop Interface Are Affected by Crop Phenology and the Amount of Forest in the Landscape

    González, Ezequiel; Salvo, Adriana; Defagó, María Teresa; Valladares, Graciela

    2016-01-01

    Edges have become prevailing habitats, mainly as a result of habitat fragmentation and agricultural expansion. The interchange of functionally relevant organisms like insects occurs through these edges and can influence ecosystem functioning in both crop and non-crop habitats. However, very few studies have focused on the directionality of insect movement through edges, and the role of crop and non-crop amount has been ignored. Using bi-directional flight interception traps we investigated interchange of herbivore, natural enemy, pollinator and detritivore insects between native forest fragments and soybean crops, simultaneously considering movement direction, forest cover in the landscape and crop phenology. In total, 52,173 specimens and 877 morphospecies were collected. We found that, within most functional and taxonomic groups, movement intensity was similar (richness and/or abundance) between directions, whereas a predominantly forest-to-crop movement characterized natural enemies. Insect movement was extensively affected by crop phenology, decreasing during crop senescence, and was enhanced by forest cover particularly at senescence. Mainly the same herbivore species moved to and from the forest, but different natural enemy species predominated in each direction. Finally, our analyses revealed greater forest contribution to natural enemy than to herbivore communities in the crop, fading with distance to the forest in both groups. By showing that larger amounts of forest lead to richer insect interchange, in both directions and in four functional groups, our study suggests that allocation to natural and cultivated habitats at landscape level could influence functioning of both systems. Moreover, natural enemies seemed to benefit more than pests from natural vegetation, with natural enemy spillover from forests likely contributing to pest control in soybean fields. Thus consequences of insect interchange seem to be mostly positive for the agroecosystem

  17. Insect bite prevention.

    Moore, Sarah J; Mordue Luntz, Anne Jennifer; Logan, James G

    2012-09-01

    Protection from the bites of arthropod (insect and acarine) vectors of disease is the first line of defense against disease transmission and should be advised in all cases when traveling abroad. Details are described of the main approaches for the prevention of bites, including topical or skin repellents, impregnated clothing, bed nets, and spatial or aerial repellents and aerosols. The bionomics of the main arthropod vectors of disease are described along with photographic plates and tabulated advice to give the traveler. An in-depth treatment of the different protection methodologies provides an up-to-date overview of the technologies involved. PMID:22963776

  18. Insect flight muscle metabolism

    Horst, D.J. van der; Beenakkers, A.M.Th.; Marrewijk, W.J.A. van

    1984-01-01

    The flight of an insect is of a very complicated and extremely energy-demanding nature. Wingbeat frequency may differ between various species but values up to 1000 Hz have been measured. Consequently metabolic activity may be very high during flight and the transition from rest to flight is accompanied by an increase of 50-100-fold in metabolic rate. Small mammals running at maximal speed and flying birds achieve metabolic rates exceeding resting levels by only 7-14-fold. The exaggerated meta...

  19. Adaptation of a polyphagous herbivore to a novel host plant extensively shapes the transcriptome of herbivore and host.

    Wybouw, Nicky; Zhurov, Vladimir; Martel, Catherine; Bruinsma, Kristie A; Hendrickx, Frederik; Grbić, Vojislava; Van Leeuwen, Thomas

    2015-09-01

    Generalist arthropod herbivores rapidly adapt to a broad range of host plants. However, the extent of transcriptional reprogramming in the herbivore and its hosts associated with adaptation remains poorly understood. Using the spider mite Tetranychus urticae and tomato as models with available genomic resources, we investigated the reciprocal genomewide transcriptional changes in both spider mite and tomato as a consequence of mite's adaptation to tomato. We transferred a genetically diverse mite population from bean to tomato where triplicated populations were allowed to propagate for 30 generations. Evolving populations greatly increased their reproductive performance on tomato relative to their progenitors when reared under identical conditions, indicative of genetic adaptation. Analysis of transcriptional changes associated with mite adaptation to tomato revealed two main components. First, adaptation resulted in a set of mite genes that were constitutively downregulated, independently of the host. These genes were mostly of an unknown function. Second, adapted mites mounted an altered transcriptional response that had greater amplitude of changes when re-exposed to tomato, relative to nonadapted mites. This gene set was enriched in genes encoding detoxifying enzymes and xenobiotic transporters. Besides the direct effects on mite gene expression, adaptation also indirectly affected the tomato transcriptional responses, which were attenuated upon feeding of adapted mites, relative to the induced responses by nonadapted mite feeding. Thus, constitutive downregulation and increased transcriptional plasticity of genes in a herbivore may play a central role in adaptation to host plants, leading to both a higher detoxification potential and reduced production of plant defence compounds. PMID:26211543

  20. Insects vis a vis radiations

    Insects have turned out to be much more radiation resistant. For most insects a dose of about 500-700 Gy is required to kill them within a few weeks of exposure; although cockroaches require 900-1000 Gy. Killing insects in less than a few days requires much higher doses. These doses are for mature insects, the immature stages of some insects can be killed by doses as low as 40 Gy. Some insects can be sterilized at even lower doses, and this has application in insect control. Screw-worms, for example, can be sterilized with doses of 25-50 Gy. By contrast, doses as low as 3 Gy caused death of humans in Hiroshima and Nagasaki and doses of about 6 Gy caused death of fire fighters in the Chernobyl accident. It is not exactly certain what the basis is for the resistance of insects to ionizing radiation. It is not animal size by itself, nor lack of penetration. It is also not because of few dividing cells as these are more radiosensitive than non-dividing ones. The speculation that insects might have lower oxygen tensions, and the lack of oxygen is known to protect cells from radiation also does not work. Insect cells might have an enhanced capacity to repair radiation damage also could not be proven. The number of chromosomes influenced radio-sensitivity, and that insects had fewer chromosomes could be true. The radiation resistance is inherent to the cells, since cells derived from insects are also radiation resistant when grown in cell culture. For example, a dose of 60 Gy is required to produce a 80% kill of insect cells, while doses of 1-2 Gy are sufficient to generate this level of killing in mammalian cells. But, nevertheless, according to recent researches, radiation from Japan's leaking Fukushima nuclear plant has caused mutations in some butterflies. It is therefore clear that insects are resistant to ionizing radiation and that this resistance is an inherent property of their cells. But it is not clear exactly what the basis of this cellular resistance is