The role of female search behaviour in determining host plant range in plant feeding insects: a test of the information processing hypothesis

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Janz, N.; Nylin, S.

1997-01-01

Recent theoretical studies have suggested that host range in herbivorous insects may be more restricted by constraints on information processing on the ovipositing females than by trade-offs in larval feeding efficiency. We have investigated if females from polyphagous species have to pay for their ability to localize and evaluate plants from different species with a lower ability to discriminate between conspecific host plants with differences in quality. Females of the monophagous butterfli...

Fungal diversity associated with Hawaiian Drosophila host plants.

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Brian S Ort

Full Text Available Hawaiian Drosophila depend primarily, sometimes exclusively, on specific host plants for oviposition and larval development, and most specialize further on a particular decomposing part of that plant. Differences in fungal community between host plants and substrate types may establish the basis for host specificity in Hawaiian Drosophila. Fungi mediate decomposition, releasing plant micronutrients and volatiles that can indicate high quality substrates and serve as cues to stimulate oviposition. This study addresses major gaps in our knowledge by providing the first culture-free, DNA-based survey of fungal diversity associated with four ecologically important tree genera in the Hawaiian Islands. Three genera, Cheirodendron, Clermontia, and Pisonia, are important host plants for Drosophila. The fourth, Acacia, is not an important drosophilid host but is a dominant forest tree. We sampled fresh and rotting leaves from all four taxa, plus rotting stems from Clermontia and Pisonia. Based on sequences from the D1/D2 domain of the 26S rDNA gene, we identified by BLAST search representatives from 113 genera in 13 fungal classes. A total of 160 operational taxonomic units, defined on the basis of ≥97% genetic similarity, were identified in these samples, but sampling curves show this is an underestimate of the total fungal diversity present on these substrates. Shannon diversity indices ranged from 2.0 to 3.5 among the Hawaiian samples, a slight reduction compared to continental surveys. We detected very little sharing of fungal taxa among the substrates, and tests of community composition confirmed that the structure of the fungal community differed significantly among the substrates and host plants. Based on these results, we hypothesize that fungal community structure plays a central role in the establishment of host preference in the Hawaiian Drosophila radiation.

Immature stages and the larval food plant of Nacaduba pactolus ceylonica Fruhstorfer, 1916 (Lepidoptera: Lycaenidae in Sri Lanka

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Tharaka Sudesh Priyadarshana

2015-10-01

Full Text Available The biology of  Nacaduba pactolus ceylonica (Large Four-lineblue , a rare butterfly endemic to Sri Lanka is described with a report of Entada rheedii (Fabaceae as the first known larval host plant. Information pertaining to the distribution of this butterfly is also provided.

Conspecific mimics and low host plant availability reduce egg laying by Heliconius erato phyllis (Fabricius (Lepidoptera, Nymphalidae

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Elna Mugrabi-Oliveira

1996-01-01

Full Text Available Oviposition response of Heliconius erato phyllis (Fabricius, 1775 (Lepidoptera, Nymphalidae to variation in host plant availability, Passiflora suberosa Linnaeus (Passifloraceae, and to presence of conspecific eggs and larvae was determined through choice experiments performed under insectary conditions. Freeze dried, painted eggs and larvae were used as mimics for testing presence of conspecific effects. Females laid more eggs on intact P. suberosa shoots without conspecifics than on those with H. erato phyllis egg and first instar mimics in both simultaneous and sequential choice trials. Oviposition response to variation in host plant availability was determined through no-choice trials, under host plant densities varying from 0.3 to 8.3 plants per female. Number of eggs laid per plant decreased exponentially with an increase in plant availability. On the contrary, daily oviposition rates (eggs /female/day increased with an increase in plant number, and levelled off when the number of plants available for oviposition was greater than potential fecundity of females. Thus, it is inferred from the results that females assess egg and larval load and prefer to lay eggs on shoots free from conspecifics. It is also inferred that they are able to recognize plant abundance and are unwilling to lay more than one egg per shoot even when host availability is scarce, as judged by reduction in daily oviposition rates under low host plant number. The consequences of laying isolated eggs on P. suberosa shoots are discussed from the viewpoint of intraspecific competition in the larval stage of H. erato phyllis.

Anthropogenic host plant expansion leads a nettle-feeding butterfly out of the forest: consequences for larval survival and developmental plasticity in adult morphology.

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Merckx, Thomas; Serruys, Mélanie; Van Dyck, Hans

2015-04-01

Recent anthropogenic eutrophication has meant that host plants of nettle-feeding insects became quasi-omnipresent in fertile regions of Western Europe. However, host plant resource quality - in terms of microclimate and nutritional value - may vary considerably between the 'original' forest habitat and 'recent' agricultural habitat. Here, we compared development in both environmental settings using a split-brood design, so as to explore to what extent larval survival and adult morphology in the nettle-feeding butterfly Aglais urticae are influenced by the anthropogenic environment. Nettles along field margins had higher C/N ratios and provided warmer microclimates to larvae. Larvae developed 20% faster and tended to improve their survival rates, on the agricultural land compared to woodland. Our split-brood approach indicated plastic responses within families, but also family effects in the phenotypic responses. Adult males and females had darker wing pigmentation in the drier and warmer agricultural environment, which contrasts with the thermal melanism hypothesis. Developmental plasticity in response to this microclimatically different and more variable habitat was associated with a broader phenotypic parameter space for the species. Both habitat expansion and developmental plasticity are likely contributors to the ecological and evolutionary success of these nettle-feeding insects in anthropogenic environments under high nitrogen load.

Preferência alimentar, efeito da planta hospedeira e da densidade larval na sobrevivência e desenvolvimento de Dione juno juno (Cramer (Lepidoptera, Nymphalidae Feeding preference, host-plant and larval density effects on survivorship and growth rates of Dione juno juno (Cramer (Lepidoptera, Nymphalidae

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Vidica Bianchi

2005-03-01

, 1753; P. capsularis Linnaeus, 1753; P. edulis Sims, 1818; P. elegans Masters, 1872; P. misera Humbold, Bonpland et Kunth, 1817; P. suberosa Linnaeus, 1753; P. tenuifila Killip, 1927 and P. warmingii Masters, 1872. Larval density effect on performance was also tested on P. edulis, by using seven larval group sizes: one, two, eight, sixteen, thirty-two and sixty-four larvae. Larval feeding preferences were evaluated through leaf disk, single and multiple choice tests. Larvae achieved the greatest survivorship on P. misera, P. tenuifila and P. edulis. None survived on P. alata, P. capsularis, P. amesthystina, P. suberosa, and P. warmingii. Larvae chose P. edulis on multiple choice tests. They ingested similar amounts of P. tenuifila, P. misera and P. caerulea on single choice tests. Larval growth rates were greater, and adults were larger when reared on P. misera compared to P. edulis. Survivorship was significantly reduced on group sizes of one, two and four larvae, and thus may account for the larval aggregation behavior on this species. We concluded that a few passion vine species other than P. edulis can act as potential host-plants for D. juno juno in Rio Grande do Sul State. From an ecological perspective, however, most of these alternative host-plant species present limitations regarding either suitability, plant size or abundance.

Light brown apple moth in California: a diversity of host plants and indigenous parasitoids.

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Wang, Xin-Geng; Levy, Karmit; Mills, Nicholas J; Daane, Kent M

2012-02-01

The light brown apple moth, Epiphyas postvittana (Walker), an Australia native tortricid, was found in California in 2006. A field survey of host plants used by E. postvittana was conducted in an urban region of the San Francisco Bay Area. An inspection of 152 plant species (66 families), within a 23-ha residential community, found E. postvittana on 75 species (36 families). Most (69 species) host plants were not Australian natives, but had a wide geographic origin; 34 species were new host records for E. postvittana. Heavily infested species were the ornamental shrubs Myrtus communis L., Pittosporum tobira (Thunb.) W.T. Aiton, Euonymus japonicus Thunb., and Sollya heterophylla Lindl. To survey for parasitoids, four urban locations were sampled, with E. postvittana collected from five commonly infested plants [M. communis, P. tobira, E. japonicus, Rosmarinus officinalis L., and Genista monspessulana (L.) L.A.S. Johnson]. Twelve primary parasitoid species and two hyperparasitoids were reared; the most common were the egg parasitoid Trichogramma fasciatum (Perkins), the larval parasitoids Meteorus ictericus Nees, and Enytus eureka (Ashmead), and the pupal parasitoid Pediobius ni Peck. Meteorus ictericus accounted for >80% of the larval parasitoids, and was recovered from larvae collected on 39 plant species. Across all samples, mean parasitism was 84.4% for eggs, 43.6% for larvae, and 57.5% for pupae. The results are discussed with respect to the potential for resident parasitoid species to suppress E. postvittana populations.

Evolution of larval competitiveness and associated life-history traits in response to host shifts in a seed beetle.

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Fox, C W; Messina, F J

2018-02-01

Resource competition is frequently strong among parasites that feed within small discrete resource patches, such as seeds or fruits. The properties of a host can influence the behavioural, morphological and life-history traits of associated parasites, including traits that mediate competition within the host. For seed parasites, host size may be an especially important determinant of competitive ability. Using the seed beetle, Callosobruchus maculatus, we performed replicated, reciprocal host shifts to examine the role of seed size in determining larval competitiveness and associated traits. Populations ancestrally associated with either a small host (mung bean) or a large one (cowpea) were switched to each other's host for 36 generations. Compared to control lines (those remaining on the ancestral host), lines switched from the small host to the large host evolved greater tolerance of co-occurring larvae within seeds (indicated by an increase in the frequency of small seeds yielding two adults), smaller egg size and higher fecundity. Each change occurred in the direction predicted by the traits of populations already adapted to cowpea. However, we did not observe the expected decline in adult mass following the shift to the larger host. Moreover, lines switched from the large host (cowpea) to the small host (mung bean) did not evolve the predicted increase in larval competitiveness or egg size, but did exhibit the predicted increase in body mass. Our results thus provide mixed support for the hypothesis that host size determines the evolution of competition-related traits of seed beetles. Evolutionary responses to the two host shifts were consistent among replicate lines, but the evolution of larval competition was asymmetric, with larval competitiveness evolving as predicted in one direction of host shift, but not the reverse. Nevertheless, our results indicate that switching hosts is sufficient to produce repeatable and rapid changes in the competition strategy

Species associations among larval helminths in an amphipod intermediate host.

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Dezfuli, B S; Giari, L; Poulin, R

2000-10-01

Larval helminths that share the same intermediate host may or may not also share the same definitive hosts. If one or more of these helminth species can manipulate the phenotype of the intermediate host, there can be great advantages or severe costs for other helminths resulting from co-occurring with a manipulator, depending on whether they have the same definitive host or not. Among 2372 specimens of the amphipod Echinogammarus stammeri collected from the river Brenta, northern Italy, there was a positive association between two acanthocephalan species with the same fish definitive hosts, the relatively common Pomphorhynchus laevis and the much less prevalent Acanthocephalus clavula. The number of cystacanths of P. laevis per infected amphipod, which ranged from one to five, did not influence the likelihood that the amphipod would also host A. clavula. A third acanthocephalan species, Polymorphus minutus,which matures in birds, showed no association with either of the two other species. These results show that associations among helminth species in intermediate hosts are not random, and are instead the product of selection favouring certain pathways of transmission.

Larval Performance in the Context of Ecological Diversification and Speciation in Lycaeides Butterflies

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Cynthia F. Scholl

2012-01-01

Full Text Available The role of ecology in diversification has been widely investigated, though few groups have been studied in enough detail to allow comparisons of different ecological traits that potentially contribute to reproductive isolation. We investigated larval performance within a species complex of Lycaeides butterflies. Caterpillars from seven populations were reared on five host plants, asking if host-specific, adaptive larval traits exist. We found large differences in performance across plants and fewer differences among populations. The patterns of performance are complex and suggest both conserved traits (i.e., plant effects across populations and more recent dynamics of local adaptation, in particular for L. melissa that has colonized an exotic host. We did not find a relationship between oviposition preference and larval performance, suggesting that preference did not evolve to match performance. Finally, we put larval performance within the context of several other traits that might contribute to ecologically based reproductive isolation in the Lycaeides complex. This larger context, involving multiple ecological and behavioral traits, highlights the complexity of ecological diversification and emphasizes the need for detailed studies on the strength of putative barriers to gene flow in order to fully understand the process of ecological speciation.

Why stay in a bad relationship? The effect of local host phenology on a generalist butterfly feeding on a low-ranked host.

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Audusseau, Hélène; de la Paz Celorio-Mancera, Maria; Janz, Niklas; Nylin, Sören

2016-06-29

In plant-feeding insects, the evolutionary retention of polyphagy remains puzzling. A better understanding of the relationship between these organisms and changes in the metabolome of their host plants is likely to suggest functional links between them, and may provide insights into how polyphagy is maintained. We investigated the phenological change of Cynoglossum officinale, and how a generalist butterfly species, Vanessa cardui, responded to this change. We used untargeted metabolite profiling to map plant seasonal changes in both primary and secondary metabolites. We compared these data to differences in larval performance on vegetative plants early and late in the season. We also performed two oviposition preference experiments to test females' ability to choose between plant developmental stages (vegetative and reproductive) early and late in the season. We found clear seasonal changes in plant primary and secondary metabolites that correlated with larval performance. The seasonal change in plant metabolome reflected changes in both nutrition and toxicity and resulted in zero survival in the late period. However, large differences among families in larval ability to feed on C. officinale suggest that there is genetic variation for performance on this host. Moreover, females accepted all plants for oviposition, and were not able to discriminate between plant developmental stages, in spite of the observed overall differences in metabolite profile potentially associated with differences in suitability as larval food. In V. cardui, migratory behavior, and thus larval feeding times, are not synchronized with plant phenology at the reproductive site. This lack of synchronization, coupled with the observed lack of discriminatory oviposition, obviously has potential fitness costs. However, this "opportunistic" behavior may as well function as a source of potential host plant evolution, promoting for example the acceptance of new plants.

Characteristics of the larval Echinococcus vogeli Rausch and Bernstein, 1972 in the natural intermediate host, the paca, Cuniculus paca L. (Rodentia: Dasyproctidae).

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Rausch, R L; D'Alessandro, A; Rausch, V R

1981-09-01

In Colombia, the natural intermediate host of Echinococcus vogeli Rausch and Bernstein, 1972 is the paca, Cuniculus paca L. (Rodentia: Dasyproctidae). The larval cestode develops in the liver of the host, where it usually is situated superficially, partly exposed beneath Glisson's capsule. The infective larva consists of a subspherical to asymmetrical, fluid-filled vesicle, up to 30 mm in diameter, enclosed by a thick laminated membrane. It typically contains numerous chambers, often interconnected, produced by endogenous proliferation of germinal and laminated tissue, within which brood capsules arise in an irregular pattern from the germinal layer. Invasive growth by means of exogenous proliferation, typical of infections in man, was not observed in the natural intermediate host. The development of the larval cestode is described on the basis of material from pacas, supplemented by observations on early-stage lesions in experimentally infected nutrias, Myocastor coypus (Molina) (Rodentia: Capromyidae). The tissue response is characterized for early-stage, mature (infective), and degenerating larvae in the comparatively long-lived intermediate host. In addition to previously reported differences in size and form of rostellar hooks, other morphologic characteristics are defined by which the larval stage of E. vogeli is distinguished from that of E. oligarthrus (Diesing, 1863). Pathogenesis by the larval E. vogeli in man, like that by the larval E. multilocularis Leuckart, 1863, is the consequence of atypical proliferation of vesicles attributable to parasite-host incompatibility.

Overexpression of host plant urease in transgenic silkworms.

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Jiang, Liang; Huang, Chunlin; Sun, Qiang; Guo, Huizhen; Peng, Zhengwen; Dang, Yinghui; Liu, Weiqiang; Xing, Dongxu; Xu, Guowen; Zhao, Ping; Xia, Qingyou

2015-06-01

Bombyx mori and mulberry constitute a model of insect-host plant interactions. Urease hydrolyzes urea to ammonia and is important for the nitrogen metabolism of silkworms because ammonia is assimilated into silk protein. Silkworms do not synthesize urease and acquire it from mulberry leaves. We synthesized the artificial DNA sequence ureas using the codon bias of B. mori to encode the signal peptide and mulberry urease protein. A transgenic vector that overexpresses ure-as under control of the silkworm midgut-specific P2 promoter was constructed. Transgenic silkworms were created via embryo microinjection. RT-PCR results showed that urease was expressed during the larval stage and qPCR revealed the expression only in the midgut of transgenic lines. Urea concentration in the midgut and hemolymph of transgenic silkworms was significantly lower than in a nontransgenic line when silkworms were fed an artificial diet. Analysis of the daily body weight and food conversion efficiency of the fourth and fifth instar larvae and economic characteristics indicated no differences between transgenic silkworms and the nontransgenic line. These results suggested that overexpression of host plant urease promoted nitrogen metabolism in silkworms.

The effect of host developmental stage at parasitism on sex-related size differentiation in a larval endoparasitoid

NARCIS (Netherlands)

Gols, R.; Harvey, J.A.

2009-01-01

1. For their larval development, parasitoids depend on the quality and quantity of resources provided by a single host. Therefore, a close relationship is predicted between the size of the host at parasitism and the size of the emerging adult wasp. This relationship is less clear for koinobiont than

The role of herbivore- and plant-related experiences in intraspecific host preference of a relatively specialized parasitoid.

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Morawo, Tolulope; Fadamiro, Henry

2017-09-06

Parasitoids use odor cues from infested plants and herbivore hosts to locate their hosts. Specialist parasitoids of generalist herbivores are predicted to rely more on herbivore-derived cues than plant-derived cues. Microplitis croceipes (Cresson) (Hymenoptera: Braconidae) is a relatively specialized larval endoparasitoid of Heliothis virescens (F.) (Lepidoptera: Noctuidae), which is a generalist herbivore on several crops including cotton and soybean. Using M. croceipes/H. virescens as a model system, we tested the following predictions about specialist parasitoids of generalist herbivores: (i) naive parasitoids will show innate responses to herbivore-emitted kairomones, regardless of host plant identity and (ii) herbivore-related experience will have a greater influence on intraspecific oviposition preference than plant-related experience. Inexperienced (naive) female M. croceipes did not discriminate between cotton-fed and soybean-fed H. virescens in oviposition choice tests, supporting our first prediction. Oviposition experience alone with either host group influenced subsequent oviposition preference while experience with infested plants alone did not elicit preference in M. croceipes, supporting our second prediction. Furthermore, associative learning of oviposition with host-damaged plants facilitated host location. Interestingly, naive parasitoids attacked more soybean-fed than cotton-fed host larvae in two-choice tests when a background of host-infested cotton odor was supplied, and vice versa. This suggests that plant volatiles may have created an olfactory contrast effect. We discussed ecological significance of the results and concluded that both plant- and herbivore-related experiences play important role in parasitoid host foraging. © 2017 Institute of Zoology, Chinese Academy of Sciences.

Novel multitrophic interactions among an exotic, generalist herbivore, its host plants and resident enemies in California.

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Hopper, Julie V; Mills, Nicholas J

2016-12-01

What happens when an exotic herbivore invades and encounters novel host plants and enemies? Here, we investigate the impacts of host plant quality and plant architecture on an exotic generalist herbivore, Epiphyas postvittana (Lepidoptera: Tortricidae) and its interactions with resident parasitoids in California. Using artificial diet and five plant species, we found significant effects of diet on the fitness of E. postvittana under laboratory conditions. In the field, based on a common garden experiment with host plants of nine species, we found that larval parasitism varied among plant species by a factor of 2.1 with a higher risk of parasitism on shorter than taller plants. Parasitism of egg masses varied by a factor of 4.7 among plant species with a higher risk of parasitism on taller than shorter plants. In the laboratory, the foraging time of a resident egg parasitoid on excised leaves varied among plant species, but did not correspond to observed egg parasitism rates on these same plants in the field. On leaves of Plantago lanceolata, the probability of egg parasitism decreased with trichome density. Overall, there was a significant effect of host plant on the intrinsic rate of increase of E. postvittana and on the extent of parasitism by resident parasitoids, but no correlation existed between these two effects. The recent decline of E. postvittana in California may be due to the low quality of some host plants and to the many resident enemies that readily attack it, perhaps due to its phylogenetic relatedness to resident tortricids.

Biology and occurrence of Inga Busk species (Lepidoptera: Oecophoridae) on Cerrado host plants.

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Diniz, Ivone R; Bernardes, Carolina; Rodovalho, Sheila; Morais, Helena C

2007-01-01

We sampled Inga Busk species caterpillars weekly in the cerrado on 15 plants of Diospyros burchellii Hern. (Ebenaceae) from January 2002 to December 2003, on 30 plants of Caryocar brasiliense (Caryocaraceae) from July 2003 to June 2004, and since 1991 on several other plant species. In total we found 15 species of Inga on cerrado host plants. Nine species were very rare, with only one to five adults reared. The other six species occurred throughout the year, with higher abundance during the dry season, from May to July, coinciding with overall peaks of caterpillar abundance in the cerrado. Caterpillars of the genus Inga build shelters by tying and lining two mature or old leaves with silk and frass, where they rest and develop (a common habit found in Oecophorinae). The final instar builds a special envelope inside the leaf shelter, where it will complete the larval stage and pupate. The species are very difficult to distinguish in the immature stages. External features were useful in identifying only four species: I. haemataula (Meyrick), I. phaecrossa (Meyrick), I. ancorata (Walsingham), and I. corystes (Meyrick). These four species are polyphagous and have wide geographical distributions. In this paper we provide information on the natural history and host plants of six Inga species common on cerrado host plants, for which there are no reports in the literature.

The Role of Female Search Behaviour in Determining Host Plant Range in Plant Feeding Insects: A Test of the Information Processing Hypothesis

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Janz, Niklas; Nylin, Soren

1997-05-01

Recent theoretical studies have suggested that host range in herbivorous insects may be more restricted by constraints on information processing on the ovipositing females than by trade-offs in larval feeding efficiency. We have investigated if females from polyphagous species have to pay for their ability to localize and evaluate plants from different species with a lower ability to discriminate between conspecific host plants with differences in quality. Females of the monophagous butterflies Polygonia satyrus, Vanessa indica and Inachis io and the polyphagous P. c-album and Cynthia cardui (all in Lepidoptera, Nymphalidae) were given a simultaneous choice of stinging nettles (Urtica dioica) of different quality. In addition, the same choice trial was given to females from two populations of P. c-album with different degrees of specificity. As predicted from the information processing hypothesis, all specialists discriminated significantly against the bad quality nettle, whereas the generalists laid an equal amount of eggs on both types of nettle. There were no corresponding differences between specialist and generalist larvae in their ability to utilize poor quality leaves. Our study therefore suggests that female host-searching behaviour plays an important role in determining host plant range.

Application of radioisotope tracer techniques in studies on host-parasite relationships, with special reference to larval trematodes. A review

International Nuclear Information System (INIS)

Christensen, N.Oe.

1981-01-01

The application of radioisotope tracer techniques in studies on various host-parasite relationships between larval trematodes and their intermediate and definite hosts is reviewed. Such studies comprise, for example, the reproduction and nutrition of various developmental stages of trematodes in relation to host and environment. The preparation and application of radiolabelled larvae are also discussed with special emphasis on their use in studies on free-living ecology and migration in hosts. (author)

(Brief report Evaluation of Suitable Host Plant, as Banker Plant for Eretmocerus mundus, Whiteflies Parasitoid

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M. J. Ardeh

2016-03-01

the parasitoid were evaluated on the two different host plants. The sex ratio was recorded in two different ways; 1 100 pupae developed on each plants were put in vials, and 2 the wasps that emerged daily from collected leaves. In the next experiment, a leaflet of each host plant (2.5  3 cm, that was infested with the second and third stages of B. tabaci, was fixed upside down on a piece of wet cotton in a Petri dish. Then, a female parasitoid was release on each to record the host finding time for one minute. Finally, the four female parasitoids were released on an infested host plant for 48 hours, then the wasps were removed and the plants were kept in a climate room. Two weeks later, the leaves were collected and put up side down on cotton pieces in Petri dishes and the duration of the larval stages, the mortality and the number of females and males that come out from them were recorded for the two hosts. Results and Discussion: In total, 438 wasps form the eggplant leaves and 297 from cotton leaves were collected, while 14 and 17 dead pupa were recorded on them, respectively. The data analysis did not show significant differences between them. In host finding experiment, 9 of 15 parasitoids could find the host during one minute on the eggplants leave, whereas, all female parasitoids could find the host on cottons leave, which was significantly different (P value of Fisher's exact test= 0.01689. In the biology parameter experiments on leaves, 192 parasitoid wasps form cotton and 158 from eggplant leaf were collected that were not significantly different (F=5.6; p=0.026. In contrast, on whole plant experiment, 156 wasps (76 females and 80males from cotton plants and 134 wasps (66 females and 68 males from eggplants were collected that were not significantly different (f=1.2; P= 0.32. Conclusion: The results showed that the number of parasitoid and the sex ratio were not significantly different between two host plants, whereas the movement and searching activity

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

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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.

Plant microRNAs in larval food regulate honeybee caste development.

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Zhu, Kegan; Liu, Minghui; Fu, Zheng; Zhou, Zhen; Kong, Yan; Liang, Hongwei; Lin, Zheguang; Luo, Jun; Zheng, Huoqing; Wan, Ping; Zhang, Junfeng; Zen, Ke; Chen, Jiong; Hu, Fuliang; Zhang, Chen-Yu; Ren, Jie; Chen, Xi

2017-08-01

The major environmental determinants of honeybee caste development come from larval nutrients: royal jelly stimulates the differentiation of larvae into queens, whereas beebread leads to worker bee fate. However, these determinants are not fully characterized. Here we report that plant RNAs, particularly miRNAs, which are more enriched in beebread than in royal jelly, delay development and decrease body and ovary size in honeybees, thereby preventing larval differentiation into queens and inducing development into worker bees. Mechanistic studies reveal that amTOR, a stimulatory gene in caste differentiation, is the direct target of miR162a. Interestingly, the same effect also exists in non-social Drosophila. When such plant RNAs and miRNAs are fed to Drosophila larvae, they cause extended developmental times and reductions in body weight and length, ovary size and fecundity. This study identifies an uncharacterized function of plant miRNAs that fine-tunes honeybee caste development, offering hints for understanding cross-kingdom interaction and co-evolution.

Cockchafer larvae smell host root scents in soil.

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Sonja Weissteiner

Full Text Available In many insect species olfaction is a key sensory modality. However, examination of the chemical ecology of insects has focussed up to now on insects living above ground. Evidence for behavioral responses to chemical cues in the soil other than CO(2 is scarce and the role played by olfaction in the process of finding host roots below ground is not yet understood. The question of whether soil-dwelling beetle larvae can smell their host plant roots has been under debate, but proof is as yet lacking that olfactory perception of volatile compounds released by damaged host plants, as is known for insects living above ground, occurs. Here we show that soil-dwelling larvae of Melolontha hippocastani are well equipped for olfactory perception and respond electrophysiologically and behaviorally to volatiles released by damaged host-plant roots. An olfactory apparatus consisting of pore plates at the antennae and about 70 glomeruli as primary olfactory processing units indicates a highly developed olfactory system. Damage induced host plant volatiles released by oak roots such as eucalyptol and anisol are detected by larval antennae down to 5 ppbv in soil air and elicit directed movement of the larvae in natural soil towards the odor source. Our results demonstrate that plant-root volatiles are likely to be perceived by the larval olfactory system and to guide soil-dwelling white grubs through the dark below ground to their host plants. Thus, to find below-ground host plants cockchafer larvae employ mechanisms that are similar to those employed by the adult beetles flying above ground, despite strikingly different physicochemical conditions in the soil.

Role of emerald ash borer (Coleoptera: Buprestidae) larval vibrations in host-quality assessment by Tetrastichus planipennisi (Hymenoptera: Eulophidae).

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Ulyshen, Michael D; Mankin, Richard W; Chen, Yigen; Duan, Jian J; Poland, Therese M; Bauer, Leah S

2011-02-01

The biological control agent Tetrastichus planipennisi Yang (Hymenoptera: Eulophidae) is a gregarious larval endoparasitoid of the emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), an invasive cambium-feeding species responsible for recent, widespread mortality of ash (Fraxinus spp.) in North America. T. planipennisi is known to prefer late-instar emerald ash borer, but the cues used to assess host size by this species and most other parasitoids of concealed hosts remain unknown. We sought to test whether vibrations produced by feeding emerald ash borer vary with larval size and whether there are any correlations between these cues and T. planipennisi progeny number (i.e., brood size) and sex ratio. The amplitudes and rates of 3-30-ms vibrational impulses produced by emerald ash borer larvae of various sizes were measured in the laboratory before presenting the larvae to T. planipennisi. Impulse-rate did not vary with emerald ash borer size, but vibration amplitude was significantly higher for large larvae than for small larvae. T. planipennisi produced a significantly higher proportion of female offspring from large hosts than small hosts and was shown in previous work to produce more offspring overall from large hosts. There were no significant correlations, however, between the T. planipennisi progeny data and the emerald ash borer sound data. Because vibration amplitude varied significantly with host size, however, we are unable to entirely reject the hypothesis that T. planipennisi and possibly other parasitoids of concealed hosts use vibrational cues to assess host quality, particularly given the low explanatory potential of other external cues. Internal chemical cues also may be important.

How does synchrony with host plant affect the performance of an outbreaking insect defoliator?

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Fuentealba, Alvaro; Pureswaran, Deepa; Bauce, Éric; Despland, Emma

2017-08-01

Phenological mismatch has been proposed as a key mechanism by which climate change can increase the severity of insect outbreaks. Spruce budworm (Choristoneura fumiferana) is a serious defoliator of North American conifers that feeds on buds in the early spring. Black spruce (Picea mariana) has traditionally been considered a poor-quality host plant since its buds open later than those of the preferred host, balsam fir (Abies balsamea). We hypothesize that advancing black spruce budbreak phenology under a warmer climate would improve its phenological synchrony with budworm and hence increase both its suitability as a host plant and resulting defoliation damage. We evaluated the relationship between tree phenology and both budworm performance and tree defoliation by placing seven cohorts of budworm larvae on black spruce and balsam fir branches at different lags with tree budburst. Our results show that on both host plants, spruce budworm survival and pupal mass decrease sharply when budbreak occurs prior to larval emergence. By contrast, emergence before budbreak decreases survival, but does not negatively impact growth or reproductive output. We also document phytochemical changes that occur as needles mature and define a window of opportunity for the budworm. Finally, larvae that emerged in synchrony with budbreak had the greatest defoliating effect on black spruce. Our results suggest that in the event of advanced black spruce phenology due to climate warming, this host species will support better budworm survival and suffer increased defoliation.

First record of folivory on a newly documented host plant for the little known geometrid moth Eupithecia yubitzae Vargas & Parra (Lepidoptera, Geometridae in northern Chile

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Héctor A. Vargas

2015-06-01

Full Text Available The native tree Schinus molle (Anacardiacae is reported for the first time as a host plant for larvae of the little known geometrid moth Eupithecia yubitzae Vargas & Parra (Lepidoptera, Geometridae in the Atacama Desert of northern Chile, based on morphology and DNA barcodes. This discovery importantly expands the host range of E. yubitzae, as previous records were restricted to Fabaceae trees. Larvae were previously known as florivorous, while these were found to be folivorous on S. molle. Furthermore, host-associated cryptic larval polychromatism was detected, as larvae collected on S. molle were found to be mostly pale green, contrasting with the dark yellow ground color of the larvae typically collected on fabaceous host plants.

Fungal-host diversity among mycoheterotrophic plants increases proportionally to their fungal-host overlap.

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Gomes, Sofia I F; Merckx, Vincent S F T; Saavedra, Serguei

2017-05-01

The vast majority of plants obtain an important proportion of vital resources from soil through mycorrhizal fungi. Generally, this happens in exchange of photosynthetically fixed carbon, but occasionally the interaction is mycoheterotrophic, and plants obtain carbon from mycorrhizal fungi. This process results in an antagonistic interaction between mycoheterotrophic plants and their fungal hosts. Importantly, the fungal-host diversity available for plants is restricted as mycoheterotrophic interactions often involve narrow lineages of fungal hosts. Unfortunately, little is known whether fungal-host diversity may be additionally modulated by plant-plant interactions through shared hosts. Yet, this may have important implications for plant competition and coexistence. Here, we use DNA sequencing data to investigate the interaction patterns between mycoheterotrophic plants and arbuscular mycorrhizal fungi. We find no phylogenetic signal on the number of fungal hosts nor on the fungal hosts shared among mycoheterotrophic plants. However, we observe a potential trend toward increased phylogenetic diversity of fungal hosts among mycoheterotrophic plants with increasing overlap in their fungal hosts. While these patterns remain for groups of plants regardless of location, we do find higher levels of overlap and diversity among plants from the same location. These findings suggest that species coexistence cannot be fully understood without attention to the two sides of ecological interactions.

Host Plants Affect the Foraging Success of Two Parasitoids that Attack Light Brown Apple Moth Epiphyas postvittana (Walker (Lepidoptera: Tortricidae.

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Yi Feng

Full Text Available The light brown apple moth, Epiphyas postvittana is a key pest of wine grapes in Australia. Two parasitoids, Dolichogenidea tasmanica and Therophilus unimaculatus, attack the larval stage of this pest. D. tasmanica is dominant in vineyards, whereas T. unimaculatus is mainly active in native vegetation. We sought to understand why they differ in their use of habitats. Plants are a major component of habitats of parasitoids, and herbivore-infested plants influence parasitoid foraging efficiency by their architecture and emission of volatile chemicals. We investigated how different plant species infested by E. postvittana could affect the foraging success of the two parasitoid species in both laboratory and field experiments. Four common host-plant species were selected for this study. In paired-choice experiments to determine the innate foraging preferences for plants, both parasitoid species showed differences in innate search preferences among plant species. The plant preference of D. tasmanica was altered by oviposition experience with hosts that were feeding on other plant species. In a behavioral assay, the two parasitoid species allocated their times engaged in various types of behavior differently when foraging on different plant species. For both parasitoids, parasitism on Hardenbergia violacea was the highest of the four plant species. Significantly more larvae dropped from Myoporum insulare when attacked than from the other three host-plant species, which indicates that parasitism is also affected by interactions between plants and host insects. In vineyards, parasitism by D. tasmanica was significantly lower on M. insulare than on the other three host-plant species, but the parasitism rates were similar among the other three plant species. Our results indicate that plants play a role in the habitat preferences of these two parasitoid species by influencing their foraging behavior, and are likely to contribute to their distributions

Caterpillars and host plant records for 59 species of Geometridae (Lepidoptera) from a montane rainforest in southern Ecuador.

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Bodner, Florian; Brehm, Gunnar; Homeier, Jürgen; Strutzenberger, Patrick; Fiedler, Konrad

2010-01-01

During four months of field surveys at the Reserva Biológica San Francisco in the south Ecuadorian Andes, caterpillars of 59 Geometridae species were collected in a montane rainforest between 1800 and 2800m altitude and reared to adults. The resulting data on host plant affiliations of these species was collated. The preimaginal stages of 58 and adult stages of all 59 species are depicted in colour plates. Observations on morphology and behaviour are briefly described. Five species, documented for the first time in the study area by means of larval collections, had not been previously collected by intensive light-trap surveys. Together with published literature records, life-history data covers 8.6% of the 1271 geometrid species observed so far in the study area. For 50 species these are the first records of their early stages, and for another 7 the data significantly extend known host plant ranges. Most larvae were collected on shrubs or trees, but more unusual host plant affiliations, such as ferns (6 geometrid species) and lichens (3 geometrid species), were also recorded. Thirty-four percent of the caterpillars were infested by wasp or tachinid parasitoids.

Which native milkweeds are acceptable host plants for larval monarch butterflies (Danaus plexippus) within the Midwestern U.S.

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Over the past two decades, the population of monarch butterflies east of the Rocky Mountains has experienced a significant decline. Habitat restoration within the summer breeding range is crucial to boost population numbers. Monarch butterfly larvae use milkweeds as their only host plant. However, l...

Larval performance of the mustard leaf beetle (Phaedon cochleariae, Coleoptera, Chrysomelidae) on white mustard (Sinapis alba) and watercress (Nasturtium officinale) leaves in dependence of plant exposure to ultraviolet radiation

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Reifenrath, Kerstin; Mueller, Caroline

2009-01-01

Short-term exposure to ambient or attenuated ultraviolet (UV) radiation resulted in shifts in plant metabolite concentrations of the Brassicaceae Sinapis alba and Nasturtium officinale. Leaf quality also varied between plant species and within species due to age. Larvae of the oligophagous leaf beetle Phaedon cochleariae were raised on these different host leaves, in order to investigate the effects of variable plant chemistry on this herbivore. The performance of P. cochleariae was influenced by chemical differences between and within plant species but it responded with high plasticity to plants stressed by ultraviolet radiation. Body mass increase and developmental times of larvae were exclusively affected by plant species and leaf-age. However, developmental differences were fully compensated in the pupal stage. We suggest that the plasticity of herbivores may depend on the degree of specialisation, and insect performance may not necessarily be altered by stress-induced host plants. - The larval performance of an oligophagous leaf beetle is influenced by chemical differences between and within plant species but responds with high plasticity to plants stressed by ultraviolet radiation.

A new host record and a new combination in Cotesia Cameron (Hymenoptera: Braconidae from India

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A. Gupta

2013-02-01

Full Text Available Cotesia tiracolae (=Apanteles tiracolae, new combination proposed, is redescribed and illustrated. It is recorded as a larval parasitoid of Phaedyma columella (Cramer (Lepidoptera: Nymphalidae feeding on the host plant Grewia tiliifolia Vahl from Mumbai, Maharashtra, India. This is the first record of larval parasitism associated with P. columella from India. P. columella, the Short Banded Sailer, is a species of nymphalid butterfly found in South Asia and Southeast Asia. The present study also represents host range extension of the parasitoid C. tiracolae to Nymphalidae.

Ant-Related Oviposition and Larval Performance in a Myrmecophilous Lycaenid

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Matthew D. Trager

2013-01-01

Full Text Available We experimentally assessed ant-related oviposition and larval performance in the Miami blue butterfly (Cyclargus thomasi bethunebakeri. Ant tending had sex-dependent effects on most measures of larval growth: female larvae generally benefitted from increased tending frequency whereas male larvae were usually unaffected. The larger size of female larvae tended by ants resulted in a substantial predicted increase in lifetime egg production. Oviposition by adult females that were tended by C. floridanus ants as larvae was similar between host plants with or without ants. However, they laid relatively more eggs on plants with ants than did females raised without ants, which laid less than a third of their eggs on plants with ants present. In summary, we found conditional benefits for larvae tended by ants that were not accompanied by oviposition preference for plants with ants present, which is a reasonable result for a system in which ant presence at the time of oviposition is not a reliable indicator of future ant presence. More broadly, our results emphasize the importance of considering the consequences of variation in interspecific interactions, life history traits, and multiple measures of performance when evaluating the costs and benefits of mutualistic relationships.

Host plant quality of Tamarix ramosissima and T. parviflora for three sibling species of the biocontrol insect Diorhabda elongata (Coleoptera: Chrysomelidae).

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Dalin, Peter; O'Neal, Melissa J; Dudley, Tom; Bean, Daniel W

2009-10-01

Several sibling species of the leaf beetle Diorhabda elongata (Brullé) have been introduced into North America for the biocontrol of saltcedars (Tamarix spp.), but only one, D. carinulata (Desbrochers), has been extensively used in the field. The first open releases took place in 2001, and widespread defoliation occurred at sites infested by Tamarix ramosissima, T. chinensis, and their hybrid forms. The beetles failed, however, to establish at sites where other Tamarix species are targeted for control. In this study, we compared the preference and performance of three Diorhabda sibling species using adult choice and larval performance experiments on the two formally targeted Tamarix species: T. ramosissima and T. parviflora. In the adult choice experiment, a greater proportion of D. carinulata was found on T. ramosissima than on T. parviflora. For the other two sibling species, D. elongata (Brullé) and D. carinata (Faldermann), adults were found in similar proportions on the two host plants. In the larval performance experiment, larval growth and survival did not differ between Tamarix species for any Diorhabda type; however, D. carinata larval biomass was 35-50% greater than the other beetles regardless of host species. Based on the few adults of D. carinulata found on T. parviflora in the adult choice experiment, we do not recommend introducing this beetle at sites where T. parviflora is targeted for biological control. The species D. carinata seems especially promising for future release because its larvae gained substantially more biomass than the other beetles during the same time period on both Tamarix species.

Climate change may alter breeding ground distributions of eastern migratory monarchs (Danaus plexippus) via range expansion of Asclepias host plants.

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Lemoine, Nathan P

2015-01-01

Climate change can profoundly alter species' distributions due to changes in temperature, precipitation, or seasonality. Migratory monarch butterflies (Danaus plexippus) may be particularly susceptible to climate-driven changes in host plant abundance or reduced overwintering habitat. For example, climate change may significantly reduce the availability of overwintering habitat by restricting the amount of area with suitable microclimate conditions. However, potential effects of climate change on monarch northward migrations remain largely unknown, particularly with respect to their milkweed (Asclepias spp.) host plants. Given that monarchs largely depend on the genus Asclepias as larval host plants, the effects of climate change on monarch northward migrations will most likely be mediated by climate change effects on Asclepias. Here, I used MaxEnt species distribution modeling to assess potential changes in Asclepias and monarch distributions under moderate and severe climate change scenarios. First, Asclepias distributions were projected to extend northward throughout much of Canada despite considerable variability in the environmental drivers of each individual species. Second, Asclepias distributions were an important predictor of current monarch distributions, indicating that monarchs may be constrained as much by the availability of Asclepias host plants as environmental variables per se. Accordingly, modeling future distributions of monarchs, and indeed any tightly coupled plant-insect system, should incorporate the effects of climate change on host plant distributions. Finally, MaxEnt predictions of Asclepias and monarch distributions were remarkably consistent among general circulation models. Nearly all models predicted that the current monarch summer breeding range will become slightly less suitable for Asclepias and monarchs in the future. Asclepias, and consequently monarchs, should therefore undergo expanded northern range limits in summer months

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

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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.

Evolution of specialization: a phylogenetic study of host range in the red milkweed beetle (Tetraopes tetraophthalmus).

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Rasmann, Sergio; Agrawal, Anurag A

2011-06-01

Specialization is common in most lineages of insect herbivores, one of the most diverse groups of organisms on earth. To address how and why specialization is maintained over evolutionary time, we hypothesized that plant defense and other ecological attributes of potential host plants would predict the performance of a specialist root-feeding herbivore (the red milkweed beetle, Tetraopes tetraophthalmus). Using a comparative phylogenetic and functional trait approach, we assessed the determinants of insect host range across 18 species of Asclepias. Larval survivorship decreased with increasing phylogenetic distance from the true host, Asclepias syriaca, suggesting that adaptation to plant traits drives specialization. Among several root traits measured, only cardenolides (toxic defense chemicals) correlated with larval survival, and cardenolides also explained the phylogenetic distance effect in phylogenetically controlled multiple regression analyses. Additionally, milkweed species having a known association with other Tetraopes beetles were better hosts than species lacking Tetraopes herbivores, and milkweeds with specific leaf area values (a trait related to leaf function and habitat affiliation) similar to those of A. syriaca were better hosts than species having divergent values. We thus conclude that phylogenetic distance is an integrated measure of phenotypic and ecological attributes of Asclepias species, especially defensive cardenolides, which can be used to explain specialization and constraints on host shifts over evolutionary time.

Close-range host searching behavior of the stemborer parasitoids Cotesia sesamiae and Dentichasmias busseolae: influence of a non-host-plant Melinis minutiflora

NARCIS (Netherlands)

Gohole, L.S.; Overholt, W.A.; Khan, Z.R.; Vet, L.E.M.

2005-01-01

Studies were conducted on the host searching behavior of the larval parasitoid Cotesia sesamiae (Cameron) (Hymenoptera: Braconidae) and the pupal parasitoid Dentichasmias busseolae Heinrich (Hymenoptera: Ichneumonidae), both of which attack lepidopteran (Crambidae, Noctuidae) cereal stemborers. The

Close-range host searching behavior of the stemborer parasitoids Cotesia sesamiae and Dentichasmias busseolae: Influence of a non-host plant Melinis minutiflora

NARCIS (Netherlands)

Gohole, L.S.; Overholt, W.A.; Khan, Z.U.; Vet, L.E.M.

2005-01-01

Studies were conducted on the host searching behavior of the larval parasitoid Cotesia sesamiae (Cameron) (Hymenoptera: Braconidae) and the pupal parasitoid Dentichasmias busseolae Heinrich (Hymenoptera: Ichneumonidae), both of which attack lepidopteran (Crambidae, Noctuidae) cereal stemborers. The

Climate Change May Alter Breeding Ground Distributions of Eastern Migratory Monarchs (Danaus plexippus) via Range Expansion of Asclepias Host Plants

Science.gov (United States)

Lemoine, Nathan P.

2015-01-01

Climate change can profoundly alter species’ distributions due to changes in temperature, precipitation, or seasonality. Migratory monarch butterflies (Danaus plexippus) may be particularly susceptible to climate-driven changes in host plant abundance or reduced overwintering habitat. For example, climate change may significantly reduce the availability of overwintering habitat by restricting the amount of area with suitable microclimate conditions. However, potential effects of climate change on monarch northward migrations remain largely unknown, particularly with respect to their milkweed (Asclepias spp.) host plants. Given that monarchs largely depend on the genus Asclepias as larval host plants, the effects of climate change on monarch northward migrations will most likely be mediated by climate change effects on Asclepias. Here, I used MaxEnt species distribution modeling to assess potential changes in Asclepias and monarch distributions under moderate and severe climate change scenarios. First, Asclepias distributions were projected to extend northward throughout much of Canada despite considerable variability in the environmental drivers of each individual species. Second, Asclepias distributions were an important predictor of current monarch distributions, indicating that monarchs may be constrained as much by the availability of Asclepias host plants as environmental variables per se. Accordingly, modeling future distributions of monarchs, and indeed any tightly coupled plant-insect system, should incorporate the effects of climate change on host plant distributions. Finally, MaxEnt predictions of Asclepias and monarch distributions were remarkably consistent among general circulation models. Nearly all models predicted that the current monarch summer breeding range will become slightly less suitable for Asclepias and monarchs in the future. Asclepias, and consequently monarchs, should therefore undergo expanded northern range limits in summer months

Climate change may alter breeding ground distributions of eastern migratory monarchs (Danaus plexippus via range expansion of Asclepias host plants.

Directory of Open Access Journals (Sweden)

Nathan P Lemoine

Full Text Available Climate change can profoundly alter species' distributions due to changes in temperature, precipitation, or seasonality. Migratory monarch butterflies (Danaus plexippus may be particularly susceptible to climate-driven changes in host plant abundance or reduced overwintering habitat. For example, climate change may significantly reduce the availability of overwintering habitat by restricting the amount of area with suitable microclimate conditions. However, potential effects of climate change on monarch northward migrations remain largely unknown, particularly with respect to their milkweed (Asclepias spp. host plants. Given that monarchs largely depend on the genus Asclepias as larval host plants, the effects of climate change on monarch northward migrations will most likely be mediated by climate change effects on Asclepias. Here, I used MaxEnt species distribution modeling to assess potential changes in Asclepias and monarch distributions under moderate and severe climate change scenarios. First, Asclepias distributions were projected to extend northward throughout much of Canada despite considerable variability in the environmental drivers of each individual species. Second, Asclepias distributions were an important predictor of current monarch distributions, indicating that monarchs may be constrained as much by the availability of Asclepias host plants as environmental variables per se. Accordingly, modeling future distributions of monarchs, and indeed any tightly coupled plant-insect system, should incorporate the effects of climate change on host plant distributions. Finally, MaxEnt predictions of Asclepias and monarch distributions were remarkably consistent among general circulation models. Nearly all models predicted that the current monarch summer breeding range will become slightly less suitable for Asclepias and monarchs in the future. Asclepias, and consequently monarchs, should therefore undergo expanded northern range limits in

Natal Host Plants Can Alter Herbivore Competition.

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Pan, Huipeng; Preisser, Evan L; Su, Qi; Jiao, Xiaoguo; Xie, Wen; Wang, Shaoli; Wu, Qingjun; Zhang, Youjun

2016-01-01

Interspecific competition between herbivores is widely recognized as an important determinant of community structure. Although researchers have identified a number of factors capable of altering competitive interactions, few studies have addressed the influence of neighboring plant species. If adaptation to/ epigenetic effects of an herbivore's natal host plant alter its performance on other host plants, then interspecific herbivore interactions may play out differently in heterogeneous and homogenous plant communities. We tested wether the natal host plant of a whitefly population affected interactions between the Middle-east Asia Minor 1 (MEAM1) and Mediterranean (MED) cryptic species of the whitefly Bemisia tabaci by rearing the offspring of a cabbage-derived MEAM1 population and a poinsettia-derived MED population together on three different host plants: cotton, poinsettia, and cabbage. We found that MED dominated on poinsettia and that MEAM1 dominated on cabbage, results consistent with previous research. MED also dominated when reared with MEAM1 on cotton, however, a result at odds with multiple otherwise-similar studies that reared both species on the same natal plant. Our work provides evidence that natal plants affect competitive interactions on another plant species, and highlights the potential importance of neighboring plant species on herbivore community composition in agricultral systems.

A Transcriptomic Analysis of Echinococcus granulosus Larval Stages: Implications for Parasite Biology and Host Adaptation

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Parkinson, John; Wasmuth, James D.; Salinas, Gustavo; Bizarro, Cristiano V.; Sanford, Chris; Berriman, Matthew; Ferreira, Henrique B.; Zaha, Arnaldo; Blaxter, Mark L.; Maizels, Rick M.; Fernández, Cecilia

2012-01-01

Background The cestode Echinococcus granulosus - the agent of cystic echinococcosis, a zoonosis affecting humans and domestic animals worldwide - is an excellent model for the study of host-parasite cross-talk that interfaces with two mammalian hosts. To develop the molecular analysis of these interactions, we carried out an EST survey of E. granulosus larval stages. We report the salient features of this study with a focus on genes reflecting physiological adaptations of different parasite stages. Methodology/Principal Findings We generated ∼10,000 ESTs from two sets of full-length enriched libraries (derived from oligo-capped and trans-spliced cDNAs) prepared with three parasite materials: hydatid cyst wall, larval worms (protoscoleces), and pepsin/H+-activated protoscoleces. The ESTs were clustered into 2700 distinct gene products. In the context of the biology of E. granulosus, our analyses reveal: (i) a diverse group of abundant long non-protein coding transcripts showing homology to a middle repetitive element (EgBRep) that could either be active molecular species or represent precursors of small RNAs (like piRNAs); (ii) an up-regulation of fermentative pathways in the tissue of the cyst wall; (iii) highly expressed thiol- and selenol-dependent antioxidant enzyme targets of thioredoxin glutathione reductase, the functional hub of redox metabolism in parasitic flatworms; (iv) candidate apomucins for the external layer of the tissue-dwelling hydatid cyst, a mucin-rich structure that is critical for survival in the intermediate host; (v) a set of tetraspanins, a protein family that appears to have expanded in the cestode lineage; and (vi) a set of platyhelminth-specific gene products that may offer targets for novel pan-platyhelminth drug development. Conclusions/Significance This survey has greatly increased the quality and the quantity of the molecular information on E. granulosus and constitutes a valuable resource for gene prediction on the parasite genome

Host Specificity in the Parasitic Plant Cytinus hypocistis

International Nuclear Information System (INIS)

Thorogood, C.J.; Hiscock, S.J.

2007-01-01

Host specificity in the parasitic plant Cytinus hypocistis was quantified at four sites in the Algarve region of Portugal from 2002 to 2007. The parasite was found to be locally host specific, and only two hosts were consistently infected: Halimium halimifolium and Cistus monspeliensis. C. hypocistis did not infect hosts in proportion to their abundance; at three sites, 100% of parasites occurred on H. halimifolium which represented just 42.4%, 3% and 19.7% of potential hosts available, respectively. At the remaining site, where H. halimifolium was absent, 100% of parasites occurred on C. monspeliensis which represented 81.1% of potential hosts available. Other species of potential host were consistently uninfected irrespective of their abundance. Ecological niche divergence of host plants H. halimifolium and C. monspeliensis may isolate host-specific races of C. hypocistis, thereby potentially driving allopatric divergence in this parasitic plant.

Climate change, phenology, and butterfly host plant utilization.

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Navarro-Cano, Jose A; Karlsson, Bengt; Posledovich, Diana; Toftegaard, Tenna; Wiklund, Christer; Ehrlén, Johan; Gotthard, Karl

2015-01-01

Knowledge of how species interactions are influenced by climate warming is paramount to understand current biodiversity changes. We review phenological changes of Swedish butterflies during the latest decades and explore potential climate effects on butterfly-host plant interactions using the Orange tip butterfly Anthocharis cardamines and its host plants as a model system. This butterfly has advanced its appearance dates substantially, and its mean flight date shows a positive correlation with latitude. We show that there is a large latitudinal variation in host use and that butterfly populations select plant individuals based on their flowering phenology. We conclude that A. cardamines is a phenological specialist but a host species generalist. This implies that thermal plasticity for spring development influences host utilization of the butterfly through effects on the phenological matching with its host plants. However, the host utilization strategy of A. cardamines appears to render it resilient to relatively large variation in climate.

Ability of a Generalist Seed Beetle to Colonize an Exotic Host: Effects of Host Plant Origin and Oviposition Host.

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Amarillo-Suárez, A; Repizo, A; Robles, J; Diaz, J; Bustamante, S

2017-08-01

The colonization of an exotic species by native herbivores is more likely to occur if that herbivore is a generalist. There is little information on the life-history mechanisms used by native generalist insects to colonize exotic hosts and how these mechanisms are affected by host properties. We examined the ability of the generalist seed beetle Stator limbatus Horn to colonize an exotic species. We compared its host preference, acceptability, performance, and egg size when ovipositing and developing on two native (Pithecellobium dulce (Roxb.) Benth and Senegalia riparia (Kunth)) and one exotic legume species (Leucaena leucocephala (Lam.)). We also analyzed the seed chemistry. We found that females recognize the exotic species as an unfavorable host for larval development and that they delayed oviposition and laid fewer and larger eggs on the exotic species than on the native species. Survivorship on the exotic host was 0%. Additionally, seeds of the native species contain five chemical compounds that are absent in the exotic species, and the exotic species contains three sterols, which are absent in the native legumes. Genetically based differences between beetles adapted to different hosts, plastic responses toward new hosts, and chemical differences among seeds are important in host colonization and recognition of the exotic host. In conclusion, the generalist nature of S. limbatus does not influence its ability to colonize L. leucocephala. Explanations for the colonization of exotic hosts by generalist native species and for the success of invasive species must be complemented with studies measuring local adaptation and plasticity.

Granulomatous responses in larval taeniid infections.

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Díaz, Á; Sagasti, C; Casaravilla, C

2018-05-01

Granulomas are responses to persistent nonliving bodies or pathogens, centrally featuring specialized macrophage forms called epithelioid and multinucleated giant cells. The larval stages of the cestode parasites of the Taeniidae family (Taenia, Echinococcus) develop for years in fixed tissue sites in mammals. In consequence, they are targets of granulomatous responses. The information on tissue responses to larval taeniids is fragmented among host and parasite species and scattered over many decades. We attempt to draw an integrated picture of these responses in solid tissues. The intensity of inflammation around live parasites spans a spectrum from minimal to high, parasite vitality correlating with low inflammation. The low end of the inflammatory spectrum features collagen capsules proximal to the parasites and moderate distal infiltration. The middle of the spectrum is dominated by classical granulomatous responses, whereas the high end features massive eosinophil invasions. Across the range of parasite species, much observational evidence suggests that eosinophils are highly effective at killing larval taeniids in solid tissues, before and during chronic granulomatous responses. The evidence available also suggests that these parasites are adapted to inhibit host granulomatous responses, in part through the exacerbation of host regulatory mechanisms including regulatory T cells and TGF-β. © 2018 John Wiley & Sons Ltd.

Does chemical aposematic (warning) signaling occur between host plants and their potential parasitic plants?

Science.gov (United States)

Lev-Yadun, Simcha

2013-07-01

Aposematism (warning) signaling is a common defensive mechanism toward predatory or herbivorous animals, i.e., interactions between different trophic levels. I propose that it should be considered at least as a working hypothesis that chemical aposematism operates between certain host plants and their plant predators, parasitic plants, and that although they are also plants, they belong to a higher trophic level. Specific host plant genotypes emit known repelling chemical signals toward parasitic plants, which reduce the level of, slow the directional parasite growth (attack) toward the signaling hosts, or even cause parasitic plants to grow away from them in response to these chemicals. Chemical host aposematism toward parasitic plants may be a common but overlooked defense from parasitic plants.

Food Plants of 19 butterflies species (Lepidoptera from Loreto, Peru

Directory of Open Access Journals (Sweden)

Joel Vásquez Bardales

2017-04-01

Full Text Available This work reports the food plants utilized by 19 species of butterflies from Allpahuayo-Mishana Research Center and the Community of San Rafael, Loreto, Peru. We report 23 plant species and one hybrid of angiosperms used by the butterflies. Larval host plants were 21 species and five were adult nectar sources. Two species were both host plant and nectar source: Passiflora coccinea Aubl. and Passiflora edulis Sims. The most frequently used plant families were Solanaceae, Passifloraceae, Fabaceae and Aristolochiaceae.

Plant fertilization interacts with life history: variation in stoichiometry and performance in nettle-feeding butterflies.

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Hélène Audusseau

Full Text Available Variation in food stoichiometry affects individual performance and population dynamics, but it is also likely that species with different life histories should differ in their sensitivity to food stoichiometry. To address this question, we investigated the ability of the three nettle-feeding butterflies (Aglais urticae, Polygonia c-album, and Aglais io to respond adaptively to induced variation in plant stoichiometry in terms of larval performance. We hypothesized that variation in larval performance between plant fertilization treatments should be functionally linked to species differences in host plant specificity. We found species-specific differences in larval performance between plant fertilization treatments that could not be explained by nutrient limitation. We showed a clear evidence of a positive correlation between food stoichiometry and development time to pupal stage and pupal mass in A. urticae. The other two species showed a more complex response. Our results partly supported our prediction that host plant specificity affects larval sensitivity to food stoichiometry. However, we suggest that most of the differences observed may instead be explained by differences in voltinism (number of generations per year. We believe that the potential of some species to respond adaptively to variation in plant nutrient content needs further attention in the face of increased eutrophication due to nutrient leakage from human activities.

Data integration aids understanding of butterfly-host plant networks.

Science.gov (United States)

Muto-Fujita, Ai; Takemoto, Kazuhiro; Kanaya, Shigehiko; Nakazato, Takeru; Tokimatsu, Toshiaki; Matsumoto, Natsushi; Kono, Mayo; Chubachi, Yuko; Ozaki, Katsuhisa; Kotera, Masaaki

2017-03-06

Although host-plant selection is a central topic in ecology, its general underpinnings are poorly understood. Here, we performed a case study focusing on the publicly available data on Japanese butterflies. A combined statistical analysis of plant-herbivore relationships and taxonomy revealed that some butterfly subfamilies in different families feed on the same plant families, and the occurrence of this phenomenon more than just by chance, thus indicating the independent acquisition of adaptive phenotypes to the same hosts. We consequently integrated plant-herbivore and plant-compound relationship data and conducted a statistical analysis to identify compounds unique to host plants of specific butterfly families. Some of the identified plant compounds are known to attract certain butterfly groups while repelling others. The additional incorporation of insect-compound relationship data revealed potential metabolic processes that are related to host plant selection. Our results demonstrate that data integration enables the computational detection of compounds putatively involved in particular interspecies interactions and that further data enrichment and integration of genomic and transcriptomic data facilitates the unveiling of the molecular mechanisms involved in host plant selection.

Multifaceted effects of host plants on entomopathogenic nematodes.

Science.gov (United States)

Hazir, Selcuk; Shapiro-Ilan, David I; Hazir, Canan; Leite, Luis G; Cakmak, Ibrahim; Olson, Dawn

2016-03-01

The success of parasites can be impacted by multi-trophic interactions. Tritrophic interactions have been observed in parasite-herbivore-host plant systems. Here we investigate aspects of multi-trophic interactions in a system involving an entomopathogenic nematode (EPN), its insect host, and host plant. Novel issues investigated include the impact of tritrophic interactions on nematode foraging behavior, the ability of EPNs to overcome negative tritrophic effects through genetic selection, and interactions with a fourth trophic level (nematode predators). We tested infectivity of the nematode, Steinernema riobrave, to corn earworm larvae (Helicoverpa zea) in three host plants, tobacco, eggplant and tomato. Tobacco reduced nematode virulence and reproduction relative to tomato and eggplant. However, successive selection (5 passages) overcame the deficiency; selected nematodes no longer exhibited reductions in phenotypic traits. Despite the loss in virulence and reproduction nematodes, first passage S. riobrave was more attracted to frass from insects fed tobacco than insects fed on other host plants. Therefore, we hypothesized the reduced virulence and reproduction in S. riobrave infecting tobacco fed insects would be based on a self-medicating tradeoff, such as deterring predation. We tested this hypothesis by assessing predatory success of the mite Sancassania polyphyllae and the springtail Sinella curviseta on nematodes reared on tobacco-fed larvae versus those fed on greater wax moth, Galleria mellonella, tomato fed larvae, or eggplant fed larvae. No advantage was observed in nematodes derived from tobacco fed larvae. In conclusion, our results indicated that insect-host plant diet has an important effect on nematode foraging, infectivity and reproduction. However, negative host plant effects, might be overcome through directed selection. We propose that host plant species should be considered when designing biocontrol programs using EPNs. Copyright © 2016

On-Plant Larval Movement and Feeding Behavior of Fall Armyworm (Lepidoptera: Noctuidae) on Reproductive Corn Stages.

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Pannuti, L E R; Baldin, E L L; Hunt, T E; Paula-Moraes, S V

2016-02-01

Spodoptera frugiperda J.E. Smith (fall armyworm) is considered one of the most destructive pests of corn throughout the Americas. Although this pest has been extensively studied, little is known about its larval movement and feeding behavior on reproductive compared to vegetative corn stages. Thus, we conducted studies with two corn stages (R1 and R3) and four corn plant zones (tassel, above ear, ear zone, and below ear) in the field at Concord, NE (USA), and in the field and greenhouse at Botucatu, SP (Brazil), to investigate on-plant larval movement. The effects of different corn tissues (opened tassel, closed tassel, silk, kernel, and leaf), two feeding sequence scenarios (closed tassel-leaf-silk-kernel and leaf-silk-kernel), and artificial diet (positive control) on larval survival and development were also evaluated in the laboratory. Ear zone has a strong effect on feeding choice and survival of fall armyworm larvae regardless of reproductive corn stage. Feeding site choice is made by first-instar. Corn leaves of reproductive plants were not suitable for early instar development, but silk and kernel tissues had a positive effect on survival and development of fall armyworm larvae on reproductive stage corn. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Quantitative Trait Loci Mapping of Western Corn Rootworm (Coleoptera: Chrysomelidae) Host Plant Resistance in Two Populations of Doubled Haploid Lines in Maize (Zea mays L.).

Science.gov (United States)

Bohn, Martin O; Marroquin, Juan J; Flint-Garcia, Sherry; Dashiell, Kenton; Willmot, David B; Hibbard, Bruce E

2018-02-09

Over the last 70 yr, more than 12,000 maize accessions have been screened for their level of resistance to western corn rootworm, Diabrotica virgifera virgifera (LeConte; Coleoptera: Chrysomelidae), larval feeding. Less than 1% of this germplasm was selected for initiating recurrent selection or other breeding programs. Selected genotypes were mostly characterized by large root systems and superior root regrowth after root damage caused by western corn rootworm larvae. However, no hybrids claiming native (i.e., host plant) resistance to western corn rootworm larval feeding are currently commercially available. We investigated the genetic basis of western corn rootworm resistance in maize materials with improved levels of resistance using linkage disequilibrium mapping approaches. Two populations of topcrossed doubled haploid maize lines (DHLs) derived from crosses between resistant and susceptible maize lines were evaluated for their level of resistance in three to four different environments. For each DHL topcross an average root damage score was estimated and used for quantitative trait loci (QTL) analysis. We found genomic regions contributing to western corn rootworm resistance on all maize chromosomes, except for chromosome 4. Models fitting all QTL simultaneously explained about 30 to 50% of the genotypic variance for root damage scores in both mapping populations. Our findings confirm the complex genetic structure of host plant resistance against western corn rootworm larval feeding in maize. Interestingly, three of these QTL regions also carry genes involved in ascorbate biosynthesis, a key compound we hypothesize is involved in the expression of western corn rootworm resistance. © The Author(s) 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Ozone affects growth and development of Pieris brassicae on the wild host plant Brassica nigra

International Nuclear Information System (INIS)

Khaling, Eliezer; Papazian, Stefano; Poelman, Erik H.; Holopainen, Jarmo K.; Albrectsen, Benedicte R.; Blande, James D.

2015-01-01

When plants are exposed to ozone they exhibit changes in both primary and secondary metabolism, which may affect their interactions with herbivorous insects. Here we investigated the performance and preferences of the specialist herbivore Pieris brassicae on the wild plant Brassica nigra under elevated ozone conditions. The direct and indirect effects of ozone on the plant-herbivore system were studied. In both cases ozone exposure had a negative effect on P. brassicae development. However, in dual-choice tests larvae preferentially consumed plant material previously fumigated with the highest concentration tested, showing a lack of correlation between larval preference and performance on ozone exposed plants. Metabolomic analysis of leaf material subjected to combinations of ozone and herbivore-feeding, and focussing on known defence metabolites, indicated that P. brassicae behaviour and performance were associated with ozone-induced alterations to glucosinolate and phenolic pools. - Highlights: • We examined the effects of ozone on Pieris brassicae performance and preference. • We studied ozone and herbivore induced changes in the metabolome of Brassica nigra. • The performance of P. brassicae did not correlate with preference of ozonated plants. • Ozone and herbivore-feeding stress changes the phytochemical pools of B. nigra. - Ozone indirectly reduces herbivore performance, which is associated with change in phytochemical pools, but does not correlate with host plant preference

Do native parasitic plants cause more damage to exotic invasive hosts than native non-invasive hosts? An implication for biocontrol.

Science.gov (United States)

Li, Junmin; Jin, Zexin; Song, Wenjing

2012-01-01

Field studies have shown that native, parasitic plants grow vigorously on invasive plants and can cause more damage to invasive plants than native plants. However, no empirical test has been conducted and the mechanism is still unknown. We conducted a completely randomized greenhouse experiment using 3 congeneric pairs of exotic, invasive and native, non-invasive herbaceous plant species to quantify the damage caused by parasitic plants to hosts and its correlation with the hosts' growth rate and resource use efficiency. The biomass of the parasitic plants on exotic, invasive hosts was significantly higher than on congeneric native, non-invasive hosts. Parasites caused more damage to exotic, invasive hosts than to congeneric, native, non-invasive hosts. The damage caused by parasites to hosts was significantly positively correlated with the biomass of parasitic plants. The damage of parasites to hosts was significantly positively correlated with the relative growth rate and the resource use efficiency of its host plants. It may be the mechanism by which parasitic plants grow more vigorously on invasive hosts and cause more damage to exotic, invasive hosts than to native, non-invasive hosts. These results suggest a potential biological control effect of native, parasitic plants on invasive species by reducing the dominance of invasive species in the invaded community.

Volatile chemical cues guide host location and host selection by parasitic plants

Science.gov (United States)

Justin B. Runyon; Mark C. Mescher; Consuelo M. De Moraes

2006-01-01

The importance of plant volatiles in mediating interactions between plant species is much debated. Here, we demonstrate that the parasitic plant Cuscuta pentagona (dodder) uses volatile cues for host location. Cuscuta pentagona seedlings exhibit directed growth toward nearby tomato plants (Lycopersicon esculentum...

Parasitic plants of the genus Cuscuta and their interaction with susceptible and resistant host plants

Directory of Open Access Journals (Sweden)

Bettina eKaiser

2015-02-01

Full Text Available By comparison with plant-microbe interaction, little is known about the interaction of parasitic plants with their hosts. Plants of the genus Cuscuta belong to the family of Cuscutaceae and comprise about 200 species, all of which live as stem holoparasites on other plants. Cuscuta spp. possess no roots nor fully expanded leaves and the vegetative portion appears to be a stem only. The parasite winds around plants and penetrates the host stems via haustoria, forming direct connections to the vascular bundles of their hosts to withdraw water, carbohydrates and other solutes. Besides susceptible hosts, a few plants exist that exhibit an active resistance against infestation by Cuscuta spp. For example, cultivated tomato (Solanum lycopersicum fends off Cuscuta reflexa by means of a hypersensitive-type response occurring in the early penetration phase. This report on the plant-plant dialogue between Cuscuta spp. and its host plants focuses on the incompatible interaction of Cuscuta reflexa with tomato.

Parasitic plants of the genus Cuscuta and their interaction with susceptible and resistant host plants.

Science.gov (United States)

Kaiser, Bettina; Vogg, Gerd; Fürst, Ursula B; Albert, Markus

2015-01-01

By comparison with plant-microbe interaction, little is known about the interaction of parasitic plants with their hosts. Plants of the genus Cuscuta belong to the family of Cuscutaceae and comprise about 200 species, all of which live as stem holoparasites on other plants. Cuscuta spp. possess no roots nor fully expanded leaves and the vegetative portion appears to be a stem only. The parasite winds around plants and penetrates the host stems via haustoria, forming direct connections to the vascular bundles of their hosts to withdraw water, carbohydrates, and other solutes. Besides susceptible hosts, a few plants exist that exhibit an active resistance against infestation by Cuscuta spp. For example, cultivated tomato (Solanum lycopersicum) fends off Cuscuta reflexa by means of a hypersensitive-type response occurring in the early penetration phase. This report on the plant-plant dialog between Cuscuta spp. and its host plants focuses on the incompatible interaction of C. reflexa with tomato.

Macromolecule exchange in Cuscuta-host plant interactions.

Science.gov (United States)

Kim, Gunjune; Westwood, James H

2015-08-01

Cuscuta species (dodders) are parasitic plants that are able to grow on many different host plants and can be destructive to crops. The connections between Cuscuta and its hosts allow movement of not only water and small nutrients, but also macromolecules including mRNA, proteins and viruses. Recent studies show that RNAs move bidirectionally between hosts and parasites and involve a large number of different genes. Although the function of mobile mRNAs has not been demonstrated in this system, small RNAs are also transmitted and a silencing construct expressed in hosts is able to affect expression of the target gene in the parasite. High throughput sequencing of host-parasite associations has the potential to greatly accelerate understanding of this remarkable interaction. Copyright © 2015 Elsevier Ltd. All rights reserved.

Data integration aids understanding of butterfly–host plant networks

Science.gov (United States)

Muto-Fujita, Ai; Takemoto, Kazuhiro; Kanaya, Shigehiko; Nakazato, Takeru; Tokimatsu, Toshiaki; Matsumoto, Natsushi; Kono, Mayo; Chubachi, Yuko; Ozaki, Katsuhisa; Kotera, Masaaki

2017-01-01

Although host-plant selection is a central topic in ecology, its general underpinnings are poorly understood. Here, we performed a case study focusing on the publicly available data on Japanese butterflies. A combined statistical analysis of plant–herbivore relationships and taxonomy revealed that some butterfly subfamilies in different families feed on the same plant families, and the occurrence of this phenomenon more than just by chance, thus indicating the independent acquisition of adaptive phenotypes to the same hosts. We consequently integrated plant–herbivore and plant–compound relationship data and conducted a statistical analysis to identify compounds unique to host plants of specific butterfly families. Some of the identified plant compounds are known to attract certain butterfly groups while repelling others. The additional incorporation of insect–compound relationship data revealed potential metabolic processes that are related to host plant selection. Our results demonstrate that data integration enables the computational detection of compounds putatively involved in particular interspecies interactions and that further data enrichment and integration of genomic and transcriptomic data facilitates the unveiling of the molecular mechanisms involved in host plant selection. PMID:28262809

RNA mobility in parasitic plant – host interactions

Science.gov (United States)

Kim, Gunjune

2017-01-01

ABSTRACT The parasitic plant Cuscuta exchanges mRNAs with its hosts. Systemic mobility of mRNAs within plants is well documented, and has gained increasing attention as studies using grafted plant systems have revealed new aspects of mobile mRNA regulation and function. But parasitic plants take this phenomenon to a new level by forming seamless connections to a wide range of host species, and raising questions about how mRNAs might function after transfer to a different species. Cuscuta and other parasitic plant species also take siRNAs from their hosts, indicating that multiple types of RNA are capable of trans-specific movement. Parasitic plants are intriguing systems for studying RNA mobility, in part because such exchange opens new possibilities for control of parasitic weeds, but also because they provide a fresh perspective into understanding roles of RNAs in inter-organismal communication. PMID:28277936

Phytophagous insect fauna tracks host plant responses to exotic grass invasion.

Science.gov (United States)

Almeida-Neto, Mário; Prado, Paulo I; Lewinsohn, Thomas M

2011-04-01

The high dependence of herbivorous insects on their host plants implies that plant invaders can affect these insects directly, by not providing a suitable habitat, or indirectly, by altering host plant availability. In this study, we sampled Asteraceae flower heads in cerrado remnants with varying levels of exotic grass invasion to evaluate whether invasive grasses have a direct effect on herbivore richness independent of the current disturbance level and host plant richness. By classifying herbivores according to the degree of host plant specialization, we also investigated whether invasive grasses reduce the uniqueness of the herbivorous assemblages. Herbivorous insect richness showed a unimodal relationship with invasive grass cover that was significantly explained only by way of the variation in host plant richness. The same result was found for polyphagous and oligophagous insects, but monophages showed a significant negative response to the intensity of the grass invasion that was independent of host plant richness. Our findings lend support to the hypothesis that the aggregate effect of invasive plants on herbivores tends to mirror the effects of invasive plants on host plants. In addition, exotic plants affect specialist insects differently from generalist insects; thus exotic plants affect not only the size but also the structural profile of herbivorous insect assemblages.

Mechanisms of host seeking by parasitic nematodes.

Science.gov (United States)

Gang, Spencer S; Hallem, Elissa A

2016-07-01

The phylum Nematoda comprises a diverse group of roundworms that includes parasites of vertebrates, invertebrates, and plants. Human-parasitic nematodes infect more than one billion people worldwide and cause some of the most common neglected tropical diseases, particularly in low-resource countries [1]. Parasitic nematodes of livestock and crops result in billions of dollars in losses each year [1]. Many nematode infections are treatable with low-cost anthelmintic drugs, but repeated infections are common in endemic areas and drug resistance is a growing concern with increasing therapeutic and agricultural administration [1]. Many parasitic nematodes have an environmental infective larval stage that engages in host seeking, a process whereby the infective larvae use sensory cues to search for hosts. Host seeking is a complex behavior that involves multiple sensory modalities, including olfaction, gustation, thermosensation, and humidity sensation. As the initial step of the parasite-host interaction, host seeking could be a powerful target for preventative intervention. However, host-seeking behavior remains poorly understood. Here we review what is currently known about the host-seeking behaviors of different parasitic nematodes, including insect-parasitic nematodes, mammalian-parasitic nematodes, and plant-parasitic nematodes. We also discuss the neural bases of these behaviors. Copyright © 2016 Elsevier B.V. All rights reserved.

Calcium signaling during the plant-plant interaction of parasitic Cuscuta reflexa with its hosts

NARCIS (Netherlands)

Albert, M.; Kaiser, B.; Krol, van der A.R.; Kaldenhoff, R.

2010-01-01

The plant parasite Cuscuta reflexa induces various responses in compatible and incompatible host plants. The visual reactions of both types of host plants including obvious morphological changes require the recognition of Cuscuta ssp. A consequently initiated signaling cascade is triggered which

Fire creates host plant patches for monarch butterflies

Science.gov (United States)

Baum, Kristen A.; Sharber, Wyatt V.

2012-01-01

Monarch butterflies (Danaus plexippus) depend on the presence of host plants (Asclepias spp.) within their breeding range for reproduction. In the southern Great Plains, Asclepias viridis is a perennial that flowers in May and June, and starts to senesce by August. It is locally abundant and readily used by monarchs as a host plant. We evaluated the effects of summer prescribed fire on A. viridis and the use of A. viridis by monarch butterflies. Summer prescribed fire generated a newly emergent population of A. viridis that was absent in other areas. Pre-migrant monarch butterflies laid eggs on A. viridis in summer burned plots in late August and September, allowing adequate time for a new generation of adult monarchs to emerge and migrate south to their overwintering grounds. Thus, summer prescribed fire may provide host plant patches and/or corridors for pre-migrant monarchs during a time when host plant availability may be limited in other areas. PMID:22859559

Calcium signaling during the plant-plant interaction of parasitic Cuscuta reflexa with its hosts.

Science.gov (United States)

Albert, Markus; Kaiser, Bettina; van der Krol, Sander; Kaldenhoff, Ralf

2010-09-01

The plant parasite Cuscuta reflexa induces various responses in compatible and incompatible host plants. The visual reactions of both types of host plants including obvious morphological changes require the recognition of Cuscuta ssp. A consequently initiated signaling cascade is triggered which leads to a tolerance of the infection or, in the case of some incompatible host plants, to resistance. Calcium (Ca(2+)) release is the major second messenger during signal transduction. Therefore, we have studied Ca(2+) spiking in tomato and tobacco during infection with C. reflexa. In our recently published study Ca(2+) signals were monitored as bioluminescence in aequorin-expressing tomato plants after the onset of C. reflexa infestation. Signals at the attachment sites were observed from 30 to 48 h after infection. In an assay with leaf disks of aequorin-expressing tomato which were treated with different C. reflexa plant extracts it turned out that the substance that induced Ca(2+) release in the host plant was closely linked to the parasite's haustoria.

Directional Selection from Host Plants Is a Major Force Driving Host Specificity in Magnaporthe Species.

Science.gov (United States)

Zhong, Zhenhui; Norvienyeku, Justice; Chen, Meilian; Bao, Jiandong; Lin, Lianyu; Chen, Liqiong; Lin, Yahong; Wu, Xiaoxian; Cai, Zena; Zhang, Qi; Lin, Xiaoye; Hong, Yonghe; Huang, Jun; Xu, Linghong; Zhang, Honghong; Chen, Long; Tang, Wei; Zheng, Huakun; Chen, Xiaofeng; Wang, Yanli; Lian, Bi; Zhang, Liangsheng; Tang, Haibao; Lu, Guodong; Ebbole, Daniel J; Wang, Baohua; Wang, Zonghua

2016-05-06

One major threat to global food security that requires immediate attention, is the increasing incidence of host shift and host expansion in growing number of pathogenic fungi and emergence of new pathogens. The threat is more alarming because, yield quality and quantity improvement efforts are encouraging the cultivation of uniform plants with low genetic diversity that are increasingly susceptible to emerging pathogens. However, the influence of host genome differentiation on pathogen genome differentiation and its contribution to emergence and adaptability is still obscure. Here, we compared genome sequence of 6 isolates of Magnaporthe species obtained from three different host plants. We demonstrated the evolutionary relationship between Magnaporthe species and the influence of host differentiation on pathogens. Phylogenetic analysis showed that evolution of pathogen directly corresponds with host divergence, suggesting that host-pathogen interaction has led to co-evolution. Furthermore, we identified an asymmetric selection pressure on Magnaporthe species. Oryza sativa-infecting isolates showed higher directional selection from host and subsequently tends to lower the genetic diversity in its genome. We concluded that, frequent gene loss or gain, new transposon acquisition and sequence divergence are host adaptability mechanisms for Magnaporthe species, and this coevolution processes is greatly driven by directional selection from host plants.

Dynamics of glucosinolate-myrosinase system during Plutella xylostella interaction to a novel host Lepidium latifolium L.

Science.gov (United States)

Kaur, Tarandeep; Bhat, Rohini; Khajuria, Manu; Vyas, Ruchika; Kumari, Anika; Nadda, Gireesh; Vishwakarma, Ram; Vyas, Dhiraj

2016-09-01

Plutella xylostella L. is a notorious pest of cruciferous crops causing worldwide losses of $4-5 billion per year. Developing classical biological control to this pest include an introduction of host plants that act as natural enemies showing deviation from the preference-performance regimen in the evolutionary ecology of plant-insect interactions. The present study was designed to understand the role of glucosinolate-myrosinase system during P. xylostella interactions with a novel host. Adult moth preference and larval performance study were conducted on a novel host Lepidium latifolium L. (LL) that has high sinigrin content and was compared with its laboratory host Arabidopsis thaliana (AT). The glucosinolate-myrosinase system was studied in a time course experiment during larval feeding in choice and no-choice experiments. Adult moths visit and prefers LL over AT for oviposition. Conversely, LL leaves were not preferred and proved detrimental for P. xylostella larvae. Aliphatic and indolic glucosinolates were found to decrease significantly (p≤0.05) in AT during initial 12h of P. xylostella challenge, whereas, they were not affected in LL. Also, MYB transcription factor expression and myrosinase activity in LL do not suggest a typical host response to a specialist insect. This preference-performance mismatch of P. xylostella on LL mediated by glucosinolate pattern suggests that this novel plant could be utilized in P. xylostella management. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Enemy-free space and habitat-specific host specialization in a butterfly.

Science.gov (United States)

Wiklund, Christer; Friberg, Magne

2008-08-01

The majority of herbivorous insects have relatively specialized food habits. This suggests that specialization has some advantage(s) over generalization. Traditionally, feeding specialization has been thought to be linked to digestive or other food-related physiological advantages, but recent theory suggests that generalist natural enemies of herbivorous insects can also provide a major selective pressure for restricted host plant range. The European swallowtail butterfly Papilio machaon utilizes various plants in the Apiaceae family as hosts, but is an ecological specialist being monophagous on Angelica archangelica in southern Sweden. This perennial monocarp grows in three seaside habitat types: (1) on the barren rocky shore in the absence of any surrounding vegetation, (2) on the rocky shore with some surrounding vegetation, and (3) on species-rich meadows. The rocky shore habitat harbors few invertebrate generalist predators, whereas a number of invertebrate predators abound in the meadowland habitat. Here, we test the importance of enemy-free space for feeding specialization in Papilio machaon by assessing survival of larvae placed by hand on A. archangelica in each of the three habitat types, and by assessing the habitat-specificity of adult female egg-laying behavior by recording the distribution of eggs laid by free-flying adult females among the three habitat types. Larval survival was substantially higher in the rocky shore habitat than in the meadowland and significantly higher on host plants without surrounding vegetation on the rocky shore. Eggs laid by free-flying females were found in all three habitat types, but were significantly more frequent in the rocky shore habitat, suggesting that females prefer to lay eggs in the habitat type where offspring survival is highest. These results show that larval survivorship on the same host plant species can be strongly habitat-specific, and suggest that enemy-free space is an underlying factor that drives

Testing local host adaptation and phenotypic plasticity in a herbivore when alternative related host plants occur sympatrically.

Directory of Open Access Journals (Sweden)

Lorena Ruiz-Montoya

Full Text Available Host race formation in phytophagous insects can be an early stage of adaptive speciation. However, the evolution of phenotypic plasticity in host use is another possible outcome. Using a reciprocal transplant experiment we tested the hypothesis of local adaptation in the aphid Brevicoryne brassicae. Aphid genotypes derived from two sympatric host plants, Brassica oleracea and B. campestris, were assessed in order to measure the extent of phenotypic plasticity in morphological and life history traits in relation to the host plants. We obtained an index of phenotypic plasticity for each genotype. Morphological variation of aphids was summarized by principal components analysis. Significant effects of recipient host on morphological variation and life history traits (establishment, age at first reproduction, number of nymphs, and intrinsic growth rate were detected. We did not detected genotype × host plant interaction; in general the genotypes developed better on B. campestris, independent of the host plant species from which they were collected. Therefore, there was no evidence to suggest local adaptation. Regarding plasticity, significant differences among genotypes in the index of plasticity were detected. Furthermore, significant selection on PC1 (general aphid body size on B. campestris, and on PC1 and PC2 (body length relative to body size on B. oleracea was detected. The elevation of the reaction norm of PC1 and the slope of the reaction norm for PC2 (i.e., plasticity were under directional selection. Thus, host plant species constitute distinct selective environments for B. brassicae. Aphid genotypes expressed different phenotypes in response to the host plant with low or nil fitness costs. Phenotypic plasticity and gene flow limits natural selection for host specialization promoting the maintenance of genetic variation in host exploitation.

Specific developmental pathways underlie host specificity in the parasitic plant Orobanche

Science.gov (United States)

Hiscock, Simon

2010-01-01

Parasitic angiosperms are an ecologically and economically important group of plants. However our understanding of the basis for host specificity in these plants is embryonic. Recently we investigated host specificity in the parasitic angiosperm Orobanche minor, and demonstrated that this host generalist parasite comprises genetically defined races that are physiologically adapted to specific hosts. Populations occurring naturally on red clover (Trifolium pratense) and sea carrot (Daucus carota subsp. gummifer) respectively, showed distinct patterns of host specificity at various developmental stages, and a higher fitness on their natural hosts, suggesting these races are locally adapted. Here we discuss the implications of our findings from a broader perspective. We suggest that differences in signal responsiveness and perception by the parasite, as well as qualitative differences in signal production by the host, may elicit host specificity in this parasitic plant. Together with our earlier demonstration that these O. minor races are genetically distinct based on molecular markers, our recent data provide a snapshot of speciation in action, driven by host specificity. Indeed, host specificity may be an underestimated catalyst for speciation in parasitic plants generally. We propose that identifying host specific races using physiological techniques will complement conventional molecular marker-based approaches to provide a framework for delineating evolutionary relationships among cryptic host-specific parasitic plants. PMID:20081361

Host Plant Species Differentiation in a Polyphagous Moth: Olfaction is Enough.

Science.gov (United States)

Conchou, Lucie; Anderson, Peter; Birgersson, Göran

2017-08-01

Polyphagous herbivorous insects need to discriminate suitable from unsuitable host plants in complex plant communities. While studies on the olfactory system of monophagous herbivores have revealed close adaptations to their host plant's characteristic volatiles, such adaptive fine-tuning is not possible when a large diversity of plants is suitable. Instead, the available literature on polyphagous herbivore preferences suggests a higher level of plasticity, and a bias towards previously experienced plant species. It is therefore necessary to take into account the diversity of plant odors that polyphagous herbivores encounter in the wild in order to unravel the olfactory basis of their host plant choice behaviour. In this study we show that a polyphagous moth, Spodoptera littoralis, has the sensory ability to distinguish five host plant species using olfaction alone, this being a prerequisite to the ability to make a choice. We have used gas chromatography mass spectrometry (GC-MS) and gas chromatography electroantennographic detection (GC-EAD) in order to describe host plant odor profiles as perceived by S. littoralis. We find that each plant emits specific combinations and proportions of GC-EAD active volatiles, leading to statistically distinct profiles. In addition, at least four of these plants show GC-EAD active compound proportions that are conserved across individual plants, a characteristic that enables insects to act upon previous olfactory experiences during host plant choice. By identifying the volatiles involved in olfactory differentiation of alternative host plants by Spodoptera littoralis, we set the groundwork for deeper investigations of how olfactory perceptions translate into behaviour in polyphagous herbivores.

Molecular mimicry modulates plant host responses to pathogens.

Science.gov (United States)

Ronald, Pamela; Joe, Anna

2018-01-25

Pathogens often secrete molecules that mimic those present in the plant host. Recent studies indicate that some of these molecules mimic plant hormones required for development and immunity. This Viewpoint reviews the literature on microbial molecules produced by plant pathogens that functionally mimic molecules present in the plant host. This article includes examples from nematodes, bacteria and fungi with emphasis on RaxX, a microbial protein produced by the bacterial pathogen Xanthomonas oryzae pv. oryzae. RaxX mimics a plant peptide hormone, PSY (plant peptide containing sulphated tyrosine). The rice immune receptor XA21 detects sulphated RaxX but not the endogenous peptide PSY. Studies of the RaxX/XA21 system have provided insight into both host and pathogen biology and offered a framework for future work directed at understanding how XA21 and the PSY receptor(s) can be differentially activated by RaxX and endogenous PSY peptides. © The Author 2017. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Duration of plant damage by host larvae affects attraction of two parasitoid species (Microplitis croceipes and Cotesia marginiventris) to cotton: implications for interspecific competition.

Science.gov (United States)

Morawo, Tolulope; Fadamiro, Henry

2014-12-01

Volatile organic compounds (VOCs) released by herbivore-damaged plants can guide parasitoids to their hosts. The quantity and quality of VOC blends emitted by plants may be affected by the duration of plant damage by herbivores, which could have potential ramifications on the recruitment of competing parasitoids. We used two parasitoid species, Microplitis croceipes and Cotesia marginiventris (Hymenoptera: Braconidae), to address the question of whether duration of plant damage affects parasitoid use of plant VOCs for host location. Both wasp species are larval endoparasitoids of Heliothis virescens (Lepidoptera: Noctuidae), an important pest of cotton. Attraction of the two parasitoid species to odors emitted by undamaged (UD), fresh (6 h infestation) damage (FD), and old (24 h infestation) damage (OD) cotton plants infested by H. virescens larvae was investigated using a headspace volatile collection system coupled with four-choice olfactometer bioassay. Both sexes of M. croceipes showed a preference for FD- and OD-plant odors over UD-plants. On the other hand, more C. marginiventris females were attracted to UD- and FD-plants than to OD-plants. GC/MS analyses showed qualitative and quantitative differences in the VOC profiles of UD, FD, and OD-plants, which may explain the observed preferences of the parasitoids. These results suggest a temporal partitioning in the recruitment of M. croceipes and C. marginiventris to H. virescens-damaged cotton, and may have potential implications for interspecific competition between the two parasitoid species.

Effects of Gamma Irradiation and Leaves Extract of Barnoof Plant on Larval Development of Agrotis ipsilon (Hufngel)

International Nuclear Information System (INIS)

Mohamed, H.F.

2006-01-01

The effects of irradiating parental male full grown pupae agrotis ipsilon with the two sub sterile doses 100 and 150 Gray (Gy) followed by treated F1 4 th instar larvae with three concentrations of the barnoof plant leaves extract (0,15000 and 30000 ppm) or each of them alone were studied. the combined treatment of gamma irradiation and the barnoof plant extract to F1 larvae had a deleterious effects on average larval duration, average weight of last larval instar, total morality, pupation, adult emergence and survival when compared with the effect of gamma irradiation or plant leaves extract which of them alone. gamma irradiation increased the susceptibility of F 1 Larvae descendant from irradiated parental male pupae with 100 and 150 Gy to the barnoof plant leaves extract. A gradual increase in susceptibility was noticed as the dose of radiation increase. the efficiency of gamma irradiation and/or plant leaves extract to inhibit the 4 th instar larvae of A-. ipsilon was evaluated. the results showed highly toxic effect to the 4 th instar larvae at the two concentrations (15000 and 30000 ppm). on the other hand the dose 150 Gy combined with 30000 ppm of plant extract treatment (Acetone or petroleum ether solvents) had highly effect on the 4 th instar larvae as compared with the other treatments

Host plants of the tarnished plant bug (Heteroptera: Miridae) in Central Texas.

Science.gov (United States)

Esquivel, J F; Mowery, S V

2007-08-01

The tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), has taken on added importance as a pest of cotton in the Cotton Belt after successful eradication efforts for the boll weevil (Anthonomus grandis grandis Boheman). Because the Southern Blacklands region of Central Texas is in advanced stages of boll weevil eradication, blooming weeds and selected row crops were sampled during a 3-yr study to determine lygus species composition and associated temporal host plants. L. lineolaris was the sole lygus species in the region. Thirteen previously unreported host plants were identified for L. lineolaris, of which 69% supported reproduction. Rapistrum rugosum L. Allioni and Ratibida columnifera (Nuttall) Wooton and Standley were primary weed hosts during the early season (17 March to 31 May). Conyza canadensis L. Cronquist variety canadensis and Ambrosia trifida L. were primary weed hosts during the midseason (1 June to 14 August) and late-season (15 August to 30 November), respectively. Sisymbrium irio L. and Lamium amplexicaule L. sustained L. lineolaris populations during the overwintering period (1 December to 16 March). The proportion of females and numbers of nymphs found in R. rugosum, C. canadensis, A. trifida, and S. irio suggests these weeds supported reproductive adults during the early, mid-, and late season and overwintering period, respectively. Medicago sativa L. was the leading crop host for L. lineolaris; Glycine max L. Merrill did not yield L. lineolaris. Few L. lineolaris were collected in Gossypium hirsutum L. These results provide a more comprehensive assessment of host plants contributing to L. lineolaris populations in central Texas.

Trophic relationships between the parasitic plant species Phelipanche ramosa (L. and different hosts depending on host phenological stage and host growth rate

Directory of Open Access Journals (Sweden)

Delphine Moreau

2016-07-01

Full Text Available Phelipanche ramosa (L. Pomel (branched broomrape is a holoparasitic plant that reproduces on crops and also on weeds, which contributes to increase the parasite seed bank in fields. This parasite extracts all its nutrients at the host's expense so that host-parasite trophic relationships are crucial to determine host and parasite growth. This study quantified the intensity with which P. ramosa draws assimilates from its host and analyzed whether it varied with host species, host phenological stage and host growth rate. A greenhouse experiment was conducted on three host species: the crop species Brassica napus (L. (oilseed rape and two weed species, Capsella bursa-pastoris (L. Medik. and Geranium dissectum (L.. Plants were grown with or without P. ramosa and under three light levels to modulate host growth rate. The proportion of host biomass loss due to parasitism by P. ramosa differed between host species (at host fructification, biomass loss ranged from 34% to 84%. Brassica napus and C. bursa-pastoris displayed a similar response to P. ramosa, probably because they belong to the same botanical family. The sensitivity to P. ramosa in each host species could be related to the precocity of P. ramosa development on them. Host compartments could be ranked as a function of their sensitivity to parasitism, with the reproductive compartment being the most severely affected, followed by stems and roots. The proportion of biomass allocated to leaves was not reduced by parasitism. The proportion of pathosystem biomass allocated to the parasite depended on host species. It generally increased with host stage progression but was constant across light induced-host growth rate, showing that P. ramosa adapts its growth to host biomass production. The rank order of host species in terms of sink strength differed from that in terms of host sensitivity. Finally, for B. napus, the biomass of individual parasite shoots decreased with increasing their number per

Olfactory responses of Plutella xylostella natural enemies to host pheromone, larval frass, and green leaf cabbage volatiles.

Science.gov (United States)

Reddy, G V P; Holopainen, J K; Guerrero, A

2002-01-01

The parasitoids Trichogramma chilonis (Hymenoptera: Trichogrammatidae) and Cotesia plutellae (Hymenoptera: Braconidae), and the predator Chrysoperla carnea (Neuroptera: Chrysopidae), are potential biological control agents for the diamondback moth, Plutella xylostella (Lepidoptera: Yponomeutidae). We present studies on the interactions between these bioagents and various host-associated volatiles using a Y olfactometer. T chilonis was attracted to a synthetic pheromone blend (Z11-16:Ald, Z11-16:Ac, and Z11-16:OH in a 1:1:0.01 ratio), to Z11-16:Ac alone, and to a 1:1 blend of Z11-16:Ac and Z11-16:Ald. C. plutellae responded to the blend and to Z11-16:Ac and Z11-16:Ald. Male and female C. carnea responded to the blend and to a 1:1 blend of the major components of the pheromone, although no response was elicited by single compounds. Among the four host larval frass volatiles tested (dipropyl disulfide, dimethyl disulfide, allyl isothiocyanate, and dimethyl trisulfide), only allyl isothiocyanate elicited significant responses in the parasitoids and predator, but C. plutellae and both sexes of C. carnea did respond to all four volatiles. Among the green leaf volatiles of cabbage (Brassica oleracea subsp. capitata), only Z3-6:Ac elicited significant responses from T. chilonis, C. plutellae, and C. carnea, but C. plutellae also responded to E2-6:Ald and Z3-6:OH. When these volatiles were blended with the pheromone, the responses were similar to those elicited by the pheromone alone, except for C. carnea males, which had an increased response. The effect of temperature on the response of the biological agents to a mixture of the pheromone blend and Z3-6:Ac was also studied. T. chilonis was attracted at temperatures of 25-35 degrees C, while C. plutellae and C. carnea responded optimally at 30-35 degrees C and 20-25 degrees C, respectively. These results indicate that the sex pheromone and larval frass volatiles from the diamondback moth, as well as volatile compounds from

Trophic Relationships between the Parasitic Plant Species Phelipanche ramosa (L.) and Different Hosts Depending on Host Phenological Stage and Host Growth Rate

Science.gov (United States)

Moreau, Delphine; Gibot-Leclerc, Stéphanie; Girardin, Annette; Pointurier, Olivia; Reibel, Carole; Strbik, Florence; Fernández-Aparicio, Mónica; Colbach, Nathalie

2016-01-01

Phelipanche ramosa (L.) Pomel (branched broomrape) is a holoparasitic plant that reproduces on crops and also on weeds, which contributes to increase the parasite seed bank in fields. This parasite extracts all its nutrients at the host’s expense so that host–parasite trophic relationships are crucial to determine host and parasite growth. This study quantified the intensity with which P. ramosa draws assimilates from its host and analyzed whether it varied with host species, host phenological stage and host growth rate. A greenhouse experiment was conducted on three host species: the crop species Brassica napus (L.) (oilseed rape) and two weed species, Capsella bursa-pastoris (L.) Medik. and Geranium dissectum (L.). Plants were grown with or without P. ramosa and under three light levels to modulate host growth rate. The proportion of host biomass loss due to parasitism by P. ramosa differed between host species (at host fructification, biomass loss ranged from 34 to 84%). B. napus and C. bursa-pastoris displayed a similar response to P. ramosa, probably because they belong to the same botanical family. The sensitivity to P. ramosa in each host species could be related to the precocity of P. ramosa development on them. Host compartments could be ranked as a function of their sensitivity to parasitism, with the reproductive compartment being the most severely affected, followed by stems and roots. The proportion of biomass allocated to leaves was not reduced by parasitism. The proportion of pathosystem biomass allocated to the parasite depended on host species. It generally increased with host stage progression but was constant across light induced-host growth rate, showing that P. ramosa adapts its growth to host biomass production. The rank order of host species in terms of sink strength differed from that in terms of host sensitivity. Finally, for B. napus, the biomass of individual parasite shoots decreased with increasing their number per host plant

Effects of host-plant population size and plant sex on a specialist leaf-miner

DEFF Research Database (Denmark)

Bañuelos, María-José; Kollmann, Johannes Christian

2011-01-01

of the host-plant, and density-dependent relationships. Leaf-miners are specialised herbivores that leave distinct traces on infested leaves in the form of egg scars, mines, signs of predation and emergence holes. This allows the life cycle of the insect to be reconstructed and the success at the different...... punctures left by adults were marginally more frequent on male plants, whereas egg scars and mines were more common on females. Overall survival rate from egg stage to adult emergence was higher on female plants. Egg density was negatively correlated with hatching, while mine density was positively...... stages to be estimated. The main stages of the leaf-miner Phytomyza ilicis were recorded in eleven populations of the evergreen host Ilex aquifolium in Denmark. Survival rates were calculated and related to population size, sex of the host plant, and egg and mine densities. Host population size...

HOST PLANT UTILIZATION, HOST RANGE OSCILLATIONS AND DIVERSIFICATION IN NYMPHALID BUTTERFLIES: A PHYLOGENETIC INVESTIGATION

Science.gov (United States)

Nylin, Sören; Slove, Jessica; Janz, Niklas

2014-01-01

It has been suggested that phenotypic plasticity is a major factor in the diversification of life, and that variation in host range in phytophagous insects is a good model for investigating this claim. We explore the use of angiosperm plants as hosts for nymphalid butterflies, and in particular the evidence for past oscillations in host range and how they are linked to host shifts and to diversification. At the level of orders of plants, a relatively simple pattern of host use and host shifts emerges, despite the 100 million years of history of the family Nymphalidae. We review the evidence that these host shifts and the accompanying diversifications were associated with transient polyphagous stages, as suggested by the “oscillation hypothesis.” In addition, we investigate all currently polyphagous nymphalid species and demonstrate that the state of polyphagy is rare, has a weak phylogenetic signal, and a very apical distribution in the phylogeny; we argue that these are signs of its transient nature. We contrast our results with data from the bark beetles Dendroctonus, in which a more specialized host use is instead the apical state. We conclude that plasticity in host use is likely to have contributed to diversification in nymphalid butterflies. PMID:24372598

Phase-dependent outbreak dynamics of geometrid moth linked to host plant phenology.

Science.gov (United States)

Jepsen, Jane U; Hagen, Snorre B; Karlsen, Stein-Rune; Ims, Rolf A

2009-12-07

Climatically driven Moran effects have often been invoked as the most likely cause of regionally synchronized outbreaks of insect herbivores without identifying the exact mechanism. However, the degree of match between host plant and larval phenology is crucial for the growth and survival of many spring-feeding pest insects, suggesting that a phenological match/mismatch-driven Moran effect may act as a synchronizing agent. We analyse the phase-dependent spatial dynamics of defoliation caused by cyclically outbreaking geometrid moths in northern boreal birch forest in Fennoscandia through the most recent massive outbreak (2000-2008). We use satellite-derived time series of the prevalence of moth defoliation and the onset of the growing season for the entire region to investigate the link between the patterns of defoliation and outbreak spread. In addition, we examine whether a phase-dependent coherence in the pattern of spatial synchrony exists between defoliation and onset of the growing season, in order to evaluate if the degree of matching phenology between the moth and their host plant could be the mechanism behind a Moran effect. The strength of regional spatial synchrony in defoliation and the pattern of defoliation spread were both highly phase-dependent. The incipient phase of the outbreak was characterized by high regional synchrony in defoliation and long spread distances, compared with the epidemic and crash phase. Defoliation spread was best described using a two-scale stratified spread model, suggesting that defoliation spread is governed by two processes operating at different spatial scale. The pattern of phase-dependent spatial synchrony was coherent in both defoliation and onset of the growing season. This suggests that the timing of spring phenology plays a role in the large-scale synchronization of birch forest moth outbreaks.

Infection of non-host model plant species with the narrow-host-range Cacao swollen shoot virus.

Science.gov (United States)

Friscina, Arianna; Chiappetta, Laura; Jacquemond, Mireille; Tepfer, Mark

2017-02-01

Cacao swollen shoot virus (CSSV) is a major pathogen of cacao (Theobroma cacao) in Africa, and long-standing efforts to limit its spread by the culling of infected trees have had very limited success. CSSV is a particularly difficult virus to study, as it has a very narrow host range, limited to several tropical tree species. Furthermore, the virus is not mechanically transmissible, and its insect vector can only be used with difficulty. Thus, the only efficient means to infect cacao plants that have been experimentally described so far are by particle bombardment or the agroinoculation of cacao plants with an infectious clone. We have genetically transformed three non-host species with an infectious form of the CSSV genome: two experimental hosts widely used in plant virology (Nicotiana tabacum and N. benthamiana) and the model species Arabidopsis thaliana. In transformed plants of all three species, the CSSV genome was able to replicate, and, in tobacco, CSSV particles could be observed by immunosorbent electron microscopy, demonstrating that the complete virus cycle could be completed in a non-host plant. These results will greatly facilitate the preliminary testing of CSSV control strategies using plants that are easy to raise and to transform genetically. © 2016 BSPP AND JOHN WILEY & SONS LTD.

Host Selection Behavior and the Fecundity of Plutella xylostella (Lepidoptera: Plutellidae) on Multiple Host Plants

Science.gov (United States)

Huang, Bin; Shi, Zhanghong; Hou, Youming

2014-01-01

Abstract Insect herbivores often have higher densities on host plants grown in monocultures than those in diverse environments. The underlying mechanisms are thought to be that polyphagous insects have difficulty in selecting food or oviposition sites when multiple host plants exist. However, this hypothesis needs to be extensively investigated. Our field experiments revealed that the population of the diamondback moths, Plutella xylostella (L.) (Lepidoptera: Plutellidae), significantly decreased in a mixed cropping field compared with a monoculture. To determine the reasons for the reduction in population in the mixed cropping field, the takeoff behavior and fecundity of females in no-choice and free-choice laboratory environments were compared by video recordings of host selection by P. xylostella . Adults displayed a significantly higher takeoff frequency in free-choice environments than those in no-choice treatments and preferred landing on Brassica campestris (L.) or Brassica juncea (Coss) plants in contrast with Brassica oleracea (L.). Female adults in the free-choice environment also laid fewer eggs compared with the monoculture. Olfaction experiments demonstrated orientation by P. xylostella to host volatiles when presented with a choice between plant odors and clean air, but females showed no preference when odors from three Brassicaceae species were presented simultaneously. We conclude that mixed cropping alters the host-finding behavior of P. xylostella resulting in reduced oviposition. PMID:25527573

Egg laying site selection by a host plant specialist leaf miner moth at two intra-plant levels in the northern Chilean Atacama Desert

Directory of Open Access Journals (Sweden)

José Storey-Palma

2014-09-01

Full Text Available Egg laying site selection by a host plant specialist leaf miner moth at two intra-plant levels in the northern Chilean Atacama Desert. The spatial distribution of the immature stages of the leaf miner Angelabella tecomae Vargas & Parra, 2005 was determined at two intra-plant levels (shoot and leaflet on the shrub Tecoma fulva fulva (Cav. D. Don (Bignoniaceae in the Azapa valley, northern Chilean Atacama Desert. An aggregated spatial pattern was detected for all the immature stages along the shoot, with an age dependent relative position: eggs and first instar larvae were clumped at apex; second, third and fourth instar larvae were mostly found at intermediate positions; meanwhile the spinning larva and pupa were clumped at basis. This pattern suggests that the females select new, actively growing leaflets for egg laying. At the leaflet level, the immature stages were found more frequently at underside. Furthermore, survivorship was higher for larvae from underside mines. All these results highlight the importance of an accurate selection of egg laying site in the life history of this highly specialized leaf miner. By contrast, eventual wrong choices in the egg laying site selection may be associated with diminished larval survivorship. The importance of the continuous availability of new plant tissue in this highly human modified arid environment is discussed in relation with the observed patterns.

Assessing the potential effects of fungicides on nontarget gut fungi (trichomycetes) and their associated larval black fly hosts

Science.gov (United States)

Wilson, Emma R.; Smalling, Kelly L.; Reilly, Timothy J.; Gray, Elmer; Bond, Laura; Steele, Lance; Kandel, Prasanna; Chamberlin, Alison; Gause, Justin; Reynolds, Nicole; Robertson, Ian; Novak, Stephen; Feris, Kevin; White, Merlin M.

2014-01-01

Fungicides are moderately hydrophobic and have been detected in water and sediment, particularly in agricultural watersheds, but typically are not included in routine water quality monitoring efforts. This is despite their widespread use and frequent application to combat fungal pathogens. Although the efficacy of these compounds on fungal pathogens is well documented, little is known about their effects on nontarget fungi. This pilot study, a field survey in southwestern Idaho from April to December 2010 on four streams with varying pesticide inputs (two agricultural and two reference sites), was conducted to assess nontarget impact of fungicides on gut fungi, or trichomycetes. Tissues of larval black flies (Diptera: Simuliidae), hosts of gut fungi, were analyzed for pesticide accumulation. Fungicides were detected in hosts from streams within agricultural watersheds but were not detected in hosts from reference streams. Gut fungi from agricultural sites exhibited decreased percent infestation, density and sporulation within the gut, and black fly tissues had elevated pesticide concentrations. Differences observed between the sites demonstrate a potential effect on this symbiotic system. Future research is needed to parse out the details of the complex biotic and abiotic relationships; however, these preliminary results indicate that impacts to nontarget organisms could have far-reaching consequences within aquatic ecosystems.

Effects of host-plant population size and plant sex on a specialist leaf-miner

Science.gov (United States)

Bañuelos, María-José; Kollmann, Johannes

2011-03-01

Animal population density has been related to resource patch size through various hypotheses such as those derived from island biogeography and resource concentration theory. This theoretical framework can be also applied to plant-herbivore interactions, and it can be modified by the sex of the host-plant, and density-dependent relationships. Leaf-miners are specialised herbivores that leave distinct traces on infested leaves in the form of egg scars, mines, signs of predation and emergence holes. This allows the life cycle of the insect to be reconstructed and the success at the different stages to be estimated. The main stages of the leaf-miner Phytomyza ilicis were recorded in eleven populations of the evergreen host Ilex aquifolium in Denmark. Survival rates were calculated and related to population size, sex of the host plant, and egg and mine densities. Host population size was negatively related to leaf-miner prevalence, with larger egg and mine densities in small populations. Percentage of eggs hatching and developing into mines, and percentage of adult flies emerging from mines also differed among host populations, but were not related to population size or host cover. Feeding punctures left by adults were marginally more frequent on male plants, whereas egg scars and mines were more common on females. Overall survival rate from egg stage to adult emergence was higher on female plants. Egg density was negatively correlated with hatching, while mine density was positively correlated with emergence of the larvae. The inverse effects of host population size were not in line with predictions based on island biogeography and resource concentration theory. We discuss how a thorough knowledge of the immigration behaviour of this fly might help to understand the patterns found.

Life history and larval morphology of Eurhinus magnificus Gyllenhal (Coleoptera: Curculionidae), a new weevil to the United States

OpenAIRE

Ulmer, Bryan J.; Duncan, Rita E.; Prena, Jens; Peña, Jorge E.

2007-01-01

Eurhinus magnificus Gyllenhal has been collected in south Florida, presumably introduced through trade with countries in its native range. Very little information has been published on the biology or taxonomy of this insect. We conducted studies to investigate various aspects of its life history and host plant associations. The pre-imaginal life stages of E. magnificus are described for the first time. Dimensions of the adult, egg, larval, and pupal stages are also provided; head capsule meas...

Effect of Tea Saponin-Treated Host Plants on Activities of Antioxidant Enzymes in Larvae of the Diamondback Moth Plutella xylostella (Lepidoptera: Plutellidae).

Science.gov (United States)

Lin, Shuo; Chen, Yixin; Bai, Yan; Cai, Hongjiao; Wei, Hui; Tian, Houjun; Zhao, Jianwei; Chen, Yong; Yang, Guang; Gu, Xiaojun; Murugan, Kadarkarai

2018-06-06

Tea saponin (TS) is extracted from the seeds of the tea plant and is generally regarded as a safe compound that has insecticidal properties and can act synergistically with other compounds. In this study, the activities of antioxidant enzymes superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and the levels of malondialdehyde (MDA) were compared in midgut tissues of third instar larvae of the diamondback moth (DBM), Plutella xylostella L. (Lepidoptera: Plutellidae). The larvae were fed on three different host plants, cabbage (Brassica oleracea L. var. capitata [Capparales: Brassicaceae]), radish (Raphanus sativus L. var. radiculus Persi [Capparales: Brassicaceae]), or rape (Brassica campestris L. [Capparales: Brassicaceae]), that had been treated with TS. Higher SOD, POD, and CAT activities were found in DBM larvae fed on cabbage after LC20 (concentration that induced 20% larval mortality) or LC50 (concentration that induced 50% larval mortality) treatment than on the control. On rape, TS treatments led to lower SOD and CAT activities than in the control and to higher POD activities after 24 h. MDA content increased in larvae fed on rape but decreased in larvae fed on radish after 12 h. Our results indicated that DBM larvae are more susceptible to TS on rape than on cabbage and radish, suggesting that this treatment may be an economic and effective means of controlling DBM on rape.

Plant pathology: monitoring a pathogen-targeted host protein.

Science.gov (United States)

Ellis, Jeff; Dodds, Peter

2003-05-13

A plant protein RIN4 is targeted and modified by bacterial pathogens as part of the disease process. At least two host resistance proteins monitor this pathogen interference and trigger the plant's defence responses.

Plant host finding by parasitic plants: a new perspective on plant to plant communication.

Science.gov (United States)

Mescher, Mark C; Runyon, Justin B; De Moraes, Consuelo M

2006-11-01

Plants release airborne chemicals that can convey ecologically relevant information to other organisms. These plant volatiles are known to mediate a large array of, often complex, interactions between plants and insects. It has been suggested that plant volatiles may have similar importance in mediating interactions among plant species, but there are few well-documented examples of plant-to-plant communication via volatiles, and the ecological significance of such interactions has been much debated. To date, nearly all studies of volatile-mediated interactions among plant species have focused on the reception of herbivore-induced volatiles by neighboring plants. We recently documented volatile effects in another system, demonstrating that the parasitic plant Cuscuta pentagona uses volatile cues to locate its hosts. This finding may broaden the discussion regarding plant-to-plant communication, and suggests that new classes of volatile-meditated interactions among plant species await discovery.

Host-plant-mediated effects of Nadefensin on herbivore and pathogen resistance in Nicotiana attenuata

Directory of Open Access Journals (Sweden)

Baldwin Ian T

2008-10-01

Full Text Available Abstract Background The adage from Shakespeare, "troubles, not as single spies, but in battalions come," holds true for Nicotiana attenuata, which is commonly attacked by both pathogens (Pseudomonas spp. and herbivores (Manduca sexta in its native habitats. Defense responses targeted against the pathogens can directly or indirectly influence the responses against the herbivores. Nadefensin is an effective induced defense gene against the bacterial pathogen Pseudomonas syringae pv tomato (PST DC3000, which is also elicited by attack from M. sexta larvae, but whether this defense protein influences M. sexta's growth and whether M. sexta-induced Nadefensin directly or indirectly influences PST DC3000 resistance are unknown. Results M. sexta larvae consumed less on WT and on Nadefensin-silenced N. attenuata plants that had previously been infected with PST DC3000 than on uninfected plants. WT plants infected with PST DC3000 showed enhanced resistance to PST DC3000 and decreased leaf consumption by M. sexta larvae, but larval mass gain was unaffected. PST DC3000-infected Nadefensin-silenced plants were less resistant to subsequent PST DC3000 challenge, and on these plants, M. sexta larvae consumed less and gained less mass. WT and Nadefensin-silenced plants previously damaged by M. sexta larvae were better able to resist subsequent PST DC3000 challenges than were undamaged plants. Conclusion These results demonstrate that Na-defensin directly mediates defense against PST DC3000 and indirectly against M. sexta in N. attenuata. In plants that were previously infected with PST DC3000, the altered leaf chemistry in PST DC3000-resistant WT plants and PST DC3000-susceptible Nadefensin-silenced plants differentially reduced M. sexta's leaf consumption and mass gain. In plants that were previously damaged by M. sexta, the combined effect of the altered host plant chemistry and a broad spectrum of anti-herbivore induced metabolomic responses was more

The Use of Arabidopsis to Study Interactions between Parasitic Angiosperms and Their Plant Hosts

Science.gov (United States)

Goldwasser, Y.; Westwood, J. H.; Yoder, J. I.

2002-01-01

Parasitic plants invade host plants in order to rob them of water, minerals and nutrients. The consequences to the infected hosts can be debilitating and some of the world's most pernicious agricultural weeds are parasitic. Parasitic genera of the Scrophulariaceae and Orobanchaceae directly invade roots of neighboring plants via underground structures called haustoria. The mechanisms by which these parasites identify and associate with host plants present unsurpassed opportunities for studying chemical signaling in plant-plant interactions. Seeds of some parasites require specific host factors for efficient germination, thereby insuring the availability of an appropriate host root prior to germination. A second set of signal molecules is required to induce haustorium development and the beginning of heterotrophy. Later stages in parasitism also require the presence of host factors, although these have not yet been well characterized. Arabidopsis is being used as a model host plant to identify genetic loci associated with stimulating parasite germination, haustorium development, and parasite support. Arabidopsis is also being employed to explore how host plants respond to parasite attack. Current methodologies and recent findings in Arabidopsis – parasitic plant interactions will be discussed. PMID:22303205

Genomes of three facultatively symbiotic Frankia sp. strainsreflect host plant biogeography

Energy Technology Data Exchange (ETDEWEB)

Normand, Philippe; Lapierre, Pascal; Tisa, Louis S.; Gogarten, J.Peter; Alloisio, Nicole; Bagnarol, Emilie; Bassi, Carla A.; Berry,Alison; Bickhart, Derek M.; Choisne, Nathalie; Couloux, Arnaud; Cournoyer, Benoit; Cruveiller, Stephane; Daubin, Vincent; Demange, Nadia; Francino, M. Pilar; Ggoltsman, Eugene; Huang, Ying; Kopp, Olga; Labarre,Laurent; Lapidus, Alla; Lavire, Celine; Marechal, Joelle; Martinez,Michele; Mastronunzio, Juliana E.; Mullin, Beth; Niemann, James; Pujic,Pierre; Rawnsley, Tania; Rouy, Zoe; Schenowitz, Chantal; Sellstedt,Anita; Tavares, Fernando; Tomkins, Jeffrey P.; Vallenet, David; Valverde,Claudio; Wall, Luis; Wang, Ying; Medigue, Claudine; Benson, David R.

2006-02-01

Filamentous actinobacteria from the genus Frankia anddiverse woody trees and shrubs together form N2-fixing actinorhizal rootnodule symbioses that are a major source of new soil nitrogen in widelydiverse biomes 1. Three major clades of Frankia sp. strains are defined;each clade is associated with a defined subset of plants from among theeight actinorhizal plant families 2,3. The evolution arytrajectoriesfollowed by the ancestors of both symbionts leading to current patternsof symbiont compatibility are unknown. Here we show that the competingprocesses of genome expansion and contraction have operated in differentgroups of Frankia strains in a manner that can be related to thespeciation of the plant hosts and their geographic distribution. Wesequenced and compared the genomes from three Frankia sp. strains havingdifferent host plant specificities. The sizes of their genomes variedfrom 5.38 Mbp for a narrow host range strain (HFPCcI3) to 7.50Mbp for amedium host range strain (ACN14a) to 9.08 Mbp for a broad host rangestrain (EAN1pec.) This size divergence is the largest yet reported forsuch closely related bacteria. Since the order of divergence of thestrains is known, the extent of gene deletion, duplication andacquisition could be estimated and was found to be inconcert with thebiogeographic history of the symbioses. Host plant isolation favoredgenome contraction, whereas host plant diversification favored genomeexpansion. The results support the idea that major genome reductions aswell as expansions can occur in facultatively symbiotic soil bacteria asthey respond to new environments in the context of theirsymbioses.

Does white clover (Trifolium repens abundance in temperate pastures determine Sitona obsoletus (Coleoptera: Curculionidae larval populations?

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Mark Richard McNeill

2016-09-01

Full Text Available To determine if host plant abundance determined the size of clover root weevil (CRW Sitona obsoletus larval populations, a study was conducted over four years in plots sown in ryegrass (Lolium perenne (cv. Nui sown at either 6 or 30 kg/ha and white clover (Trifolium repens sown at a uniform rate of 8 kg/ha. This provided a range of % white clover content to investigate CRW population establishment and impacts on white clover survival. Larval sampling was carried out in spring (October when larval densities are near their spring peak at Lincoln (Canterbury, New Zealand with % clover measured in autumn (April and spring (September of each year. Overall, mean larval densities measured in spring 2012, 2013, 2014 and 2015 were 310, 38, 59 and 31 larvae m-2, respectively. There was a significant decline in larval populations between 2012 and 2013, but spring populations were relatively uniform thereafter. The mean % white clover measured in autumns of 2012 to 2015 was 17, 10, 3 and 11%, respectively. In comparison, mean spring % white clover from 2012 to 2015, averaged c. 5% each year. Analysis relating spring (October larval populations to % white clover measured in each plot in autumn (April found the 2012 larval population to be statistically significantly larger in the ryegrass 6 kg/ha plots than 30 kg/ha plots. Thereafter, sowing rate had no significant effect on larval populations. From 2013 to 2015, spring larval populations had a negative relationship with the previous autumn % white clover with the relationship highly significant for the 2014 data. When CRW larval populations in spring 2013 to 2015 were predicted from the 2013 to 2015 autumn % white clover, respectively, based on their positive relationship in 2012, the predicted densities were substantially larger than those observed. Conversely, when 2015 spring larval data and % clover was regressed against 2012-2014 larval populations, observed densities tended to be higher than predicted

Does White Clover (Trifolium repens) Abundance in Temperate Pastures Determine Sitona obsoletus (Coleoptera: Curculionidae) Larval Populations?

Science.gov (United States)

McNeill, Mark R; van Koten, Chikako; Cave, Vanessa M; Chapman, David; Hodgson, Hamish

2016-01-01

To determine if host plant abundance determined the size of clover root weevil (CRW) Sitona obsoletus larval populations, a study was conducted over 4 years in plots sown in ryegrass ( Lolium perenne ) (cv. Nui) sown at either 6 or 30 kg/ha and white clover ( Trifolium repens ) sown at a uniform rate of 8 kg/ha. This provided a range of % white clover content to investigate CRW population establishment and impacts on white clover survival. Larval sampling was carried out in spring (October) when larval densities are near their spring peak at Lincoln (Canterbury, New Zealand) with % clover measured in autumn (April) and spring (September) of each year. Overall, mean larval densities measured in spring 2012-2015 were 310, 38, 59, and 31 larvae m -2 , respectively. There was a significant decline in larval populations between 2012 and 2013, but spring populations were relatively uniform thereafter. The mean % white clover measured in autumns of 2012 to 2015 was 17, 10, 3, and 11%, respectively. In comparison, mean spring % white clover from 2012 to 2015, averaged c. 5% each year. Analysis relating spring (October) larval populations to % white clover measured in each plot in autumn (April) found the 2012 larval population to be statistically significantly larger in the ryegrass 6 kg/ha plots than 30 kg/ha plots. Thereafter, sowing rate had no significant effect on larval populations. From 2013 to 2015, spring larval populations had a negative relationship with the previous autumn % white clover with the relationship highly significant for the 2014 data. When CRW larval populations in spring 2013 to 2015 were predicted from the 2013 to 2015 autumn % white clover, respectively, based on their positive relationship in 2012, the predicted densities were substantially larger than those observed. Conversely, when 2015 spring larval data and % clover was regressed against 2012-2014 larval populations, observed densities tended to be higher than predicted, but the numbers

Distribución temporal y espacial de poblaciones larvarias de Spodoptera frugiperda (Smith (Lep.: Noctuidae en diferentes hospederos en provincias del norte de la Argentina Spatial and temporal distribution of Spodoptera frugiperda (Smith (Lep.: Noctuidae larval populations on different host plants in northern Argentina provinces

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M. Gabriela Murúa

Full Text Available Para estudiar la distribución temporal y espacial de larvas del "cogollero del maíz" Spodoptera frugiperda en diferentes plantas hospederas, se realizaron muestreos sistemáticos desde el año 2004 al 2007 en diferentes asociaciones de cultivos en las provincias de Tucumán, Salta y Santiago del Estero. Se consideró "asociación de cultivos" a una zona donde coexistían simultáneamente (en tiempo y espacio más de dos cultivos colindantes. Los cultivos monitoreados fueron maíz, sorgo granífero, alfalfa, caña de azúcar, soja, trigo, cártamo, garbanzo y malezas. En cada uno se muestrearon cinco puntos al azar de 1 m² y se revisaron las plantas, recolectándose las posturas y/o larvas presentes. Se encontraron 3620 larvas. La mayor cantidad se recolectó durante los meses del verano en las tres campañas monitoreadas en todas las provincias. Su presencia estuvo relacionada con la aparición de los cultivos estivales como el maíz y el sorgo granífero, en todas las provincias. La mayor cantidad de larvas se obtuvieron en maíz (2894, independientemente de los otros cultivos que formaban parte de la asociación. Siguiendo en orden de importancia, los otros hospederos con larvas fueron: sorgo granífero (272, alfalfa (125 y malezas (282. En base al número de larvas encontradas, la soja, trigo y caña de azúcar, cultivos que estuvieron presentes en casi todas las asociaciones, no son hospederos preferenciales de esta especie.In order to study the spatial and temporal distribution of fall armyworm Spodoptera frugiperda larval populations on different host plants, systematic samplings were made from 2004 to 2007 in different crop associations in the provinces of Tucumán, Salta and Santiago del Estero. A zone where more than two adjacent crops coexisted simultaneously (in time and space was considered a crop association. Sampled crops were corn, sorghum, alfalfa, sugarcane, soybean, wheat, safflower, chickpea and weeds. Five one

Parasitic infection by larval helminths in Antarctic fishes: pathological changes and impact on the host body condition index.

Science.gov (United States)

Santoro, Mario; Mattiucci, Simonetta; Work, Thierry; Cimmaruta, Roberta; Nardi, Valentina; Cipriani, Paolo; Bellisario, Bruno; Nascetti, Giuseppe

2013-07-22

We examined pathological changes and relationship between body condition index (BCI) and parasitic infection in 5 species of fish, including 42 icefish Chionodraco hamatus (Channichtyidae), 2 dragonfish Cygnodraco mawsoni (Bathydraconidae), 30 emerald rock cod Trematomus bernacchii, 46 striped rock cod T. hansoni and 9 dusty rock cod T. newnesi (Nototheniidae) from the Ross Sea, Antarctica. All parasites were identified by a combination of morphology and mtDNA cytochrome-oxidase-2 sequence (mtDNA cox2) analysis, except Contracaecum osculatum s.l., for which only the latter was used. Five larval taxa were associated with pathological changes including 2 sibling species (D and E) of the C. osculatum species complex and 3 cestodes including plerocercoids of a diphyllobothridean, and 2 tetraphyllidean forms including cercoids with monolocular and bilocular bothridia. The most heavily infected hosts were C. hamatus and C. mawsoni, with C. hamatus most often infected by C. osculatum sp. D and sp. E and diphyllobothrideans, while C. mawsoni was most often infected with tetraphyllidean forms. Histologically, all fish showed varying severity of chronic inflammation associated with larval forms of helminths. Diphyllobothrideans and C. osculatum spp. were located in gastric muscularis or liver and were associated with necrosis and mild to marked fibrosis. Moderate multifocal rectal mucosal chronic inflammation was associated with attached tetraphyllidean scolices. C. hamatus showed a strong negative correlation between BCI and parasite burden.

Disruption of Vector Host Preference with Plant Volatiles May Reduce Spread of Insect-Transmitted Plant Pathogens.

Science.gov (United States)

Martini, Xavier; Willett, Denis S; Kuhns, Emily H; Stelinski, Lukasz L

2016-05-01

Plant pathogens can manipulate the odor of their host; the odor of an infected plant is often attractive to the plant pathogen vector. It has been suggested that this odor-mediated manipulation attracts vectors and may contribute to spread of disease; however, this requires further broad demonstration among vector-pathogen systems. In addition, disruption of this indirect chemical communication between the pathogen and the vector has not been attempted. We present a model that demonstrates how a phytophathogen (Candidatus Liberibacter asiaticus) can increase its spread by indirectly manipulating the behavior of its vector (Asian citrus psyllid, Diaphorina citri Kuwayama). The model indicates that when vectors are attracted to pathogen-infected hosts, the proportion of infected vectors increases, as well as, the proportion of infected hosts. Additionally, the peak of infected host populations occurs earlier as compared with controls. These changes in disease dynamics were more important during scenarios with higher vector mortality. Subsequently, we conducted a series of experiments to disrupt the behavior of the Asian citrus psyllid. To do so, we exposed the vector to methyl salicylate, the major compound released following host infection with the pathogen. We observed that during exposure or after pre-exposure to methyl salicylate, the host preference can be altered; indeed, the Asian citrus psyllids were unable to select infected hosts over uninfected counterparts. We suggest mechanisms to explain these interactions and potential applications of disrupting herbivore host preference with plant volatiles for sustainable management of insect vectors.

Large-Scale Evolutionary Patterns of Host Plant Associations in the Lepidoptera

DEFF Research Database (Denmark)

Menken, S.B.J.; Boomsma, J.J.; van Nieukerken, E.J.

2010-01-01

We characterized evolutionary patterns of host plant use across about 2500 species of British Lepidoptera, using character optimization and independent phylogenetic contrasts among 95 operational taxa, and evaluated the extent to which caterpillars are monophagous, use woody host plants, and feed...

Treehoppers (Homoptera, Membracidae in southeastern Brazil: use of host plants

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Benedito C. Lopes

1995-09-01

Full Text Available A survey on the use of host plants by treehoppers in plants in cerrado (savanna vegetation at Moji-Guaçu (São Paulo, Southeastern Brazil was made. Fifty-two species of treehoppers were recorded in association with 40 host plant species from October 1980 to February 1982. The families Araliaceae, Asteraceae, Leguminosae, Malpighiaceae, Myrtaceae and Nyctaginaceae were the most commonly used for oviposition. Byrsonima intermedia A. Juss. (Malpighiaceae had the highest number of associated treehopper species (10 species. The abundance of treehopper individuals was related to the hot and rainy season (from October to February, while during the cold and dry season (from March to September there was a decrease in the number of these Homoptera. After the occurrence of a frost, few adults and nymphs were observed on the host plants for one to two months.

Adaptation to the Host Environment by Plant-Pathogenic Fungi.

Science.gov (United States)

van der Does, H Charlotte; Rep, Martijn

2017-08-04

Many fungi can live both saprophytically and as endophyte or pathogen inside a living plant. In both environments, complex organic polymers are used as sources of nutrients. Propagation inside a living host also requires the ability to respond to immune responses of the host. We review current knowledge of how plant-pathogenic fungi do this. First, we look at how fungi change their global gene expression upon recognition of the host environment, leading to secretion of effectors, enzymes, and secondary metabolites; changes in metabolism; and defense against toxic compounds. Second, we look at what is known about the various cues that enable fungi to sense the presence of living plant cells. Finally, we review literature on transcription factors that participate in gene expression in planta or are suspected to be involved in that process because they are required for the ability to cause disease.

Coevolutionary arms race versus host defense chase in a tropical herbivore-plant system.

Science.gov (United States)

Endara, María-José; Coley, Phyllis D; Ghabash, Gabrielle; Nicholls, James A; Dexter, Kyle G; Donoso, David A; Stone, Graham N; Pennington, R Toby; Kursar, Thomas A

2017-09-05

Coevolutionary models suggest that herbivores drive diversification and community composition in plants. For herbivores, many questions remain regarding how plant defenses shape host choice and community structure. We addressed these questions using the tree genus Inga and its lepidopteran herbivores in the Amazon. We constructed phylogenies for both plants and insects and quantified host associations and plant defenses. We found that similarity in herbivore assemblages between Inga species was correlated with similarity in defenses. There was no correlation with phylogeny, a result consistent with our observations that the expression of defenses in Inga is independent of phylogeny. Furthermore, host defensive traits explained 40% of herbivore community similarity. Analyses at finer taxonomic scales showed that different lepidopteran clades select hosts based on different defenses, suggesting taxon-specific histories of herbivore-host plant interactions. Finally, we compared the phylogeny and defenses of Inga to phylogenies for the major lepidopteran clades. We found that closely related herbivores fed on Inga with similar defenses rather than on closely related plants. Together, these results suggest that plant defenses might be more evolutionarily labile than the herbivore traits related to host association. Hence, there is an apparent asymmetry in the evolutionary interactions between Inga and its herbivores. Although plants may evolve under selection by herbivores, we hypothesize that herbivores may not show coevolutionary adaptations, but instead "chase" hosts based on the herbivore's own traits at the time that they encounter a new host, a pattern more consistent with resource tracking than with the arms race model of coevolution.

Host plant quality mediates competition between arbuscular mycorrhizal fungi

NARCIS (Netherlands)

Knegt, B.; Jansa, J.; Franken, O.; Engelmoer, D.J.P.; Werner, G.D.A.; Bücking, H.; Kiers, E.T.

2016-01-01

Arbuscular mycorrhizal fungi exchange soil nutrients for carbon from plant hosts. Empirical works suggests that hosts may selectively provide resources to different fungal species, ultimately affecting fungal competition. However, fungal competition may also be mediated by colonization strategies of

The Influence of Learning on Host Plant Preference in a Significant Phytopathogen Vector, Diaphorina citri.

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Dara G Stockton

Full Text Available Although specialist herbivorous insects are guided by innate responses to host plant cues, host plant preference may be influenced by experience and is not dictated by instinct alone. The effect of learning on host plant preference was examined in the Asian citrus psyllid, Diaphorina citri; vector of the causal agent of citrus greening disease or huanglongbing. We investigated: a whether development on specific host plant species influenced host plant preference in mature D. citri; and b the extent of associative learning in D. citri in the form of simple and compound conditioning. Learning was measured by cue selection in a 2-choice behavioral assay and compared to naïve controls. Our results showed that learned responses in D. citri are complex and diverse. The developmental host plant species influenced adult host plant preference, with female psyllids preferring the species on which they were reared. However, such preferences were subject to change with the introduction of an alternative host plant within 24-48 hrs, indicating a large degree of experience-dependent response plasticity. Additionally, learning occurred for multiple sensory modalities where novel olfactory and visual environmental cues were associated with the host plant. However, males and females displayed differing discriminatory abilities. In compound conditioning tasks, males exhibited recognition of a compound stimulus alone while females were capable of learning the individual components. These findings suggest D. citri are dynamic animals that demonstrate host plant preference based on developmental and adult experience and can learn to recognize olfactory and visual host plant stimuli in ways that may be sex specific. These experience-based associations are likely used by adults to locate and select suitable host plants for feeding and reproduction and may suggest the need for more tailored lures and traps, which reflect region-specific cultivars or predominate

The Influence of Learning on Host Plant Preference in a Significant Phytopathogen Vector, Diaphorina citri.

Science.gov (United States)

Stockton, Dara G; Martini, Xavier; Patt, Joseph M; Stelinski, Lukasz L

2016-01-01

Although specialist herbivorous insects are guided by innate responses to host plant cues, host plant preference may be influenced by experience and is not dictated by instinct alone. The effect of learning on host plant preference was examined in the Asian citrus psyllid, Diaphorina citri; vector of the causal agent of citrus greening disease or huanglongbing. We investigated: a) whether development on specific host plant species influenced host plant preference in mature D. citri; and b) the extent of associative learning in D. citri in the form of simple and compound conditioning. Learning was measured by cue selection in a 2-choice behavioral assay and compared to naïve controls. Our results showed that learned responses in D. citri are complex and diverse. The developmental host plant species influenced adult host plant preference, with female psyllids preferring the species on which they were reared. However, such preferences were subject to change with the introduction of an alternative host plant within 24-48 hrs, indicating a large degree of experience-dependent response plasticity. Additionally, learning occurred for multiple sensory modalities where novel olfactory and visual environmental cues were associated with the host plant. However, males and females displayed differing discriminatory abilities. In compound conditioning tasks, males exhibited recognition of a compound stimulus alone while females were capable of learning the individual components. These findings suggest D. citri are dynamic animals that demonstrate host plant preference based on developmental and adult experience and can learn to recognize olfactory and visual host plant stimuli in ways that may be sex specific. These experience-based associations are likely used by adults to locate and select suitable host plants for feeding and reproduction and may suggest the need for more tailored lures and traps, which reflect region-specific cultivars or predominate Rutaceae in the area

The Ratio between Field Attractive and Background Volatiles Encodes Host-Plant Recognition in a Specialist Moth.

Science.gov (United States)

Knudsen, Geir K; Norli, Hans R; Tasin, Marco

2017-01-01

Volatiles emitted by plants convey an array of information through different trophic levels. Animals such as host-seeking herbivores encounter plumes with filaments from both host and non-host plants. While studies showed a behavioral effect of non-host plants on herbivore host location, less information is available on how a searching insect herbivore perceives and flies upwind to a host-plant odor plume within a background of non-host volatiles. We hypothesized here that herbivorous insects in search of a host-plant can discriminate plumes of host and non-host plants and that the taxonomic relatedness of the non-host have an effect on finding the host. We also predicted that the ratio between certain plant volatiles is cognized as host-plant recognition cue by a receiver herbivorous insect. To verify these hypotheses we measured the wind tunnel response of the moth Argyresthia conjugella to the host plant rowan, to non-host plants taxonomically related (Rosaceae, apple and pear) or unrelated to the host (Pinaceae, spruce) and to binary combination of host and non-host plants. Volatiles were collected from all plant combinations and delivered to the test insect via an ultrasonic sprayer as an artificial plume. While the response to the rowan as a plant was not affected by the addition of any of the non-host plants, the attraction to the corresponding sprayed headspace decreased when pear or apple but not spruce were added to rowan. A similar result was measured toward the odor exiting a jar where freshly cut plant material of apple or pear or spruce was intermixed with rowan. Dose-response gas-chromatography coupled to electroantennography revealed the presence of seven field attractive and seven background non-attractive antennally active compounds. Although the abundance of field attractive and of some background volatiles decreased in all dual combinations in comparison with rowan alone, an increased amount of the background compounds (3E)-4,8-Dimethyl-1

Host plants of leaf worm, Spodoptera litura (Fabricius (Lepidoptera: noctuidae in Pakistan

Directory of Open Access Journals (Sweden)

Munir Ahmad

2013-04-01

Full Text Available Spodoptera litura is a notorious leaf feeding insect pest of more than one hundred plants around the Asia-Pacific region. Host plant survey for two years from three different locations in cotton belt revealed 27 plant species as host plants of S. litura belonging to 25 genera of 14 families including cultivated crops, vegetables, weeds, fruits and ornamental plants. Major host plants on which it thrived for maximum period were Gossypium hirsutum L., Ricinus communis L., Brassica oleracea var. botrytis L., Colocasia esculenta L., Trianthema portulacastrum L. and Sesbania sesban L.. Eggs were also collected from tree plants but larvae did not complete their development. Reliance of S. litura on major plant species of cultivated crops necessitates their regular monitoring especially during March to April for their population abundance and early warning for their management on commercial crops like cotton.

Interactions of seedborne bacterial pathogens with host and non-host plants in relation to seed infestation and seedling transmission.

Science.gov (United States)

Dutta, Bhabesh; Gitaitis, Ronald; Smith, Samuel; Langston, David

2014-01-01

The ability of seed-borne bacterial pathogens (Acidovorax citrulli, Clavibacter michiganensis subsp. michiganensis, Pseudomonas syringae pv. tomato, Xanthomonas euvesicatoria, and Pseudomonas syringae pv. glycinea) to infest seeds of host and non-host plants (watermelon, tomato, pepper, and soybean) and subsequent pathogen transmission to seedlings was investigated. A non-pathogenic, pigmented strain of Serratia marcescens was also included to assess a null-interacting situation with the same plant species. Flowers of host and non-host plants were inoculated with 1 × 10(6) colony forming units (CFUs)/flower for each bacterial species and allowed to develop into fruits or umbels (in case of onion). Seeds harvested from each host/non-host bacterial species combination were assayed for respective bacteria by plating on semi-selective media. Additionally, seedlots for each host/non-host bacterial species combination were also assayed for pathogen transmission by seedling grow-out (SGO) assays under greenhouse conditions. The mean percentage of seedlots infested with compatible and incompatible pathogens was 31.7 and 30.9% (by plating), respectively and they were not significantly different (P = 0.67). The percentage of seedlots infested with null-interacting bacterial species was 16.8% (by plating) and it was significantly lower than the infested lots generated with compatible and incompatible bacterial pathogens (P = 0.03). None of the seedlots with incompatible/null-interacting bacteria developed symptoms on seedlings; however, when seedlings were assayed for epiphytic bacterial presence, 19.5 and 9.4% of the lots were positive, respectively. These results indicate that the seeds of non-host plants can become infested with incompatible and null-interacting bacterial species through flower colonization and they can be transmitted via epiphytic colonization of seedlings. In addition, it was also observed that flowers and seeds of non-host plants can be colonized by

Interactions of seedborne bacterial pathogens with host and non-host plants in relation to seed infestation and seedling transmission.

Directory of Open Access Journals (Sweden)

Bhabesh Dutta

Full Text Available The ability of seed-borne bacterial pathogens (Acidovorax citrulli, Clavibacter michiganensis subsp. michiganensis, Pseudomonas syringae pv. tomato, Xanthomonas euvesicatoria, and Pseudomonas syringae pv. glycinea to infest seeds of host and non-host plants (watermelon, tomato, pepper, and soybean and subsequent pathogen transmission to seedlings was investigated. A non-pathogenic, pigmented strain of Serratia marcescens was also included to assess a null-interacting situation with the same plant species. Flowers of host and non-host plants were inoculated with 1 × 10(6 colony forming units (CFUs/flower for each bacterial species and allowed to develop into fruits or umbels (in case of onion. Seeds harvested from each host/non-host bacterial species combination were assayed for respective bacteria by plating on semi-selective media. Additionally, seedlots for each host/non-host bacterial species combination were also assayed for pathogen transmission by seedling grow-out (SGO assays under greenhouse conditions. The mean percentage of seedlots infested with compatible and incompatible pathogens was 31.7 and 30.9% (by plating, respectively and they were not significantly different (P = 0.67. The percentage of seedlots infested with null-interacting bacterial species was 16.8% (by plating and it was significantly lower than the infested lots generated with compatible and incompatible bacterial pathogens (P = 0.03. None of the seedlots with incompatible/null-interacting bacteria developed symptoms on seedlings; however, when seedlings were assayed for epiphytic bacterial presence, 19.5 and 9.4% of the lots were positive, respectively. These results indicate that the seeds of non-host plants can become infested with incompatible and null-interacting bacterial species through flower colonization and they can be transmitted via epiphytic colonization of seedlings. In addition, it was also observed that flowers and seeds of non-host plants can be

Integrative analyses unveil speciation linked to host plant shift in Spialia butterflies.

Science.gov (United States)

Hernández-Roldán, Juan L; Dapporto, Leonardo; Dincă, Vlad; Vicente, Juan C; Hornett, Emily A; Šíchová, Jindra; Lukhtanov, Vladimir A; Talavera, Gerard; Vila, Roger

2016-09-01

Discovering cryptic species in well-studied areas and taxonomic groups can have profound implications in understanding eco-evolutionary processes and in nature conservation because such groups often involve research models and act as flagship taxa for nature management. In this study, we use an array of techniques to study the butterflies in the Spialia sertorius species group (Lepidoptera, Hesperiidae). The integration of genetic, chemical, cytogenetic, morphological, ecological and microbiological data indicates that the sertorius species complex includes at least five species that differentiated during the last three million years. As a result, we propose the restitution of the species status for two taxa often treated as subspecies, Spialia ali (Oberthür, 1881) stat. rest. and Spialia therapne (Rambur, 1832) stat. rest., and describe a new cryptic species Spialia rosae Hernández-Roldán, Dapporto, Dincă, Vicente & Vila sp. nov. Spialia sertorius (Hoffmannsegg, 1804) and S. rosae are sympatric and synmorphic, but show constant differences in mitochondrial DNA, chemical profiles and ecology, suggesting that S. rosae represents a case of ecological speciation involving larval host plant and altitudinal shift, and apparently associated with Wolbachia infection. This study exemplifies how a multidisciplinary approach can reveal elusive cases of hidden diversity. © 2016 John Wiley & Sons Ltd.

The Ratio between Field Attractive and Background Volatiles Encodes Host-Plant Recognition in a Specialist Moth

Directory of Open Access Journals (Sweden)

Geir K. Knudsen

2017-12-01

Full Text Available Volatiles emitted by plants convey an array of information through different trophic levels. Animals such as host-seeking herbivores encounter plumes with filaments from both host and non-host plants. While studies showed a behavioral effect of non-host plants on herbivore host location, less information is available on how a searching insect herbivore perceives and flies upwind to a host-plant odor plume within a background of non-host volatiles. We hypothesized here that herbivorous insects in search of a host-plant can discriminate plumes of host and non-host plants and that the taxonomic relatedness of the non-host have an effect on finding the host. We also predicted that the ratio between certain plant volatiles is cognized as host-plant recognition cue by a receiver herbivorous insect. To verify these hypotheses we measured the wind tunnel response of the moth Argyresthia conjugella to the host plant rowan, to non-host plants taxonomically related (Rosaceae, apple and pear or unrelated to the host (Pinaceae, spruce and to binary combination of host and non-host plants. Volatiles were collected from all plant combinations and delivered to the test insect via an ultrasonic sprayer as an artificial plume. While the response to the rowan as a plant was not affected by the addition of any of the non-host plants, the attraction to the corresponding sprayed headspace decreased when pear or apple but not spruce were added to rowan. A similar result was measured toward the odor exiting a jar where freshly cut plant material of apple or pear or spruce was intermixed with rowan. Dose-response gas-chromatography coupled to electroantennography revealed the presence of seven field attractive and seven background non-attractive antennally active compounds. Although the abundance of field attractive and of some background volatiles decreased in all dual combinations in comparison with rowan alone, an increased amount of the background compounds (3E-4

Odour maps in the brain of butterflies with divergent host-plant preferences.

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Mikael A Carlsson

Full Text Available Butterflies are believed to use mainly visual cues when searching for food and oviposition sites despite that their olfactory system is morphologically similar to their nocturnal relatives, the moths. The olfactory ability in butterflies has, however, not been thoroughly investigated. Therefore, we performed the first study of odour representation in the primary olfactory centre, the antennal lobes, of butterflies. Host plant range is highly variable within the butterfly family Nymphalidae, with extreme specialists and wide generalists found even among closely related species. Here we measured odour evoked Ca(2+ activity in the antennal lobes of two nymphalid species with diverging host plant preferences, the specialist Aglais urticae and the generalist Polygonia c-album. The butterflies responded with stimulus-specific combinations of activated glomeruli to single plant-related compounds and to extracts of host and non-host plants. In general, responses were similar between the species. However, the specialist A. urticae responded more specifically to its preferred host plant, stinging nettle, than P. c-album. In addition, we found a species-specific difference both in correlation between responses to two common green leaf volatiles and the sensitivity to these compounds. Our results indicate that these butterflies have the ability to detect and to discriminate between different plant-related odorants.

Specificity of salt marsh diazotrophs for vegetation zones and plant hosts

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Debra Aline Davis

2012-03-01

Full Text Available Salt marshes located on the east coast of temperate North America are highly productive, typically nitrogen-limited, and support diverse assemblages of nitrogen fixing (diazotrophic bacteria. The distributions of these diazotrophs are strongly influenced by plant host and abiotic environmental parameters. Crab Haul Creek Basin, North Inlet, SC, USA is a tidally dominated marsh that displays discrete plant zones distributed along an elevation gradient from the tidal creek bank to the terrestrial forest. These zones are defined by gradients of abiotic environmental variables, particularly salinity and sulfide. DGGE fingerprinting and phylogenetic analyses of recovered sequences demonstrated that the distributions of some diazotrophs indicate plant host specificity and that diazotroph assemblages across the marsh gradient are heavily influenced by edaphic conditions. Broadly distributed diazotrophs capable of maintaining populations in all environmental conditions across the gradient are also present in these assemblages. Parsimony test results confirm that diazotroph assemblages in different plant zones are significantly (p<0.01 different across the marsh landscape. Results also indicated that diazotroph assemblages associated with different plant hosts growing in the same area of the marsh were structurally similar confirming the influence of edaphic parameters on these assemblages. Principal Component Analysis of DGGE gel banding patterns confirmed these results. This article reviews and analyzes data from North Inlet Estuary, addressing diazotroph assemblage structure and the influence of plant host and environmental conditions. New data demonstrate the heterogeneity of salt marsh rhizosphere microenvironments, and corroborate previous findings from different plant hosts growing at several locations within this estuary. These data support the hypothesis that the biogeography of microorganisms is non-random and is partially driven by

Impact of vector dispersal and host-plant fidelity on the dissemination of an emerging plant pathogen.

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Jes Johannesen

Full Text Available Dissemination of vector-transmitted pathogens depend on the survival and dispersal of the vector and the vector's ability to transmit the pathogen, while the host range of vector and pathogen determine the breath of transmission possibilities. In this study, we address how the interaction between dispersal and plant fidelities of a pathogen (stolbur phytoplasma tuf-a and its vector (Hyalesthes obsoletus: Cixiidae affect the emergence of the pathogen. Using genetic markers, we analysed the geographic origin and range expansion of both organisms in Western Europe and, specifically, whether the pathogen's dissemination in the northern range is caused by resident vectors widening their host-plant use from field bindweed to stinging nettle, and subsequent host specialisation. We found evidence for common origins of pathogen and vector south of the European Alps. Genetic patterns in vector populations show signals of secondary range expansion in Western Europe leading to dissemination of tuf-a pathogens, which might be newly acquired and of hybrid origin. Hence, the emergence of stolbur tuf-a in the northern range was explained by secondary immigration of vectors carrying stinging nettle-specialised tuf-a, not by widening the host-plant spectrum of resident vectors with pathogen transmission from field bindweed to stinging nettle nor by primary co-migration from the resident vector's historical area of origin. The introduction of tuf-a to stinging nettle in the northern range was therefore independent of vector's host-plant specialisation but the rapid pathogen dissemination depended on the vector's host shift, whereas the general dissemination elsewhere was linked to plant specialisation of the pathogen but not of the vector.

Host plant use drives genetic differentiation in syntopic populations of Maculinea alcon

DEFF Research Database (Denmark)

Tartally, András; Kelager, Andreas; Fürst, Matthias Alois

2016-01-01

The rare socially parasitic butterfly Maculinea alcon occurs in two forms, which are characteristic of hygric or xeric habitats and which exploit different host plants and host ants. The status of these two forms has been the subject of considerable controversy. Populations of the two forms...... on different host plants, each with a distinct flowering phenology, providing a temporal rather than spatial barrier to gene flow....

Experimental assemblage of novel plant-herbivore interactions: ecological host shifts after 40 million years of isolation.

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Garcia-Robledo, Carlos; Horvitz, Carol C; Kress, W John; Carvajal-Acosta, A Nalleli; Erwin, Terry L; Staines, Charles L

2017-11-01

Geographic isolation is the first step in insect herbivore diet specialization. Such specialization is postulated to increase insect fitness, but may simultaneously reduce insect ability to colonize novel hosts. During the Paleocene-Eocene, plants from the order Zingiberales became isolated either in the Paleotropics or in the Neotropics. During the Cretaceous, rolled-leaf beetles diversified in the Neotropics concurrently with Neotropical Zingiberales. Using a community of Costa Rican rolled-leaf beetles and their Zingiberales host plants as study system, we explored if previous geographic isolation precludes insects to expand their diets to exotic hosts. We recorded interactions between rolled-leaf beetles and native Zingiberales by combining DNA barcodes and field records for 7450 beetles feeding on 3202 host plants. To determine phylogenetic patterns of diet expansions, we set 20 field plots including five exotic Zingiberales, recording beetles feeding on these exotic hosts. In the laboratory, using both native and exotic host plants, we reared a subset of insect species that had expanded their diets to the exotic plants. The original plant-herbivore community comprised 24 beetle species feeding on 35 native hosts, representing 103 plant-herbivore interactions. After exotic host plant introduction, 20% of the beetle species expanded their diets to exotic Zingiberales. Insects only established on exotic hosts that belong to the same plant family as their native hosts. Laboratory experiments show that beetles are able to complete development on these novel hosts. In conclusion, rolled-leaf beetles are pre-adapted to expand their diets to novel host plants even after millions of years of geographic isolation.

Multilocus Sequence Analysis of Cercospora spp. from Different Host Plant Families

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Floreta Fiska Yuliarni

2014-06-01

Full Text Available Identification of the genus Cercospora is still complicated due to the host preferences often being used as the main criteria to propose a new name. We determined the relationship between host plants and multilocus sequence variations (ITS rDNA including 5.8S rDNA, elongation factor 1-α, and calmodulin in Cercospora spp. to investigate the host specificity. We used 53 strains of Cercospora spp. infecting 12 plant families for phylogenetic analysis. The sequences of 23 strains of Cercospora spp. infecting the plant families of Asteraceae, Cucurbitaceae, and Solanaceae were determined in this study. The sequences of 30 strains of Cercospora spp. infecting the plant families of Fabaceae, Amaranthaceae, Apiaceae, Plumbaginaceae, Malvaceae, Cistaceae, Plantaginaceae, Lamiaceae, and Poaceae were obtained from GenBank. The molecular phylogenetic analysis revealed that the majority of Cercospora species lack host specificity, and only C. zinniicola, C. zeina, C. zeae-maydis, C. cocciniae, and C. mikaniicola were found to be host-specific. Closely related species of Cercospora could not be distinguished using molecular analyses of ITS, EF, and CAL gene regions. The topology of the phylogenetic tree based on the CAL gene showed a better topology and Cercospora species separation than the trees developed based on the ITS rDNA region or the EF gene.

Host specificity, phenotype matching and the evolution of reproductive isolation in a coevolved plant-pollinator mutualism.

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Himler, Anna G; Machado, Carlos A

2009-12-01

Coevolutionary interactions between plants and their associated pollinators and seed dispersers are thought to have promoted the diversification of flowering plants (Raven 1977; Regal 1977; Stebbins 1981). The actual mechanisms by which pollinators could drive species diversification in plants are not fully understood. However, it is thought that pollinator host specialization can influence the evolution of reproductive isolation among plant populations because the pollinator's choice of host is what determines patterns of gene flow in its host plant, and host choice may also have important consequences on pollinator and host fitness (Grant 1949; Bawa 1992). In this issue of Molecular Ecology, Smith et al. (2009) present a very interesting study that addresses how host specialization affects pollinator fitness and patterns of gene flow in a plant host. Several aspects of this study match elements of a seminal mathematical model of plant-pollinator codivergence (Kiester et al. 1984) suggesting that reciprocal selection for matched plant and pollinator reproductive traits may lead to speciation in the host and its pollinator when there is strong host specialization and a pattern of geographic subdivision. Smith et al.'s study represents an important step to fill the gap in our understanding of how reciprocal selection may lead to speciation in coevolved plant-pollinator mutualisms.

Survival relative to new and ancestral host plants, phytoplasma infection, and genetic constitution in host races of a polyphagous insect disease vector

Science.gov (United States)

Maixner, Michael; Albert, Andreas; Johannesen, Jes

2014-01-01

Dissemination of vectorborne diseases depends strongly on the vector's host range and the pathogen's reservoir range. Because vectors interact with pathogens, the direction and strength of a vector's host shift is vital for understanding epidemiology and is embedded in the framework of ecological specialization. This study investigates survival in host-race evolution of a polyphagous insect disease vector, Hyalesthes obsoletus, whether survival is related to the direction of the host shift (from field bindweed to stinging nettle), the interaction with plant-specific strains of obligate vectored pathogens/symbionts (stolbur phytoplasma), and whether survival is related to genetic differentiation between the host races. We used a twice repeated, identical nested experimental design to study survival of the vector on alternative hosts and relative to infection status. Survival was tested with Kaplan–Meier analyses, while genetic differentiation between vector populations was quantified with microsatellite allele frequencies. We found significant direct effects of host plant (reduced survival on wrong hosts) and sex (males survive longer than females) in both host races and relative effects of host (nettle animals more affected than bindweed animals) and sex (males more affected than females). Survival of bindweed animals was significantly higher on symptomatic than nonsymptomatic field bindweed, but in the second experiment only. Infection potentially had a positive effect on survival in nettle animals but due to low infection rates the results remain suggestive. Genetic differentiation was not related to survival. Greater negative plant-transfer effect but no negative effect of stolbur in the derived host race suggests preadaptation to the new pathogen/symbiont strain before strong diversifying selection during the specialization process. Physiological maladaptation or failure to accept the ancestral plant will have similar consequences, namely positive assortative

Glucosinolates from Host Plants Influence Growth of the Parasitic Plant Cuscuta gronovii and Its Susceptibility to Aphid Feeding.

Science.gov (United States)

Smith, Jason D; Woldemariam, Melkamu G; Mescher, Mark C; Jander, Georg; De Moraes, Consuelo M

2016-09-01

Parasitic plants acquire diverse secondary metabolites from their hosts, including defense compounds that target insect herbivores. However, the ecological implications of this phenomenon, including the potential enhancement of parasite defenses, remain largely unexplored. We studied the translocation of glucosinolates from the brassicaceous host plant Arabidopsis (Arabidopsis thaliana) into parasitic dodder vines (Convolvulaceae; Cuscuta gronovii) and its effects on the parasite itself and on dodder-aphid interactions. Aliphatic and indole glucosinolates reached concentrations in parasite tissues higher than those observed in corresponding host tissues. Dodder growth was enhanced on cyp79B2 cyp79B3 hosts (without indole glucosinolates) but inhibited on atr1D hosts (with elevated indole glucosinolates) relative to wild-type hosts, which responded to parasitism with localized elevation of indole and aliphatic glucosinolates. These findings implicate indole glucosinolates in defense against parasitic plants. Rates of settling and survival on dodder vines by pea aphids (Acyrthosiphon pisum) were reduced significantly when dodder parasitized glucosinolate-producing hosts (wild type and atr1D) compared with glucosinolate-free hosts (cyp79B2 cyp79B3 myb28 myb29). However, settling and survival of green peach aphids (Myzus persicae) were not affected. M. persicae population growth was actually reduced on dodder parasitizing glucosinolate-free hosts compared with wild-type or atr1D hosts, even though stems of the former contain less glucosinolates and more amino acids. Strikingly, this effect was reversed when the aphids fed directly upon Arabidopsis, which indicates an interactive effect of parasite and host genotype on M. persicae that stems from host effects on dodder. Thus, our findings indicate that glucosinolates may have both direct and indirect effects on dodder-feeding herbivores. © 2016 American Society of Plant Biologists. All rights reserved.

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

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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.

Congruence and diversity of butterfly-host plant associations at higher taxonomic levels.

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Ferrer-Paris, José R; Sánchez-Mercado, Ada; Viloria, Ángel L; Donaldson, John

2013-01-01

We aggregated data on butterfly-host plant associations from existing sources in order to address the following questions: (1) is there a general correlation between host diversity and butterfly species richness?, (2) has the evolution of host plant use followed consistent patterns across butterfly lineages?, (3) what is the common ancestral host plant for all butterfly lineages? The compilation included 44,148 records from 5,152 butterfly species (28.6% of worldwide species of Papilionoidea) and 1,193 genera (66.3%). The overwhelming majority of butterflies use angiosperms as host plants. Fabales is used by most species (1,007 spp.) from all seven butterfly families and most subfamilies, Poales is the second most frequently used order, but is mostly restricted to two species-rich subfamilies: Hesperiinae (56.5% of all Hesperiidae), and Satyrinae (42.6% of all Nymphalidae). We found a significant and strong correlation between host plant diversity and butterfly species richness. A global test for congruence (Parafit test) was sensitive to uncertainty in the butterfly cladogram, and suggests a mixed system with congruent associations between Papilionidae and magnoliids, Hesperiidae and monocots, and the remaining subfamilies with the eudicots (fabids and malvids), but also numerous random associations. The congruent associations are also recovered as the most probable ancestral states in each node using maximum likelihood methods. The shift from basal groups to eudicots appears to be more likely than the other way around, with the only exception being a Satyrine-clade within the Nymphalidae that feed on monocots. Our analysis contributes to the visualization of the complex pattern of interactions at superfamily level and provides a context to discuss the timing of changes in host plant utilization that might have promoted diversification in some butterfly lineages.

Congruence and diversity of butterfly-host plant associations at higher taxonomic levels.

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José R Ferrer-Paris

Full Text Available We aggregated data on butterfly-host plant associations from existing sources in order to address the following questions: (1 is there a general correlation between host diversity and butterfly species richness?, (2 has the evolution of host plant use followed consistent patterns across butterfly lineages?, (3 what is the common ancestral host plant for all butterfly lineages? The compilation included 44,148 records from 5,152 butterfly species (28.6% of worldwide species of Papilionoidea and 1,193 genera (66.3%. The overwhelming majority of butterflies use angiosperms as host plants. Fabales is used by most species (1,007 spp. from all seven butterfly families and most subfamilies, Poales is the second most frequently used order, but is mostly restricted to two species-rich subfamilies: Hesperiinae (56.5% of all Hesperiidae, and Satyrinae (42.6% of all Nymphalidae. We found a significant and strong correlation between host plant diversity and butterfly species richness. A global test for congruence (Parafit test was sensitive to uncertainty in the butterfly cladogram, and suggests a mixed system with congruent associations between Papilionidae and magnoliids, Hesperiidae and monocots, and the remaining subfamilies with the eudicots (fabids and malvids, but also numerous random associations. The congruent associations are also recovered as the most probable ancestral states in each node using maximum likelihood methods. The shift from basal groups to eudicots appears to be more likely than the other way around, with the only exception being a Satyrine-clade within the Nymphalidae that feed on monocots. Our analysis contributes to the visualization of the complex pattern of interactions at superfamily level and provides a context to discuss the timing of changes in host plant utilization that might have promoted diversification in some butterfly lineages.

Identification of cotton fleahopper (Hemiptera: Miridae) host plants in central Texas and compendium of reported hosts in the United States.

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Esquivel, J F; Esquivel, S V

2009-06-01

The cotton fleahopper, Pseudatomoscelis seriatus (Reuter), is an early-season pest of developing cotton in Central Texas and other regions of the Cotton Belt. Cotton fleahopper populations develop on spring weed hosts and move to cotton as weed hosts senesce or if other weed hosts are not readily available. To identify weed hosts that were seasonably available for the cotton fleahopper in Central Texas, blooming weed species were sampled during early-season (17 March-31 May), mid-season (1 June-14 August), late-season (15 August-30 November), and overwintering (1 December-16 March) periods. The leading hosts for cotton fleahopper adults and nymphs were evening primrose (Oenothera speciosa T. Nuttall) and Mexican hat [Ratibida columnifera (T. Nuttall) E. Wooton and P. Standley], respectively, during the early season. During the mid-season, silver-leaf nightshade (Solanum elaeagnifolium A. Cavanilles) was consistently a host for fleahopper nymphs and adults. Woolly croton (Croton capitatus A. Michaux) was a leading host during the late season. Cotton fleahoppers were not collected during the overwintering period. Other suitable hosts were available before previously reported leading hosts became available. Eight previously unreported weed species were documented as temporary hosts. A compendium of reported hosts, which includes >160 plant species representing 35 families, for the cotton fleahopper is provided for future research addressing insect-host plant associations. Leading plant families were Asteraceae, Lamiaceae, and Onagraceae. Results presented here indicate a strong argument for assessing weed species diversity and abundance for the control of the cotton fleahopper in the Cotton Belt.

Non-Host Plant Volatiles Disrupt Sex Pheromone Communication in a Specialist Herbivore

OpenAIRE

Wang, Fumin; Deng, Jianyu; Schal, Coby; Lou, Yonggen; Zhou, Guoxin; Ye, Bingbing; Yin, Xiaohui; Xu, Zhihong; Shen, Lize

2016-01-01

The ecological effects of plant volatiles on herbivores are manifold. Little is known, however, about the impacts of non-host plant volatiles on intersexual pheromonal communication in specialist herbivores. We tested the effects of several prominent constitutive terpenoids released by conifers and Eucalyptus trees on electrophysiological and behavioral responses of an oligophagous species, Plutella xylostella, which feeds on Brassicaceae. The non-host plant volatile terpenoids adversely affe...

Coevolution of a Persistent Plant Virus and Its Pepper Hosts.

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Safari, Maliheh; Roossinck, Marilyn J

2018-05-30

There are many nonpathogenic viruses that are maintained in a persistent lifestyle in plants. Plant persistent viruses are widespread, replicating in their hosts for many generations. So far, Endornaviridae is the only family of plant persistent viruses with a single-stranded RNA genome, containing one large open reading frame. Bell pepper endornavirus (BPEV), Hot pepper endornavirus, Capsicum frutescens endornavirus 1 (CFEV 1) have been identified from peppers. Peppers are native to Central and South America and, as domesticated plants, human selection accelerated their evolution. We investigated the evolution of these endornaviruses in different peppers including Capsicum annuum, C. chacoense, C.chinense, C. frutescens, C.bacccutum, and C. pubescens using two fragments from the viral helicase (Hel) and RNA dependent RNA polymerase (RdRp) domains. In addition, using single nucleotide polymorphisms, we analyzed the pepper host populations and phylogenies. The endornaviruses phylogeny was correlated with its Capsicum species host. In this study, BPEV was limited to C. annuum species, and the RdRp and Hel phylogenies identified two clades that correlated with the host pungency. No C. annuum infected with CFEV 1 was found in this study, but the CFEV 1 RdRp fragment was recovered from C. chinense, C. frutescens, C. bacccutum, and C. pubescens. Hence, during pepper speciation, the ancestor of CFEV 1 may have evolved as a new endornavirus, BPEV, in C. annuum peppers.

Patterns of host ant use by sympatric populations of Maculinea alcon and M. 'rebeli' in the Carpathian Basin

DEFF Research Database (Denmark)

Tartally, A.; Nash, David Richard; Lengyel, S.

2008-01-01

Maculinea butterflies show social parasitism via obligatory myrmecophily as their larvae are adopted and raised to pupation by Myrmica ants. Suitable hosts differ for different Maculinea species, and host ant specificity can further differ at the population-level. Although early studies suggested...... single ant species as main hosts for each Maculinea species, it has recently become clear that their host ant specificity is more complex. Maculinea alcon and Maculinea ‘rebeli’ have variously been separated according to adult and larval morphology, phenology, and their use of different ecosystems......, including host plant and host ant species. However, recent genetic evidence has questioned their separation as good species. Here we compare the use of host ants by M. alcon and M. ‘rebeli’ at the regional scale in NE-Hungary and Transylvania (Romania), where molecular studies have found no species...

Exploring two plant hosts for expression of diterpenoid pathway genes

DEFF Research Database (Denmark)

Bach, Søren Spanner

Plants produce more than 10.000 diterpenoid compounds of which the large majority is involved in specialized metabolism, while a few are involved in general metabolism. Specialized metabolism diterpenoids have functions in interactions of plants with other organisms and selected ones are utilized....... Since only small changes in the amino acid sequence can influence the roduct outcome of a diterpene synthase (diTPS), prediction of the catalytic activity diTPS of a is not possible purely based on phylogenetic relationship. Thus, functional characterization is required in to determine the catalytic...... and aracterization of diTPSs deriving from the plant kingdom, a plant expression host offers several advantages such as the presence of all relevant compartments (plastids and endoplasmic reticulum) and the universal C5 building blocks for isoprenoid biosynthesis. In addition, a plant based xpression host...

Geography and major host evolutionary transitions shape the resource use of plant parasites.

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Calatayud, Joaquín; Hórreo, José Luis; Madrigal-González, Jaime; Migeon, Alain; Rodríguez, Miguel Á; Magalhães, Sara; Hortal, Joaquín

2016-08-30

The evolution of resource use in herbivores has been conceptualized as an analog of the theory of island biogeography, assuming that plant species are islands separated by phylogenetic distances. Despite its usefulness, this analogy has paradoxically led to neglecting real biogeographical processes in the study of macroevolutionary patterns of herbivore-plant interactions. Here we show that host use is mostly determined by the geographical cooccurrence of hosts and parasites in spider mites (Tetranychidae), a globally distributed group of plant parasites. Strikingly, geography accounts for most of the phylogenetic signal in host use by these parasites. Beyond geography, only evolutionary transitions among major plant lineages (i.e., gymnosperms, commelinids, and eudicots) shape resource use patterns in these herbivores. Still, even these barriers have been repeatedly overcome in evolutionary time, resulting in phylogenetically diverse parasite communities feeding on similar hosts. Therefore, our results imply that patterns of apparent evolutionary conservatism may largely be a byproduct of the geographic cooccurrence of hosts and parasites.

Host influence on irradiation bioefficacy : growth and development of Spodoptera litura (Fabricius)

International Nuclear Information System (INIS)

Seth, R.K.

1995-01-01

Survival and development of Spodoptera litura(F), a polyphagous pest was ascertained on a range of host plants, common and economic in the Indian context. Castor, cotton, green gram and okra constituted the preferred host group showing significantly better growth rate (GR) and growth index (GI) than the group of less preferred host plants that included groundnut, red gram, rose leaf and rose petal. Ontogenic growth profile vis-a-vis irradiation was studied with recording of GI at L3, pupa and adult levels in response to gamma dosages administered in L1 stage. Irradiation effect on the growth index was mainly due to reduction in survival, which was further pronounced owing to delay in development. On all the preferred host plants, adult-G1 was reduced by more than 50 per cent at 40 Gy gamma dose; whereas the same dose on less preferred host plants could prevent adult emergence on ground nut and red gram, and inhibited pupa formation on rose diet. The percentage mortality of larvae exhibiting delayed development was markedly more in the less preferred host group. Dose dependent reduction was observed in the larval growth rate of L3, L5 and L6 instars on all the host plants. 20 Gy exhibited almost same intensity of adverse impact in less preferred host group as was shown by 40 Gy in preferred hosts. 20 Gy dose reduced the pupal weight and conversion ratio of treated insects significantly. Age influence was evident on irradiation efficacy on all the diets. Insects treated in the later instar had less radiosusceptibility as compared to the young irradiated larvae. Irradiation had a negative correlation with survival and weight gain during the course of development that in turn bore a positive relation with the increase in radiation dosage. Food is an important governing factor in influencing the insects survival value and developmental behaviour and may modify its intrinsic sensitivity towards irradiation stress. (author). 21 refs., 1 fig., 5 tabs

Differential Larval Toxicity and Oviposition Altering Activity of Some Indigenous Plant Extracts against Dengue and Chikungunya Vector Aedes albopictus.

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Ruchi Yadav

2014-12-01

Full Text Available Mosquitoes are well known as vectors of several disease causing pathogens. The extensive use of synthetic insecticides in the mosquito control strategies resulted to the development of pesticide resistance and fostered environmental deterioration. Hence in recent years plants become alternative source of mosquito control agents. The present study assessed the larvicidal and oviposition altering activity of six different plants species-Alstonia scholaris, Callistemon viminalis, Hyptis suaveolens, Malvastrum coromandelianum, Prosopis juliflora, Vernonia cinerea against Aedes albopictus mosquito in laboratory.Leaf extracts of all the six plants species in five different solvents of various polarities were used in the range of 20-400ppm for larval bioassay and 50,100 and 200ppm for cage bioassay (for the study of oviposition behavior against Ae. albopictus. The larval mortality data were recorded after 24 h and subjected to Probit analysis to determine the lethal concentrations (LC50, while OAI (Oviposition activity index was calculated for oviposition altering activity of the plant extracts.Vernonia cinerea extract in acetone and C. viminalis extract in isopropanol were highly effective against Aedes albopictus larvae with LC50 value 64.57, 71.34ppm respectively. Acetone extract of P. juliflora found to be strong oviposition-deterrent which inhibited >2 fold egg laying (OAI-0.466 at 100ppm.Vernonia cinerea and C. viminallis leaf extracts have the potential to be used as larvicide and P. juliflora as an oviposition-deterrent for the control of Ae. albopictus mosquito.

Differential Larval Toxicity and Oviposition Altering Activity of Some Indigenous Plant Extracts against Dengue and Chikungunya Vector Aedes albopictus

Science.gov (United States)

Yadav, Ruchi; Tyagi, Varun; Tikar, Sachin N; Sharma, Ajay K; Mendki, Murlidhar J; Jain, Ashok K; Sukumaran, Devanathan

2014-01-01

Background: Mosquitoes are well known as vectors of several disease causing pathogens. The extensive use of synthetic insecticides in the mosquito control strategies resulted to the development of pesticide resistance and fostered environmental deterioration. Hence in recent years plants become alternative source of mosquito control agents. The present study assessed the larvicidal and oviposition altering activity of six different plants species-Alstonia scholaris, Callistemon viminalis, Hyptis suaveolens, Malvastrum coromandelianum, Prosopis juliflora, Vernonia cinerea against Aedes albopictus mosquito in laboratory. Methods: Leaf extracts of all the six plants species in five different solvents of various polarities were used in the range of 20–400ppm for larval bioassay and 50,100 and 200ppm for cage bioassay (for the study of oviposition behavior) against Ae. albopictus. The larval mortality data were recorded after 24 h and subjected to Probit analysis to determine the lethal concentrations (LC50), while OAI (Oviposition activity index) was calculated for oviposition altering activity of the plant extracts. Results: Vernonia cinerea extract in acetone and C. viminalis extract in isopropanol were highly effective against Aedes albopictus larvae with LC50 value 64.57, 71.34ppm respectively. Acetone extract of P. juliflora found to be strong oviposition-deterrent which inhibited >2 fold egg laying (OAI-0.466) at 100ppm. Conclusion: Vernonia cinerea and C. viminallis leaf extracts have the potential to be used as larvicide and P. juliflora as an oviposition-deterrent for the control of Ae. albopictus mosquito. PMID:26114131

Tyrosine pathway regulation is host-mediated in the pea aphid symbiosis during late embryonic and early larval development.

Science.gov (United States)

Rabatel, Andréane; Febvay, Gérard; Gaget, Karen; Duport, Gabrielle; Baa-Puyoulet, Patrice; Sapountzis, Panagiotis; Bendridi, Nadia; Rey, Marjolaine; Rahbé, Yvan; Charles, Hubert; Calevro, Federica; Colella, Stefano

2013-04-10

Nutritional symbioses play a central role in insects' adaptation to specialized diets and in their evolutionary success. The obligatory symbiosis between the pea aphid, Acyrthosiphon pisum, and the bacterium, Buchnera aphidicola, is no exception as it enables this important agricultural pest insect to develop on a diet exclusively based on plant phloem sap. The symbiotic bacteria provide the host with essential amino acids lacking in its diet but necessary for the rapid embryonic growth seen in the parthenogenetic viviparous reproduction of aphids. The aphid furnishes, in exchange, non-essential amino acids and other important metabolites. Understanding the regulations acting on this integrated metabolic system during the development of this insect is essential in elucidating aphid biology. We used a microarray-based approach to analyse gene expression in the late embryonic and the early larval stages of the pea aphid, characterizing, for the first time, the transcriptional profiles in these developmental phases. Our analyses allowed us to identify key genes in the phenylalanine, tyrosine and dopamine pathways and we identified ACYPI004243, one of the four genes encoding for the aspartate transaminase (E.C. 2.6.1.1), as specifically regulated during development. Indeed, the tyrosine biosynthetic pathway is crucial for the symbiotic metabolism as it is shared between the two partners, all the precursors being produced by B. aphidicola. Our microarray data are supported by HPLC amino acid analyses demonstrating an accumulation of tyrosine at the same developmental stages, with an up-regulation of the tyrosine biosynthetic genes. Tyrosine is also essential for the synthesis of cuticular proteins and it is an important precursor for cuticle maturation: together with the up-regulation of tyrosine biosynthesis, we observed an up-regulation of cuticular genes expression. We were also able to identify some amino acid transporter genes which are essential for the switch

Host plant affects morphometric variation of Diaphorina citri (Hemiptera: Liviidae

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Thomson M. Paris

2016-11-01

Full Text Available The Asian citrus psyllid (ACP, Diaphorina citri Kuwayama, is one of the most serious citrus pests worldwide due to its role as vector of huanglongbing or citrus greening disease. While some optimal plant species for ACP oviposition and development have been identified, little is known of the influence of host plants on ACP size and shape. Our goal was to determine how size and shape of ACP wing and body size varies when development occurs on different host plants in a controlled rearing environment. ACP were reared on six different rutaceous species; Bergera koenigii, Citrus aurantifolia, Citrus macrophylla, Citrus maxima, Citrus taiwanica and Murraya paniculata. Adults were examined for morphometric variation using traditional and geometric analysis based on 12 traits or landmarks. ACP reared on C. taiwanica were consistently smaller than those reared on the other plant species. Wing aspect ratio also differed between C. maxima and C. taiwanica. Significant differences in shape were detected with those reared on M. paniculata having narrower wings than those reared on C. macrophylla. This study provides evidence of wing size and shape differences of ACP based on host plant species which potentially may impact dispersal. Further study is needed to determine if behavioral and physiological differences are associated with the observed phenotypic differences.

Host plant affects morphometric variation of Diaphorina citri (Hemiptera: Liviidae).

Science.gov (United States)

Paris, Thomson M; Allan, Sandra A; Hall, David G; Hentz, Matthew G; Hetesy, Gabriella; Stansly, Philip A

2016-01-01

The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama, is one of the most serious citrus pests worldwide due to its role as vector of huanglongbing or citrus greening disease. While some optimal plant species for ACP oviposition and development have been identified, little is known of the influence of host plants on ACP size and shape. Our goal was to determine how size and shape of ACP wing and body size varies when development occurs on different host plants in a controlled rearing environment. ACP were reared on six different rutaceous species; Bergera koenigii , Citrus aurantifolia , Citrus macrophylla , Citrus maxima , Citrus taiwanica and Murraya paniculata . Adults were examined for morphometric variation using traditional and geometric analysis based on 12 traits or landmarks. ACP reared on C. taiwanica were consistently smaller than those reared on the other plant species. Wing aspect ratio also differed between C. maxima and C. taiwanica . Significant differences in shape were detected with those reared on M. paniculata having narrower wings than those reared on C. macrophylla . This study provides evidence of wing size and shape differences of ACP based on host plant species which potentially may impact dispersal. Further study is needed to determine if behavioral and physiological differences are associated with the observed phenotypic differences.

Host plant use among closely related Anaea butterfly species (Lepidoptera, Nymphalidae, Charaxinae

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QUEIROZ J. M.

2002-01-01

Full Text Available There is a great number of Charaxinae (Lepidoptera: Nymphalidae species in the tropics whose larvae feed on several plant families. However the genus Anaea is almost always associated with Croton species (Euphorbiaceae. This work describes patterns of host plant use by immature and adult abundance on different vertical strata of sympatric Anaea species in a forest of Southeastern Brazil. Quantitative samples of leaves were taken in April/1999 and May/2000 to collect eggs and larvae of four Anaea species on C.alchorneicarpus, C. floribundus and C. salutaris in a semideciduous forest. Sampled leaves were divided into three classes of plant phenological stage: saplings, shrubs and trees. The results showed that the butterfly species are segregating in host plant use on two scales: host plant species and plant phenological stages. C. alchorneicarpus was used by only one Anaea species, whereas C. floribundus was used by three species and C. salutaris by four Anaea species. There was one Anaea species concentrated on sapling, another on sapling/shrub and two others on shrub/tree leaves. Adults of Anaea were more frequent at canopy traps but there were no differences among species caught in traps at different vertical positions. This work supplements early studies on host plant use among Charaxinae species and it describes how a guild of closely related butterfly species may be organized in a complex tropical habitat.

Variation in the effectiveness of biotic defence: the case of an opportunistic ant-plant protection mutualism.

Science.gov (United States)

Giusto, Bruno; Anstett, Marie-Charlotte; Dounias, Edmond; McKey, Doyle B

2001-11-01

Benefits to plants in facultative ant protection mutualisms are highly variable. This allows examination of the sources of this variation and the mechanisms by which ants protect plants. We studied opportunistic interactions between ants and an extrafloral nectary-bearing vine, Dioscorea praehensilis, during 3 different years. Variation in plant protection among years was striking. Several factors affected the effectiveness of the biotic defence. Stems recently emerged from the underground tuber were self-supporting, contacting no other plants and encountering few foraging ants. Stems then became lianescent, and contact with supporting plants greatly increased ant recruitment. Both species and number of ant workers influenced the effect of ants on the major herbivore, the chrysomelid beetle Lilioceris latipennis. Protective actions included limitation of oviposition (reduction in the number of eggs laid on the plant) and predation, leading to increased larval mortality. The probability of successful predation was strongly dependent on larval size. If temporarily low ant-patrolling activity allows larvae to grow beyond a critical size, their mechanical (thick integument) or chemical (plant-derived compounds in a fecal shield) defences become more effective against ants. Secondary metabolites derived from the host plant thus appear to be important for the anti-predator mechanisms of this beetle, being necessary for its survival and reproduction on a host plant that actively recruits ants as a biotic defence against herbivores.

Field dodder life cycle and interaction with host plants

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Sarić-Krsmanović Marija

2017-01-01

Full Text Available Field dodder is a parasitic plant that attaches to stems and leaves of broadleaf plants, including weeds, field crops, vegetables and ornamentals, across most agricultural regions of the world. Effective field dodder control is extremely difficult to achieve due to the nature of attachment and close association between the host and the parasite, which require a highly effective and selective herbicide to destroy the parasite without damaging its host. To establish a strategy for controlling parasite growth and restricting the spread of field dodder in crop fields, it is important to learn more about this weed, its life cycle and development.

HOST PLANT PREFERENCES OF BEMISIA TABACI GENNADIUS

Institute of Scientific and Technical Information of China (English)

JINGYing; HUANGJian; MARui-yan; HANJu-cai

2003-01-01

The preferences of Bemisia tabaci Gennadius for five host plants:poinsettia, tomato, cabbage,sweet potato and flowering Chinese cabbage, was tested using a Y-tube olfactometer and a desiccator in the labo-ratory. The results show that B. tabaci adults were attracted by the odors of the five plants. The order of prefer-ence was poinsettia > flowering Chinese cabbage > sweet potato > cabbage > tomato. Preference was extremely sig-nificant between poinsettia and the other four plants, and between flowering Chinese cabbage, cabbage and toma-to. There was no significant difference in preference for flowering Chinese cabbage and sweet potato, sweet pota-to, cabbage and tomato or between cabbage and tomato.

Role of volatiles emitted by host and non-host plants in the foraging behaviour of Dentichasmias busseolae, a pupal parasitoid of the spotted stemborer Chilo partellus

NARCIS (Netherlands)

Gohole, L.S.; Overholt, W.A.; Khan, Z.R.; Vet, L.E.M.

2003-01-01

The role of volatiles from stemborer host and non-host plants in the host-finding process of Dentichasmias busseolae Heinrich (Hymenoptera: Ichneumonidae) a pupal parasitoid of Chilo partellus (Swinhoe) (Lepidoptera: Crambidae) was studied. The non-host plant, molasses grass (Melinis minutiflora

Non-Host Plant Volatiles Disrupt Sex Pheromone Communication in a Specialist Herbivore.

Science.gov (United States)

Wang, Fumin; Deng, Jianyu; Schal, Coby; Lou, Yonggen; Zhou, Guoxin; Ye, Bingbing; Yin, Xiaohui; Xu, Zhihong; Shen, Lize

2016-09-02

The ecological effects of plant volatiles on herbivores are manifold. Little is known, however, about the impacts of non-host plant volatiles on intersexual pheromonal communication in specialist herbivores. We tested the effects of several prominent constitutive terpenoids released by conifers and Eucalyptus trees on electrophysiological and behavioral responses of an oligophagous species, Plutella xylostella, which feeds on Brassicaceae. The non-host plant volatile terpenoids adversely affected the calling behavior (pheromone emission) of adult females, and the orientation responses of adult males to sex pheromone were also significantly inhibited by these terpenoids in a wind tunnel and in the field. We suggest that disruption of both pheromone emission and orientation to sex pheromone may explain, at least in part, an observed reduction in herbivore attack in polyculture compared with monoculture plantings. We also propose that mating disruption of both male and female moths with non-host plant volatiles may be a promising alternative pest management strategy.

Non-Host Plant Volatiles Disrupt Sex Pheromone Communication in a Specialist Herbivore

Science.gov (United States)

Wang, Fumin; Deng, Jianyu; Schal, Coby; Lou, Yonggen; Zhou, Guoxin; Ye, Bingbing; Yin, Xiaohui; Xu, Zhihong; Shen, Lize

2016-01-01

The ecological effects of plant volatiles on herbivores are manifold. Little is known, however, about the impacts of non-host plant volatiles on intersexual pheromonal communication in specialist herbivores. We tested the effects of several prominent constitutive terpenoids released by conifers and Eucalyptus trees on electrophysiological and behavioral responses of an oligophagous species, Plutella xylostella, which feeds on Brassicaceae. The non-host plant volatile terpenoids adversely affected the calling behavior (pheromone emission) of adult females, and the orientation responses of adult males to sex pheromone were also significantly inhibited by these terpenoids in a wind tunnel and in the field. We suggest that disruption of both pheromone emission and orientation to sex pheromone may explain, at least in part, an observed reduction in herbivore attack in polyculture compared with monoculture plantings. We also propose that mating disruption of both male and female moths with non-host plant volatiles may be a promising alternative pest management strategy. PMID:27585907

Suppression of Plant Defenses by Herbivorous Mites Is Not Associated with Adaptation to Host Plants

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Jéssica T. Paulo

2018-06-01

Full Text Available Some herbivores suppress plant defenses, which may be viewed as a result of the coevolutionary arms race between plants and herbivores. However, this ability is usually studied in a one-herbivore-one-plant system, which hampers comparative studies that could corroborate this hypothesis. Here, we extend this paradigm and ask whether the herbivorous spider-mite Tetranychus evansi, which suppresses the jasmonic-acid pathway in tomato plants, is also able to suppress defenses in other host plants at different phylogenetic distances from tomatoes. We test this using different plants from the Solanales order, namely tomato, jimsonweed, tobacco, and morning glory (three Solanaceae and one Convolvulaceae, and bean plants (Fabales. First, we compare the performance of T. evansi to that of the other two most-commonly found species of the same genus, T. urticae and T. ludeni, on several plants. We found that the performance of T. evansi is higher than that of the other species only on tomato plants. We then showed, by measuring trypsin inhibitor activity and life history traits of conspecific mites on either clean or pre-infested plants, that T. evansi can suppress plant defenses on all plants except tobacco. This study suggests that the suppression of plant defenses may occur on host plants other than those to which herbivores are adapted.

Remotely Sensing Larval Population Dynamics of Rice Field Anophelines

Science.gov (United States)

Beck, Louisa R.; Dister, Sheri W.; Wood, Byron L.; Washino, Robert K.

1997-01-01

The primary objective of both studies was to determine if RS and GIS techniques could be used to distinguish between high and low larval-producing rice fields in California. Results of the first study suggested that early-season green-up and proximity to livestock pastures were positively correlated with high larval abundance. Based on the early-season spectral differences between high and low larval-producing fields, it appeared that canopy development and tillering influenced mosquito habitat quality. At that time, rice fields consisted of a mixture of plants and water, a combination that allowed An. freeborni females to lay eggs in partial sunlight, protected from both predators and wind. This established a population earlier in the season than in other, 'less-green' fields where tillering and plant emergence was too minimal for ovipositioning. The study also indicated the importance of the distance that a mosquito would have to fly in order to take a bloodmeal prior to ovipositing. These associations were fully explored in an expanded study two years later. The second study confirmed the positive relationship between early season canopy development and larval abundance, and also demonstrated the relationship between abundance and distance-to-pasture. The association between greenness (as measured using NDVI), distance-to-pasture, and abundance is illustrated. The second study also indicated the siginificance of the landscape context of rice fields for larval production. Fields that included opportunities for feeding and resting within the flight range of the mosquito had higher abundances than did fields that were in a homogeneous rice area.

Host plant selection by a monophagous herbivore is not mediated by quantitative changes in unique plant chemistry : Agonopterix alstroemeriana and Conium maculatum

OpenAIRE

Castells, Eva

2008-01-01

Host plant selection by ovipositing females is a key process determining the success of phytophagous insects. In oligophagous lepidopterans, host-specific plant secondary chemicals are expected to be dominant factors governing oviposition behavior; distinctive compounds can serve as high-contrast signals that clearly differentiate confamilial hosts from non-hosts increasing the accuracy of host quality evaluation. Agonopterix alstroemeriana (Clerk) (Lepidoptera: Oecophoridae) and Conium macul...

Are ant feces nutrients for plants? A metabolomics approach to elucidate the nutritional effects on plants hosting weaver ants

DEFF Research Database (Denmark)

Vidkjær, Nanna Hjort; Wollenweber, Bernd; Gislum, René

2015-01-01

Weaver ants (genus Oecophylla) are tropical carnivorous ant species living in high numbers in the canopies of trees. The ants excrete copious amounts of fecal matter on leaf surfaces, and these feces may provide nutrients to host trees. This hypothesis is supported by studies of ant......-plant interactions involving other ant species that have demonstrated the transfer of nutrients from ants to plants. In this 7-months study, a GC–MS-based metabolomics approach along with an analysis of total nitrogen and carbon levels was used to study metabolic changes in ant-hosting Coffea arabica plants compared...... with control plants. The results showed elevated levels of total nitrogen, amino acids, fatty acids, caffeine, and secondary metabolites of the phenylpropanoid pathway in leaves from ant-hosting plants. Minor effects were observed for sugars, whereas little or no effect was observed for organic acids, despite...

Plant parasitic nematode effectors target host defence and nuclear functions to establish feeding cells

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Michaël eQuentin

2013-03-01

Full Text Available Plant parasitic nematodes are microscopic worms, the most damaging species of which have adopted a sedentary lifestyle within their hosts. These obligate endoparasites have a biotrophic relationship with plants, in which they induce the differentiation of root cells into hypertrophied, multinucleate feeding cells. Effectors synthesised in the oesophageal glands of the nematode are injected into the plant cells via the syringe-like stylet and play a key role in manipulating the host machinery. The establishment of specialized feeding cells requires these effectors to modulate many aspects of plant cell morphogenesis and physiology, including defence responses. This cell reprogramming requires changes to host nuclear processes. Some proteins encoded by parasitism genes target host nuclei. Several of these proteins were immunolocalised within feeding cell nuclei or shown to interact with host nuclear proteins. Comparative genomics and functional analyses are gradually revealing the roles of nematode effectors. We describe here these effectors and their hypothesised roles in the unique feeding behaviour of these pests.

The potential for host switching via ecological fitting in the emerald ash borer-host plant system.

Science.gov (United States)

Cipollini, Don; Peterson, Donnie L

2018-02-27

The traits used by phytophagous insects to find and utilize their ancestral hosts can lead to host range expansions, generally to closely related hosts that share visual and chemical features with ancestral hosts. Host range expansions often result from ecological fitting, which is the process whereby organisms colonize and persist in novel environments, use novel resources, or form novel associations with other species because of the suites of traits that they carry at the time they encounter the novel environment. Our objective in this review is to discuss the potential and constraints on host switching via ecological fitting in emerald ash borer, Agrilus planipennis, an ecologically and economically important invasive wood boring beetle. Once thought of as an ash (Fraxinus spp.) tree specialist, recent studies have revealed a broader potential host range than was expected for this insect. We discuss the demonstrated host-use capabilities of this beetle, as well as the potential for and barriers to the adoption of additional hosts by this beetle. We place our observations in the context of biochemical mechanisms that mediate the interaction of these beetles with their host plants and discuss whether evolutionary host shifts are a possible outcome of the interaction of this insect with novel hosts.

An Endoparasitoid Avoids Hyperparasitism by Manipulating Immobile Host Herbivore to Modify Host Plant Morphology

Science.gov (United States)

Fujii, Tomohisa; Matsuo, Kazunori; Abe, Yoshihisa; Yukawa, Junichi; Tokuda, Makoto

2014-01-01

Many parasitic organisms have an ability to manipulate their hosts to increase their own fitness. In parasitoids, behavioral changes of mobile hosts to avoid or protect against predation and hyperparasitism have been intensively studied, but host manipulation by parasitoids associated with endophytic or immobile hosts has seldom been investigated. We examined the interactions between a gall inducer Masakimyia pustulae (Diptera: Cecidomyiidae) and its parasitoids. This gall midge induces dimorphic leaf galls, thick and thin types, on Euonymus japonicus (Celastraceae). Platygaster sp. was the most common primary parasitoid of M. pustulae. In galls attacked by Platygaster sp., whole gall thickness as well as thicknesses of upper and lower gall wall was significantly larger than unparasitized galls, regardless of the gall types, in many localities. In addition, localities and tree individuals significantly affected the thickness of gall. Galls attacked by Platygaster sp. were seldom hyperparasitized in the two gall types. These results strongly suggest that Platygaster sp. manipulates the host plant's development to avoid hyperparasitism by thickening galls. PMID:25033216

Parasitic plants in agriculture: Chemical ecology of germination and host-plant location as targets for sustainable control: A review

Science.gov (United States)

Justin B. Runyon; John F. Tooker; Mark C. Mescher; Consuelo M. De Moraes

2009-01-01

Parasitic plants are among the most problematic pests of agricultural crops worldwide. Effective means of control are generally lacking, in part because of the close physiological connection between the established parasite and host plant hindering efficient control using traditional methods. Seed germination and host location are critical early-growth stages that...

Do fungivores trigger the transfer of protective metabolites from host plants to arbuscular mycorrhizal hyphae?

Science.gov (United States)

Duhamel, Marie; Pel, Roel; Ooms, Astra; Bücking, Heike; Jansa, Jan; Ellers, Jacintha; van Straalen, Nico M; Wouda, Tjalf; Vandenkoornhuyse, Philippe; Kiers, E Toby

2013-09-01

A key objective in ecology is to understand how cooperative strategies evolve and are maintained in species networks. Here, we focus on the tri-trophic relationship between arbuscular mycorrhizal (AM) fungi, host plants, and fungivores to ask if host plants are able to protect their mutualistic mycorrhizal partners from being grazed. Specifically, we test whether secondary metabolites are transferred from hosts to fungal partners to increase their defense against fungivores. We grew Plantago lanceolata hosts with and without mycorrhizal inoculum, and in the presence or absence of fungivorous springtails. We then measured fungivore effects on host biomass and mycorrhizal abundance (using quantitative PCR) in roots and soil. We used high-performance liquid chromatography to measure host metabolites in roots, shoots, and hyphae, focusing on catalpol, aucubin, and verbascoside. Our most striking result was that the metabolite catalpol was consistently found in AM fungal hyphae in host plants exposed to fungivores. When fungivores were absent, catalpol was undetectable in hyphae. Our results highlight the potential for plant-mediated protection of the mycorrhizal hyphal network.

Diversity begets diversity: host expansions and the diversification of plant-feeding insects

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Nylin Sören

2006-01-01

Full Text Available Abstract Background Plant-feeding insects make up a large part of earth's total biodiversity. While it has been shown that herbivory has repeatedly led to increased diversification rates in insects, there has been no compelling explanation for how plant-feeding has promoted speciation rates. There is a growing awareness that ecological factors can lead to rapid diversification and, as one of the most prominent features of most insect-plant interactions, specialization onto a diverse resource has often been assumed to be the main process behind this diversification. However, specialization is mainly a pruning process, and is not able to actually generate diversity by itself. Here we investigate the role of host colonizations in generating insect diversity, by testing if insect speciation rate is correlated with resource diversity. Results By applying a variant of independent contrast analysis, specially tailored for use on questions of species richness (MacroCAIC, we show that species richness is strongly correlated with diversity of host use in the butterfly family Nymphalidae. Furthermore, by comparing the results from reciprocal sister group selection, where sister groups were selected either on the basis of diversity of host use or species richness, we find that it is likely that diversity of host use is driving species richness, rather than vice versa. Conclusion We conclude that resource diversity is correlated with species richness in the Nymphalidae and suggest a scenario based on recurring oscillations between host expansions – the incorporation of new plants into the repertoire – and specialization, as an important driving force behind the diversification of plant-feeding insects.

Host Plants Identification for Adult Agrotis ipsilon, a Long-Distance Migratory Insect

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Yongqiang Liu

2016-06-01

Full Text Available In this study, we determined the host relationship of Agrotis ipsilon moths by identifying pollen species adhering them during their long-distance migration. Pollen carried by A. ipsilon moths was collected from 2012 to 2014 on a small island in the center of the Bohai Strait, which is a seasonal migration pathway of this pest species. Genomic DNA of single pollen grains was amplified by using whole genome amplification technology, and a portion of the chloroplast rbcL sequence was then amplified from this material. Pollen species were identified by a combination of DNA barcoding and pollen morphology. We found 28 species of pollen from 18 families on the tested moths, mainly from Angiosperm, Dicotyledoneae. From this, we were able to determine that these moths visit woody plants more than herbaceous plants that they carry more pollen in the early and late stages of the migration season, and that the amounts of pollen transportation were related to moth sex, moth body part, and plant species. In general, 31% of female and 26% of male moths were found to be carrying pollen. Amounts of pollen on the proboscis was higher for female than male moths, while the reverse was true for pollen loads on the antennae. This work provides a new approach to study the interactions between noctuid moth and their host plants. Identification of plant hosts for adult moths furthers understanding of the coevolution processes between moths and their host plants.

Spodoptera frugiperda (Lepidoptera: Noctuidae) host-plant variants: two host strains or two distinct species?

Science.gov (United States)

Dumas, Pascaline; Legeai, Fabrice; Lemaitre, Claire; Scaon, Erwan; Orsucci, Marion; Labadie, Karine; Gimenez, Sylvie; Clamens, Anne-Laure; Henri, Hélène; Vavre, Fabrice; Aury, Jean-Marc; Fournier, Philippe; Kergoat, Gael J; d'Alençon, Emmanuelle

2015-06-01

The moth Spodoptera frugiperda is a well-known pest of crops throughout the Americas, which consists of two strains adapted to different host-plants: the first feeds preferentially on corn, cotton and sorghum whereas the second is more associated with rice and several pasture grasses. Though morphologically indistinguishable, they exhibit differences in their mating behavior, pheromone compositions, and show development variability according to the host-plant. Though the latter suggest that both strains are different species, this issue is still highly controversial because hybrids naturally occur in the wild, not to mention the discrepancies among published results concerning mating success between the two strains. In order to clarify the status of the two host-plant strains of S. frugiperda, we analyze features that possibly reflect the level of post-zygotic isolation: (1) first generation (F1) hybrid lethality and sterility; (2) patterns of meiotic segregation of hybrids in reciprocal second generation (F2), as compared to the meiosis of the two parental strains. We found a significant reduction of mating success in F1 in one direction of the cross and a high level of microsatellite markers showing transmission ratio distortion in the F2 progeny. Our results support the existence of post-zygotic reproductive isolation between the two laboratory strains and are in accordance with the marked level of genetic differentiation that was recovered between individuals of the two strains collected from the field. Altogether these results provide additional evidence in favor of a sibling species status for the two strains.

Plants of the fynbos biome harbour host species-specific bacterial communities.

Science.gov (United States)

Miyambo, Tsakani; Makhalanyane, Thulani P; Cowan, Don A; Valverde, Angel

2016-08-01

The fynbos biome in South Africa is globally recognised as a plant biodiversity hotspot. However, very little is known about the bacterial communities associated with fynbos plants, despite interactions between primary producers and bacteria having an impact on the physiology of both partners and shaping ecosystem diversity. This study reports on the structure, phylogenetic composition and potential roles of the endophytic bacterial communities located in the stems of three fynbos plants (Erepsia anceps, Phaenocoma prolifera and Leucadendron laureolum). Using Illumina MiSeq 16S rRNA sequencing we found that different subpopulations of Deinococcus-Thermus, Alphaproteobacteria, Acidobacteria and Firmicutes dominated the endophytic bacterial communities. Alphaproteobacteria and Actinobacteria were prevalent in P. prolifera, whereas Deinococcus-Thermus dominated in L. laureolum, revealing species-specific host-bacteria associations. Although a high degree of variability in the endophytic bacterial communities within hosts was observed, we also detected a core microbiome across the stems of the three plant species, which accounted for 72% of the sequences. Altogether, it seems that both deterministic and stochastic processes shaped microbial communities. Endophytic bacterial communities harboured putative plant growth-promoting bacteria, thus having the potential to influence host health and growth. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Enhanced resistance to Spodoptera litura in endophyte infected cauliflower plants.

Science.gov (United States)

Thakur, Abhinay; Kaur, Sanehdeep; Kaur, Amarjeet; Singh, Varinder

2013-04-01

Endophytic fungi, which live within host plant tissues without causing any visible symptom of disease, are important mediators of plant-herbivore interactions. These endophytes enhance resistance of host plant against insect herbivores mainly by productions of various alkaloid based defensive compounds in the plant tissue or through alterations of plant nutritional quality. Two endophytic fungi, i.e., Nigrospora sp. and Cladosporium sp., were isolated from Tinospora cordifolia (Thunb.) Miers, a traditional indian medicinal plant. Cauliflower (Brassica oleracea L.) plants were inoculated with these two endophytic fungi. The effect of endophyte infected and uninfected cauliflower plants were measured on the survival and development of Spodoptera litura (Fab.), a polyphagous pest. Endophyte infected cauliflower plants showed resistance to S. litura in the form of significant increase in larval and pupal mortality in both the fungi. Inhibitory effects of endophytic fungi also were observed on adult emergence, longevity, reproductive potential, as well as hatchability of eggs. Thus, it is concluded that antibiosis to S. litura could be imparted by artificial inoculation of endophytes and this could be used to develop alternative ecologically safe control strategies.

Plant surface wax affects parasitoid's response to host footprints

Science.gov (United States)

Rostás, Michael; Ruf, Daniel; Zabka, Vanessa; Hildebrandt, Ulrich

2008-10-01

The plant surface is the substrate upon which herbivorous insects and natural enemies meet and thus represents the stage for interactions between the three trophic levels. Plant surfaces are covered by an epicuticular wax layer which is highly variable depending on species, cultivar or plant part. Differences in wax chemistry may modulate ecological interactions. We explored whether caterpillars of Spodoptera frugiperda, when walking over a plant surface, leave a chemical trail (kairomones) that can be detected by the parasitoid Cotesia marginiventris. Chemistry and micromorphology of cuticular waxes of two barley eceriferum wax mutants ( cer-za.126, cer-yp.949) and wild-type cv. Bonus (wt) were assessed. The plants were then used to investigate potential surface effects on the detectability of caterpillar kairomones. Here we provide evidence that C. marginiventris responds to chemical footprints of its host. Parasitoids were able to detect the kairomone on wild-type plants and on both cer mutants but the response to cer-yp.949 (reduced wax, high aldehyde fraction) was less pronounced. Experiments with caterpillar-treated wt and mutant leaves offered simultaneously, confirmed this observation: no difference in wasp response was found when wt was tested against cer-za.126 (reduced wax, wt-like chemical composition) but wt was significantly more attractive than cer-yp.949. This demonstrates for the first time that the wax layer can modulate the detectability of host kairomones.

Novel observations of larval fire survival, feeding behavior, and host plant use in the regal fritillary, Speyeria idalia (Drury) (Nymphalidae)

Science.gov (United States)

McCullough, Kelsey; Albanese, Gene; Haukos, David A.

2017-01-01

Speyeria idalia is a prairie specialist that has experienced dramatic population declines throughout its range. Speyeria idalia is nearly extirpated from the eastern portion of its former range; however, populations within Kansas are relatively stable. We made several previously undescribed field observations of late-instar larvae and post-diapause female S. idalia in northeastern Kansas during 2014–2016. We report finding late-instar larvae at locations that were burned within weeks of detection. The observations of larvae shortly following a burn suggests that S. idalia larvae are capable of surviving fire and contradicts our current knowledge of this species. Additionally, we describe a feeding behavior characteristic of late-instar larvae. Larvae observed in the field and lab stripped leaves of host plants leaving only stems. This strip-style feeding behavior provided unique feeding evidence that was valuable to detecting the presence of larvae in the field. Finally, we documented larvae and post-diapause, egg depositing females using Viola sororia. The use of this relatively widespread and common plant by S. idalia populations in the Central Great Plains has only been implicitly documented but may have important conservation implications. These novel observations further our knowledge of the ecology of this imperiled species and provide timely information that may improve research and conservation management efforts directed toward S. idalia populations.

Host Plant Volatiles and the Sexual Reproduction of the Potato Aphid, Macrosiphum euphorbiae

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Jessica Hurley

2014-10-01

Full Text Available In late summer, heteroecious aphids, such as the potato aphid, Macrosiphum euphorbiae, move from their secondary summer host plants to primary host plants, where the sexual oviparae mate and lay diapausing eggs. We tested the hypothesis that volatiles of the primary host, Rosa rugosa, would attract the gynoparae, the parthenogenetic alate morph that produce oviparae, as well as the alate males foraging for suitable mates. In wind tunnel assays, both gynoparae and males oriented towards and reached rose cuttings significantly more often than other odour sources, including potato, a major secondary host. The response of males was as high to rose cuttings alone as to potato with a calling virgin oviparous female. These findings are discussed within the seasonal ecology of host alternating aphids.

Ecological and genetic factors influencing the transition between host-use strategies in sympatric Heliconius butterflies.

Science.gov (United States)

Merrill, R M; Naisbit, R E; Mallet, J; Jiggins, C D

2013-09-01

Shifts in host-plant use by phytophagous insects have played a central role in their diversification. Evolving host-use strategies will reflect a trade-off between selection pressures. The ecological niche of herbivorous insects is partitioned along several dimensions, and if populations remain in contact, recombination will break down associations between relevant loci. As such, genetic architecture can profoundly affect the coordinated divergence of traits and subsequently the ability to exploit novel habitats. The closely related species Heliconius cydno and H. melpomene differ in mimetic colour pattern, habitat and host-plant use. We investigate the selection pressures and genetic basis underlying host-use differences in these two species. Host-plant surveys reveal that H. melpomene specializes on a single species of Passiflora. This is also true for the majority of other Heliconius species in secondary growth forest at our study site, as expected under a model of interspecific competition. In contrast, H. cydno, which uses closed-forest habitats where both Heliconius and Passiflora are less common, appears not to be restricted by competition and uses a broad selection of the available Passiflora. However, other selection pressures are likely involved, and field experiments reveal that early larval survival of both butterfly species is highest on Passiflora menispermifolia, but most markedly so for H. melpomene, the specialist on that host. Finally, we demonstrate an association between host-plant acceptance and colour pattern amongst interspecific hybrids, suggesting that major loci underlying these important ecological traits are physically linked in the genome. Together, our results reveal ecological and genetic associations between shifts in habitat, host use and mimetic colour pattern that have likely facilitated both speciation and coexistence. © 2013 The Authors. Journal of Evolutionary Biology © 2013 European Society For Evolutionary Biology.

Transcriptional profile and differential fitness in a specialist milkweed insect across host plants varying in toxicity.

Science.gov (United States)

Birnbaum, Stephanie S L; Rinker, David C; Gerardo, Nicole M; Abbot, Patrick

2017-12-01

Interactions between plants and herbivorous insects have been models for theories of specialization and co-evolution for over a century. Phytochemicals govern many aspects of these interactions and have fostered the evolution of adaptations by insects to tolerate or even specialize on plant defensive chemistry. While genomic approaches are providing new insights into the genes and mechanisms insect specialists employ to tolerate plant secondary metabolites, open questions remain about the evolution and conservation of insect counterdefences, how insects respond to the diversity defences mounted by their host plants, and the costs and benefits of resistance and tolerance to plant defences in natural ecological communities. Using a milkweed-specialist aphid (Aphis nerii) model, we test the effects of host plant species with increased toxicity, likely driven primarily by increased secondary metabolites, on aphid life history traits and whole-body gene expression. We show that more toxic plant species have a negative effect on aphid development and lifetime fecundity. When feeding on more toxic host plants with higher levels of secondary metabolites, aphids regulate a narrow, targeted set of genes, including those involved in canonical detoxification processes (e.g., cytochrome P450s, hydrolases, UDP-glucuronosyltransferases and ABC transporters). These results indicate that A. nerii marshal a variety of metabolic detoxification mechanisms to circumvent milkweed toxicity and facilitate host plant specialization, yet, despite these detoxification mechanisms, aphids experience reduced fitness when feeding on more toxic host plants. Disentangling how specialist insects respond to challenging host plants is a pivotal step in understanding the evolution of specialized diet breadths. © 2017 John Wiley & Sons Ltd.

[Oviposition, development, and reproduction of Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) fed on different hosts of economic importance].

Science.gov (United States)

Barros, Eduardo M; Torres, Jorge B; Bueno, Adeney F

2010-01-01

The host selection for oviposition by Spodoptera frugiperda (J.E. Smith) among corn, millet, cotton and soybean, and its relationship with the biological characteristics were investigated. Free and non-choice tests for oviposition using plots containing five plants each, from each host in plastic greenhouse, resulted in similar oviposition preference among the host plants. In addition, selected biological characteristics of S. frugiperda were determined in the laboratory with larvae feeding on host leaves, and the combination of leaf and cotton boll. Neonate larvae exhibited low success of colonization on cotton boll compared to the leaves of all other hosts. Spodoptera frugiperda fed only on cotton bolls exhibited longer larval and pupal development, and longer adult life span; however with similar egg production. Larvae fed cotton leaves during six days and then transferred to cotton bolls, however, exhibited development and reproduction similar to those reared on corn or only on cotton leaves. Therefore, the variations on immature stages of S. frugiperda were not related with host selection for oviposition which was similar among the studied hosts. Based on our data, the millet as a winter, rotational, and cover crop is a potential host for S. frugiperda, while leaves and cotton bolls were diets of intermediate suitability as compared to corn and soybean leaves.

A Bacterial Parasite Effector Mediates Insect Vector Attraction in Host Plants Independently of Developmental Changes

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Orlovskis, Zigmunds; Hogenhout, Saskia A.

2016-01-01

Parasites can take over their hosts and trigger dramatic changes in host appearance and behavior that are typically interpreted as extended phenotypes that promote parasite survival and fitness. For example, Toxoplasma gondii is thought to manipulate the behaviors of infected rodents to aid transmission to cats and parasitic trematodes of the genus Ribeiroia alter limb development in their amphibian hosts to facilitate predation of the latter by birds. Plant parasites and pathogens also reprogram host development and morphology. However, whereas some parasite-induced morphological alterations may have a direct benefit to the fitness of the parasite and may therefore be adaptive, other host alterations may be side effects of parasite infections having no adaptive effects on parasite fitness. Phytoplasma parasites of plants often induce the development of leaf-like flowers (phyllody) in their host plants, and we previously found that the phytoplasma effector SAP54 generates these leaf-like flowers via the degradation of plant MADS-box transcription factors (MTFs), which regulate all major aspects of development in plants. Leafhoppers prefer to reproduce on phytoplasma-infected and SAP54-trangenic plants leading to the hypothesis that leafhopper vectors are attracted to plants with leaf-like flowers. Surprisingly, here we show that leafhopper attraction occurs independently of the presence of leaf-like flowers. First, the leafhoppers were also attracted to SAP54 transgenic plants without leaf-like flowers and to single leaves of these plants. Moreover, leafhoppers were not attracted to leaf-like flowers of MTF-mutant plants without the presence of SAP54. Thus, the primary role of SAP54 is to attract leafhopper vectors, which spread the phytoplasmas, and the generation of leaf-like flowers may be secondary or a side effect of the SAP54-mediated degradation of MTFs. PMID:27446117

77 FR 54331 - Endangered and Threatened Wildlife and Plants; 12-Month Finding on a Petition To List the Mardon...

Science.gov (United States)

2012-09-04

... habitat requirements include food resources for adults (flower nectar), larval host plants (grasses and... strongly preferred as nectar sources, and Scot's broom is strongly avoided (Hays et al. 2000, p. 14...) are also reported as nectar sources from this region (Beyer and Black 2007, p. 15; Potter and...

Transcriptional Responses in the Hemiparasitic Plant Triphysaria versicolor to Host Plant Signals1[w

Science.gov (United States)

Matvienko, Marta; Torres, Manuel J.; Yoder, John I.

2001-01-01

Parasitic plants in the Scrophulariaceae use chemicals released by host plant roots to signal developmental processes critical for heterotrophy. Haustoria, parasitic plant structures that attach to and invade host roots, develop on roots of the hemiparasitic plant Triphysaria versicolor within a few hours of exposure to either maize (Zea mays) root exudate or purified haustoria-inducing factors. We prepared a normalized, subtractive cDNA library enriched for transcripts differentially abundant in T. versicolor root tips treated with the allelopathic quinone 2,6-dimethoxybenzoquinone (DMBQ). Northern analyses estimated that about 10% of the cDNAs represent transcripts strongly up-regulated in roots exposed to DMBQ. Northern and reverse northern analyses demonstrated that most DMBQ-responsive messages were similarly up-regulated in T. versicolor roots exposed to maize root exudates. From the cDNA sequences we assembled a unigene set of 137 distinct transcripts and assigned functions by homology comparisons. Many of the proteins encoded by the transcripts are predicted to function in quinone detoxification, whereas others are more likely associated with haustorium development. The identification of genes transcriptionally regulated by haustorium-inducing factors provides a framework for dissecting genetic pathways recruited by parasitic plants during the transition to heterotrophic growth. PMID:11553755

Molecular interrogation of the feeding behaviour of field captured individual insects for interpretation of multiple host plant use.

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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.

Cellular and Molecular Interactions of Rhabdoviruses with their Insect and Plant Hosts

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The rhabdoviruses form a large family (Rhabdoviridae) whose host ranges include humans, other vertebrates, invertebrates, and plants. There are about 75 plant-infecting rhabdoviruses described, several of which are economically important pathogens that are persistently transmitted to their plant ho...

Adaptive Potential for the Invasion of Novel Host Plants in the Bean Weevil: Patterns of the Reproductive Behavior in Populations That Used Different Host Plants

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Dragana Milanović

2007-01-01

Full Text Available The goal of this work was to examine interpopulation patterns in the reproductive behavior of populations of bean weevil (Acanthoscelides obtectus Say; Coleoptera: Bruchidae that had different levels of specialization on their native host plant – the bean (Phaseolus vulgaris L., as well as on a novel host plant – the chickpea (Cicer arietinum Thorn. The obtained pattern of interpopulation mating behavior seemed exactly as if the males on chickpea had evolved a specific odor and/or a courtship ritual that females of populationson bean found repulsive. Unlike females, the males of bean populations seemed to be willing to mate with females from the population on chickpea equally as with their own females. Such an asymmetric pattern of reproductive isolation between populations ofa species has been often considered an initial phase of a process of speciation. Thus, our results could be a good starting point for further, thorough examination of both the role of the level of host specialization in females and the role of biochemical characteristics of male pheromone (and/or their cuticular hydrocarbones in the evolution of pre-reproductive isolation between insect populations.As the results of this study, together those of previous studies on A. obtectus, suggest great evolutionary potential for invasions of and fast specialization on novel host plants, they could provide valuable information for the development of long-term strategiesunder the programmes of Integrated Pest Management.

Long Frontal Projections Help Battus philenor (Lepidoptera: Papilionidae) Larvae Find Host Plants.

Science.gov (United States)

Kandori, Ikuo; Tsuchihara, Kazuko; Suzuki, Taichi A; Yokoi, Tomoyuki; Papaj, Daniel R

2015-01-01

Animals sometimes develop conspicuous projections on or near their heads as, e.g., weaponry, burrowing or digging tools, and probes to search for resources. The frontal projections that insects generally use to locate and assess resources are segmented appendages, including antennae, maxillary palps, and labial palps. There is no evidence to date that arthropods, including insects, use projections other than true segmental appendages to locate food. In this regard, it is noteworthy that some butterfly larvae possess a pair of long antenna-like projections on or near their heads. To date, the function of these projections has not been established. Larvae of pipevine swallowtail butterflies Battus philenor (Papilionidae) have a pair of long frontal fleshy projections that, like insect antennae generally, can be actively moved. In this study, we evaluated the possible function of this pair of long moveable frontal projections. In laboratory assays, both frontal projections and lateral ocelli were shown to increase the frequency with which search larvae found plants. The frontal projections increased finding of host and non-host plants equally, suggesting that frontal projections do not detect host-specific chemical cues. Detailed SEM study showed that putative mechanosensillae are distributed all around the frontal as well as other projections. Taken together, our findings suggest that the frontal projections and associated mechanosensillae act as vertical object detectors to obtain tactile information that, together with visual information from lateral ocelli and presumably chemical information from antennae and mouthparts, help larvae to find host plants. Field observations indicate that host plants are small and scattered in southern Arizona locations. Larvae must therefore find multiple host plants to complete development and face significant challenges in doing so. The frontal projections may thus be an adaptation for finding a scarce resource before starving to

Rotylenchulus reniformis on Greenhouse-grown Foliage Plants: Host Range and Sources of Inoculum.

Science.gov (United States)

Starr, J L

1991-10-01

Two sources of inoculum of reniform nematodes, Rotylenchulus reniformis, were identified for infestation of ornamental foliage plants in commercial greenhouses. These were water from a local canal system and rooted cuttings purchased from other sources. Eight ornamental plant species were identified as good hosts for the reniform nematode, with each species supporting a reniform population density equal to or greater than that supported by 'Rutgers' tomato and a reproduction factor of greater than 1.0. Nine other plant species were identified as poor hosts.

MicroRNAs from the parasitic plant Cuscuta campestris target host messenger RNAs.

Science.gov (United States)

Shahid, Saima; Kim, Gunjune; Johnson, Nathan R; Wafula, Eric; Wang, Feng; Coruh, Ceyda; Bernal-Galeano, Vivian; Phifer, Tamia; dePamphilis, Claude W; Westwood, James H; Axtell, Michael J

2018-01-03

Dodders (Cuscuta spp.) are obligate parasitic plants that obtain water and nutrients from the stems of host plants via specialized feeding structures called haustoria. Dodder haustoria facilitate bidirectional movement of viruses, proteins and mRNAs between host and parasite, but the functional effects of these movements are not known. Here we show that Cuscuta campestris haustoria accumulate high levels of many novel microRNAs (miRNAs) while parasitizing Arabidopsis thaliana. Many of these miRNAs are 22 nucleotides in length. Plant miRNAs of this length are uncommon, and are associated with amplification of target silencing through secondary short interfering RNA (siRNA) production. Several A. thaliana mRNAs are targeted by 22-nucleotide C. campestris miRNAs during parasitism, resulting in mRNA cleavage, secondary siRNA production, and decreased mRNA accumulation. Hosts with mutations in two of the loci that encode target mRNAs supported significantly higher growth of C. campestris. The same miRNAs that are expressed and active when C. campestris parasitizes A. thaliana are also expressed and active when it infects Nicotiana benthamiana. Homologues of target mRNAs from many other plant species also contain the predicted target sites for the induced C. campestris miRNAs. These data show that C. campestris miRNAs act as trans-species regulators of host-gene expression, and suggest that they may act as virulence factors during parasitism.

Plant rhabdoviruses: new insights and research needs in the interplay of negative-strand RNA viruses with plant and insect hosts.

Science.gov (United States)

Mann, Krin S; Dietzgen, Ralf G

2014-08-01

Rhabdoviruses are taxonomically classified in the family Rhabdoviridae, order Mononegavirales. As a group, rhabdoviruses can infect plants, invertebrates and vertebrates. Plant cyto- and nucleorhabdoviruses infect a wide variety of species across both monocot and dicot families, including agriculturally important crops such as lettuce, wheat, barley, rice, maize, potato and tomato. Plant rhabdoviruses are transmitted by and replicate in hemipteran insects such as aphids (Aphididae), leafhoppers (Cicadellidae), or planthoppers (Delphacidae). These specific interactions between plants, viruses and insects offer new insights into host adaptation and molecular virus evolution. This review explores recent advances as well as knowledge gaps in understanding of replication, RNA silencing suppression and movement of plant rhabdoviruses with respect to both plant and insect hosts.

Glucosinolates from Host Plants Influence Growth of the Parasitic Plant Cuscuta gronovii and Its Susceptibility to Aphid Feeding1[OPEN

Science.gov (United States)

2016-01-01

Parasitic plants acquire diverse secondary metabolites from their hosts, including defense compounds that target insect herbivores. However, the ecological implications of this phenomenon, including the potential enhancement of parasite defenses, remain largely unexplored. We studied the translocation of glucosinolates from the brassicaceous host plant Arabidopsis (Arabidopsis thaliana) into parasitic dodder vines (Convolvulaceae; Cuscuta gronovii) and its effects on the parasite itself and on dodder-aphid interactions. Aliphatic and indole glucosinolates reached concentrations in parasite tissues higher than those observed in corresponding host tissues. Dodder growth was enhanced on cyp79B2 cyp79B3 hosts (without indole glucosinolates) but inhibited on atr1D hosts (with elevated indole glucosinolates) relative to wild-type hosts, which responded to parasitism with localized elevation of indole and aliphatic glucosinolates. These findings implicate indole glucosinolates in defense against parasitic plants. Rates of settling and survival on dodder vines by pea aphids (Acyrthosiphon pisum) were reduced significantly when dodder parasitized glucosinolate-producing hosts (wild type and atr1D) compared with glucosinolate-free hosts (cyp79B2 cyp79B3 myb28 myb29). However, settling and survival of green peach aphids (Myzus persicae) were not affected. M. persicae population growth was actually reduced on dodder parasitizing glucosinolate-free hosts compared with wild-type or atr1D hosts, even though stems of the former contain less glucosinolates and more amino acids. Strikingly, this effect was reversed when the aphids fed directly upon Arabidopsis, which indicates an interactive effect of parasite and host genotype on M. persicae that stems from host effects on dodder. Thus, our findings indicate that glucosinolates may have both direct and indirect effects on dodder-feeding herbivores. PMID:27482077

Host plant specialization in the generalist moth Heliothis virescens and the role of egg imprinting

NARCIS (Netherlands)

Karpinski, A.; Haenniger, S.; Schöfl, G.; Heckel, D.G.; Groot, A.T.

2014-01-01

Even though generalist insects are able to feed on many different host plants, local specialization may occur, which could lead to genetic differentiation. In this paper we assessed the level and extent of host plant specialization in the generalist herbivore Heliothis virescens Fabricius

Host plants of Melon Fly, Bactrocera cucurbitae(Coquillett)(Diptera:Tephritidae); and provisional list of suitable host plants of the Melon Fly, Bactrocera(Zeugodacus)cucurbitae(Coquillett)(Diptera:Tephritidae),Version 2.0

Science.gov (United States)

The melon fly, Bactrocera cucurbitae (Coquillett), is a widespread, economically important tephritid fruit fly (Diptera: Tephritidae) species. Bactrocera cucurbitae infests fruits and vegetables of a number of different plant species, with many host plants in the plant family Cucurbitaceae, but with...

Distance and sex determine host plant choice by herbivorous beetles.

Directory of Open Access Journals (Sweden)

Daniel J Ballhorn

Full Text Available 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?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.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, whereas the presence of a slightly damaged

Gravisensitivity of various host plant -virus systems in simulated microgravity

Science.gov (United States)

Mishchenko, Lidiya; Taran, Oksana; Gordejchyk, Olga

In spite of considerable achievements in the study of gravity effects on plant development, some issues of gravitropism, like species-specificity and gravitation response remain unclear. The so-lution of such problems is connected with the aspects of life supply, in piloted space expeditions. The role of microgravity remains practically unstudied in the development of relations in the system host plant-virus, which are important for biotechnologies in crop production. It is ev-ident that the conditions of space flight can act as stressors, and the stress inducted by them favors the reactivation of latest herpes viruses in humans (satish et al., 2009) Viral infections of plants, which also can be in a latest state at certain stages of plant organism development, cause great damage to the growth and development of a host plant. Space flight conditions may cause both reactivation of latent viral infection in plants and its elimination, as it has been found by us for the system WSMW -wheat (Mishchenko et al., 2004). Our further research activities were concentrated on the identification of gravisensitivity in the system virus -potato plant to find out whether there was any species -related specificity of the reaction. In our research we used potato plants of Krymska Rosa, Zhuravushka, Agave, Belarosa, Kupalinka, and Zdubytok varieties. Simulated microgravity was ensured by clinostats KG-8 and Cycle -2. Gravisensitiv-ity has been studied the systems including PVX, PVM and PVY. Virus concentrations have been determined by ELISA using LOEWE reagents (placecountry-regionGermany). Virus iden-tification by morphological features were done by electron microscopy. For the system PVX -potato plant, we found the reduction in virus antigens content with prolonged clinostating. On the 18th day of cultivation, the plants showed a high level of X-virus antigen content on both stationary (control) and clinostated variants. On 36th and 47th day, depending plant variety, clinostated

Larval Settlement of the Nemertean Egg Predator Carcinonemertes errans on the Dungeness Crab, Metacarcinus magister

DEFF Research Database (Denmark)

Dunn, Paul; Young, Craig

2014-01-01

, competent larvae of C. errans settled on the crab’s exoskeleton and migrated under the abdominal flap within 24 h. When removed from the host, recently settled worms retained their larval characteristics. After 48 h on the host, however, metamorphosis proceeded and larvae became juvenile worms. Additional...

Excretory/secretory products in the Echinococcus granulosus metacestode: is the intermediate host complacent with infection caused by the larval form of the parasite?

Science.gov (United States)

Santos, Guilherme B Dos; Monteiro, Karina M; da Silva, Edileuza Danieli; Battistella, Maria Eduarda; Ferreira, Henrique B; Zaha, Arnaldo

2016-12-01

The genus Echinococcus consists of parasites that have a life cycle with two mammalian hosts. Their larval stage, called the hydatid cyst, develops predominantly in the liver and lungs of intermediate hosts. The hydatid cyst is the causative agent of cystic hydatid disease and the species Echinococcus granulosus, G1 haplotype, is responsible for the vast majority of cases in humans, cattle and sheep. Protein characterization in hydatid cysts is essential for better understanding of the host-parasite relationship and the fertility process of Echinococcus. The aims of this work were the identification and quantitative comparison of proteins found in hydatid fluid from fertile and infertile cysts from E. granulosus, in order to highlight possible mechanisms involved in cyst fertility or infertility. Hydatid fluid samples containing proteins from both E. granulosus and Bos taurus were analysed by LC-MS/MS. Our proteomic analysis of fertile and infertile cysts allowed identification of a total of 498 proteins, of which 153 proteins were exclusively identified in the fertile cyst, 271 in the infertile cyst, and 74 in both. Functional in silico analysis allowed us to highlight some important aspects: (i) clues about the possible existence of an "arms race" involving parasite and host responses in fertile and infertile cysts; (ii) a number of proteins in hydatid fluid without functional annotation or with possible alternative functions; (iii) the presence of extracellular vesicles such as exosomes, which was confirmed by transmission electron microscopy. Copyright © 2016 Australian Society for Parasitology. Published by Elsevier Ltd. All rights reserved.

The Bacterial Pathogen Xylella fastidiosa Affects the Leaf Ionome of Plant Hosts during Infection

Science.gov (United States)

De La Fuente, Leonardo; Parker, Jennifer K.; Oliver, Jonathan E.; Granger, Shea; Brannen, Phillip M.; van Santen, Edzard; Cobine, Paul A.

2013-01-01

Xylella fastidiosa is a plant pathogenic bacterium that lives inside the host xylem vessels, where it forms biofilm believed to be responsible for disrupting the passage of water and nutrients. Here, Nicotiana tabacum was infected with X. fastidiosa, and the spatial and temporal changes in the whole-leaf ionome (i.e. the mineral and trace element composition) were measured as the host plant transitioned from healthy to diseased physiological status. The elemental composition of leaves was used as an indicator of the physiological changes in the host at a specific time and relative position during plant development. Bacterial infection was found to cause significant increases in concentrations of calcium prior to the appearance of symptoms and decreases in concentrations of phosphorous after symptoms appeared. Field-collected leaves from multiple varieties of grape, blueberry, and pecan plants grown in different locations over a four-year period in the Southeastern US showed the same alterations in Ca and P. This descriptive ionomics approach characterizes the existence of a mineral element-based response to X. fastidiosa using a model system suitable for further manipulation to uncover additional details of the role of mineral elements during plant-pathogen interactions. This is the first report on the dynamics of changes in the ionome of the host plant throughout the process of infection by a pathogen. PMID:23667547

The bacterial pathogen Xylella fastidiosa affects the leaf ionome of plant hosts during infection.

Directory of Open Access Journals (Sweden)

Leonardo De La Fuente

Full Text Available Xylella fastidiosa is a plant pathogenic bacterium that lives inside the host xylem vessels, where it forms biofilm believed to be responsible for disrupting the passage of water and nutrients. Here, Nicotiana tabacum was infected with X. fastidiosa, and the spatial and temporal changes in the whole-leaf ionome (i.e. the mineral and trace element composition were measured as the host plant transitioned from healthy to diseased physiological status. The elemental composition of leaves was used as an indicator of the physiological changes in the host at a specific time and relative position during plant development. Bacterial infection was found to cause significant increases in concentrations of calcium prior to the appearance of symptoms and decreases in concentrations of phosphorous after symptoms appeared. Field-collected leaves from multiple varieties of grape, blueberry, and pecan plants grown in different locations over a four-year period in the Southeastern US showed the same alterations in Ca and P. This descriptive ionomics approach characterizes the existence of a mineral element-based response to X. fastidiosa using a model system suitable for further manipulation to uncover additional details of the role of mineral elements during plant-pathogen interactions. This is the first report on the dynamics of changes in the ionome of the host plant throughout the process of infection by a pathogen.

Volatile fragrances associated with flowers mediate the host plant alternation of a polyphagous mirid bug

Science.gov (United States)

Apolygus lucorum (Meyer-Dür) (Hemiptera: Miridae) is an important insect pest of cotton, fruit trees and other crops in China, and exhibits a particularly broad host range. Adult A. lucorum greatly prefers host plants at the flowering stage, and their populations track flowering plants both spatiall...

BACULOVIRUS REPLICATION ALTERS HORMONE-REGULATED HOST DEVELOPMENT.

Science.gov (United States)

The baculovirus Lymantria dispar nuclear polyhedrosis virus interferes with insect larval development by altering the host's hormonal system. The level of haemolymph ecdysteroids, the insect moulting hormone, was found to be higher in virus-infected larvae than in uninfected cont...

A holoparasitic plant severely reduces the vegetative and reproductive performance of its host plant in the Caatinga, a Brazilian seasonally dry forest

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Oswaldo Cruz Neto

Full Text Available ABSTRACT Host-parasite interactions between plants may reduce the vegetative and reproductive performance of the host plant. Although it is well established that parasitic plants may negatively affect the metabolism and the number of vegetative/reproductive structures of their hosts, the effects of this interaction on the reproductive characteristics of the host plant are poorly understood. Here we document the interaction between Cuscuta partita (Convolvulaceae and its main host, Zornia diphylla (Fabaceae, in the Caatinga of northeastern Brazil. We measured diverse reproductive/vegetative attributes of Z. diphylla in 60 plots randomly distributed in patches that were parasitized and not parasitized by C. partita. Both vegetative and reproductive attributes, such as the number of branches, leaves and flowers, and the individual biomass of Z. diphylla were significantly reduced by the parasitism. The number of pollen grains and ovules per flower were not affected by the parasitism, but since the parasitism reduced flower production, the total number of pollen and ovules per individual and population may also be reduced. Additionally, pollen viability was significantly reduced in the flowers of parasitized individuals. We conclude that C. partita may negatively impact the vegetative and reproductive performance of its main host, Z. diphylla in distinct ways in the Caatinga.

Optimal control issues in plant disease with host demographic factor and botanical fungicides

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Anggriani, N.; Mardiyah, M.; Istifadah, N.; Supriatna, A. K.

2018-03-01

In this paper, we discuss a mathematical model of plant disease with the effect of fungicide. We assume that the fungicide is given as a preventive treatment to infectious plants. The model is constructed based on the development of the disease in which the monomolecular is monocyclic. We show the value of the Basic Reproduction Number (BRN) ℛ0 of the plant disease transmission. The BRN is computed from the largest eigenvalue of the next generation matrix of the model. The result shows that in the region where ℛ0 greater than one there is a single stable endemic equilibrium. However, in the region where ℛ0 less than one this endemic equilibrium becomes unstable. The dynamics of the model is highly sensitive to changes in contact rate and infectious period. We also discuss the optimal control of the infected plant host by considering a preventive treatment aimed at reducing the infected host plant. The obtaining optimal control shows that it can reduce the number of infected hosts compared to that without control. Some numerical simulations are also given to illustrate our analytical results.

Chemical similarity between historical and novel host plants promotes range and host expansion of the mountain pine beetle in a naïve host ecosystem.

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Erbilgin, Nadir; Ma, Cary; Whitehouse, Caroline; Shan, Bin; Najar, Ahmed; Evenden, Maya

2014-02-01

Host plant secondary chemistry can have cascading impacts on host and range expansion of herbivorous insect populations. We investigated the role of host secondary compounds on pheromone production by the mountain pine beetle (Dendroctonus ponderosae) (MPB) and beetle attraction in response to a historical (lodgepole pine, Pinus contorta var. latifolia) and a novel (jack pine, Pinus banksiana) hosts, as pheromones regulate the host colonization process. Beetles emit the same pheromones from both hosts, but more trans-verbenol, the primary aggregation pheromone, was emitted by female beetles on the novel host. The phloem of the novel host contains more α-pinene, a secondary compound that is the precursor for trans-verbenol production in beetle, than the historical host. Beetle-induced emission of 3-carene, another secondary compound found in both hosts, was also higher from the novel host. Field tests showed that the addition of 3-carene to the pheromone mixture mimicking the aggregation pheromones produced from the two host species increased beetle capture. We conclude that chemical similarity between historical and novel hosts has facilitated host expansion of MPB in jack pine forests through the exploitation of common host secondary compounds for pheromone production and aggregation on the hosts. Furthermore, broods emerging from the novel host were larger in terms of body size. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

Biology and host range of Tecmessa elegans (Lepidoptera: Notodontidae), a leaf-feeding moth evaluated as a potential biological control agent for Schinus terebinthifolius (Sapindales: Anacardiaceae) in the United States.

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Oleiro, Marina; Mc Kay, Fernando; Wheeler, Gregory S

2011-06-01

During surveys for natural enemies that could be used as classical biological control agents of Schinus terebinthifolius Raddi (Brazilian pepper), the caterpillar, Tecmessa elegans Schaus (Lepidoptera: Notodontidae), was recorded feeding on the leaves of the shrub in South America. The biology and larval and adult host range of this species were examined to determine the insect's suitability for biological control of this invasive weed in North America and Hawaii. Biological observations indicate that the larvae have five instars. When disturbed, the late instar larvae emit formic acid from a prothoracic gland that may protect larvae from generalist predators. Larval host range tests conducted both in South and North America indicated that this species feeds and completes development primarily on members of the Anacardiaceae within the tribe Rhoeae. Oviposition tests indicated that when given a choice in large cages the adults will select the target weed over Pistacia spp. However, considering the many valued plant species in its host range, especially several North American natives, this species will not be considered further for biological control of S. terebinthifolius in North America.

An olfactory receptor from Apolygus lucorum (Meyer-Dur) mainly tuned to volatiles from flowering host plants.

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Yan, Shu-Wei; Zhang, Jin; Liu, Yang; Li, Guo-Qing; Wang, Gui-Rong

2015-08-01

Apolygus lucorum (Meyer-Dür) (Hemiptera: Miridae) is one of the most serious agricultural pests, feeding on a wide range of cultivated plants, including cotton, cereals and vegetables in the north of China. This insect can frequently switch between habitats and host plants over seasons and prefer plants in bloom. A. lucorum relies heavily on olfaction to locate its host plants finely discriminating different plant volatiles in the environment. Despite its economical importance, research on the olfactory system of this species has been so far very limited. In this study, we have identified and characterized an olfactory receptor which is sensitively tuned to (Z)-3-Hexenyl acetate and several flowering compounds. Besides being present in the bouquet of some flowers, these compounds are produced by plants that have suffered attacks and are supposed to act as chemical messengers between plants. This OR may play an important role in the selection of host plants. Copyright © 2015 Elsevier Ltd. All rights reserved.

Growth but not photosynthesis response of a host plant to infection by a holoparasitic plant depends on nitrogen supply.

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Hao Shen

Full Text Available Parasitic plants can adversely influence the growth of their hosts by removing resources and by affecting photosynthesis. Such negative effects depend on resource availability. However, at varied resource levels, to what extent the negative effects on growth are attributed to the effects on photosynthesis has not been well elucidated. Here, we examined the influence of nitrogen supply on the growth and photosynthesis responses of the host plant Mikania micrantha to infection by the holoparasite Cuscuta campestris by focusing on the interaction of nitrogen and infection. Mikania micrantha plants fertilized at 0.2, 1 and 5 mM nitrate were grown with and without C. campestris infection. We observed that the infection significantly reduced M. micrantha growth at each nitrate fertilization and more severely at low than at high nitrate. Such alleviation at high nitrate was largely attributed to a stronger influence of infection on root biomass at low than at high nitrate fertilization. However, although C. campestris altered allometry and inhibited host photosynthesis, the magnitude of the effects was independent of nitrate fertilizations. The infection reduced light saturation point, net photosynthesis at saturating irradiances, apparent quantum yield, CO2 saturated rate of photosynthesis, carboxylation efficiency, the maximum carboxylation rate of Rubisco, and maximum light-saturated rate of electron transport, and increased light compensation point in host leaves similarly across nitrate levels, corresponding to a similar magnitude of negative effects of the parasite on host leaf soluble protein and Rubisco concentrations, photosynthetic nitrogen use efficiency and stomatal conductance across nitrate concentrations. Thus, the more severe inhibition in host growth at low than at high nitrate supplies cannot be attributed to a greater parasite-induced reduction in host photosynthesis, but the result of a higher proportion of host resources

Growth but Not Photosynthesis Response of a Host Plant to Infection by a Holoparasitic Plant Depends on Nitrogen Supply

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Shen, Hao; Xu, Shu-Jun; Hong, Lan; Wang, Zhang-Ming; Ye, Wan-Hui

2013-01-01

Parasitic plants can adversely influence the growth of their hosts by removing resources and by affecting photosynthesis. Such negative effects depend on resource availability. However, at varied resource levels, to what extent the negative effects on growth are attributed to the effects on photosynthesis has not been well elucidated. Here, we examined the influence of nitrogen supply on the growth and photosynthesis responses of the host plant Mikania micrantha to infection by the holoparasite Cuscuta campestris by focusing on the interaction of nitrogen and infection. Mikania micrantha plants fertilized at 0.2, 1 and 5 mM nitrate were grown with and without C. campestris infection. We observed that the infection significantly reduced M. micrantha growth at each nitrate fertilization and more severely at low than at high nitrate. Such alleviation at high nitrate was largely attributed to a stronger influence of infection on root biomass at low than at high nitrate fertilization. However, although C. campestris altered allometry and inhibited host photosynthesis, the magnitude of the effects was independent of nitrate fertilizations. The infection reduced light saturation point, net photosynthesis at saturating irradiances, apparent quantum yield, CO2 saturated rate of photosynthesis, carboxylation efficiency, the maximum carboxylation rate of Rubisco, and maximum light-saturated rate of electron transport, and increased light compensation point in host leaves similarly across nitrate levels, corresponding to a similar magnitude of negative effects of the parasite on host leaf soluble protein and Rubisco concentrations, photosynthetic nitrogen use efficiency and stomatal conductance across nitrate concentrations. Thus, the more severe inhibition in host growth at low than at high nitrate supplies cannot be attributed to a greater parasite-induced reduction in host photosynthesis, but the result of a higher proportion of host resources transferred to the parasite at

Plant-herbivore interaction: dissection of the cellular pattern of Tetranychus urticae feeding on the host plant

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Nicolas Bensoussan

2016-07-01

Full Text Available The two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae, is one of the most polyphagous herbivores feeding on cell contents of over 1,100 plant species including more than 150 crops. It is being established as a model for chelicerate herbivores with tools that enable tracking of reciprocal responses in plant-spider mite interactions. However, despite their important pest status and a growing understanding of the molecular basis of interactions with plant hosts, knowledge of the way mites interface with the plant while feeding and the plant damage directly inflicted by mites is lacking. Here, utilizing histology and microscopy methods, we uncovered several key features of T. urticae feeding. By following the stylet path within the plant tissue, we determined that the stylet penetrates the leaf either in between epidermal pavement cells or through a stomatal opening, without damaging the epidermal cellular layer. Our recordings of mite feeding established that duration of the feeding event ranges from several minutes to more than half an hour, during which time mites consume a single mesophyll cell in a pattern that is common to both bean and Arabidopsis plant hosts. In addition, this study determined that leaf chlorotic spots, a common symptom of mite herbivory, do not form as an immediate consequence of mite feeding. Our results establish a cellular context for the plant-spider mite interaction that will support our understanding of the molecular mechanisms and cell signaling associated with spider mite feeding.

Transfer of phloem-mobile substances from the host plants to the holoparasite Cuscuta sp.

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Birschwilks, Mandy; Haupt, Sophie; Hofius, Daniel; Neumann, Stefanie

2006-01-01

During the development of the haustorium, searching hyphae of the parasite and the host parenchyma cells are connected by plasmodesmata. Using transgenic tobacco plants expressing a GFP-labelled movement protein of the tobacco mosaic virus, it was demonstrated that the interspecific plasmodesmata are open. The transfer of substances in the phloem from host to the parasite is not selective. After simultaneous application of (3)H-sucrose and (14)C-labelled phloem-mobile amino acids, phytohormones, and xenobiotica to the host, corresponding percentages of the translocated compounds are found in the parasite. An open continuity between the host phloem and the Cuscuta phloem via the haustorium was demonstrated in CLSM pictures after application of the phloem-mobile fluorescent probes, carboxyfluorescein (CF) and hydroxypyrene trisulphonic acid (HPTS), to the host. Using a Cuscuta bridge (14)C-sucrose and the virus PVY(N) were transferred from one host plant to the another. The results of translocation experiments with labelled compounds, phloem-mobile dyes and the virus should be considered as unequivocal evidence for a symplastic transfer of phloem solutes between Cuscuta species and their compatible hosts.

Use of model plant hosts to identify Pseudomonas aeruginosa virulence factors

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Rahme, Laurence G.; Tan, Man-Wah; Le, Long; Wong, Sandy M.; Tompkins, Ronald G.; Calderwood, Stephen B.; Ausubel, Frederick M.

1997-01-01

We used plants as an in vivo pathogenesis model for the identification of virulence factors of the human opportunistic pathogen Pseudomonas aeruginosa. Nine of nine TnphoA mutant derivatives of P. aeruginosa strain UCBPP-PA14 that were identified in a plant leaf assay for less pathogenic mutants also exhibited significantly reduced pathogenicity in a burned mouse pathogenicity model, suggesting that P. aeruginosa utilizes common strategies to infect both hosts. Seven of these nine mutants contain TnphoA insertions in previously unknown genes. These results demonstrate that an alternative nonvertebrate host of a human bacterial pathogen can be used in an in vivo high throughput screen to identify novel bacterial virulence factors involved in mammalian pathogenesis. PMID:9371831

Vitex agnus-castus is a preferred host plant for Hyalesthes obsoletus.

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Sharon, Rakefet; Soroker, Victoria; Wesley, S Daniel; Zahavi, Tirtza; Harari, Ally; Weintraub, Phyllis G

2005-05-01

Hyalesthes obsoletus Signoret (Homoptera: Cixiidae) is a polyphagous planthopper that transmits stolbur phytoplasma (a causative agent of "yellows" disease) to various weeds, members of the Solanaceae, and wine grapes (Vitis vinifera L.) in Europe and the Middle East. Planthoppers were collected by hand vacuuming eight native plant species. Vitex agnus-castus L., a shrub in the Verbenaceae, hosted the largest number of H. obsoletus, although Olea europaea L. also served as a host for adults. Using a Y-olfactometer, we compared the planthoppers relative preference for V. agnus-castus, Convolvulus arvensis, and V. vinifera. V. agnus-castus was more attractive to both male and female H. obsoletus than the other plants. H. obsoletus antennal response was stronger to volatiles collected from V. agnuscastus than from Cabernet Sauvignon variety of V. vinifera. To determine if V. agnus-castus would serve as a reservoir for the pathogen, H. obsoletus were collected from leaf and stem samples of native V. agnus-castus, and were tested by polymerase chain reaction (PCR) for the presence of phytoplasma DNA. While 14% and 25% (2003 and 2004, respectively) of the insects tested positive for phytoplasma DNA, none of the plant samples tested positive. To determine if V. agnus-castus could serve as a host plant for the development of the planthopper, we placed emergence cages beneath field shrubs and enclosed wild-caught H. obsoletus in a cage with a potted young shrub. We found adult H. obsoletus in the emergence cases and planthopper nymphs in the soil of the potted plant. We concluded that V. agnus-castus is attractive to H. obsoletus, which seems to be refractory to phytoplasma infections and warrants further testing as a trap plant near vineyards.

Soundscapes and Larval Settlement: Larval Bivalve Responses to Habitat-Associated Underwater Sounds.

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Eggleston, David B; Lillis, Ashlee; Bohnenstiehl, DelWayne R

2016-01-01

We quantified the effects of habitat-associated sounds on the settlement response of two species of bivalves with contrasting habitat preferences: (1) Crassostrea virginicia (oyster), which prefers to settle on other oysters, and (2) Mercenaria mercenaria (clam), which settles on unstructured habitats. Oyster larval settlement in the laboratory was significantly higher when exposed to oyster reef sound compared with either off-reef or no-sound treatments. Clam larval settlement did not vary according to sound treatments. Similar to laboratory results, field experiments showed that oyster larval settlement in "larval housings" suspended above oyster reefs was significantly higher compared with off-reef sites.

Helminths parasitizing larval fish from Pantanal, Brazil.

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Lacerda, A C F; Santin, M; Takemoto, R M; Pavanelli, G C; Bialetzki, A; Tavernari, F C

2009-03-01

Fish larvae of 'corvinas' (Pachyurus bonariensis and Plagioscion ternetzi) from Sinhá Mariana Lagoon, Mato Grosso State, were collected from March 2000 to March 2004, in order to determine the parasitic fauna of fishes. Larvae from the two species were parasitized by the same endoparasites: Contracaecum sp. Type 2 (larvae) (Nematoda: Anisakidae) in the mesentery and Neoechinorhynchus (Neoechinorhynchus) paraguayensis (Acanthocephala: Neoechinorhynchidae) in the stomach and the terminal portion of the intestine. Statistical analysis showed that there was a significant positive correlation between the standard length of hosts and the abundance of acanthocephalans and nematodes, and that the prevalence of nematodes presented a significant positive correlation with the standard length of the two species of hosts, indicating the presence of a cumulative process of infection. The present study constitutes the first record of nematodes and acanthocephalans parasitizing larval fish, as well as the first record of endoparasites in fish larvae in Brazil. In addition, it lists a new locality and two species of hosts for Contracaecum sp. Type 2 (larva) and N. (N.) paraguayensis.

Activity of xyloglucan endotransglucosylases/hydrolases suggests a role during host invasion by the parasitic plant Cuscuta reflexa.

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Olsen, Stian; Krause, Kirsten

2017-01-01

The parasitic vines of the genus Cuscuta form haustoria that grow into other plants and connect with their vascular system, thus allowing the parasite to feed on its host. A major obstacle that meets the infection organ as it penetrates the host tissue is the rigid plant cell wall. In the present study, we examined the activity of xyloglucan endotransglucosylases/hydrolases (XTHs) during the host-invasive growth of the haustorium. The level of xyloglucan endotransglucosylation (XET) activity was found to peak at the penetrating stage of Cuscuta reflexa on its host Pelargonium zonale. In vivo colocalization of XET activity and donor substrate demonstrated XET activity at the border between host and parasite. A test for secretion of XET-active enzymes from haustoria of C. reflexa corroborated this and further indicated that the xyloglucan-modifying enzymes originated from the parasite. A known inhibitor of XET, Coomassie Brilliant Blue R250, was shown to reduce the level of XET in penetrating haustoria of C. reflexa. Moreover, the coating of P. zonale petioles with the inhibitor compound lowered the number of successful haustorial invasions of this otherwise compatible host plant. The presented data indicate that the activity of Cuscuta XTHs at the host-parasite interface is essential to penetration of host plant tissue.

Invaded Invaders: Infection of Invasive Brown Treesnakes on Guam by an Exotic Larval Cestode with a Life Cycle Comprised of Non-Native Hosts.

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Elden T Holldorf

Full Text Available Multiple host introductions to the same non-native environment have the potential to complete life cycles of parasites incidentally transported with them. Our goal was to identify a recently detected parasitic flatworm in the invasive Brown Treesnake (Boiga irregularis on the remote Pacific island of Guam. We considered possible factors influencing parasite transmission, and tested for correlations between infection status and potential indicators of host fitness. We used genetic data from the parasite and information about the native ranges of other possible non-native hosts to hypothesize how it arrived on Guam and how its life cycle may be currently supported.We identified the parasite by comparing larval morphology and mtDNA sequences with other Pseudophyllid tapeworms. We assessed probability of infection in individual snakes using logistic regression and examined different factors influencing presence of parasites in hosts.We identified the parasite as the pseudophyllid cestode Spirometra erinaceieuropaei, with all sampled worms from multiple snakes sharing a single mtDNA haplotype. Infection appears to be limited to the only freshwater watershed on the island, where infection prevalence was high (77.5%. Larger snakes had a higher probability of being infected, consistent with the chronic nature of such infections. While infection status was positively correlated with body condition, infected snakes tended to have lower intra-peritoneal fat body mass, potentially indicating a negative effect on energy stores.We discovered that B. irregularis inhabiting a small area of forested habitat in a freshwater watershed on Guam are often infected by a novel parasite of Asian origin. While further work is needed, this species of Spirometra, itself a non-native species, likely depends on a suite of recently introduced hosts from different parts of the world to complete the life cycle. This baseline study provides little evidence of any effects on host

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

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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. Copyright © 2015 Elsevier Ltd. All rights reserved.

Simulation of climate-tick-host-landscape interactions: Effects of shifts in the seasonality of host population fluctuations on tick densities.

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Wang, Hsiao-Hsuan; Grant, W E; Teel, P D; Hamer, S A

2015-12-01

Tick vector systems are comprised of complex climate-tick-host-landscape interactions that are difficult to identify and estimate from empirical observations alone. We developed a spatially-explicit, individual-based model, parameterized to represent ecological conditions typical of the south-central United States, to examine effects of shifts in the seasonal occurrence of fluctuations of host densities on tick densities. Simulated shifts in the seasonal occurrence of periods of high and low host densities affected both the magnitude of unfed tick densities and the seasonality of tick development. When shifting the seasonal densities of all size classes of hosts (small, medium, and large) synchronously, densities of nymphs were affected more by smaller shifts away from the baseline host seasonality than were densities of larval and adult life stages. When shifting the seasonal densities of only a single size-class of hosts while holding other size classes at their baseline levels, densities of larval, nymph, and adult life stages responded differently. Shifting seasonal densities of any single host-class earlier resulted in a greater increase in adult tick density than when seasonal densities of all host classes were shifted earlier simultaneously. The mean densities of tick life stages associated with shifts in host densities resulted from system-level interactions of host availability with tick phenology. For example, shifting the seasonality of all hosts ten weeks earlier resulted in an approximately 30% increase in the relative degree of temporal co-occurrence of actively host-seeking ticks and hosts compared to baseline, whereas shifting the seasonality of all hosts ten weeks later resulted in an approximately 70% decrease compared to baseline. Differences among scenarios in the overall presence of active host-seeking ticks in the system were due primarily to the degree of co-occurrence of periods of high densities of unfed ticks and periods of high densities

Evolutionary tools for phytosanitary risk analysis: phylogenetic signal as a predictor of host range of plant pests and pathogens.

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Gilbert, Gregory S; Magarey, Roger; Suiter, Karl; Webb, Campbell O

2012-12-01

Assessing risk from a novel pest or pathogen requires knowing which local plant species are susceptible. Empirical data on the local host range of novel pests are usually lacking, but we know that some pests are more likely to attack closely related plant species than species separated by greater evolutionary distance. We use the Global Pest and Disease Database, an internal database maintained by the United States Department of Agriculture Animal and Plant Health Inspection Service - Plant Protection and Quarantine Division (USDA APHIS-PPQ), to evaluate the strength of the phylogenetic signal in host range for nine major groups of plant pests and pathogens. Eight of nine groups showed significant phylogenetic signal in host range. Additionally, pests and pathogens with more known hosts attacked a phylogenetically broader range of hosts. This suggests that easily obtained data - the number of known hosts and the phylogenetic distance between known hosts and other species of interest - can be used to predict which plant species are likely to be susceptible to a particular pest. This can facilitate rapid assessment of risk from novel pests and pathogens when empirical host range data are not yet available and guide efficient collection of empirical data for risk evaluation.

Evolutionary tools for phytosanitary risk analysis: phylogenetic signal as a predictor of host range of plant pests and pathogens

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Gilbert, Gregory S; Magarey, Roger; Suiter, Karl; Webb, Campbell O

2012-01-01

Assessing risk from a novel pest or pathogen requires knowing which local plant species are susceptible. Empirical data on the local host range of novel pests are usually lacking, but we know that some pests are more likely to attack closely related plant species than species separated by greater evolutionary distance. We use the Global Pest and Disease Database, an internal database maintained by the United States Department of Agriculture Animal and Plant Health Inspection Service – Plant Protection and Quarantine Division (USDA APHIS-PPQ), to evaluate the strength of the phylogenetic signal in host range for nine major groups of plant pests and pathogens. Eight of nine groups showed significant phylogenetic signal in host range. Additionally, pests and pathogens with more known hosts attacked a phylogenetically broader range of hosts. This suggests that easily obtained data – the number of known hosts and the phylogenetic distance between known hosts and other species of interest – can be used to predict which plant species are likely to be susceptible to a particular pest. This can facilitate rapid assessment of risk from novel pests and pathogens when empirical host range data are not yet available and guide efficient collection of empirical data for risk evaluation. PMID:23346231

Nectar-living yeasts of a tropical host plant community: diversity and effects on community-wide floral nectar traits

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2017-01-01

We characterize the diversity of nectar-living yeasts of a tropical host plant community at different hierarchical sampling levels, measure the associations between yeasts and nectariferous plants, and measure the effect of yeasts on nectar traits. Using a series of hierarchically nested sampling units, we extracted nectar from an assemblage of host plants that were representative of the diversity of life forms, flower shapes, and pollinator types in the tropical area of Yucatan, Mexico. Yeasts were isolated from single nectar samples; their DNA was identified, the yeast cell density was estimated, and the sugar composition and concentration of nectar were quantified using HPLC. In contrast to previous studies from temperate regions, the diversity of nectar-living yeasts in the plant community was characterized by a relatively high number of equally common species with low dominance. Analyses predict highly diverse nectar yeast communities in a relatively narrow range of tropical vegetation, suggesting that the diversity of yeasts will increase as the number of sampling units increases at the level of the species, genera, and botanical families of the hosts. Significant associations between specific yeast species and host plants were also detected; the interaction between yeasts and host plants impacted the effect of yeast cell density on nectar sugars. This study provides an overall picture of the diversity of nectar-living yeasts in tropical host plants and suggests that the key factor that affects the community-wide patterns of nectar traits is not nectar chemistry, but rather the type of yeasts interacting with host plants. PMID:28717591

Nectar-living yeasts of a tropical host plant community: diversity and effects on community-wide floral nectar traits

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Azucena Canto

2017-07-01

Full Text Available We characterize the diversity of nectar-living yeasts of a tropical host plant community at different hierarchical sampling levels, measure the associations between yeasts and nectariferous plants, and measure the effect of yeasts on nectar traits. Using a series of hierarchically nested sampling units, we extracted nectar from an assemblage of host plants that were representative of the diversity of life forms, flower shapes, and pollinator types in the tropical area of Yucatan, Mexico. Yeasts were isolated from single nectar samples; their DNA was identified, the yeast cell density was estimated, and the sugar composition and concentration of nectar were quantified using HPLC. In contrast to previous studies from temperate regions, the diversity of nectar-living yeasts in the plant community was characterized by a relatively high number of equally common species with low dominance. Analyses predict highly diverse nectar yeast communities in a relatively narrow range of tropical vegetation, suggesting that the diversity of yeasts will increase as the number of sampling units increases at the level of the species, genera, and botanical families of the hosts. Significant associations between specific yeast species and host plants were also detected; the interaction between yeasts and host plants impacted the effect of yeast cell density on nectar sugars. This study provides an overall picture of the diversity of nectar-living yeasts in tropical host plants and suggests that the key factor that affects the community-wide patterns of nectar traits is not nectar chemistry, but rather the type of yeasts interacting with host plants.

First host plant records for Iridopsis hausmanni Vargas (Lepidoptera, Geometridae in the coastal valleys of northern Chile

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Héctor A. Vargas

2014-03-01

Full Text Available First host plant records for Iridopsis hausmanni Vargas (Lepidoptera, Geometridae in the coastal valleys of northern Chile. The trees Haplorhus peruviana Engl. and Schinus molle L. (Anacardiaceae are mentioned as the first host plant records for the little known native moth Iridopsis hausmanni Vargas, 2007 (Lepidoptera, Geometridae, Ennominae in the coastal valleys of the northern Chilean Atacama Desert. This is also the first record of Anacardiaceae as host plant for a Neotropical species of Iridopsis Warren, 1894.

White Fringetree as a Novel Larval Host for Emerald Ash Borer.

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Cipollini, Don

2015-02-01

Emerald ash borer is an invasive Asian pest of ash species in North America. All North American species of ash tested so far are susceptible to it, but there are no published reports of this insect developing fully in non-ash hosts in the field in North America. I report here evidence that emerald ash borer can attack and complete development in white fringetree, Chionanthus virginicus L., a species native to the southeastern United States that is also planted ornamentally. Four of 20 mature ornamental white fringetrees examined in the Dayton, Ohio area showed external symptoms of emerald ash borer attack, including the presence of adult exit holes, canopy dieback, and bark splitting and other deformities. Removal of bark from one of these trees yielded evidence of at least three generations of usage by emerald ash borer larvae, several actively feeding live larvae, and a dead adult confirmed as emerald ash borer. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Shifts in diversification rates and host jump frequencies shaped the diversity of host range among Sclerotiniaceae fungal plant pathogens.

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Navaud, Olivier; Barbacci, Adelin; Taylor, Andrew; Clarkson, John P; Raffaele, Sylvain

2018-03-01

The range of hosts that a parasite can infect in nature is a trait determined by its own evolutionary history and that of its potential hosts. However, knowledge on host range diversity and evolution at the family level is often lacking. Here, we investigate host range variation and diversification trends within the Sclerotiniaceae, a family of Ascomycete fungi. Using a phylogenetic framework, we associate diversification rates, the frequency of host jump events and host range variation during the evolution of this family. Variations in diversification rate during the evolution of the Sclerotiniaceae define three major macro-evolutionary regimes with contrasted proportions of species infecting a broad range of hosts. Host-parasite cophylogenetic analyses pointed towards parasite radiation on distant hosts long after host speciation (host jump or duplication events) as the dominant mode of association with plants in the Sclerotiniaceae. The intermediate macro-evolutionary regime showed a low diversification rate, high frequency of duplication events and the highest proportion of broad host range species. Our findings suggest that the emergence of broad host range fungal pathogens results largely from host jumps, as previously reported for oomycete parasites, probably combined with low speciation rates. These results have important implications for our understanding of fungal parasites evolution and are of particular relevance for the durable management of disease epidemics. © 2018 The Authors. Molecular Ecology Published by John Wiley & Sons Ltd.

Strepsicrates smithiana Walsingham (Lepidoptera, Tortricidae: first record from Chile and a newly documented host plant

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Héctor A. Vargas

2012-09-01

Full Text Available Strepsicrates smithiana Walsingham (Lepidoptera, Tortricidae: first record from Chile and a newly documented host plant. Strepsicrates smithiana Walsingham, 1892 (Lepidoptera, Tortricidae is recorded for the first time from Chile. Male and female adults were reared from leaf-tying larvae collected on Myrica pavonis (Myricaceae, which is a new host plant record for S. smithiana.

Recent evolutionary radiation and host plant specialization in the Xylella fastidiosa subspecies native to the United States.

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Nunney, Leonard; Vickerman, Danel B; Bromley, Robin E; Russell, Stephanie A; Hartman, John R; Morano, Lisa D; Stouthamer, Richard

2013-04-01

The bacterial pathogen, Xylella fastidiosa, infects many plant species in the Americas, making it a good model for investigating the genetics of host adaptation. We used multilocus sequence typing (MLST) to identify isolates of the native U.S. subsp. multiplex that were largely unaffected by intersubspecific homologous recombination (IHR) and to investigate how their evolutionary history influences plant host specialization. We identified 110 "non-IHR" isolates, 2 minimally recombinant "intermediate" ones (including the subspecific type), and 31 with extensive IHR. The non-IHR and intermediate isolates defined 23 sequence types (STs) which we used to identify 22 plant hosts (73% trees) characteristic of the subspecies. Except for almond, subsp. multiplex showed no host overlap with the introduced subspecies (subspecies fastidiosa and sandyi). MLST sequences revealed that subsp. multiplex underwent recent radiation (<25% of subspecies age) which included only limited intrasubspecific recombination (ρ/θ = 0.02); only one isolated lineage (ST50 from ash) was older. A total of 20 of the STs grouped into three loose phylogenetic clusters distinguished by nonoverlapping hosts (excepting purple leaf plum): "almond," "peach," and "oak" types. These host differences were not geographical, since all three types also occurred in California. ST designation was a good indicator of host specialization. ST09, widespread in the southeastern United States, only infected oak species, and all peach isolates were ST10 (from California, Florida, and Georgia). Only ST23 had a broad host range. Hosts of related genotypes were sometimes related, but often host groupings crossed plant family or even order, suggesting that phylogenetically plastic features of hosts affect bacterial pathogenicity.

Large-scale gene expression reveals different adaptations of Hyalopterus persikonus to winter and summer host plants.

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Cui, Na; Yang, Peng-Cheng; Guo, Kun; Kang, Le; Cui, Feng

2017-06-01

Host alternation, an obligatory seasonal shifting between host plants of distant genetic relationship, has had significant consequences for the diversification and success of the superfamily of aphids. However, the underlying molecular mechanism remains unclear. In this study, the molecular mechanism of host alternation was explored through a large-scale gene expression analysis of the mealy aphid Hyalopterus persikonus on winter and summer host plants. More than four times as many unigenes of the mealy aphid were significantly upregulated on summer host Phragmites australis than on winter host Rosaceae plants. In order to identify gene candidates related to host alternation, the differentially expressed unigenes of H. persikonus were compared to salivary gland expressed genes and secretome of Acyrthosiphon pisum. Genes involved in ribosome and oxidative phosphorylation and with molecular functions of heme-copper terminal oxidase activity, hydrolase activity and ribosome binding were potentially upregulated in salivary glands of H. persikonus on the summer host. Putative secretory proteins, such as detoxification enzymes (carboxylesterases and cytochrome P450s), antioxidant enzymes (peroxidase and superoxide dismutase), glutathione peroxidase, glucose dehydrogenase, angiotensin-converting enzyme, cadherin, and calreticulin, were highly expressed in H. persikonus on the summer host, while a SCP GAPR-1-like family protein and a salivary sheath protein were highly expressed in the aphids on winter hosts. These results shed light on phenotypic plasticity in host utilization and seasonal adaptation of aphids. © 2016 Institute of Zoology, Chinese Academy of Sciences.

Small proteins of plant-pathogenic fungi secreted during host colonization.

NARCIS (Netherlands)

Rep, M.

2005-01-01

Small proteins secreted by plant pathogenic fungi in their hosts have been implicated in disease symptom development as well as in R-gene mediated disease resistance. Characteristically, this class of proteins shows very limited phylogenetic distribution, possibly due to accelerated evolution

Looking for a similar partner: host plants shape mating preferences of herbivorous insects by altering their contact pheromones.

Science.gov (United States)

Geiselhardt, Sven; Otte, Tobias; Hilker, Monika

2012-09-01

The role of phenotypical plasticity in ecological speciation and the evolution of sexual isolation remains largely unknown. We investigated whether or not divergent host plant use in an herbivorous insect causes assortative mating by phenotypically altering traits involved in mate recognition. We found that males of the mustard leaf beetle Phaedon cochleariae preferred to mate with females that were reared on the same plant species to females provided with a different plant species, based on divergent cuticular hydrocarbon profiles that serve as contact pheromones. The cuticular hydrocarbon phenotypes of the beetles were host plant specific and changed within 2 weeks after a shift to a novel host plant species. We suggest that plant-induced phenotypic divergence in mate recognition cues may act as an early barrier to gene flow between herbivorous insect populations on alternative host species, preceding genetic divergence and thus, promoting ecological speciation. © 2012 Blackwell Publishing Ltd/CNRS.

Mistletoes, their host plants and the effects of browsing by large mammals in Addo Elephant National Park

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J.J. Midgley

1991-09-01

Full Text Available There are at least four plant hemiparasites [=mistletoes, viz. Viscaceae (3 species, Loranthaceae (1 species] within the Addo Elephant National Park. Highly selective utilisation of these plant parasites by large browsing animals has resulted in severe decline of these plants within the elephant enclosure. The parasites are often associated with spinescent host plants. We suggest this has less to do with escaping herbivory by large mammals and more to do with spinescent plants being optimum hosts because they are a richer nutritient source for plant parasites than most non-spinescent plants.

Host physiological condition regulates parasitic plant performance: Arceuthobium vaginatum subsp. cryptopodum on Pinus ponderosa.

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Bickford, Christopher P; Kolb, Thomas E; Geils, Brian W

2005-12-01

Much research has focused on effects of plant parasites on host-plant physiology and growth, but little is known about effects of host physiological condition on parasite growth. Using the parasitic dwarf mistletoe Arceuthobium vaginatum subsp. cryptopodum (Viscaceae) and its host Pinus ponderosa, we investigated whether changes in host physiological condition influenced mistletoe shoot development in northern Arizona forests. We conducted two studies in two consecutive years and used forest thinning (i.e., competitive release) to manipulate host physiological condition. We removed dwarf mistletoe shoots in April, before the onset of the growing season, and measured the amount of regrowth in the first season after forest thinning (Study I: n=38 trees; Study II: n=35 trees). Thinning increased tree uptake of water and carbon in both studies, but had no effect on leaf N concentration or delta13C. Mistletoe shoot growth was greater on trees with high uptake of water and carbon in thinned stands than trees with low uptake in unthinned stands. These findings show that increased resource uptake by host trees increases resources to these heterotrophic dwarf mistletoes, and links mistletoe performance to changes in host physiological condition.

Hijacking of the host SCF ubiquitin ligase machinery by plant pathogens

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Shimpei eMagori

2011-11-01

Full Text Available The SCF (SKP1-CUL1-F-box protein ubiquitin ligase complex mediates polyubiquitination of proteins targeted for degradation, thereby controlling a plethora of biological processes in eukaryotic cells. Although this ubiquitination machinery is found and functional only in eukaryotes, many non-eukaryotic pathogens also encode F-box proteins, the critical subunits of the SCF complex. Increasing evidence indicates that such non-eukaryotic F-box proteins play an essential role in subverting or exploiting the host ubiquitin/proteasome system for efficient pathogen infection. A recent bioinformatic analysis has identified more than 70 F-box proteins in 22 different bacterial species, suggesting that use of pathogen-encoded F-box effectors in the host cell may be a widespread infection strategy. In this review, we focus on plant pathogen-encoded F-box effectors, such as VirF of Agrobacterium tumefaciens, GALAs of Ralstonia solanacearum, and P0 of Poleroviruses, and discuss the molecular mechanism by which plant pathogens use these factors to manipulate the host cell for their own benefit.

Temporal and host-related variation in frequencies of genes that enable Phyllotreta nemorum to utilize a novel host plant, Barbarea vulgaris

NARCIS (Netherlands)

Nielsen, J.K.; Jong, de P.W.

2005-01-01

The flea beetle, Phyllotreta nemorum L. (Coleoptera: Chrysomelidae), is an intermediate specialist feeding on a small number of plants within the family Brassicaceae. The most commonly used host plant is Sinapis arvensis L., whereas the species is found more rarely on Cardaria draba (L.) Desv.,

Occurrence of Terranova larval types (Nematoda: Anisakidae in Australian marine fish with comments on their specific identities

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Shokoofeh Shamsi

2016-03-01

is known that they have seasonal presence in Australian southern coasts. The genetic distinction of Terranova larval type in the present study from Pseudoterranova spp. along with the presence of more species of elasmobranchs in Australian waters (definitive hosts of Terranova spp. and Pulchrascaris spp. than seals (definitive hosts of Pseudoterranova spp. suggest that Terranova larval type in the present study belong to either genus Terranova or Pulchrascaris, which are not known to cause disease in humans. The present study provides essential information that could be helpful to identify Australian Terranova larval types in future studies. Examination and characterisation of further specimens, especially adults of Terranova and Pulchrascaris, is necessary to fully elucidate the identity of these larvae.

Contrasting effects of land use intensity and exotic host plants on the specialization of interactions in plant-herbivore networks.

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de Araújo, Walter Santos; Vieira, Marcos Costa; Lewinsohn, Thomas M; Almeida-Neto, Mário

2015-01-01

Human land use tends to decrease the diversity of native plant species and facilitate the invasion and establishment of exotic ones. Such changes in land use and plant community composition usually have negative impacts on the assemblages of native herbivorous insects. Highly specialized herbivores are expected to be especially sensitive to land use intensification and the presence of exotic plant species because they are neither capable of consuming alternative plant species of the native flora nor exotic plant species. Therefore, higher levels of land use intensity might reduce the proportion of highly specialized herbivores, which ultimately would lead to changes in the specialization of interactions in plant-herbivore networks. This study investigates the community-wide effects of land use intensity on the degree of specialization of 72 plant-herbivore networks, including effects mediated by the increase in the proportion of exotic plant species. Contrary to our expectation, the net effect of land use intensity on network specialization was positive. However, this positive effect of land use intensity was partially canceled by an opposite effect of the proportion of exotic plant species on network specialization. When we analyzed networks composed exclusively of endophagous herbivores separately from those composed exclusively of exophagous herbivores, we found that only endophages showed a consistent change in network specialization at higher land use levels. Altogether, these results indicate that land use intensity is an important ecological driver of network specialization, by way of reducing the local host range of herbivore guilds with highly specialized feeding habits. However, because the effect of land use intensity is offset by an opposite effect owing to the proportion of exotic host species, the net effect of land use in a given herbivore assemblage will likely depend on the extent of the replacement of native host species with exotic ones.

The influence of substrate material on ascidian larval settlement.

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Chase, Anna L; Dijkstra, Jennifer A; Harris, Larry G

2016-05-15

Submerged man-made structures present novel habitat for marine organisms and often host communities that differ from those on natural substrates. Although many factors are known to contribute to these differences, few studies have directly examined the influence of substrate material on organism settlement. We quantified larval substrate preferences of two species of ascidians, Ciona intestinalis (cryptogenic, formerly C. intestinalis type B) and Botrylloides violaceus (non-native), on commonly occurring natural (granite) and man-made (concrete, high-density polyethylene, PVC) marine materials in laboratory trials. Larvae exhibited species-specific settlement preferences, but generally settled more often than expected by chance on concrete and HDPE. Variation in settlement between materials may reflect preferences for rougher substrates, or may result from the influence of leached chemicals on ascidian settlement. These findings indicate that an experimental plate material can influence larval behavior and may help us understand how substrate features may contribute to differences in settlement in the field. Copyright © 2016 Elsevier Ltd. All rights reserved.

Host-driven divergence in the parasitic plant Orobanche minor Sm. (Orobanchaceae).

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Thorogood, C J; Rumsey, F J; Harris, S A; Hiscock, S J

2008-10-01

Many parasitic angiosperms have a broad host range and are therefore considered to be host generalists. Orobanche minor is a nonphotosynthetic root parasite that attacks a range of hosts from taxonomically disparate families. In the present study, we show that O. minor sensu lato may comprise distinct, genetically divergent races isolated by the different ecologies of their hosts. Using a three-pronged approach, we tested the hypothesis that intraspecific taxa O. minor var. minor and O. minor ssp. maritima parasitizing either clover (Trifolium pratense) or sea carrot (Daucus carota ssp.gummifer), respectively, are in allopatric isolation. Morphometric analysis revealed evidence of divergence but this was insufficient to define discrete, host-specific taxa. Intersimple sequence repeat (ISSR) marker-based data provided stronger evidence of divergence, suggesting that populations were isolated from gene flow. Phylogenetic analysis, using sequence-characterized amplified region (SCAR) markers derived from ISSR loci, provided strong evidence for divergence by clearly differentiating sea carrot-specific clades and mixed-host clades. Low levels of intrapopulation SCAR marker sequence variation and floral morphology suggest that populations on different hosts are probably selfing and inbreeding. Morphologically cryptic Orobanche taxa may therefore be isolated from gene flow by host ecology. Together, these data suggest that host specificity may be an important driver of allopatric speciation in parasitic plants.

Soundscapes and Larval Settlement: Characterizing the Stimulus from a Larval Perspective.

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Lillis, Ashlee; Eggleston, David B; Bohnenstiehl, DelWayne R

2016-01-01

There is growing evidence that underwater sounds serve as a cue for the larvae of marine organisms to locate suitable settlement habitats; however, the relevant spatiotemporal scales of variability in habitat-related sounds and how this variation scales with larval settlement processes remain largely uncharacterized, particularly in estuarine habitats. Here, we provide an overview of the approaches we have developed to characterize an estuarine soundscape as it relates to larval processes, and a conceptual framework is provided for how habitat-related sounds may influence larval settlement, using oyster reef soundscapes as an example.

Host plant selection and oviposition behaviour of whitefly Bemisia ...

African Journals Online (AJOL)

user

2010-11-19

Nov 19, 2010 ... habitat at 34 - 36°C, 70 - 80% relative humidity (RH) in a normal day light. ... higher on S. malagna L. leaves as compare to other two host plants ... 1468 Afr. J. Biotechnol. ... each species were arranged in the demarcated plot shape covered ... ficant Difference (LSD) test (Steel and Tori, 1980) and was run.

Tools for evaluating Lipolexis oregmae (Hymenoptera: Aphidiidae) in the field: Effects of host aphid and host plant on mummy location and color plus improved methods for obtaining adults

International Nuclear Information System (INIS)

Singh, R.; Hoy, M.A.

2007-01-01

Lipolexis oregmae Gahan was introduced into Florida in a classical biological control program directed against the brown citrus aphid, Toxoptera citricida (Kirkaldy), on citrus. Prior to evaluating distribution, host range, and potential nontarget effects of L. oregmae in Florida, we evaluated the role of other potential host aphids and host plants on mummy production and location. Under laboratory conditions, this parasitoid produced the most progeny on the target pest, the brown citrus aphid on citrus. This parasitoid, unlike the majority of aphidiids, did not produce mummies on any of the host plants tested when reared in black citrus aphid T. aurantii (Boyer de Fonscolombe) on grapefruit, spirea aphid Aphis spiraecola Patch on grapefruit and pittosporum, cowpea aphid A. craccivora Koch on grapefruit and cowpeas, or melon aphid A. gossypii Glover on grapefruit and cucumber. Thus, sampling for L. oregmae mummies of these host aphids and host plants must involve holding foliage in the laboratory until mummies are produced. This parasitoid requires high relative humidity to produce adults because no adults emerged when mummies were held in gelatin capsules, but high rates of emergence were observed when mummies were held on 1.5% agar plates. In addition, we compared the color of 6 aphid hosts and the color of mummies produced by L. oregmae when reared in them to determine if color of mummies could be used to identify L. oregmae . Mummy color varied between aphid hosts and tested host plants, and is not a useful tool for identifying L. oregmae for nontarget effects. (author) [es

Biology of the citrus blackfly, Aleurocanthus woglumi Ashby (Hemiptera: Aleyrodidae), in three host plants

International Nuclear Information System (INIS)

Pena, Marcia R.; Silva, Neliton M. da

2009-01-01

The citrus blackfly, Aleurocanthus woglumi Ashby, was detected in Brazil in 2001. The aim of this research was to evaluate the biology, biometry and host preference of A. woglumi in sweet orange, acid lime Tahiti and mango. Experiments were set in laboratory conditions with insects collected in rangpur lime plants in Manaus, State of Amazonas, from January to June of 2006. The following parameters were evaluated: number of spirals (ovo positions) and eggs per plant, number of eggs by spiral per plant, survival of the immature (eggs, 1st, 2nd, 3rd and 4th instars), and length and survival of the immature stage. The mean embrionary period was 15 days for the three hosts. The 4th nymph (puparium) was the longest during nymph development. Second and third instars had the highest survival. The mean length of the egg-adult cycle was 70 days for the three hosts evaluated. The eggs were laid in a spiral shape on the adaxial leaf surface. The 1st instars moved to short distances from the spiral, while the 2nd, 3rd and 4th are sessile and have bristles on the whole body. Based on the highest oviposition and the highest survival of the immature stage of the citrus blackfly in acid lime Tahiti, this plant can be considered the most suitable host to A. woglumi. (author)

Selectivity by host plants affects the distribution of arbuscular mycorrhizal fungi: evidence from ITS rDNA sequence metadata

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Yang Haishui

2012-04-01

Full Text Available Abstract Background Arbuscular mycorrhizal fungi (AMF can form obligate symbioses with the vast majority of land plants, and AMF distribution patterns have received increasing attention from researchers. At the local scale, the distribution of AMF is well documented. Studies at large scales, however, are limited because intensive sampling is difficult. Here, we used ITS rDNA sequence metadata obtained from public databases to study the distribution of AMF at continental and global scales. We also used these sequence metadata to investigate whether host plant is the main factor that affects the distribution of AMF at large scales. Results We defined 305 ITS virtual taxa (ITS-VTs among all sequences of the Glomeromycota by using a comprehensive maximum likelihood phylogenetic analysis. Each host taxonomic order averaged about 53% specific ITS-VTs, and approximately 60% of the ITS-VTs were host specific. Those ITS-VTs with wide host range showed wide geographic distribution. Most ITS-VTs occurred in only one type of host functional group. The distributions of most ITS-VTs were limited across ecosystem, across continent, across biogeographical realm, and across climatic zone. Non-metric multidimensional scaling analysis (NMDS showed that AMF community composition differed among functional groups of hosts, and among ecosystem, continent, biogeographical realm, and climatic zone. The Mantel test showed that AMF community composition was significantly correlated with plant community composition among ecosystem, among continent, among biogeographical realm, and among climatic zone. The structural equation modeling (SEM showed that the effects of ecosystem, continent, biogeographical realm, and climatic zone were mainly indirect on AMF distribution, but plant had strongly direct effects on AMF. Conclusion The distribution of AMF as indicated by ITS rDNA sequences showed a pattern of high endemism at large scales. This pattern indicates high specificity

Selectivity by host plants affects the distribution of arbuscular mycorrhizal fungi: evidence from ITS rDNA sequence metadata.

Science.gov (United States)

Yang, Haishui; Zang, Yanyan; Yuan, Yongge; Tang, Jianjun; Chen, Xin

2012-04-12

Arbuscular mycorrhizal fungi (AMF) can form obligate symbioses with the vast majority of land plants, and AMF distribution patterns have received increasing attention from researchers. At the local scale, the distribution of AMF is well documented. Studies at large scales, however, are limited because intensive sampling is difficult. Here, we used ITS rDNA sequence metadata obtained from public databases to study the distribution of AMF at continental and global scales. We also used these sequence metadata to investigate whether host plant is the main factor that affects the distribution of AMF at large scales. We defined 305 ITS virtual taxa (ITS-VTs) among all sequences of the Glomeromycota by using a comprehensive maximum likelihood phylogenetic analysis. Each host taxonomic order averaged about 53% specific ITS-VTs, and approximately 60% of the ITS-VTs were host specific. Those ITS-VTs with wide host range showed wide geographic distribution. Most ITS-VTs occurred in only one type of host functional group. The distributions of most ITS-VTs were limited across ecosystem, across continent, across biogeographical realm, and across climatic zone. Non-metric multidimensional scaling analysis (NMDS) showed that AMF community composition differed among functional groups of hosts, and among ecosystem, continent, biogeographical realm, and climatic zone. The Mantel test showed that AMF community composition was significantly correlated with plant community composition among ecosystem, among continent, among biogeographical realm, and among climatic zone. The structural equation modeling (SEM) showed that the effects of ecosystem, continent, biogeographical realm, and climatic zone were mainly indirect on AMF distribution, but plant had strongly direct effects on AMF. The distribution of AMF as indicated by ITS rDNA sequences showed a pattern of high endemism at large scales. This pattern indicates high specificity of AMF for host at different scales (plant taxonomic

Combining Phylogenetic and Occurrence Information for Risk Assessment of Pest and Pathogen Interactions with Host Plants

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Ángel L. Robles-Fernández

2017-08-01

Full Text Available Phytosanitary agencies conduct plant biosecurity activities, including early detection of potential introduction pathways, to improve control and eradication of pest and pathogen incursions. For such actions, analytical tools based on solid scientific knowledge regarding plant-pest or pathogen relationships for pest risk assessment are needed. Recent evidence indicating that closely related species share a higher chance of becoming infected or attacked by pests has allowed the identification of taxa with different degrees of vulnerability. Here, we use information readily available online about pest-host interactions and their geographic distributions, in combination with host phylogenetic reconstructions, to estimate a pest-host interaction (in some cases infection index in geographic space as a more comprehensive, spatially explicit tool for risk assessment. We demonstrate this protocol using phylogenetic relationships for 20 beetle species and 235 host plant genera: first, we estimate the probability of a host sharing pests, and second, we project the index in geographic space. Overall, the predictions allow identification of the pest-host interaction type (e.g., generalist or specialist, which is largely determined by both host range and phylogenetic constraints. Furthermore, the results can be valuable in terms of identifying hotspots where pests and vulnerable hosts interact. This knowledge is useful for anticipating biological invasions or spreading of disease. We suggest that our understanding of biotic interactions will improve after combining information from multiple dimensions of biodiversity at multiple scales (e.g., phylogenetic signal and host-vector-pathogen geographic distribution.

Anopheline larval habitats seasonality and species distribution: a prerequisite for effective targeted larval habitats control programmes.

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Eliningaya J Kweka

Full Text Available Larval control is of paramount importance in the reduction of malaria vector abundance and subsequent disease transmission reduction. Understanding larval habitat succession and its ecology in different land use managements and cropping systems can give an insight for effective larval source management practices. This study investigated larval habitat succession and ecological parameters which influence larval abundance in malaria epidemic prone areas of western Kenya.A total of 51 aquatic habitats positive for anopheline larvae were surveyed and visited once a week for a period of 85 weeks in succession. Habitats were selected and identified. Mosquito larval species, physico-chemical parameters, habitat size, grass cover, crop cycle and distance to nearest house were recorded. Polymerase chain reaction revealed that An. gambiae s.l was the most dominant vector species comprised of An.gambiae s.s (77.60% and An.arabiensis (18.34%, the remaining 4.06% had no amplification by polymerase chain reaction. Physico-chemical parameters and habitat size significantly influenced abundance of An. gambiae s.s (P = 0.024 and An. arabiensis (P = 0.002 larvae. Further, larval species abundance was influenced by crop cycle (P≤0.001, grass cover (P≤0.001, while distance to nearest houses significantly influenced the abundance of mosquito species larvae (r = 0.920;P≤0.001. The number of predator species influenced mosquito larval abundance in different habitat types. Crop weeding significantly influenced with the abundance of An.gambiae s.l (P≤0.001 when preceded with fertilizer application. Significantly higher anopheline larval abundance was recorded in habitats in pasture compared to farmland (P = 0.002. When habitat stability and habitat types were considered, hoof print were the most productive followed by disused goldmines.These findings suggest that implementation of effective larval control programme should be targeted with larval

Wild plant species growing closely connected in a subalpine meadow host distinct root-associated bacterial communities

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Kristin Aleklett

2015-02-01

Full Text Available Plant roots are known to harbor large and diverse communities of bacteria. It has been suggested that plant identity can structure these root-associated communities, but few studies have specifically assessed how the composition of root microbiota varies within and between plant species growing under natural conditions. We assessed the community composition of endophytic and epiphytic bacteria through high throughput sequencing using 16S rDNA derived from root tissues collected from a population of a wild, clonal plant (Orange hawkweed–Pilosella aurantiaca as well as two neighboring plant species (Oxeye daisy–Leucanthemum vulgare and Alsike clover–Trifolium hybridum. Our first goal was to determine if plant species growing in close proximity, under similar environmental conditions, still hosted unique root microbiota. Our results showed that plants of different species host distinct bacterial communities in their roots. In terms of community composition, Betaproteobacteria (especially the family Oxalobacteraceae were found to dominate in the root microbiota of L. vulgare and T. hybridum samples, whereas the root microbiota of P. aurantiaca had a more heterogeneous distribution of bacterial abundances where Gammaproteobacteria and Acidobacteria occupied a larger portion of the community. We also explored the extent of individual variance within each plant species investigated, and found that in the plant species thought to have the least genetic variance among individuals (P. aurantiaca still hosted just as diverse microbial communities. Whether all plant species host their own distinct root microbiota and plants more closely related to each other share more similar bacterial communities still remains to be fully explored, but among the plants examined in this experiment there was no trend that the two species belonging to the same family shared more similarities in terms of bacterial community composition.

Effects of phylogeny, leaf traits, and the altitudinal distribution of host plants on herbivore assemblages on congeneric Acer species.

Science.gov (United States)

Nakadai, Ryosuke; Murakami, Masashi; Hirao, Toshihide

2014-08-01

Historical, niche-based, and stochastic processes have been proposed as the mechanisms that drive community assembly. In plant-herbivore systems, these processes can correspond to phylogeny, leaf traits, and the distribution of host plants, respectively. Although patterns of herbivore assemblages among plant species have been repeatedly examined, the effects of these factors among co-occurring congeneric host plant species have rarely been studied. Our aim was to reveal the process of community assembly for herbivores by investigating the effects of phylogeny, leaf traits, and the altitudinal distribution of closely related host plants of the genus Acer. We sampled leaf functional traits for 30 Acer species in Japan. Using a newly constructed phylogeny, we determined that three of the six measured leaf traits (leaf thickness, C/N ratio, and condensed tannin content) showed a phylogenetic signal. In a field study, we sampled herbivore communities on 14 Acer species within an elevation gradient and examined relationships between herbivore assemblages and host plants. We found that herbivore assemblages were significantly correlated with phylogeny, leaf traits, phylogenetic signals, and the altitudinal distribution of host plants. Our results indicate that the interaction between historical and current ecological processes shapes herbivore community assemblages.

Feeding Behaviour on Host Plants May Influence Potential Exposure to Bt Maize Pollen of Aglais Urticae Larvae (Lepidoptera, Nymphalidae).

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Lang, Andreas; Otto, Mathias

2015-08-31

Non-target butterfly larvae may be harmed by feeding on host plants dusted with Bt maize pollen. Feeding patterns of larvae and their utilization of host plants can affect the adverse Bt impact because the maize pollen is distributed unequally on the plant. In a field study, we investigated the feeding of larvae of the Small Tortoiseshell, Aglais urticae, on nettles, Urtica dioica. Young larvae used smaller host plants than older larvae. In general, the position of the larvae was in the top part of the host plant, but older larvae showed a broader vertical distribution on the nettles. Leaf blades and leaf tips were the plant parts most often consumed. Leaf veins were consumed but midribs were fed on to a lesser extent than other plant veins, particularly by young larvae. The feeding behavior of the larvae may increase possible exposure to Bt maize pollen because pollen densities are expected to be higher on the top parts and along leaf veins of nettles.

Feeding Behaviour on Host Plants May Influence Potential Exposure to Bt Maize Pollen of Aglais Urticae Larvae (Lepidoptera, Nymphalidae

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Andreas Lang

2015-08-01

Full Text Available Non-target butterfly larvae may be harmed by feeding on host plants dusted with Bt maize pollen. Feeding patterns of larvae and their utilization of host plants can affect the adverse Bt impact because the maize pollen is distributed unequally on the plant. In a field study, we investigated the feeding of larvae of the Small Tortoiseshell, Aglais urticae, on nettles, Urtica dioica. Young larvae used smaller host plants than older larvae. In general, the position of the larvae was in the top part of the host plant, but older larvae showed a broader vertical distribution on the nettles. Leaf blades and leaf tips were the plant parts most often consumed. Leaf veins were consumed but midribs were fed on to a lesser extent than other plant veins, particularly by young larvae. The feeding behavior of the larvae may increase possible exposure to Bt maize pollen because pollen densities are expected to be higher on the top parts and along leaf veins of nettles.

Sympatric diversification vs. immigration: deciphering host-plant specialization in a polyphagous insect, the stolbur phytoplasma vector Hyalesthes obsoletus (Cixiidae).

Science.gov (United States)

Imo, Miriam; Maixner, Michael; Johannesen, Jes

2013-04-01

The epidemiology of vector transmitted plant diseases is highly influenced by dispersal and the host-plant range of the vector. Widening the vector's host range may increase transmission potential, whereas specialization may induce specific disease cycles. The process leading to a vector's host shift and its epidemiological outcome is therefore embedded in the frameworks of sympatric evolution vs. immigration of preadapted populations. In this study, we analyse whether a host shift of the stolbur phytoplasma vector, Hyalesthes obsoletus from field bindweed to stinging nettle in its northern distribution range evolved sympatrically or by immigration. The exploitation of stinging nettle has led to outbreaks of the grapevine disease bois noir caused by a stinging nettle-specific phytoplasma strain. Microsatellite data from populations from northern and ancestral ranges provide strong evidence for sympatric host-race evolution in the northern range: Host-plant associated populations were significantly differentiated among syntopic sites (0.054 nettle-specific phytoplasma strain by plant-unspecific vectors. The evolution of host races in the northern range has led to specific vector-based bois noir disease cycles. © 2013 Blackwell Publishing Ltd.

Effects of Increased UVB radiation on plant-insect interactions: Plantago lanceolata and Junonia coenia

International Nuclear Information System (INIS)

McCloud, E.S.; Berenbaum, M.R.

1993-01-01

Seeds of P. lanceolata were collected from a local population and 4 replicates of 42 maternal families were grown for 90 days in the greenhouse with at two levels of supplemental UVB radiation (6 and 12 kJ day -1 BE 300 ). Higher UVB radiation increased leaf hair density and decreased plant size during early growth; family identity affected these also. Leaves excised from a subset of the plants were fed to ultimate instar larvae of J. coenia and assayed for iridoids. Increased UVB radiation did not alter the iridoid content of the leaves or the growth of the larvae. In a separate experiment, P. lanceolata growing under the two levels of UVB irradiation were infested with neonate larvae and larval growth was monitored. Larval growth was not markedly altered by enhanced UVB. These findings suggest that increased UVB is unlikely to alter the suitability of P. lanceolata as a host for J. coenia

Lifestyle of the biotroph Agrobacterium tumefaciens in the ecological niche constructed on its host plant.

Science.gov (United States)

González-Mula, Almudena; Lang, Julien; Grandclément, Catherine; Naquin, Delphine; Ahmar, Mohammed; Soulère, Laurent; Queneau, Yves; Dessaux, Yves; Faure, Denis

2018-07-01

Agrobacterium tumefaciens constructs an ecological niche in its host plant by transferring the T-DNA from its Ti plasmid into the host genome and by diverting the host metabolism. We combined transcriptomics and genetics for understanding the A. tumefaciens lifestyle when it colonizes Arabidopsis thaliana tumors. Transcriptomics highlighted: a transition from a motile to sessile behavior that mobilizes some master regulators (Hfq, CtrA, DivK and PleD); a remodeling of some cell surface components (O-antigen, succinoglucan, curdlan, att genes, putative fasciclin) and functions associated with plant defense (Ef-Tu and flagellin pathogen-associated molecular pattern-response and glycerol-3-phosphate and nitric oxide signaling); and an exploitation of a wide variety of host resources, including opines, amino acids, sugars, organic acids, phosphate, phosphorylated compounds, and iron. In addition, construction of transgenic A. thaliana lines expressing a lactonase enzyme showed that Ti plasmid transfer could escape host-mediated quorum-quenching. Finally, construction of knock-out mutants in A. tumefaciens showed that expression of some At plasmid genes seemed more costly than the selective advantage they would have conferred in tumor colonization. We provide the first overview of A. tumefaciens lifestyle in a plant tumor and reveal novel signaling and trophic interplays for investigating host-pathogen interactions. © 2018 The Authors. New Phytologist © 2018 New Phytologist Trust.

Reindeer as hosts for nematode parasites of sheep and cattle.

Science.gov (United States)

Hrabok, J T; Oksanen, A; Nieminen, M; Rydzik, A; Uggla, A; Waller, P J

2006-03-31

The reindeer husbandry range of Scandinavia overlaps with sheep, goat, and cattle pastures. The aim of this study was to determine whether reindeer are suitable hosts for ovine or bovine nematode parasites, and thus may spread these parasites into the reindeer husbandry regions. To render worm-free, twelve 4-month-old male reindeer calves, six lambs, and six bovine calves were given ivermectin at 200 microg/kg body weight. Five weeks post-treatment, six reindeer calves were each artificially dosed with 10,000 third-stage larvae (L3) of gastrointestinal nematodes derived from sheep, and an additional six reindeer with L3 derived from cattle. Lambs and bovine calves received the same dose of ovine and bovine larvae as reindeer, from the same larval source, respectively. Faecal samples collected on five occasions after the larval dosing revealed that by the fourth week, all reindeer calves, lambs, and bovine calves were infected. Animals were slaughtered on days 40 (reindeer) or 47 (lambs and bovine calves) after the larval dosing. Reindeer calves were most susceptible to L3 derived from sheep. The overall mean intensity of Haemochus contortus, Trichostrongylus axei, and Teladorsagia circumcincta, did not differ between reindeer and sheep; however, early fourth-stage larvae of H. contortus were more abundant in reindeer (p = 0.002). The establishment of bovine-derived Ostertagia ostertagi was similar in reindeer (62%) and bovine calves (57%), but larval inhibition was much higher in reindeer (91%, p bovine derived Cooperia oncophora was recorded in reindeer calves (2%) compared with bovine calves (59%). These results show that young reindeer are susceptible hosts to the important gastrointestinal parasites of sheep (T. circumcincta, H. contortus) and cattle (O. ostertagi), as well as being a suitable host for T. axei.

Arrested larval development in cattle nematodes.

Science.gov (United States)

Armour, J; Duncan, M

1987-06-01

Most economically important cattle nematodes are able to arrest their larval development within the host - entering a period of dormancy or hypobiosis. Arrested larvae have a low death rate, and large numbers can accumulate in infected cattle during the grazing season. Because of this, outbreaks of disease caused by such nematodes can occur at times when recent infection with the parasites could not have occurred, for example during winter in temperature northern climates when cattle are normally housed. The capacity to arrest is a heritable trait. It is seen as an adaptation by the parasite to avoid further development to its free-living stages during times when the climate is unsuitable for free-living survival. But levels of arrestment can vary markedly in different regions, in different cattle, and under different management regimes. Climatic factors, previous conditioning, host immune status, and farm management all seem to affect arrestment levels. In this article, James Armour and Mary Duncan review the biological basis of the phenomenon, and discuss the apparently conflicting views on how it is controlled.

Genetic determinism and evolutionary reconstruction of a host jump in a plant virus

DEFF Research Database (Denmark)

Vassilakos, Nikon; Simon, Vincent; Tzima, Aliki

2016-01-01

In spite of their widespread occurrence, only few host jumps by plant viruses have been evidenced and the molecular bases of even fewer have been determined. A combination of three independent approaches, 1) experimental evolution followed by reverse genetics analysis, 2) positive selection...... analysis, and 3) locus-by-locus analysis of molecular variance (AMOVA) allowed reconstructing the Potato virus Y (PVY; genus Potyvirus, family Potyviridae) jump to pepper (Capsicum annuum), probably from other solanaceous plants. Synthetic chimeras between infectious cDNA clones of two PVY isolates...... independently and conferred adaptation to C. annuum. In addition to increasing our knowledge of host jumps in plant viruses, this study illustrates also the efficiency of locus-by-locus AMOVA and combined approaches to identify adaptive mutations in the genome of RNA viruses....

Monitoring larval populations of the Douglas-fir tussock moth and the western spruce budworm on permanent plots: sampling methods and statistical properties of data

Science.gov (United States)

A.R. Mason; H.G. Paul

1994-01-01

Procedures for monitoring larval populations of the Douglas-fir tussock moth and the western spruce budworm are recommended based on many years experience in sampling these species in eastern Oregon and Washington. It is shown that statistically reliable estimates of larval density can be made for a population by sampling host trees in a series of permanent plots in a...

Host plants, distribution, and ecological association of Hoplolaimus columbus.

Science.gov (United States)

Lewis, S A; Smith, F H

1976-07-01

Selected species and cultivars of plants were evaluated for host suitability for Hoplolaimus columbus under greenhouse and fieht conditions. Sixteen agronomic plant cultivars were assayed for infection and reproduction after 2-6 months. Lima bean, soybean, cotton, and sweet corn were most favorable for nematode reproduction, whereas sweet potato was a nonhost plant. Field corn and watermelon, which tolerated H. columbus without significant yield losses, are suited for alternative crops in the southern coastal plain. Populations of H. columbus occurred in 15% of soyhean and 25% of cotton soil samples assayed. Population levels of H. columbus and Helicotylenchus spp. were correlated with fluctuations in various soil nutrient factors, whereas Meloidogyne spp. and Scutellonema spp. were not. No correlation was detected between the presence of H. columbus and populations of other nematode genera stndied.

Vitellogenin and vitellogenin receptor gene expression profiles in Spodoptera exigua are related to host plant suitability.

Science.gov (United States)

Zhao, Jing; Sun, Yang; Xiao, Liubin; Tan, Yongan; Jiang, Yiping; Bai, Lixin

2018-04-01

The beet armyworm Spodoptera exigua, a worldwide phytophagous pest, causes considerable economic agricultural losses. Understanding the relationship between its fecundity and the host plant is a basic and important component of early forecasting of beet armyworm outbreaks. However, little is known about the molecular mechanism by which distinct hosts affect S. exigua fecundity. In this study, key life-history parameters of S. exigua reared on distinct hosts were investigated; the host plants could be ranked as lettuce > shallot > tomato > celery in their order of suitability. Full-length S. exigua vitellogenin receptor (SeVgR) cDNA was cloned, and sex-, stage- and tissue-specific expression characteristics were assessed. Spodoptera exigua vitellogenin (SeVg) and SeVgR expression levels were markedly modulated by host nutrients (P lettuce, the most preferred and most nutritive host, than in those reared on tomato and celery. Interestingly, significant linear regression correlations were found between SeVg and SeVgR expression levels and key S. exigua life-history parameters, especially life span, pupa weight, and female fecundity (P < 0.01). Host plant type and suitability could affect the expression pattern of SeVg and SeVgR, which influenced S. exigua fecundity. Vg and VgR have the potential to be used as molecular markers of S. exigua fecundity and for forecasting outbreaks of S. exigua on different hosts. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Influence of host plants on sexual communication in the herbivorous bug Lygocoris pabulinus

NARCIS (Netherlands)

Groot, A.T.; Visser, J.H.

2001-01-01

Host plant volatiles may be involved in the sexual communication of insects in several ways. In the pheromone-producing sex, these volatiles may affect pheromone production or release and, in the receptive sex, plant volatiles may have a synergistic effect on the attraction to sex pheromone. We

Fast Decline of Pythium zingiberum in Soil and Its Recolonization by Cultivating Susceptible Host Plants

OpenAIRE

ICHITANI, Takio; SHIMIZU, Tokiya

1984-01-01

This experiment demonstrates the fast decline of Pythium zingiberum in soil and its recolonization by cultivating mioga, susceptible host plant, and discusses growth and survival of the pathogen in the host rhizosphere in cultivated fields.

In vitro screening of six anthelmintic plant products against larval Haemonchus contortus with a modified methyl-thiazolyl-tetrazolium reduction assay.

Science.gov (United States)

Hördegen, P; Cabaret, J; Hertzberg, H; Langhans, W; Maurer, V

2006-11-03

Because of the increasing anthelmintic resistance and the impact of conventional anthelmintics on the environment, it is important to look for alternative strategies against gastrointestinal nematodes. Phytotherapy could be one of the major options to control these pathologies. Extracts or ingredients of six different plant species were tested against exsheathed infective larvae of Haemonchus contortus using a modified methyl-thiazolyl-tetrazolium (MTT) reduction assay. Pyrantel tartrate was used as reference anthelmintic. Bromelain, the enzyme complex of the stem of Ananas comosus (Bromeliaceae), the ethanolic extracts of seeds of Azadirachta indica (Meliaceae), Caesalpinia crista (Caesalpiniaceae) and Vernonia anthelmintica (Asteraceae), and the ethanolic extracts of the whole plant of Fumaria parviflora (Papaveraceae) and of the fruit of Embelia ribes (Myrsinaceae) showed an anthelmintic efficacy of up to 93%, relative to pyrantel tartrate. Based on these results obtained with larval Haemonchus contortus, the modified MTT reduction assay could be a possible method for testing plant products with anthelmintic properties.

Microhabitat influence on larval fish assemblages within ...

Science.gov (United States)

We examined larval and juvenile fish assemblage structure in relation to microhabitat variables within the St. Louis River estuary, a drowned river mouth of Lake Superior. Fish were sampled in vegetated beds throughout the estuary, across a gradient of vegetation types and densities (including disturbed, preserved and post-restoration sites). Canonical correspondence analysis, relating species abundances to environmental variables revealed that plant species richness, turbidity and aquatic plant cover were most influential in structuring assemblages. Results from this microhabitat analysis at this crucial life stage has potential to inform wetland restoration efforts within the St. Louis River and other Great Lake coastal wetlands. not applicable

Annotated world bibliography of host plants of the melon fly, Bactrocera cucurbitae (Cocquillett) (Diptera:Tephritidae)

Science.gov (United States)

The melon fly, Bactrocera cucurbitae(Coquillett), is a widespread, economically important tephritid fruit fly (Diptera: Tephritidae) species. Bactrocera cucurbitae infests fruits and vegetables of a number of different plant species, with many host plants in the plant family Cucurbitaceae, but with ...

Host-plant preference and performance of the vine weevil Otiorhynchus sulcatus

NARCIS (Netherlands)

van Tol, R.W.H.M.; van Dijk, N.; Sabelis, M.W.

2004-01-01

The relationship between reproductive performance and preference for potential host plants of the vine weevil is investigated, as shown in tests on contact (or feeding) preference, presented herein, and tests on olfactory preference, published elsewhere. Assessment of reproductive performance shows

Host plant preference and performance of the vine weevil Otiorhynchus sulcatus

NARCIS (Netherlands)

Tol, van R.W.H.M.; Dijk, van N.; Sabelis, M.W.

2004-01-01

1. The relationship between reproductive performance and preference for potential host plants of the vine weevil is investigated, as shown in tests on contact (or feeding) preference, presented herein, and tests on olfactory preference, published elsewhere. 2. Assessment of reproductive performance

Nitric oxide production by necrotrophic pathogen Macrophomina phaseolina and the host plant in charcoal rot disease of jute: complexity of the interplay between necrotroph-host plant interactions.

Directory of Open Access Journals (Sweden)

Tuhin Subhra Sarkar

Full Text Available M. phaseolina, a global devastating necrotrophic fungal pathogen causes charcoal rot disease in more than 500 host plants. With the aim of understanding the plant-necrotrophic pathogen interaction associated with charcoal rot disease of jute, biochemical approach was attempted to study cellular nitric oxide production under diseased condition. This is the first report on M. phaseolina infection in Corchorus capsularis (jute plants which resulted in elevated nitric oxide, reactive nitrogen species and S nitrosothiols production in infected tissues. Time dependent nitric oxide production was also assessed with 4-Amino-5-Methylamino-2',7'-Difluorofluorescein Diacetate using single leaf experiment both in presence of M. phaseolina and xylanases obtained from fungal secretome. Cellular redox status and redox active enzymes were also assessed during plant fungal interaction. Interestingly, M. phaseolina was found to produce nitric oxide which was detected in vitro inside the mycelium and in the surrounding medium. Addition of mammalian nitric oxide synthase inhibitor could block the nitric oxide production in M. phaseolina. Bioinformatics analysis revealed nitric oxide synthase like sequence with conserved amino acid sequences in M. phaseolina genome sequence. In conclusion, the production of nitric oxide and reactive nitrogen species may have important physiological significance in necrotrophic host pathogen interaction.

Behavioral responses of Schistocerca americana (Orthoptera: Acrididae) to Azadirex (neem)-treated host plants.

Science.gov (United States)

Capinera, John L; Froeba, Jason G

2007-02-01

Azadirex (azadirachtin and other biologically active extracts from neem trees) has been shown to have considerable potential to be used in integrated pest management systems based on its growth regulator/insecticide properties. Less well known are the antifeedant properties. The feeding-deterrent properties of a commercial azadirex formulation (Azatrol EC) were evaluated using both no-choice and choice tests, the American grasshopper, Schistocerca americana (Drury), and four host plants [savoy cabbage, Brassica oleracea variety capitata L.; cos (romaine) lettuce, Lactuca sativa variety longifolia Lam.; sweet orange, Citrus sinensis variety Hamlin L.; and peregrina, Jatropha integerrima Jacq.]. These studies demonstrated that azadirex application can significantly affect the feeding behavior of grasshoppers. Some degree of protection can be afforded to plants that differ markedly in their innate attractiveness to the insect, although the level of protection varies among hosts. The tendency of grasshoppers to sometimes feed on azadirex-treated foliage suggests that it will be difficult to prevent damage from occurring at all times, on all hosts. No evidence of rapid habituation to azadirex was detected. Rapid loss of efficacy was observed under field conditions, suggesting that daily retreatment might be necessary to maintain protection of plants from feeding.

The role of selected plant metabolites in host plant choice by caterpillars of Acrobasis advenella (Zincken, 1818 (Lepidoptera, Pyralidae

Directory of Open Access Journals (Sweden)

Górska-Drabik Edyta

2017-03-01

Full Text Available Acrobasis advenella is an oligophagous species feeding on plants of the Rosaceae family. The differences in concentrations of host plant quality components, above all primary metabolites and the presence or absence of secondary metabolites, directly affects herbivore growth and development. The objectives of this research were to determine the food preferences of 1st instar larvae according to the chemical composition of host plants. The highest acceptance of rowan in the free choice test by 1st instar larvae, as compared to hawthorn and black chokeberry, is positively influenced by the high content of total sugars and phenolic acids. The conclusion to be drawn from the results is that the differences in food choice by 1st instar larvae feeding on fruits could have been due to the different chemical compositions of the fruit.

Echinococcus multilocularis and Its Intermediate Host: A Model of Parasite-Host Interplay

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Dominique Angèle Vuitton

2010-01-01

Full Text Available Host-parasite interactions in the E. multilocularis-intermediate host model depend on a subtle balance between cellular immunity, which is responsible for host's resistance towards the metacestode, the larval stage of the parasite, and tolerance induction and maintenance. The pathological features of alveolar echinococcosis. the disease caused by E. multilocularis, are related both to parasitic growth and to host's immune response, leading to fibrosis and necrosis, The disease spectrum is clearly dependent on the genetic background of the host as well as on acquired disturbances of Th1-related immunity. The laminated layer of the metacestode, and especially its carbohydrate components, plays a major role in tolerance induction. Th2-type and anti-inflammatory cytokines, IL-10 and TGF-β, as well as nitric oxide, are involved in the maintenance of tolerance and partial inhibition of cytotoxic mechanisms. Results of studies in the experimental mouse model and in patients suggest that immune modulation with cytokines, such as interferon-α, or with specific antigens could be used in the future to treat patients with alveolar echinococcosis and/or to prevent this very severe parasitic disease.

Museum specimens reveal loss of pollen host plants as key factor driving wild bee decline in The Netherlands

Science.gov (United States)

Scheper, Jeroen; Reemer, Menno; van Kats, Ruud; Ozinga, Wim A.; van der Linden, Giel T. J.; Schaminée, Joop H. J.; Siepel, Henk; Kleijn, David

2014-01-01

Evidence for declining populations of both wild and managed bees has raised concern about a potential global pollination crisis. Strategies to mitigate bee loss generally aim to enhance floral resources. However, we do not really know whether loss of preferred floral resources is the key driver of bee decline because accurate assessment of host plant preferences is difficult, particularly for species that have become rare. Here we examine whether population trends of wild bees in The Netherlands can be explained by trends in host plants, and how this relates to other factors such as climate change. We determined host plant preference of bee species using pollen loads on specimens in entomological collections that were collected before the onset of their decline, and used atlas data to quantify population trends of bee species and their host plants. We show that decline of preferred host plant species was one of two main factors associated with bee decline. Bee body size, the other main factor, was negatively related to population trend, which, because larger bee species have larger pollen requirements than smaller species, may also point toward food limitation as a key factor driving wild bee loss. Diet breadth and other potential factors such as length of flight period or climate change sensitivity were not important in explaining twentieth century bee population trends. These results highlight the species-specific nature of wild bee decline and indicate that mitigation strategies will only be effective if they target the specific host plants of declining species. PMID:25422416

Arabidopsis thaliana: A model host plant to study plant-pathogen interaction using Chilean field isolates of Botrytis cinerea

Directory of Open Access Journals (Sweden)

JUAN GONZÁLEZ

2006-01-01

Full Text Available One of the fungal pathogens that causes more agriculture damage is Botrytis cinerea. Botrytis is a constant threat to crops because the fungus infects a wide range of host species, both native and cultivated. Furthermore, Botrytis persists on plant debris in and on the soil. Some of the most serious diseases caused by Botrytis include gray mold on vegetables and fruits, such as grapes and strawberries. Botrytis also causes secondary soft rot of fruits and vegetables during storage, transit and at the market. In many plant-pathogen interactions, resistance often is associated with the deposition of callose, accumulation of autofluorescent compounds, the synthesis and accumulation of salicylic acid as well as pathogenesis-related proteins. Arabidopsis thaliana has been used as a plant model to study plant-pathogen interaction. The genome of Arabidopsis has been completely sequenced and this plant serves as a good genetic and molecular model. In this study, we demonstrate that Chilean field isolates infect Arabidopsis thaliana and that Arabidopsis subsequently activates several defense response mechanisms associated with a hypersensitive response. Furthermore, we propose that Arabidopsis may be used as a model host species to analyze the diversity associated with infectivity among populations of Botrytis cinerea field isolates

The neural bases of host plant selection in a Neuroecology framework.

Science.gov (United States)

Reisenman, Carolina E; Riffell, Jeffrey A

2015-01-01

Understanding how animals make use of environmental information to guide behavior is a fundamental problem in the field of neuroscience. Similarly, the field of ecology seeks to understand the role of behavior in shaping interactions between organisms at various levels of organization, including population-, community- and even ecosystem-level scales. Together, the newly emerged field of "Neuroecology" seeks to unravel this fundamental question by studying both the function of neurons at many levels of the sensory pathway and the interactions between organisms and their natural environment. The interactions between herbivorous insects and their host plants are ideal examples of Neuroecology given the strong ecological and evolutionary forces and the underlying physiological and behavioral mechanisms that shaped these interactions. In this review we focus on an exemplary herbivorous insect within the Lepidoptera, the giant sphinx moth Manduca sexta, as much is known about the natural behaviors related to host plant selection and the involved neurons at several level of the sensory pathway. We also discuss how herbivore-induced plant odorants and secondary metabolites in floral nectar in turn can affect moth behavior, and the underlying neural mechanisms.

Preference of a polyphagous mirid bug, Apolygus lucorum (Meyer-Dür for flowering host plants.

Directory of Open Access Journals (Sweden)

Hongsheng Pan

Full Text Available Apolygus lucorum (Meyer-Dür (Hemiptera: Miridae is one of the most important herbivores in a broad range of cultivated plants, including cotton, cereals, vegetables, and fruit crops in China. In this manuscript, we report on a 6-year long study in which (adult A. lucorum abundance was recorded on 174 plant species from 39 families from early July to mid-September. Through the study period per year, the proportion of flowering plants exploited by adult A. lucorum was significantly greater than that of non-flowering plants. For a given plant species, A. lucorum adults reached peak abundance at the flowering stage, when the plant had the greatest attraction to the adults. More specifically, mean adult abundance on 26 species of major host plants and their relative standard attraction were 10.3-28.9 times and 9.3-19.5 times higher at flowering stage than during non-flowering periods, respectively. Among all the tested species, A. lucorum adults switched food plants according to the succession of flowering plant species. In early July, A. lucorum adults preferred some plant species in bloom, such as Vigna radiata, Gossypium hirsutum, Helianthus annuus and Chrysanthemum coronarium; since late July, adults dispersed into other flowering hosts (e.g. Ricinus communis, Impatiens balsamina, Humulus scandens, Ocimum basilicum, Agastache rugosus and Coriandrum sativum; in early September, they largely migrated to flowering Artemisia spp. (e.g. A. argyi, A. lavandulaefolia, A. annua and A. scoparia. Our findings underscore the important role of flowering plays in the population dynamics and inter-plant migration of this mirid bug. Also, our work helps understand evolutionary aspects of host plant use in polyphagous insects such as A. lucorum, and provides baseline information for the development of sustainable management strategies of this key agricultural pest.

Field Attraction of Carob Moth to Host Plants and Conspecific Females

NARCIS (Netherlands)

Hosseini, S.A.; Goldansaz, S.H.; Menken, S.B.J.; van Wijk, M.; Roessingh, P.; Groot, A.T.

2017-01-01

The carob moth, Ectomyelois ceratoniae (Zeller; Lepidoptera: Pyralidae), is a devastating pest in high-value crops around the world. An efficient sex pheromone attractant is still missing for the management of this pest, because the major pheromone component is unstable. Host plant volatiles attract

Location of Host and Host Habitat by Fruit Fly Parasitoids

Directory of Open Access Journals (Sweden)

Pascal Rousse

2012-11-01

Full Text Available Augmentative releases of parasitoids may be a useful tool for the area-wide management of tephritid pests. The latter are parasitized by many wasp species, though only a few of them are relevant for augmentative biocontrol purposes. To date, nearly all the actual or potential biocontrol agents for such programs are egg or larval Opiinae parasitoids (Hymenoptera: Braconidae. Here, we review the literature published on their habitat and host location behavior, as well as the factors that modulate this behavior, which is assumed to be sequential; parasitoids forage first for the host habitat and then for the host itself. Parasitoids rely on chemical, visual, and mechanical stimuli, often strongly related to their ecology. Behavioral modulation factors include biotic and abiotic factors including learning, climatic conditions and physiological state of the insect. Finally, conclusions and perspectives for future research are briefly highlighted. A detailed knowledge of this behavior may be very useful for selecting the release sites for both inundative/augmentative releases of mass-reared parasitoids and inoculative releases for classical biocontrol.

Non-nodulated bacterial leaf symbiosis promotes the evolutionary success of its host plants in the coffee family (Rubiaceae).

Science.gov (United States)

Verstraete, Brecht; Janssens, Steven; Rønsted, Nina

2017-08-01

Every plant species on Earth interacts in some way or another with microorganisms and it is well known that certain forms of symbiosis between different organisms can drive evolution. Within some clades of Rubiaceae (coffee family), a specific plant-bacteria interaction exists in which non-pathological endophytes are present in the leaves of their hosts. It is hypothesized that the bacterial endophytes, either alone or by interacting with the host, provide chemical protection against herbivory or pathogens by producing toxic or otherwise advantageous secondary metabolites. If the bacteria indeed have a direct beneficial influence on their hosts, it is reasonable to assume that the endophytes may increase the fitness of their hosts and therefore it is probable that their presence also has an influence on the long-term evolution of the particular plant lineages. In this study, the possible origin in time of non-nodulated bacterial leaf symbiosis in the Vanguerieae tribe of Rubiaceae is elucidated and dissimilarities in evolutionary dynamics between species with endophytes versus species without are investigated. Bacterial leaf symbiosis is shown to have most probably originated in the Late Miocene, a period when the savannah habitat is believed to have expanded on the African continent and herbivore pressure increased. The presence of bacterial leaf endophytes appears to be restricted to Old World lineages so far. Plant lineages with leaf endophytes show a significantly higher speciation rate than plant lineages without endophytes, while there is only a small difference in extinction rate. The transition rate shows that evolving towards having endophytes is twice as fast as evolving towards not having endophytes, suggesting that leaf symbiosis must be beneficial for the host plants. We conclude that the presence of bacterial leaf endophytes may also be an important driver for speciation of host plants. Copyright © 2017 Elsevier Inc. All rights reserved.

Infestation of Raoiella indica Hirst (Trombidiformes: Tenuipalpidae) on Host Plants of High Socio-Economic Importance for Tropical America.

Science.gov (United States)

Otero-Colina, G; González-Gómez, R; Martínez-Bolaños, L; Otero-Prevost, L G; López-Buenfil, J A; Escobedo-Graciamedrano, R M

2016-06-01

The mite Raoiella indica Hirst was recently introduced into America, where it has shown amazing ability to disseminate and broaden its range of hosts. An experiment was conducted in Cancún, Mexico, to determine infestation levels of this mite on plants recorded as hosts: coconut palm (Cocos nucifera) of cultivars Pacific Tall and Malayan Dwarf, oil palm (Elaeis guineensis) hybrids Deli x Ghana and Deli x Nigeria, Dwarf Giant banana (Musa acuminata, AAA subgroup Cavendish), Horn plantain (M. acuminata x Musa balbisiana, AAB subgroup Plantain), lobster claw (Heliconia bihai), and red ginger (Alpinia purpurata). Nursery plants of these host species or cultivars were artificially infested with R. indica in February 2011. In the four replications of 10 plants, each plant was infested with 200 R. indica specimens, and the numbers of infesting mites were recorded for 6 months. A maximum of 18,000 specimens per plant were observed on coconut Pacific Tall and Malayan Dwarf, followed by lobster claw, with a maximum of 1000 specimens per plant. Infestations were minimal for the remaining plants. Mite numbers on all plants declined naturally during the rainy season. All plant materials sustained overlapping mite generations, indicating that they are true hosts. Complementarily, infestation level was determined in backyard bananas and plantains. Correlations of infestation with plant height, distance from coconuts, and exposure to direct sunlight were estimated. Both bananas and plantains were infested by R. indica even when situated far from infested coconut palms. A Spearman correlation was found between infestation and plant height, although it was significant only for Silk plantain.

Virus Infection of Plants Alters Pollinator Preference: A Payback for Susceptible Hosts?

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Davey, Matthew P.; Bruce, Toby J. A.; Caulfield, John C.; Furzer, Oliver J.; Reed, Alison; Robinson, Sophie I.; Miller, Elizabeth; Davis, Christopher N.; Pickett, John A.; Whitney, Heather M.; Glover, Beverley J.; Carr, John P.

2016-01-01

Plant volatiles play important roles in attraction of certain pollinators and in host location by herbivorous insects. Virus infection induces changes in plant volatile emission profiles, and this can make plants more attractive to insect herbivores, such as aphids, that act as viral vectors. However, it is unknown if virus-induced alterations in volatile production affect plant-pollinator interactions. We found that volatiles emitted by cucumber mosaic virus (CMV)-infected tomato (Solanum lycopersicum) and Arabidopsis thaliana plants altered the foraging behaviour of bumblebees (Bombus terrestris). Virus-induced quantitative and qualitative changes in blends of volatile organic compounds emitted by tomato plants were identified by gas chromatography-coupled mass spectrometry. Experiments with a CMV mutant unable to express the 2b RNA silencing suppressor protein and with Arabidopsis silencing mutants implicate microRNAs in regulating emission of pollinator-perceivable volatiles. In tomato, CMV infection made plants emit volatiles attractive to bumblebees. Bumblebees pollinate tomato by ‘buzzing’ (sonicating) the flowers, which releases pollen and enhances self-fertilization and seed production as well as pollen export. Without buzz-pollination, CMV infection decreased seed yield, but when flowers of mock-inoculated and CMV-infected plants were buzz-pollinated, the increased seed yield for CMV-infected plants was similar to that for mock-inoculated plants. Increased pollinator preference can potentially increase plant reproductive success in two ways: i) as female parents, by increasing the probability that ovules are fertilized; ii) as male parents, by increasing pollen export. Mathematical modeling suggested that over a wide range of conditions in the wild, these increases to the number of offspring of infected susceptible plants resulting from increased pollinator preference could outweigh underlying strong selection pressures favoring pathogen resistance

Virus Infection of Plants Alters Pollinator Preference: A Payback for Susceptible Hosts?

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Simon C Groen

2016-08-01

Full Text Available Plant volatiles play important roles in attraction of certain pollinators and in host location by herbivorous insects. Virus infection induces changes in plant volatile emission profiles, and this can make plants more attractive to insect herbivores, such as aphids, that act as viral vectors. However, it is unknown if virus-induced alterations in volatile production affect plant-pollinator interactions. We found that volatiles emitted by cucumber mosaic virus (CMV-infected tomato (Solanum lycopersicum and Arabidopsis thaliana plants altered the foraging behaviour of bumblebees (Bombus terrestris. Virus-induced quantitative and qualitative changes in blends of volatile organic compounds emitted by tomato plants were identified by gas chromatography-coupled mass spectrometry. Experiments with a CMV mutant unable to express the 2b RNA silencing suppressor protein and with Arabidopsis silencing mutants implicate microRNAs in regulating emission of pollinator-perceivable volatiles. In tomato, CMV infection made plants emit volatiles attractive to bumblebees. Bumblebees pollinate tomato by 'buzzing' (sonicating the flowers, which releases pollen and enhances self-fertilization and seed production as well as pollen export. Without buzz-pollination, CMV infection decreased seed yield, but when flowers of mock-inoculated and CMV-infected plants were buzz-pollinated, the increased seed yield for CMV-infected plants was similar to that for mock-inoculated plants. Increased pollinator preference can potentially increase plant reproductive success in two ways: i as female parents, by increasing the probability that ovules are fertilized; ii as male parents, by increasing pollen export. Mathematical modeling suggested that over a wide range of conditions in the wild, these increases to the number of offspring of infected susceptible plants resulting from increased pollinator preference could outweigh underlying strong selection pressures favoring pathogen

Herbivore Oral Secreted Bacteria Trigger Distinct Defense Responses in Preferred and Non-Preferred Host Plants.

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Wang, Jie; Chung, Seung Ho; Peiffer, Michelle; Rosa, Cristina; Hoover, Kelli; Zeng, Rensen; Felton, Gary W

2016-06-01

Insect symbiotic bacteria affect host physiology and mediate plant-insect interactions, yet there are few clear examples of symbiotic bacteria regulating defense responses in different host plants. We hypothesized that plants would induce distinct defense responses to herbivore- associated bacteria. We evaluated whether preferred hosts (horsenettle) or non-preferred hosts (tomato) respond similarly to oral secretions (OS) from the false potato beetle (FPB, Leptinotarsa juncta), and whether the induced defense triggered by OS was due to the presence of symbiotic bacteria in OS. Both horsenettle and tomato damaged by antibiotic (AB) treated larvae showed higher polyphenol oxidase (PPO) activity than those damaged by non-AB treated larvae. In addition, application of OS from AB treated larvae induced higher PPO activity compared with OS from non-AB treated larvae or water treatment. False potato beetles harbor bacteria that may provide abundant cues that can be recognized by plants and thus mediate corresponding defense responses. Among all tested bacterial isolates, the genera Pantoea, Acinetobacter, Enterobacter, and Serratia were found to suppress PPO activity in tomato, while only Pantoea sp. among these four isolates was observed to suppress PPO activity in horsenettle. The distinct PPO suppression caused by symbiotic bacteria in different plants was similar to the pattern of induced defense-related gene expression. Pantoea inoculated FPB suppressed JA-responsive genes and triggered a SA-responsive gene in both tomato and horsenettle. However, Enterobacter inoculated FPB eliminated JA-regulated gene expression and elevated SA-regulated gene expression in tomato, but did not show evident effects on the expression levels of horsenettle defense-related genes. These results indicate that suppression of plant defenses by the bacteria found in the oral secretions of herbivores may be a more widespread phenomenon than previously indicated.

Predation success by a plant-ant indirectly favours the growth and fitness of its host myrmecophyte.

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Alain Dejean

Full Text Available Mutualisms, or interactions between species that lead to net fitness benefits for each species involved, are stable and ubiquitous in nature mostly due to "byproduct benefits" stemming from the intrinsic traits of one partner that generate an indirect and positive outcome for the other. Here we verify if myrmecotrophy (where plants obtain nutrients from the refuse of their associated ants can explain the stability of the tripartite association between the myrmecophyte Hirtella physophora, the ant Allomerus decemarticulatus and an Ascomycota fungus. The plant shelters and provides the ants with extrafloral nectar. The ants protect the plant from herbivores and integrate the fungus into the construction of a trap that they use to capture prey; they also provide the fungus and their host plant with nutrients. During a 9-month field study, we over-provisioned experimental ant colonies with insects, enhancing colony fitness (i.e., more winged females were produced. The rate of partial castration of the host plant, previously demonstrated, was not influenced by the experiment. Experimental plants showed higher δ(15N values (confirming myrmecotrophy, plus enhanced vegetative growth (e.g., more leaves produced increased the possibility of lodging ants in leaf pouches and fitness (i.e., more fruits produced and more flowers that matured into fruit. This study highlights the importance of myrmecotrophy on host plant fitness and the stability of ant-myrmecophyte mutualisms.

Entrainment of larval fishes at two nuclear power plants on the Missouri River in Nebraska

International Nuclear Information System (INIS)

Cada, G.F.

1977-01-01

A sampling program to assess the effects of entrainment in the cooling water systems at the Fort Calhoun and Cooper Nuclear Stations on larval fishes was carried out in the months of May, June, and July of 1974--1976. Fish larvae were collected with 2.3 m long, 0.5 m diameter Nitex plankton nets. The samples were taken to laboratory facilities where the living and dead larvae were separated from the debris, counted, and preserved for later identification and measurement. Samples collected above the intake structures of the power plants were used to determine the seasonal patterns, species composition, and abundance of ichthyoplankton in this region of the Missouri River. Relatively low larval fish densities throughout May and early June were generally followed by a single 2 to 3 week long peak in density in late June and early July, due primarily to the larvae of Aplodinotus grunniens. The observed densities then declined to near zero by the end of July. The horizontal distribution of ichthyoplankton was determined by dividing the river above the intake into three sections and sampling the sites sequentially. The highest concentrations of larvae were generally found along the cutting bank (Nebraska shore) and the lowest in the middle of the river. Twenty-four hour sampling was conducted to identify possible diurnal differences in the ichthyoplankton densities above the intake. On six occasions, collections were made every two hours over a 24-hour period. Although great variations in densities were noted over the sampling period, significant differences between mean day and night densities were demonstrated only once, and no recurring temporal pattern in drift rates was identified. Net-induced sampling mortality was found to be a significant factor in the analysis of entrainment mortality

Larval spirurida (Nematoda) from the crab Macrophthalmus hirtipes in New Zealand

DEFF Research Database (Denmark)

Moravec, Frantisek; Fredensborg, Brian Lund; Latham, A David M

2003-01-01

to a species of Ascarophis van Beneden, 1871 (Cystidicolidae), the genus including parasites of fishes, whereas the smaller larvae (about 4-5 mm long) belonged to the Acuariidae, a family with species parasitic as adults mostly in aquatic birds. In a sample of 82 specimens of M. hirtipes collected in July 2002....... Apparently, crabs play a role as intermediate hosts of these nematode species. This is the first record of larval representatives of Cystidicolidae and Acuariidae from invertebrates in the Australasian Region....

Plasticity in host utilization by two host-associated populations of Aphis gossypii Glover.

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Barman, A K; Gadhave, K R; Dutta, B; Srinivasan, R

2018-06-01

Biological and morphological plasticity in polyphagous insect herbivores allow them to exploit diverse host plant species. Geographical differences in resource availability can lead to preferential host exploitation and result in inconsistent host specialization. Biological and molecular data provide insights into specialization and plasticity of such herbivore populations. In agricultural landscapes, Aphis gossypii encounters several crop and non-crop hosts, which exist in temporal and spatial proximity. We investigated the host-specialization of two A. gossypii host-associated populations (HAPs), which were field collected from cotton and squash (cotton-associated population and melon-associated population), and later maintained separately in the greenhouse. The two aphid populations were exposed to seven plant species (cotton, okra, watermelon, squash, cucumber, pigweed, and morning glory), and evaluated for their host utilization plasticity by estimating aphid's fitness parameters (nymphal period, adult period, fecundity, and intrinsic rate of increase). Four phenotypical characters (body length, head capsule width, hind tibia length and cornicle length) were also measured from the resulting 14 different HAP × host plant combinations. Phylogenetic analysis of mitochondrial COI sequences showed no genetic variation between the two HAPs. Fitness parameters indicated a significant variation between the two aphid populations, and the variation was influenced by host plants. The performance of melon-aphids was poor (up to 89% reduction in fecundity) on malvaceous hosts, cotton and okra. However, cotton-aphids performed better on cucurbitaceous hosts, squash and watermelon (up to 66% increased fecundity) compared with the natal host, cotton. Both HAPs were able to reproduce on two weed hosts. Cotton-aphids were smaller than melon-aphids irrespective of their host plants. Results from this study suggest that the two HAPs in the study area do not have strict host

Parasites of larval black flies (Diptera: Simuliidae in Thailand

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Sanae Jitklang

2012-12-01

Full Text Available Parasites of larval black flies are reported for the first time from Thailand, including mermithid nematodes(Mermithidae, microsporidian fungi (Zygomycota, and the fungus Coelomycidium simulii Debaisieux (Blastocladiomycetes.The following nine species of black flies were infected with one or more parasites: Simulium asakoae, S. chamlongi,S. chiangmaiense, S. fenestratum, S. feuerborni, S. nakhonense, S. nodosum, S. quinquestriatum, and S. tani. The prevalenceof patent infections per host species per season was 0.1–7.1% for mermithids, 0.1–6.0% for microsporidia, and 0.1–3.0% forC. simulii.

A bacterial E3 ubiquitin ligase targets a host protein kinase to disrupt plant immunity.

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Rosebrock, Tracy R; Zeng, Lirong; Brady, Jennifer J; Abramovitch, Robert B; Xiao, Fangming; Martin, Gregory B

2007-07-19

Many bacterial pathogens of plants and animals use a type III secretion system to deliver diverse virulence-associated 'effector' proteins into the host cell. The mechanisms by which these effectors act are mostly unknown; however, they often promote disease by suppressing host immunity. One type III effector, AvrPtoB, expressed by the plant pathogen Pseudomonas syringae pv. tomato, has a carboxy-terminal domain that is an E3 ubiquitin ligase. Deletion of this domain allows an amino-terminal region of AvrPtoB (AvrPtoB(1-387)) to be detected by certain tomato varieties leading to immunity-associated programmed cell death. Here we show that a host kinase, Fen, physically interacts with AvrPtoB(1-387 )and is responsible for activating the plant immune response. The AvrPtoB E3 ligase specifically ubiquitinates Fen and promotes its degradation in a proteasome-dependent manner. This degradation leads to disease susceptibility in Fen-expressing tomato lines. Various wild species of tomato were found to exhibit immunity in response to AvrPtoB(1-387 )and not to full-length AvrPtoB. Thus, by acquiring an E3 ligase domain, AvrPtoB has thwarted a highly conserved host resistance mechanism.

Genetic differentiation associated with host plants and geography among six widespread lineages of South American Blepharoneura fruit flies (Tephritidae)

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Tropical herbivorous insects are astonishingly diverse and many are highly host-specific. Much evidence suggests that herbivorous insect diversity is a function of host-plant diversity; yet, the diversity of some lineages exceeds the diversity of plants. Although most lineages of herbivorous fruit f...

Contrasting Plasticity in Ovariole Number Induced by A Dietary Effect of the Host Plants between Cactophilic Drosophila Species

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Daniela Peluso

2016-05-01

Full Text Available Under the preference-performance hypothesis, natural selection will favor females that choose oviposition sites that optimize the fitness of their offspring. Such a preference-performance relationship may entail important consequences mainly on fitness-related traits. We used the well-characterized cactus-Drosophila system to investigate the reproductive capacity in the pair of sibling species D. buzzatii and D. koepferae reared in two alternative host plants. According to our hypothesis, ovariole number (as a proxy of reproductive capacity depends on host plant selection. Our results indicate that the capacity of D. buzzatii showed to be mild, only increasing the number of ovarioles by as much as 10% when reared in its preferred host. In contrast, D. koepferae exhibited a similar reproductive capacity across host cacti, even though it showed a preference for its primary host cactus. Our study also revealed that D. buzzatii has a larger genetic variation for phenotypic plasticity than its sibling, although ovariole number did not show clear-cut differences between species. We will discuss the weak preference-performance pattern observed in these cactophilic species in the light of nutritional and toxicological differences found between the natural host plants.

Treeline proximity alters an alpine plant-herbivore interaction.

Science.gov (United States)

Illerbrun, Kurt; Roland, Jens

2011-05-01

Rising treeline threatens the size and contiguity of alpine meadows worldwide. As trees encroach into previously open habitat, the movement and population dynamics of above-treeline alpine species may be disrupted. This process is well documented in studies of the Rocky Mountain apollo butterfly (Parnassius smintheus). However, subtler consequences of treeline rise remain poorly understood. In this study, we examine whether treeline proximity affects feeding behaviour of P. smintheus larvae, due to altered habitat affecting the distribution and availability of their host plant, lance-leaved stonecrop (Sedum lanceolatum). Understanding differential larval exploitation of food resources in relation to the treeline is an important step in predicting the consequences of continued treeline rise. Parnassius smintheus larvae feed more intensively on S. lanceolatum away from the treeline despite the relative paucity of hosts in these areas, and despite higher fitness penalties associated with the plant's herbivory-induced chemical defenses. Sedum lanceolatum growing near the treeline is less attractive, and therefore represents a less significant resource for P. smintheus larvae than its abundance might imply. If treeline rise continues, we suggest that this pattern of altered resource exploitation may represent a mechanism by which larvae are adversely affected even while adult movement among and within meadows appears sufficient for maintaining population health, and total host availability seems ample.

The Role of Endophytic Microorganisms of Medicinal Plants in the Adaptation of Host Plant

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Zhivetev M.A.

2015-09-01

Full Text Available Cultures of microorganisms were isolated from endosphere of Lake Baikal littoral zone plants: Veronica chamaedrys L., Alchemilla subscrenata Buser, Achillea asiatica Serg., Taraxacum officinale Wigg., Plantago major L. Morphology and biochemical properties of isolated bacteria were studied. For the majority of the endophytic bacterial cultures cellulolitic and proteolytic activity has been shown, which necessary for the effective colonization of plant tissue. For many cultures revealed ability in varying degrees to form a biofilm to improve survival in a vegetative organism. Their potencial role in adaptation of plant-hosts under conditions of climat Baikal region was shown. In particular, 9 of cultures demonstrated ability to act as nitrogen retainer. The vast majority of bacterial cultures did not have phytotoxicity or demonstrated its low level, reflecting and minimum negative effects of them on plant. Moreover, culture with encryption P3, isolated from Plantago major in August, showed a stimulatory effect in experiments on phytotoxicity. This same culture possessed the highest ability to secrete sugars as at +26°С and at +4°С.

Native-plant hosts of Meloidogyne spp. from Western Paraná, Brazil

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Vanessa A. Antes

2012-04-01

Full Text Available The present study was focused on the parasitism of Meloidogyne species on the roots of native nursery plants from the Atlantic forest. Native plants were selected from a commercial nursery in Western Paraná, searching for the natural infection of Meloidogyne. Also, the seeds of native plants were cultivated in sterile soil and inoculated with M. incognita. In both the experiments, the number of galls and number of eggs and J2 per root, allied to the reproduction factor of M. incognita on each inoculated plant were assessed. Natural infection by M. javanica was found on Cordia ecalyculata, Citharexyllum myrianthum and Aspidosperma subincanum and by M. incognita on Croton urucurana, Lonchocarpus muehlbergianus, Tabebuia impetiginosa and T. serratifolia. Meloidogyne incognita induced galls formation on Genipa americana, Schinus terebinthifolius and Rollinia mucosa after inoculation, which suggested that those plants could host this nematode in natural biomes. Nursery soil should be disinfested before seeding the native forest plants for reforestation purposes

A New Method for in Situ Measurement of Bt-Maize Pollen Deposition on Host-Plant Leaves

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Rudolph Vögel

2011-02-01

Full Text Available Maize is wind pollinated and produces huge amounts of pollen. In consequence, the Cry toxins expressed in the pollen of Bt maize will be dispersed by wind in the surrounding vegetation leading to exposure of non-target organisms (NTO. NTO like lepidopteran larvae may be affected by the uptake of Bt-pollen deposited on their host plants. Although some information is available to estimate pollen deposition on host plants, recorded data are based on indirect measurements such as shaking or washing off pollen, or removing pollen with adhesive tapes. These methods often lack precision and they do not include the necessary information such as the spatial and temporal variation of pollen deposition on the leaves. Here, we present a new method for recording in situ the amount and the distribution of Bt-maize pollen deposited on host plant leaves. The method is based on the use of a mobile digital microscope (Dino-Lite Pro, including DinoCapture software, which can be used in combination with a notebook in the field. The method was evaluated during experiments in 2008 to 2010. Maize pollen could be correctly identified and pollen deposition as well as the spatial heterogeneity of maize pollen deposition was recorded on maize and different lepidopteran host plants (Centaurea scabiosa, Chenopodium album, Rumex spp., Succina pratensis and Urtica dioica growing adjacent to maize fields.

Analysis of T-DNA/Host-Plant DNA Junction Sequences in Single-Copy Transgenic Barley Lines

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Joanne G. Bartlett

2014-01-01

Full Text Available Sequencing across the junction between an integrated transfer DNA (T-DNA and a host plant genome provides two important pieces of information. The junctions themselves provide information regarding the proportion of T-DNA which has integrated into the host plant genome, whilst the transgene flanking sequences can be used to study the local genetic environment of the integrated transgene. In addition, this information is important in the safety assessment of GM crops and essential for GM traceability. In this study, a detailed analysis was carried out on the right-border T-DNA junction sequences of single-copy independent transgenic barley lines. T-DNA truncations at the right-border were found to be relatively common and affected 33.3% of the lines. In addition, 14.3% of lines had rearranged construct sequence after the right border break-point. An in depth analysis of the host-plant flanking sequences revealed that a significant proportion of the T-DNAs integrated into or close to known repetitive elements. However, this integration into repetitive DNA did not have a negative effect on transgene expression.

Corruption of host seven-transmembrane proteins by pathogenic microbes: a common theme in animals and plants?

Science.gov (United States)

Panstruga, Ralph; Schulze-Lefert, Paul

2003-04-01

Human diseases like AIDS, malaria, and pneumonia are caused by pathogens that corrupt host chemokine G-protein coupled receptors for molecular docking. Comparatively, little is known about plant host factors that are required for pathogenesis and that may serve as receptors for the entry of pathogenic microbes. Here, we review potential analogies between human chemokine receptors and the plant seven-transmembrane MLO protein, a candidate serving a dual role as docking molecule and defence modulator for the phytopathogenic powdery mildew fungus.

Arabidopsis thaliana is a susceptible host plant for the holoparasite Cuscuta spec.

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Birschwilks, Mandy; Sauer, Norbert; Scheel, Dierk; Neumann, Stefanie

2007-10-01

Arabidopsis thaliana and Cuscuta spec. represent a compatible host-parasite combination. Cuscuta produces a haustorium that penetrates the host tissue. In early stages of development the searching hyphae on the tip of the haustorial cone are connected to the host tissue by interspecific plasmodesmata. Ten days after infection, translocation of the fluorescent dyes, Texas Red (TR) and 5,6-carboxyfluorescein (CF), demonstrates the existence of a continuous connection between xylem and phloem of the host and parasite. Cuscuta becomes the dominant sink in this host-parasite system. Transgenic Arabidopsis plants expressing genes encoding the green fluorescent protein (GFP; 27 kDa) or a GFP-ubiquitin fusion (36 kDa), respectively, under the companion cell (CC)-specific AtSUC2 promoter were used to monitor the transfer of these proteins from the host sieve elements to those of Cuscuta. Although GFP is transferred unimpedly to the parasite, the GFP-ubiquitin fusion could not be detected in Cuscuta. A translocation of the GFP-ubiquitin fusion protein was found to be restricted to the phloem of the host, although a functional symplastic pathway exists between the host and parasite, as demonstrated by the transport of CF. These results indicate a peripheral size exclusion limit (SEL) between 27 and 36 kDa for the symplastic connections between host and Cuscuta sieve elements. Forty-six accessions of A. thaliana covering the entire range of its genetic diversity, as well as Arabidopsis halleri, were found to be susceptible towards Cuscuta reflexa.

Host habitat assessment by a parasitoid using fungal volatiles

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Steidle Johannes LM

2007-02-01

Full Text Available Abstract Background The preference – performance hypothesis predicts that oviposition preference of insects should correlate with host suitability for offspring development. Therefore, insect females have to be able to assess not only the quality of a given host but also the environmental conditions of the respective host habitat. Chemical cues are a major source of information used by insects for this purpose. Primary infestation of stored grain by stored product pests often favors the intense growth of mold. This can lead to distinct sites of extreme environmental conditions (hot-spots with increased insect mortality. We studied the influence of mold on chemical orientation, host recognition, and fitness of Lariophagus distinguendus, a parasitoid of beetle larvae developing in stored grain. Results Volatiles of wheat infested by Aspergillus sydowii and A. versicolor repelled female parasitoids in an olfactometer. Foraging L. distinguendus females are known to be strongly attracted to the odor of larval host feces from the granary weevil Sitophilus granarius, which may adhere in remarkable amounts to the surface of the grains. Feces from moldy weevil cultures elicited neutral responses but parasitoids clearly avoided moldy feces when non-moldy feces were offered simultaneously. The common fungal volatile 1-octen-3-ol was the major component of the odor of larval feces from moldy weevil cultures and repelled female parasitoids at naturally occurring doses. In bioassays investigating host recognition behavior of L. distinguendus, females spent less time on grains containing hosts from moldy weevil cultures and showed less drumming and drilling behavior than on non-moldy controls. L. distinguendus had a clearly reduced fitness on hosts from moldy weevil cultures. Conclusion We conclude that L. distinguendus females use 1-octen-3-ol for host habitat assessment to avoid negative fitness consequences due to secondary mold infestation of host

Genetic Factors and Host Traits Predict Spore Morphology for a Butterfly Pathogen

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Jacobus C. de Roode

2013-08-01

Full Text Available Monarch butterflies (Danaus plexippus throughout the world are commonly infected by the specialist pathogen Ophryocystis elektroscirrha (OE. This protozoan is transmitted when larvae ingest infectious stages (spores scattered onto host plant leaves by infected adults. Parasites replicate internally during larval and pupal stages, and adult monarchs emerge covered with millions of dormant spores on the outsides of their bodies. Across multiple monarch populations, OE varies in prevalence and virulence. Here, we examined geographic and genetic variation in OE spore morphology using clonal parasite lineages derived from each of four host populations (eastern and western North America, South Florida and Hawaii. Spores were harvested from experimentally inoculated, captive-reared adult monarchs. Using light microscopy and digital image analysis, we measured the size, shape and color of 30 replicate spores per host. Analyses examined predictors of spore morphology, including parasite source population and clone, parasite load, and the following host traits: family line, sex, wing area, and wing color (orange and black pigmentation. Results showed significant differences in spore size and shape among parasite clones, suggesting genetic determinants of morphological variation. Spore size also increased with monarch wing size, and monarchs with larger and darker orange wings tended to have darker colored spores, consistent with the idea that parasite development depends on variation in host quality and resources. We found no evidence for effects of source population on variation in spore morphology. Collectively, these results provide support for heritable variation in spore morphology and a role for host traits in affecting parasite development.

Multiple candidate effectors from the oomycete pathogen Hyaloperonospora arabidopsidis suppress host plant immunity.

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Georgina Fabro

2011-11-01

Full Text Available Oomycete pathogens cause diverse plant diseases. To successfully colonize their hosts, they deliver a suite of effector proteins that can attenuate plant defenses. In the oomycete downy mildews, effectors carry a signal peptide and an RxLR motif. Hyaloperonospora arabidopsidis (Hpa causes downy mildew on the model plant Arabidopsis thaliana (Arabidopsis. We investigated if candidate effectors predicted in the genome sequence of Hpa isolate Emoy2 (HaRxLs were able to manipulate host defenses in different Arabidopsis accessions. We developed a rapid and sensitive screening method to test HaRxLs by delivering them via the bacterial type-three secretion system (TTSS of Pseudomonas syringae pv tomato DC3000-LUX (Pst-LUX and assessing changes in Pst-LUX growth in planta on 12 Arabidopsis accessions. The majority (~70% of the 64 candidates tested positively contributed to Pst-LUX growth on more than one accession indicating that Hpa virulence likely involves multiple effectors with weak accession-specific effects. Further screening with a Pst mutant (ΔCEL showed that HaRxLs that allow enhanced Pst-LUX growth usually suppress callose deposition, a hallmark of pathogen-associated molecular pattern (PAMP-triggered immunity (PTI. We found that HaRxLs are rarely strong avirulence determinants. Although some decreased Pst-LUX growth in particular accessions, none activated macroscopic cell death. Fewer HaRxLs conferred enhanced Pst growth on turnip, a non-host for Hpa, while several reduced it, consistent with the idea that turnip's non-host resistance against Hpa could involve a combination of recognized HaRxLs and ineffective HaRxLs. We verified our results by constitutively expressing in Arabidopsis a sub-set of HaRxLs. Several transgenic lines showed increased susceptibility to Hpa and attenuation of Arabidopsis PTI responses, confirming the HaRxLs' role in Hpa virulence. This study shows TTSS screening system provides a useful tool to test whether

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

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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.

Feeding on Host Plants with Different Concentrations and Structures of Pyrrolizidine Alkaloids Impacts the Chemical-Defense Effectiveness of a Specialist Herbivore.

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Martins, Carlos H Z; Cunha, Beatriz P; Solferini, Vera N; Trigo, José R

2015-01-01

Sequestration of chemical defenses from host plants is a strategy widely used by herbivorous insects to avoid predation. Larvae of the arctiine moth Utetheisa ornatrix feeding on unripe seeds and leaves of many species of Crotalaria (Leguminosae) sequester N-oxides of pyrrolizidine alkaloids (PAs) from these host plants, and transfer them to adults through the pupal stage. PAs confer protection against predation on all life stages of U. ornatrix. As U. ornatrix also uses other Crotalaria species as host plants, we evaluated whether the PA chemical defense against predation is independent of host plant use. We fed larvae from hatching to pupation with either leaves or seeds of one of eight Crotalaria species (C. incana, C. juncea, C. micans, C. ochroleuca, C. pallida, C. paulina, C. spectabilis, and C. vitellina), and tested if adults were preyed upon or released by the orb-weaving spider Nephila clavipes. We found that the protection against the spider was more effective in adults whose larvae fed on seeds, which had a higher PA concentration than leaves. The exceptions were adults from larvae fed on C. paulina, C. spectabilis and C. vitellina leaves, which showed high PA concentrations. With respect to the PA profile, we describe for the first time insect-PAs in U. ornatrix. These PAs, biosynthesized from the necine base retronecine of plant origin, or monocrotaline- and senecionine-type PAs sequestered from host plants, were equally active in moth chemical defense, in a dose-dependent manner. These results are also partially explained by host plant phylogeny, since PAs of the host plants do have a phylogenetic signal (clades with high and low PA concentrations in leaves) which is reflected in the adult defense.

Feeding on Host Plants with Different Concentrations and Structures of Pyrrolizidine Alkaloids Impacts the Chemical-Defense Effectiveness of a Specialist Herbivore.

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Carlos H Z Martins

Full Text Available Sequestration of chemical defenses from host plants is a strategy widely used by herbivorous insects to avoid predation. Larvae of the arctiine moth Utetheisa ornatrix feeding on unripe seeds and leaves of many species of Crotalaria (Leguminosae sequester N-oxides of pyrrolizidine alkaloids (PAs from these host plants, and transfer them to adults through the pupal stage. PAs confer protection against predation on all life stages of U. ornatrix. As U. ornatrix also uses other Crotalaria species as host plants, we evaluated whether the PA chemical defense against predation is independent of host plant use. We fed larvae from hatching to pupation with either leaves or seeds of one of eight Crotalaria species (C. incana, C. juncea, C. micans, C. ochroleuca, C. pallida, C. paulina, C. spectabilis, and C. vitellina, and tested if adults were preyed upon or released by the orb-weaving spider Nephila clavipes. We found that the protection against the spider was more effective in adults whose larvae fed on seeds, which had a higher PA concentration than leaves. The exceptions were adults from larvae fed on C. paulina, C. spectabilis and C. vitellina leaves, which showed high PA concentrations. With respect to the PA profile, we describe for the first time insect-PAs in U. ornatrix. These PAs, biosynthesized from the necine base retronecine of plant origin, or monocrotaline- and senecionine-type PAs sequestered from host plants, were equally active in moth chemical defense, in a dose-dependent manner. These results are also partially explained by host plant phylogeny, since PAs of the host plants do have a phylogenetic signal (clades with high and low PA concentrations in leaves which is reflected in the adult defense.

Brood size and sex ratio in response to host quality and wasp traits in the gregarious parasitoid Oomyzus sokolowskii (Hymenoptera: Eulophidae

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Xianwei Li

2017-01-01

Full Text Available This laboratory study investigated whether the larval-pupal parasitoid Oomyzus sokolowskii females adjust their brood size and sex ratio in response to body size and stage of Plutella xylostella larval hosts, as well as to their own body size and the order of oviposition. These factors were analyzed using multiple regression with simultaneous entry of them and their two-way interactions. Parasitoids brood size tended to increase with host body size at parasitism when the 4th instar larval host was attacked, but did not change when the 2nd and 3rd instar larvae were attacked. Parasitoids did not vary in brood size according to their body size, but decreased with their bouts of oviposition on a linear trend from 10 offspring adults emerged per host in the first bout of oviposition down to eight in the third. Parasitoid offspring sex ratio did not change with host instar, host body weight, wasp body size, and oviposition bout. Proportions of male offspring per brood were from 11% to 13% from attacking the 2nd to 4th instar larvae and from 13% to 16% across three successive bouts of oviposition, with a large variation for smaller host larvae and wasps. When fewer than 12 offspring were emerged from a host, one male was most frequently produced; when more than 12 offspring were emerged, two or more males were produced. Our study suggests that O. sokolowskii females may optimize their clutch size in response to body size of mature P. xylostella larvae, and their sex allocation in response to clutch size.

A parasitic nematode releases cytokinin that controls cell division and orchestrates feeding site formation in host plants.

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Siddique, Shahid; Radakovic, Zoran S; De La Torre, Carola M; Chronis, Demosthenis; Novák, Ondřej; Ramireddy, Eswarayya; Holbein, Julia; Matera, Christiane; Hütten, Marion; Gutbrod, Philipp; Anjam, Muhammad Shahzad; Rozanska, Elzbieta; Habash, Samer; Elashry, Abdelnaser; Sobczak, Miroslaw; Kakimoto, Tatsuo; Strnad, Miroslav; Schmülling, Thomas; Mitchum, Melissa G; Grundler, Florian M W

2015-10-13

Sedentary plant-parasitic cyst nematodes are biotrophs that cause significant losses in agriculture. Parasitism is based on modifications of host root cells that lead to the formation of a hypermetabolic feeding site (a syncytium) from which nematodes withdraw nutrients. The host cell cycle is activated in an initial cell selected by the nematode for feeding, followed by activation of neighboring cells and subsequent expansion of feeding site through fusion of hundreds of cells. It is generally assumed that nematodes manipulate production and signaling of the plant hormone cytokinin to activate cell division. In fact, nematodes have been shown to produce cytokinin in vitro; however, whether the hormone is secreted into host plants and plays a role in parasitism remained unknown. Here, we analyzed the spatiotemporal activation of cytokinin signaling during interaction between the cyst nematode, Heterodera schachtii, and Arabidopsis using cytokinin-responsive promoter:reporter lines. Our results showed that cytokinin signaling is activated not only in the syncytium but also in neighboring cells to be incorporated into syncytium. An analysis of nematode infection on mutants that are deficient in cytokinin or cytokinin signaling revealed a significant decrease in susceptibility of these plants to nematodes. Further, we identified a cytokinin-synthesizing isopentenyltransferase gene in H. schachtii and show that silencing of this gene in nematodes leads to a significant decrease in virulence due to a reduced expansion of feeding sites. Our findings demonstrate the ability of a plant-parasitic nematode to synthesize a functional plant hormone to manipulate the host system and establish a long-term parasitic interaction.

[Host plants of Aphis gossypii (Aphididae), vector of virus of Cucumis melo melon (Cucurbitaceae) in Costa Rica].

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Sánchez, M V; Agüero, R; Rivera, C

2001-03-01

Plant species associated with commercial melon crops and surrounding areas were examined to identity the natural host plants of Aphis gossypii Glover. The study was conducted in two farms located in different melon production areas and plant life zones of Costa Rica. Plant species diversity, percent coverage and distribution over time were recorded during one year. Differences between locations were observed. A total of 86 plant species (49 families) and 72 plant species (40 families) were identified associated to the crop in farms A and B, respectively. In both farms a total of 24 species plants (16 families) were colonized by A. gossypii and 16 (10 families) are new reports of host plant species for this aphid. The new reports are: Justicia comata, Tetramerium nervosum, Alternanthera pubiflora, Cassia massoni, C. reticulata, Cleome viscosa, C. spinosa, Croton argenteus, Caperonia palustris, Chamaesyce gyssopilopia, Phyllantus amarus, Sida decumbens, Ludwigia erecta, Passiflora foetida, Guazuma ulmifolia and Corchorus orinocensis.

Role of emerald ash borer (Coleoptera: Buprestidae) larval vibrations in host-quality assessments by Tetrastichus planipennisi (Hymenoptera: Eulophidae)

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Michael D. Ulyshen; Richard W. Mankin; Yigen Chen; Jian J. Duan; Therese M. Poland; Leah S. Bauer

2011-01-01

The biological control agent Tetrastichus planipennisi Yang (Hymenoptera: Eulophidae) is a gregarious larval endoparasitoid of the emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), an invasive cambium-feeding species responsible for recent, widespread mortality of ash (Fraxinus spp.) in...

The Complex Cell Wall Composition of Syncytia Induced by Plant Parasitic Cyst Nematodes Reflects Both Function and Host Plant.

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Zhang, Li; Lilley, Catherine J; Imren, Mustafa; Knox, J Paul; Urwin, Peter E

2017-01-01

Plant-parasitic cyst nematodes induce the formation of specialized feeding structures, syncytia, within their host roots. These unique plant organs serve as the sole nutrient resource for development and reproduction throughout the biotrophic interaction. The multinucleate syncytium, which arises through local dissolution of cell walls and protoplast fusion of multiple adjacent cells, has dense cytoplasm containing numerous organelles, surrounded by thickened outer cell walls that must withstand high turgor pressure. However, little is known about how the constituents of the syncytial cell wall and their conformation support its role during nematode parasitism. We used a set of monoclonal antibodies, targeted to a range of plant cell wall components, to reveal the microstructures of syncytial cell walls induced by four of the most economically important cyst nematode species, Globodera pallida , Heterodera glycines , Heterodera avenae and Heterodera filipjevi , in their respective potato, soybean, and spring wheat host roots. In situ fluorescence analysis revealed highly similar cell wall composition of syncytia induced by G. pallida and H. glycines . Both consisted of abundant xyloglucan, methyl-esterified homogalacturonan and pectic arabinan. In contrast, the walls of syncytia induced in wheat roots by H. avenae and H. filipjevi contain little xyloglucan but are rich in feruloylated xylan and arabinan residues, with variable levels of mixed-linkage glucan. The overall chemical composition of syncytial cell walls reflected the general features of root cell walls of the different host plants. We relate specific components of syncytial cell walls, such as abundant arabinan, methyl-esterification status of pectic homogalacturonan and feruloylation of xylan, to their potential roles in forming a network to support both the strength and flexibility required for syncytium function.

Common mycorrhizal networks amplify competition by preferential mineral nutrient allocation to large host plants.

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Weremijewicz, Joanna; Sternberg, Leonel da Silveira Lobo O'Reilly; Janos, David P

2016-10-01

Arbuscular mycorrhizal (AM) fungi interconnect plants in common mycorrhizal networks (CMNs) which can amplify competition among neighbors. Amplified competition might result from the fungi supplying mineral nutrients preferentially to hosts that abundantly provide fixed carbon, as suggested by research with organ-cultured roots. We examined whether CMNs supplied (15) N preferentially to large, nonshaded, whole plants. We conducted an intraspecific target-neighbor pot experiment with Andropogon gerardii and several AM fungi in intact, severed or prevented CMNs. Neighbors were supplied (15) N, and half of the target plants were shaded. Intact CMNs increased target dry weight (DW), intensified competition and increased size inequality. Shading decreased target weight, but shaded plants in intact CMNs had mycorrhizal colonization similar to that of sunlit plants. AM fungi in intact CMNs acquired (15) N from the substrate of neighbors and preferentially allocated it to sunlit, large, target plants. Sunlit, intact CMN, target plants acquired as much as 27% of their nitrogen from the vicinity of their neighbors, but shaded targets did not. These results suggest that AM fungi in CMNs preferentially provide mineral nutrients to those conspecific host individuals best able to provide them with fixed carbon or representing the strongest sinks, thereby potentially amplifying asymmetric competition below ground. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

Modeling the effects of integrating larval habitat source reduction and insecticide treated nets for malaria control.

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Laith Yakob

Full Text Available Integrated vector management for malaria control has received a lot of recent interest. Attacking multiple points in the transmission cycle is hoped to act synergistically and improve upon current single-tool interventions based on the use of insecticide-treated bed nets (ITNs. In the present study, we theoretically examined the application of larval habitat source reduction with ITNs in reducing malaria transmission. We selected this type of environmental management to complement ITNs because of a potential secondary mode of action that both control strategies share. In addition to increasing vector mortality, ITNs reduce the rate at which female mosquitoes locate human hosts for blood feeding, thereby extending their gonotrophic cycle. Similarly, while reducing adult vector emergence and abundance, source reduction of larval habitats may prolong the cycle duration by extending delays in locating oviposition sites. We found, however, that source reduction of larval habitats only operates through this secondary mode of action when habitat density is below a critical threshold. Hence, we illustrate how this strategy becomes increasingly effective when larval habitats are limited. We also demonstrate that habitat source reduction is better suited to human populations of higher density and in the presence of insecticide resistance or when the insecticidal properties of ITNs are depleted.

Chemical modification of L-glutamine to alpha-amino glutarimide on autoclaving facilitates Agrobacterium infection of host and non-host plants: A new use of a known compound

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Das Pralay

2011-05-01

Full Text Available Abstract Background Accidental autoclaving of L-glutamine was found to facilitate the Agrobacterium infection of a non host plant like tea in an earlier study. In the present communication, we elucidate the structural changes in L-glutamine due to autoclaving and also confirm the role of heat transformed L-glutamine in Agrobacterium mediated genetic transformation of host/non host plants. Results When autoclaved at 121°C and 15 psi for 20 or 40 min, L-glutamine was structurally modified into 5-oxo proline and 3-amino glutarimide (α-amino glutarimide, respectively. Of the two autoclaved products, only α-amino glutarimide facilitated Agrobacterium infection of a number of resistant to susceptible plants. However, the compound did not have any vir gene inducing property. Conclusions We report a one pot autoclave process for the synthesis of 5-oxo proline and α-amino glutarimide from L-glutamine. Xenobiotic detoxifying property of α-amino glutarimide is also proposed.

Among-population variation in tolerance to larval herbivory by Anthocharis cardamines in the polyploid herb Cardamine pratensis.

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Malin A E König

Full Text Available Plants have two principal defense mechanisms to decrease fitness losses to herbivory: tolerance, the ability to compensate fitness after damage, and resistance, the ability to avoid damage. Variation in intensity of herbivory among populations should result in variation in plant defense levels if tolerance and resistance are associated with costs. Yet little is known about how levels of tolerance are related to resistance and attack intensity in the field, and about the costs of tolerance. In this study, we used information about tolerance and resistance against larval herbivory by the butterfly Anthocharis cardamines under controlled conditions together with information about damage in the field for a large set of populations of the perennial plant Cardamine pratensis. Plant tolerance was estimated in a common garden experiment where plants were subjected to a combination of larval herbivory and clipping. We found no evidence of that the proportion of damage that was caused by larval feeding vs. clipping influenced plant responses. Damage treatments had a negative effect on the three measured fitness components and also resulted in an earlier flowering in the year after the attack. Tolerance was related to attack intensity in the population of origin, i.e. plants from populations with higher attack intensity were more likely to flower in the year following damage. However, we found no evidence of a relationship between tolerance and resistance. These results indicate that herbivory drives the evolution for increased tolerance, and that changes in tolerance are not linked to changes in resistance. We suggest that the simultaneous study of tolerance, attack intensity in the field and resistance constitutes a powerful tool to understand how plant strategies to avoid negative effects of herbivore damage evolve.

New records and new host plants of powdery mildews (Erysiphales) from Idaho and Oregon (USA)

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Uwe Braun; S. Krishna Mohan

2013-01-01

In the course of routine examinations of powdery mildews collected in Idaho and Oregon, USA, some of the identified species proved to be new to North America, in some cases on new host plants. Leveillula papilionacearum and L. picridis are first records from the USA. Astragalus filipes, Dalea ornata and D. searlsiae are new hosts for Leveillula papilionacearum....

A global phylogeny of leafmining Ectoedemia moths (Lepidoptera: Nepticulidae): exploring host plant family shifts and allopatry as drivers of speciation.

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Doorenweerd, Camiel; van Nieukerken, Erik J; Menken, Steph B J

2015-01-01

Host association patterns in Ectoedemia (Lepidoptera: Nepticulidae) are also encountered in other insect groups with intimate plant relationships, including a high degree of monophagy, a preference for ecologically dominant plant families (e.g. Fagaceae, Rosaceae, Salicaceae, and Betulaceae) and a tendency for related insect species to feed on related host plant species. The evolutionary processes underlying these patterns are only partly understood, we therefore assessed the role of allopatry and host plant family shifts in speciation within Ectoedemia. Six nuclear and mitochondrial DNA markers with a total aligned length of 3692 base pairs were used to infer phylogenetic relationships among 92 species belonging to the subgenus Ectoedemia of the genus Ectoedemia, representing a thorough taxon sampling with a global coverage. The results support monophyletic species groups that are congruent with published findings based on morphology. We used the obtained phylogeny to explore host plant family association and geographical distribution to investigate if host shifts and allopatry have been instrumental in the speciation of these leafmining insects. We found that, even though most species within species groups commonly feed on plants from one family, shifts to a distantly related host family have occasionally occurred throughout the phylogeny and such shifts are most commonly observed towards Betulaceae. The largest radiations have occurred within species groups that feed on Fagaceae, Rosaceae, and Salicaceae. Most species are restricted to one of the seven global biogeographic regions, but within species groups representatives are commonly found in different biogeographic regions. Although we find general patterns with regard to host use and biogeography, there are differences between clades that suggest that different drivers of speciation, and perhaps drivers that we did not examine, have shaped diversity patterns in different clades.

Parasitismo larval de Crocidosema (=Epinotia aporema (Lepidoptera: Tortricidae en el noreste de la provincia de Buenos Aires (Argentina Larval parasitism of Crocidosema (=Epinotia aporema (Lepidoptera: Tortricidae in north-eastern Buenos Aires province (Argentina

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Gerardo Liljesthröm

2005-07-01

Full Text Available En la interacción huésped-parasitoide las plantas suelen emitir señales capaces de aumentar la eficiencia de los parasitoides. Las larvas de Crocidosema (=Epinotia aporema (Walsingham se alimentan endofíticamente de leguminosas herbáceas y constituyen una plaga de la soja (Glycine max Merrill. En este estudio analizamos el parasitismo larval de C. aporema en Melilotus albus Medikus, Galega officinalis L, Lupinus albus L y G. max, en el noreste de Buenos Aires. La densidad larval fue mayor en L. albus (109,2 larvas/m² que en las restantes leguminosas: 3,7; 6,9 y 11,3 en M. albus, G. officinalis y G. max, respectivamente. Sin embargo, el parasitismo y número de especies parasitoides fueron menores en L. albus (9,5% por el ectoparasitoide generalista Bracon sp. que en M. albus (32,6%, Bracon sp. y los endoparasitoides Trathala sp.y Bassus sp.; G. officinalis y G. max (26,4% y 50,6% respectivamente, con Trathala sp. y Bracon sp. en ambas. Lupinus albus fue la única especie vegetal que reaccionó a la alimentación de C. aporema con producción de exudados pegajosos y olorosos que podrían haber repelido los endoparasitoides, actuando como un refugio parcial para C. aporema. Además, al ser positivamente seleccionada por C. aporema, esta leguminosa podría utilizarse como franja trampa para su control en cultivos de soja, de manera compatible con tácticas de control biológico por conservación de enemigos naturales.In host-parasitoid interactions, parasitoid efficiency may be increased by different quantity and quality of plant signals. Crocidosema (=Epinotia aporema (Walsingham is a pest on soybean, with larvae feeding endophitically on various herbaceous leguminosae. In this study we analyzed larval parasitism of C. aporema on Melilotus albus Medikus, Galega officinalis L, Lupinus albus L and Glycine max Merrill in the north-east of the Buenos Aires province. Larval density was higher on L. albus (109,2 larvae/m², than on the other

Reevaluating the conceptual framework for applied research on host-plant resistance.

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Stout, Michael J

2013-06-01

Applied research on host-plant resistance to arthropod pests has been guided over the past 60 years by a framework originally developed by Reginald Painter in his 1951 book, Insect Resistance in Crop Plants. Painter divided the "phenomena" of resistance into three "mechanisms," nonpreference (later renamed antixenosis), antibiosis, and tolerance. The weaknesses of this framework are discussed. In particular, this trichotomous framework does not encompass all known mechanisms of resistance, and the antixenosis and antibiosis categories are ambiguous and inseparable in practice. These features have perhaps led to a simplistic approach to understanding arthropod resistance in crop plants. A dichotomous scheme is proposed as a replacement, with a major division between resistance (plant traits that limit injury to the plant) and tolerance (plant traits that reduce amount of yield loss per unit injury), and the resistance category subdivided into constitutive/inducible and direct/indirect subcategories. The most important benefits of adopting this dichotomous scheme are to more closely align the basic and applied literatures on plant resistance and to encourage a more mechanistic approach to studying plant resistance in crop plants. A more mechanistic approach will be needed to develop novel approaches for integrating plant resistance into pest management programs. © 2012 Institute of Zoology, Chinese Academy of Sciences.

Host and Symbiont Jointly Control Gut Microbiota during Complete Metamorphosis

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Johnston, Paul R.; Rolff, Jens

2015-01-01

Holometabolous insects undergo a radical anatomical re-organisation during metamorphosis. This poses a developmental challenge: the host must replace the larval gut but at the same time retain symbiotic gut microbes and avoid infection by opportunistic pathogens. By manipulating host immunity and bacterial competitive ability, we study how the host Galleria mellonella and the symbiotic bacterium Enterococcus mundtii interact to manage the composition of the microbiota during metamorphosis. Disenabling one or both symbiotic partners alters the composition of the gut microbiota, which incurs fitness costs: adult hosts with a gut microbiota dominated by pathogens such as Serratia and Staphylococcus die early. Our results reveal an interaction that guarantees the safe passage of the symbiont through metamorphosis and benefits the resulting adult host. Host-symbiont “conspiracies” as described here are almost certainly widespread in holometobolous insects including many disease vectors. PMID:26544881

Effects of water availability on emerald ash borer larval performance and phloem phenolics of Manchurian and black ash.

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Chakraborty, Sourav; Whitehill, Justin G A; Hill, Amy L; Opiyo, Stephen O; Cipollini, Don; Herms, Daniel A; Bonello, Pierluigi

2014-04-01

The invasive emerald ash borer (EAB) beetle is a significant threat to the survival of North American ash. In previous work, we identified putative biochemical and molecular markers of constitutive EAB resistance in Manchurian ash, an Asian species co-evolved with EAB. Here, we employed high-throughput high-performance liquid chromatography with photodiode array detection and mass spectrometry (HPLC-PDA-MS) to characterize the induced response of soluble phloem phenolics to EAB attack in resistant Manchurian and susceptible black ash under conditions of either normal or low water availability, and the effects of water availability on larval performance. Total larval mass per tree was lower in Manchurian than in black ash. Low water increased larval numbers and mean larval mass overall, but more so in Manchurian ash. Low water did not affect levels of phenolics in either host species, but six phenolics decreased in response to EAB. In both ashes, pinoresinol A was induced by EAB, especially in Manchurian ash. Pinoresinol A and pinoresinol B were negatively correlated with each other in both species. The higher accumulation of pinoresinol A in Manchurian ash after attack may help explain the resistance of this species to EAB, but none of the responses measured here could explain increased larval performance in trees subjected to low water availability. © 2013 John Wiley & Sons Ltd.

Evaluating the non-rice host plant species of Sesamia inferens (Lepidoptera: Noctuidae) as natural refuges: resistance management of Bt rice.

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Liu, Zhuorong; Gao, Yulin; Luo, Ju; Lai, Fengxiang; Li, Yunhe; Fu, Qiang; Peng, Yufa

2011-06-01

Although rice (Oryza sativa L.) lines that express Bacillus thuringiensis (Bt) toxins have shown great potential for managing the major Lepidoptera pests of rice in southern China, including Sesamia inferens, their long-term use is dependent on managing resistance development to Bt toxins in pest populations. The maintenance of "natural" refuges, non-Bt expressing plants that are hosts for a target pest, has been proposed as a means to minimize the evolution of resistance to Bt toxins in transgenic plants. In the current study, field surveys and greenhouse experiments were conducted to identify host plants of S. inferens that could serve as "natural" refuges in rice growing areas of southern China. A field survey showed that 34 plant species in four families can be alternative host plants of S. inferens. Based on injury level under field conditions, rice (Oryza sativa L.); water oat (Zizania latifolia Griseb.); corn (Zea mays L.); tidalmarsh flatsedge (Cyperus serotinus Rottb.); and narrow-leaved cat-tail (Typha angustifolia Linn.) were identified as the primary host plant species of S. inferens. Greenhouse experiments further demonstrated that water oat, corn, and narrow-leaved cat-tail could support the survival and development of S. inferens. Interestingly, greenhouse experiments showed that S. inferens preferred to lay eggs on tidalmarsh flatsedge compared with the other three nonrice host species, although no pupae were found in the plants examined in field surveys. Few larvae were found to survive on tidalmarsh flatsedge in greenhouse bioassays, suggesting that tidalmarsh flatsedge could serve as a "dead-end" trap crop for S. inferens, but is not a candidate to serve as natural refuge to maintain susceptible S. inferens. Overall, these results suggest that water-oat, corn, and narrow-leaved cat-tail might serve as "natural refuge" for S. inferens in rice planting area of southern China when Bt rice varieties are planted.

Botanical compound p-anisaldehyde repels larval lone star tick, Amblyomma americanum (L.) (Acari: Ixodidae), and halts reproduction by gravid adults

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The lone star tick, Amblyomma americanum (L.), widely distributed across eastern, southeastern, and midwestern regions of the United States and south into Mexico, is an obligate blood feeder that attaches to three hosts during the larval, nymphal, and adult stages. White-tailed deer and wild turkey ...

Fitness cost of resistance to Bt cotton linked with increased gossypol content in pink bollworm larvae.

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Jennifer L Williams

Full Text Available Fitness costs of resistance to Bacillus thuringiensis (Bt crops occur in the absence of Bt toxins, when individuals with resistance alleles are less fit than individuals without resistance alleles. As costs of Bt resistance are common, refuges of non-Bt host plants can delay resistance not only by providing susceptible individuals to mate with resistant individuals, but also by selecting against resistance. Because costs typically vary across host plants, refuges with host plants that magnify costs or make them less recessive could enhance resistance management. Limited understanding of the physiological mechanisms causing fitness costs, however, hampers attempts to increase costs. In several major cotton pests including pink bollworm (Pectinophora gossypiella, resistance to Cry1Ac cotton is associated with mutations altering cadherin proteins that bind this toxin in susceptible larvae. Here we report that the concentration of gossypol, a cotton defensive chemical, was higher in pink bollworm larvae with cadherin resistance alleles than in larvae lacking such alleles. Adding gossypol to the larval diet decreased larval weight and survival, and increased the fitness cost affecting larval growth, but not survival. Across cadherin genotypes, the cost affecting larval growth increased as the gossypol concentration of larvae increased. These results suggest that increased accumulation of plant defensive chemicals may contribute to fitness costs associated with resistance to Bt toxins.

The wasp larva's last supper: 100 million years of evolutionary stasis in the larval development of rhopalosomatid wasps (Hymenoptera: Rhopalosomatidae

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V. Lohrmann

2017-08-01

Full Text Available Rhopalosomatidae are an unusual family of wasps (Hymenoptera: Aculeata comprising less than 100 species found in the tropics and subtropics of all continents except Europe and Antarctica. Whereas some species resemble nocturnal Ichneumonidae, others might be mistaken for spider wasps or different groups of brachypterous Hymenoptera. Despite their varied morphology, all members of the family supposedly develop as larval ectoparasitoids of crickets (Orthoptera: Grylloidea. Here, we report on the first record of a fossil rhopalosomatid larva which was discovered in mid-Cretaceous amber from northern Myanmar (Burma. The larva is attached to the lateral side of a cricket between the metafemur and the abdomen, impacting the natural position of the hind leg, exactly as documented for modern species. Additionally, the larval gestalt is strikingly similar to those of extant forms. These observations imply that this behavioral specialization, e.g., host association and positioning on host, likely evolved in the stem of the family at least 100 million years ago.

Does host complement kill Borrelia burgdorferi within ticks?

Science.gov (United States)

Rathinavelu, Sivaprakash; Broadwater, Anne; de Silva, Aravinda M

2003-02-01

The Lyme disease spirochete, Borrelia burgdorferi, inhabits the gut lumen of the tick vector. At this location the spirochete is exposed to host blood when a tick feeds. We report here on studies that were done with normal and complement-deficient (C3-knockout) mice to determine if the host complement system killed spirochetes within the vector. We found that spirochete numbers within feeding nymphs were not influenced by complement, most likely because host complement was inactivated within the vector. The Lyme disease outer surface protein A (OspA) vaccine is a transmission-blocking vaccine that targets spirochetes in the vector. In experiments with mice hyperimmunized with OspA, complement was not required to kill spirochetes within nymphs and to block transmission from nymphs to the vaccinated host. However, host complement did enhance the ability of OspA antibody to block larvae from acquiring spirochetes. Thus, the effects of OspA antibody on nymphal transmission and larval acquisition appear to be based on different mechanisms.

Turbulence-enhanced prey encounter rates in larval fish : Effects of spatial scale, larval behaviour and size

DEFF Research Database (Denmark)

Kiørboe, Thomas; MacKenzie, Brian

1995-01-01

Turbulent water motion has several effects on the feeding ecology of larval fish and other planktivorous predators. In this paper, we consider the appropriate spatial scales for estimating relative velocities between larval fish predators and their prey, and the effect that different choices of s...... in the range in which turbulent intensity has an overall positive effect on larval fish ingestion rate probability. However, experimental data to test the model predictions are lacking. We suggest that the model inputs require further empirical study....

Negative plant-phyllosphere feedbacks in native Asteraceae hosts - a novel extension of the plant-soil feedback framework.

Science.gov (United States)

Whitaker, Briana K; Bauer, Jonathan T; Bever, James D; Clay, Keith

2017-08-01

Over the past 25 years, the plant-soil feedback (PSF) framework has catalyzed our understanding of how belowground microbiota impact plant fitness and species coexistence. Here, we apply a novel extension of this framework to microbiota associated with aboveground tissues, termed 'plant-phyllosphere feedback (PPFs)'. In parallel greenhouse experiments, rhizosphere and phyllosphere microbiota of con- and heterospecific hosts from four species were independently manipulated. In a third experiment, we tested the combined effects of soil and phyllosphere feedback under field conditions. We found that three of four species experienced weak negative PSF whereas, in contrast, all four species experienced strong negative PPFs. Field-based feedback estimates were highly negative for all four species, though variable in magnitude. Our results suggest that phyllosphere microbiota, like rhizosphere microbiota, can potentially mediate plant species coexistence via negative feedbacks. Extension of the PSF framework to the phyllosphere is needed to more fully elucidate plant-microbiota interactions. © 2017 John Wiley & Sons Ltd/CNRS.

A Century of Plant Pathology: A Retrospective View on Understanding Host-Parasite Interactions.

Science.gov (United States)

Keen, N T

2000-09-01

▪ Abstract  The twentieth century has been productive for the science of plant pathology and the field of host-parasite interactions-both in understanding how pathogens and plant defense work and in developing more effective means of disease control. Early in the twentieth century, plant pathology adopted a philosophy that encouraged basic scientific investigation of pathogens and disease defense. That philosophy led to the strategy of developing disease-resistant plants as a prima facie disease-control measure-and in the process saved billions of dollars and avoided the use of tons of pesticides. Plant pathology rapidly adopted molecular cloning and its spin-off technologies, and these have fueled major advances in our basic understanding of plant diseases. This knowledge and the development of efficient technologies for producing transgenic plants convey optimism that plant diseases will be more efficiently controlled in the twenty-first century.

Geographic variation in host fish use and larval metamorphosis for the endangered dwarf wedgemussel

Science.gov (United States)

White, Barbara (St. John); Ferreri, C. Paola; Lellis, William A.; Wicklow, Barry J.; Cole, Jeffrey C.

2017-01-01

Host fishes play a crucial role in survival and dispersal of freshwater mussels (Unionoida), particularly rare unionids at conservation risk. Intraspecific variation in host use is not well understood for many mussels, including the endangered dwarf wedgemussel (Alasmidonta heterodon) in the USA.Host suitability of 33 fish species for dwarf wedgemussel glochidia (larvae) from the Delaware and Connecticut river basins was tested in laboratory experiments over 9 years. Relative suitability of three different populations of a single host fish, the tessellated darter (Etheostoma olmstedi), from locations in the Connecticut, Delaware, and Susquehanna river basins, was also tested.Connecticut River basin A. heterodon metamorphosed into juvenile mussels on tessellated darter, slimy sculpin (Cottus cognatus), and Atlantic salmon (Salmo salar) parr. Delaware River basin mussels metamorphosed using these three species, as well as brown trout (Salmo trutta), banded killifish (Fundulus diaphanus), mottled sculpin (Cottus bairdii), striped bass (Morone saxatilis), and shield darter (Percina peltata). Atlantic salmon, striped bass, and sculpins were highly effective hosts, frequently generating 5+ juveniles per fish (JPF) and metamorphosis success (MS; proportion of attaching larvae that successfully metamorphose) ≥ 0.4, and producing juveniles in repeated trials.In experiments on tessellated darters, mean JPF and MS values decreased as isolation between the mussel source (Connecticut River) and each fish source increased; mean JPF = 10.45, 6.85, 4.14, and mean MS = 0.50, 0.41, and 0.34 in Connecticut, Delaware, and Susquehanna river darters, respectively. Host suitability of individual darters was highly variable (JPF = 2–11; MS = 0.20–1.0).The results show that mussel–host fish compatibility in A. heterodon differs among Atlantic coastal rivers, and suggest that hosts including anadromous Atlantic salmon and striped bass may help sustain A. heterodon in parts of

Diversification rates, host plant shifts and an updated molecular phylogeny of Andean Eois moths (Lepidoptera: Geometridae.

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Patrick Strutzenberger

Full Text Available Eois is one of the best-investigated genera of tropical moths. Its close association with Piper plants has inspired numerous studies on life histories, phylogeny and evolutionary biology. This study provides an updated view on phylogeny, host plant use and temporal patterns of speciation in Eois. Using sequence data (2776 bp from one mitochondrial (COI and one nuclear gene (Ef1-alpha for 221 Eois species, we confirm and reinforce previous findings regarding temporal patterns of diversification. Deep diversification within Andean Eois took place in the Miocene followed by a sustained high rate of diversification until the Pleistocene when a pronounced slowdown of speciation is evident. In South America, Eois diversification is very likely to be primarily driven by the Andean uplift which occurred concurrently with the entire evolutionary history of Eois. A massively expanded dataset enabled an in-depth look into the phylogenetic signal contained in host plant usage. This revealed several independent shifts from Piper to other host plant genera and families. Seven shifts to Peperomia, the sister genus of Piper were detected, indicating that the shift to Peperomia was an easy one compared to the singular shifts to the Chloranthaceae, Siparunaceae and the Piperacean genus Manekia. The potential for close co-evolution of Eois with Piper host plants is therefore bound to be limited to smaller subsets within Neotropical Eois instead of a frequently proposed genus-wide co-evolutionary scenario. In regards to Eois systematics we confirm the monophyly of Neotropical Eois in relation to their Old World counterparts. A tentative biogeographical hypothesis is presented suggesting that Eois originated in tropical Asia and subsequently colonized the Neotropics and Africa. Within Neotropical Eois we were able to identify the existence of six clades not recognized in previous studies and confirm and reinforce the monophyly of all 9 previously delimited

Distribution of larval and pupal stages of Simulium (Diptera: Simuliidae) flies in the Nilgiris hills of Tamil Nadu.

Science.gov (United States)

Soundararajan, C; Nagarajan, K; Arul Prakash, M

2017-09-01

Endemicity of onchocerciasis (river blindness) in humans is linked to the location of Simulium spp. (black fly). The distribution of immature stages of Simulium in Sholur, Pykara, Gudalur, Coonoor and Kotagiri streams of the Nilgiris hills of Tamil Nadu was investigated during the months of May and July 2012. Out of these five streams, only Sholur was infested with larval and pupal stages of Simulium spp. Out of six plants collected from various water bodies, larval and pupal stages were found on the leaves and stems of an aquatic plant Nasturtium officinale and on the roots and leaves of Pennisetum glandulosum. The stages of Simulium were observed only during the summer month of May.

The genetic architecture of a complex ecological trait: host plant use in the specialist moth, HELIOTHIS SUBFLEXA

Science.gov (United States)

The study of the genetic basis of ecological adaptation remains in its infancy, and most studies have focused on phenotypically simple traits. Host plant use by herbivorous insects is phenotypically complex. While research has illuminated the evolutionary determinants of host use, knowledge of its...

Herbivore handling of a plant's trichome: the case of Heliconius charithonia (L.) (Lepidoptera: Nymphalidae) and Passiflora lobata (Killip) Hutch. (Passifloraceae)

International Nuclear Information System (INIS)

Cardoso, Marcio Z.

2008-01-01

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)

Non-thermal plasma treatment diminishes fungal viability and up-regulates resistance genes in a plant host.

Science.gov (United States)

Panngom, Kamonporn; Lee, Sang Hark; Park, Dae Hoon; Sim, Geon Bo; Kim, Yong Hee; Uhm, Han Sup; Park, Gyungsoon; Choi, Eun Ha

2014-01-01

Reactive oxygen and nitrogen species can have either harmful or beneficial effects on biological systems depending on the dose administered and the species of organism exposed, suggesting that application of reactive species can possibly produce contradictory effects in disease control, pathogen inactivation and activation of host resistance. A novel technology known as atmospheric-pressure non-thermal plasma represents a means of generating various reactive species that adversely affect pathogens (inactivation) while simultaneously up-regulating host defense genes. The anti-microbial efficacy of this technology was tested on the plant fungal pathogen Fusarium oxysporum f.sp. lycopersici and its susceptible host plant species Solanum lycopercicum. Germination of fungal spores suspended in saline was decreased over time after exposed to argon (Ar) plasma for 10 min. Although the majority of treated spores exhibited necrotic death, apoptosis was also observed along with the up-regulation of apoptosis related genes. Increases in the levels of peroxynitrite and nitrite in saline following plasma treatment may have been responsible for the observed spore death. In addition, increased transcription of pathogenesis related (PR) genes was observed in the roots of the susceptible tomato cultivar (S. lycopercicum) after exposure to the same Ar plasma dose used in fungal inactivation. These data suggest that atmospheric-pressure non-thermal plasma can be efficiently used to control plant fungal diseases by inactivating fungal pathogens and up-regulating mechanisms of host resistance.

Evaluating sampling strategies for larval cisco (Coregonus artedi)

Science.gov (United States)

Myers, J.T.; Stockwell, J.D.; Yule, D.L.; Black, J.A.

2008-01-01

To improve our ability to assess larval cisco (Coregonus artedi) populations in Lake Superior, we conducted a study to compare several sampling strategies. First, we compared density estimates of larval cisco concurrently captured in surface waters with a 2 x 1-m paired neuston net and a 0.5-m (diameter) conical net. Density estimates obtained from the two gear types were not significantly different, suggesting that the conical net is a reasonable alternative to the more cumbersome and costly neuston net. Next, we assessed the effect of tow pattern (sinusoidal versus straight tows) to examine if propeller wash affected larval density. We found no effect of propeller wash on the catchability of larval cisco. Given the availability of global positioning systems, we recommend sampling larval cisco using straight tows to simplify protocols and facilitate straightforward measurements of volume filtered. Finally, we investigated potential trends in larval cisco density estimates by sampling four time periods during the light period of a day at individual sites. Our results indicate no significant trends in larval density estimates during the day. We conclude estimates of larval cisco density across space are not confounded by time at a daily timescale. Well-designed, cost effective surveys of larval cisco abundance will help to further our understanding of this important Great Lakes forage species.

Mining the plant-herbivore interface with a leafmining Drosophila of Arabidopsis

Science.gov (United States)

Whiteman, Noah K.; Groen, Simon C.; Chevasco, Daniela; Bear, Ashley; Beckwith, Noor; Gregory, T. Ryan; Denoux, Carine; Mammarella, Nicole; Ausubel, Frederick M.; Pierce, Naomi E.

2010-01-01

Experimental infections of Arabidopsis thaliana (Arabidopsis) with genomically characterized plant pathogens such as Pseudomonas syringae have facilitated dissection of canonical eukaryotic defense pathways and parasite virulence factors. Plants are also attacked by herbivorous insects, and the development of an ecologically relevant genetic model herbivore that feeds on Arabidopsis will enable the parallel dissection of host defense and reciprocal resistance pathways such as those involved in xenobiotic metabolism. An ideal candidate is Scaptomyza flava, a drosophilid fly whose leafmining larvae are true herbivores that can be found in nature feeding on Arabidopsis and other crucifers. Here we describe the eukaryotic life cycle of S. flava on Arabidopsis, and use multiple approaches to characterize the response of Arabidopsis to S. flava attack. Oviposition choice tests and growth performance assays on different Arabidopsis ecotypes, defense-related mutants, and hormone and chitin-treated plants revealed significant differences in host preference and variation in larval performance across Arabidopsis accessions. The jasmonate (JA) and glucosinolate pathways in Arabidopsis are important in mediating quantitative resistance against S. flava, and priming with JA or chitin resulted in increased resistance. Expression of xenobiotic detoxification genes was reduced in S. flava larvae reared on Arabidopsis JA signaling mutants, and increased in plants pre-treated with chitin. These results and future research directions are discussed in the context of developing a genetic model system to analyze insect/plant interactions. PMID:21073583

An Evaluation of Butterfly Gardens for Restoring Habitat for the Monarch Butterfly (Lepidoptera: Danaidae).

Science.gov (United States)

Cutting, Brian T; Tallamy, Douglas W

2015-10-01

The eastern migratory monarch butterfly (Danaus plexippus L.) population in North America hit record low numbers during the 2013-2014 overwintering season, prompting pleas by scientists and conservation groups to plant the butterfly's milkweed host plants (Asclepias spp.) in residential areas. While planting butterfly gardens with host plants seems like an intuitive action, no previous study has directly compared larval survival in gardens and natural areas to demonstrate that gardens are suitable habitats for Lepidoptera. In this study, milkweed was planted in residential gardens and natural areas. In 2009 and 2010, plants were monitored for oviposition by monarch butterflies and survival of monarch eggs and caterpillars. Monarchs oviposited significantly more frequently in gardens than in natural sites, with 2.0 and 6.2 times more eggs per plant per observation in 2009 and 2010, respectively. There were no significant differences in overall subadult survival between gardens and natural areas. Significant differences in survival were measured for egg and larval cohorts when analyzed separately, but these were not consistent between years. These results suggest that planting gardens with suitable larval host plants can be an effective tool for restoring habitat for monarch butterflies. If planted over a large area, garden plantings may be useful as a partial mitigation for dramatic loss of monarch habitat in agricultural settings. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Novel synthetic compounds enhance the attractiveness of host-plant volatiles: An opportunity to boost detection and monitoring of Asian citrus psyllid?

Science.gov (United States)

In the absence of pheromone attractants, host-plant volatiles offer the most likely means of improving capture levels of Asian citrus psyllid (ACP) with sticky cards and other types of visual traps. However, developing scent lures that can compete with the attractiveness of actual host-plants, espe...

Isolated and Community Contexts Produce Distinct Responses by Host Plants to the Presence of Ant-Aphid Interaction: Plant Productivity and Seed Viability

Science.gov (United States)

Santiago, Graziele Silva; Zurlo, Luana Fonseca; Ribas, Carla Rodrigues; Carvalho, Rafaela Pereira; Alves, Guilherme Pereira; Carvalho, Mariana Comanucci Silva; Souza, Brígida

2017-01-01

Ant-aphid interactions may affect host plants in several ways, however, most studies measure only the amount of fruit and seed produced, and do not test seed viability. Therefore, the aim of this study was to assess the effects of the presence of ant-aphid interactions upon host plant productivity and seed viability in two different contexts: isolated and within an arthropod community. For this purpose we tested the hypothesis that in both isolated and community contexts, the presence of an ant-aphid interaction will have a positive effect on fruit and seed production, seed biomass and rate of seed germination, and a negative effect on abnormal seedling rates, in comparison to plants without ants. We performed a field mesocosm experiment containing five treatments: Ant-aphid, Aphid, Community, Ant-free community and Control. We counted fruits and seeds produced by each treatment, and conducted experiments for seed biomass and germinability. We found that in the community context the presence of an ant-aphid interaction negatively affected fruit and seed production. We think this may be because aphid attendance by tending-ants promotes aphid damage to the host plant, but without an affect on seed weight and viability. On the other hand, when isolated, the presence of an ant-aphid interaction positively affected fruit and seed production. These positive effects are related to the cleaning services offered to aphids by tending-ants, which prevent the development of saprophytic fungi on the surface of leaves, which would cause a decrease in photosynthetic rates. Our study is important because we evaluated some parameters of plant fitness that have not been addressed very well by other studies involving the effects of ant-aphid interactions mainly on plants with short life cycles. Lastly, our context dependent approach sheds new light on how ecological interactions can vary among different methods of crop management. PMID:28141849

Isolated and Community Contexts Produce Distinct Responses by Host Plants to the Presence of Ant-Aphid Interaction: Plant Productivity and Seed Viability.

Directory of Open Access Journals (Sweden)

Ernesto Oliveira Canedo-Júnior

Full Text Available Ant-aphid interactions may affect host plants in several ways, however, most studies measure only the amount of fruit and seed produced, and do not test seed viability. Therefore, the aim of this study was to assess the effects of the presence of ant-aphid interactions upon host plant productivity and seed viability in two different contexts: isolated and within an arthropod community. For this purpose we tested the hypothesis that in both isolated and community contexts, the presence of an ant-aphid interaction will have a positive effect on fruit and seed production, seed biomass and rate of seed germination, and a negative effect on abnormal seedling rates, in comparison to plants without ants. We performed a field mesocosm experiment containing five treatments: Ant-aphid, Aphid, Community, Ant-free community and Control. We counted fruits and seeds produced by each treatment, and conducted experiments for seed biomass and germinability. We found that in the community context the presence of an ant-aphid interaction negatively affected fruit and seed production. We think this may be because aphid attendance by tending-ants promotes aphid damage to the host plant, but without an affect on seed weight and viability. On the other hand, when isolated, the presence of an ant-aphid interaction positively affected fruit and seed production. These positive effects are related to the cleaning services offered to aphids by tending-ants, which prevent the development of saprophytic fungi on the surface of leaves, which would cause a decrease in photosynthetic rates. Our study is important because we evaluated some parameters of plant fitness that have not been addressed very well by other studies involving the effects of ant-aphid interactions mainly on plants with short life cycles. Lastly, our context dependent approach sheds new light on how ecological interactions can vary among different methods of crop management.

Insect Gallers and Their Plant Hosts: From Omics Data to Systems Biology

Directory of Open Access Journals (Sweden)

Caryn N. Oates

2016-11-01

Full Text Available Gall-inducing insects are capable of exerting a high level of control over their hosts’ cellular machinery to the extent that the plant’s development, metabolism, chemistry, and physiology are all altered in favour of the insect. Many gallers are devastating pests in global agriculture and the limited understanding of their relationship with their hosts prevents the development of robust management strategies. Omics technologies are proving to be important tools in elucidating the mechanisms involved in the interaction as they facilitate analysis of plant hosts and insect effectors for which little or no prior knowledge exists. In this review, we examine the mechanisms behind insect gall development using evidence from omics-level approaches. The secretion of effector proteins and induced phytohormonal imbalances are highlighted as likely mechanisms involved in gall development. However, understanding how these components function within the system is far from complete and a number of questions need to be answered before this information can be used in the development of strategies to engineer or breed plants with enhanced resistance.

Strong selection on mandible and nest features in a carpenter bee that nests in two sympatric host plants

OpenAIRE

Flores-Prado, Luis; Pinto, Carlos F; Rojas, Alejandra; Fontúrbel, Francisco E

2014-01-01

Host plants are used by herbivorous insects as feeding or nesting resources. In wood-boring insects, host plants features may impose selective forces leading to phenotypic differentiation on traits related to nest construction. Carpenter bees build their nests in dead stems or dry twigs of shrubs and trees; thus, mandibles are essential for the nesting process, and the nest is required for egg laying and offspring survival. We explored the shape and intensity of natural selection on phenotypi...

The photosynthetic bacteria Rhodobacter capsulatus and Synechocystis sp. PCC 6803 as new hosts for cyclic plant triterpene biosynthesis.

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Anita Loeschcke

Full Text Available Cyclic triterpenes constitute one of the most diverse groups of plant natural products. Besides the intriguing biochemistry of their biosynthetic pathways, plant triterpenes exhibit versatile bioactivities, including antimicrobial effects against plant and human pathogens. While prokaryotes have been extensively used for the heterologous production of other classes of terpenes, the synthesis of cyclic triterpenes, which inherently includes the two-step catalytic formation of the universal linear precursor 2,3-oxidosqualene, is still a major challenge. We thus explored the suitability of the metabolically versatile photosynthetic α-proteobacterium Rhodobacter capsulatus SB1003 and cyanobacterium Synechocystis sp. PCC 6803 as alternative hosts for biosynthesis of cyclic plant triterpenes. Therefore, 2,3-oxidosqualene production was implemented and subsequently combined with different cyclization reactions catalyzed by the representative oxidosqualene cyclases CAS1 (cycloartenol synthase, LUP1 (lupeol synthase, THAS1 (thalianol synthase and MRN1 (marneral synthase derived from model plant Arabidopsis thaliana. While successful accumulation of 2,3-oxidosqualene could be detected by LC-MS analysis in both hosts, cyclase expression resulted in differential production profiles. CAS1 catalyzed conversion to only cycloartenol, but expression of LUP1 yielded lupeol and a triterpenoid matching an oxidation product of lupeol, in both hosts. In contrast, THAS1 expression did not lead to cyclic product formation in either host, whereas MRN1-dependent production of marnerol and hydroxymarnerol was observed in Synechocystis but not in R. capsulatus. Our findings thus indicate that 2,3-oxidosqualene cyclization in heterologous phototrophic bacteria is basically feasible but efficient conversion depends on both the respective cyclase enzyme and individual host properties. Therefore, photosynthetic α-proteo- and cyanobacteria are promising alternative candidates

Population genetic structure of the lettuce root aphid, Pemphigus bursarius (L.), in relation to geographic distance, gene flow and host plant usage.

Science.gov (United States)

Miller, N J; Birley, A J; Overall, A D J; Tatchell, G M

2003-09-01

Microsatellite markers were used to examine the population structure of Pemphigus bursarius, a cyclically parthenogenetic aphid. Substantial allele frequency differences were observed between populations on the primary host plant (collected shortly after sexual reproduction) separated by distances as low as 14 km. This suggested that migratory movements occur over relatively short distances in this species. However, the degree of allele frequency divergence between populations was not correlated with their geographical separation, indicating that isolation by distance was not the sole cause of spatial genetic structuring. Significant excesses of homozygotes were observed in several populations. Substantial allele frequency differences were also found between aphids on the primary host and those sampled from a secondary host plant after several parthenogenetic generations at the same location in two successive years. This could have been due to the existence of obligately parthenogenetic lineages living on the secondary host or genetically divergent populations confined to different secondary host plant species but sharing a common primary host.

Identification of differentially expressed genes in brown planthopper Nilaparvata lugens (Hemiptera: Delphacidae) responding to host plant resistance.

Science.gov (United States)

Yang, Zhifan; Zhang, Futie; Zhu, Lili; He, Guangcun

2006-02-01

The brown planthopper Nilaparvata lugens Stål is one of the major insect pests of rice Oryza sativa L. The host resistance exhibits profound effects on growth, development and propagation of N. lugens. To investigate the molecular response of N. lugens to host resistance, a cDNA-amplified fragment length polymorphism (cDNA-AFLP) technique was employed to identify the differentially expressed genes in the nymphs feeding on three rice varieties. Of the 2,800 cDNA bands analysed, 54 were up-regulated and seven down-regulated qualitatively in N. lugens when the ingestion sources were changed from susceptible rice plants to resistant ones. Sequence analysis of the differential transcript-derived fragments showed that the genes involved in signalling, stress response, gene expression regulation, detoxification and metabolism were regulated by host resistance. Four of the transcript-derived fragments corresponding to genes encoding for a putative B subunit of phosphatase PP2A, a nemo kinase, a cytochrome P450 monooxygenase and a prolyl endopeptidase were further characterized in detail. Northern blot analysis confirmed that the expression of the four genes was enhanced in N. lugens feeding on resistant rice plants. The roles of these genes in the defensive response of N. lugens to host plant resistance were discussed.

Regulation Involved in Colonization of Intercellular Spaces of Host Plants in Ralstonia solanacearum

Directory of Open Access Journals (Sweden)

Yasufumi Hikichi

2017-06-01

Full Text Available A soil-borne bacterium Ralstonia solanacearum invading plant roots first colonizes the intercellular spaces of the root, and eventually enters xylem vessels, where it replicates at high levels leading to wilting symptoms. After invasion into intercellular spaces, R. solanacearum strain OE1-1 attaches to host cells and expression of the hrp genes encoding components of the type III secretion system (T3SS. OE1-1 then constructs T3SS and secrets effectors into host cells, inducing expression of the host gene encoding phosphatidic acid phosphatase. This leads to suppressing plant innate immunity. Then, OE1-1 grows on host cells, inducing quorum sensing (QS. The QS contributes to regulation of OE1-1 colonization of intercellular spaces including mushroom-type biofilm formation on host cells, leading to its virulence. R. solanacearum strains AW1 and K60 produce methyl 3-hydroxypalmitate (3-OH PAME as a QS signal. The methyltransferase PhcB synthesizes 3-OH PAME. When 3-OH PAME reaches a threshold level, it increases the ability of the histidine kinase PhcS to phosphorylate the response regulator PhcR. This results in elevated levels of functional PhcA, the global virulence regulator. On the other hand, strains OE1-1 and GMI1000 produce methyl 3-hydroxymyristate (3-OH MAME as a QS signal. Among R. solanacearum strains, the deduced PhcB and PhcS amino acid sequences are related to the production of QS signals. R. solanacearum produces aryl-furanone secondary metabolites, ralfuranones, which are extracellularly secreted and required for its virulence, dependent on the QS. Interestingly, ralfuranones affect the QS feedback loop. Taken together, integrated signaling via ralfuranones influences the QS, contributing to pathogen virulence.

A chitinase is required for Xylella fastidiosa colonization of its insect and plant hosts.

Science.gov (United States)

Labroussaa, Fabien; Ionescu, Michael; Zeilinger, Adam R; Lindow, Steven E; Almeida, Rodrigo P P

2017-04-01

Xylella fastidiosa colonizes the xylem network of host plant species as well as the foregut of its required insect vectors to ensure efficient propagation. Disease management strategies remain inefficient due to a limited comprehension of the mechanisms governing both insect and plant colonization. It was previously shown that X. fastidiosa has a functional chitinase (ChiA), and that chitin likely serves as a carbon source for this bacterium. We expand on that research, showing that a chiA mutant strain is unable to grow on chitin as the sole carbon source. Quantitative PCR assays allowed us to detect bacterial cells in the foregut of vectors after pathogen acquisition; populations of the wild-type and complemented mutant strain were both significantly larger than the chiA mutant strain 10 days, but not 3 days, post acquisition. These results indicate that adhesion of the chiA mutant strain to vectors may not be impaired, but that cell multiplication is limited. The mutant was also affected in its transmission by vectors to plants. In addition, the chiA mutant strain was unable to colonize host plants, suggesting that the enzyme has other substrates associated with plant colonization. Lastly, ChiA requires other X. fastidiosa protein(s) for its in vitro chitinolytic activity. The observation that the chiA mutant strain is not able to colonize plants warrants future attention to be paid to the substrates for this enzyme.

Seasonal forcing in a host-macroparasite system.

Science.gov (United States)

Taylor, Rachel A; White, Andrew; Sherratt, Jonathan A

2015-01-21

Seasonal forcing represents a pervasive source of environmental variability in natural systems. Whilst it is reasonably well understood in interacting populations and host-microparasite systems, it has not been studied in detail for host-macroparasite systems. In this paper we analyse the effect of seasonal forcing in a general host-macroparasite system with explicit inclusion of the parasite larval stage and seasonal forcing applied to the birth rate of the host. We emphasise the importance of the period of the limit cycles in the unforced system on the resulting dynamics in the forced system. In particular, when subject to seasonal forcing host-macroparasite systems are capable of multi-year cycles, multiple solution behaviour, quasi-periodicity and chaos. The host-macroparasite systems show a larger potential for multiple solution behaviour and a wider range of periodic solutions compared to similar interacting population and microparasite systems. By examining the system for parameters that represent red grouse and the macroparasite nematode Trichostrongylus tenuis we highlight how seasonality could be an important factor in explaining the wide range of seemingly uncorrelated cycle periods observed in grouse abundance in England and Scotland. Copyright © 2014 Elsevier Ltd. All rights reserved.

Effects of pseudo-microgravity on symbiosis between endophyte, Neotyphodium, and its host plant, tall fescue (Festuca arundinacea)

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Tomita-Yokotani, K.; Wakabayashi, K.; Hiraishi, K.; Yoshida, S.; Hashimoto, H.; Shinozaki, S.; Yamashita, M.

Endophyte is a group of microbes that symbiotically live in plant body Endophyte provides host plant its metabolites that protect the plant from insect pests In addition to this host plants are resistive against environmental stress In general endophyte lives in seeds to seeds of the infected plants through multiple generations The infection of fungi has never been observed and their original pathway is still unknown in nature The aim of this study is to examine whether this stable symbiosis between endophytes and its host plant would be modified under pseudo-microgravity or not We also aim to observe the infection under an exotic environment in terms of gravity We found that the internal hyphae of both the incubated plant under pseudo-microgravity and the ground control became indistinct with the number of incubation days A part of the endophyte in the seed under its autolysis was suggested because the amount of fungi in the base of the shoot that was observed with the incubated plant under the ground control was far less than that in the seed before sowing Hyphae began to grow in the germinating seed after a 3-day incubation period However a lot of aggregated fungi still existed in the 3-day incubated seed under pseudo-microgravity Moreover hyphae in the 3-day incubated seed under pseudo-microgravity were more indistinctly than that under the ground control The fungi were observed in the boundary of the seed and the shoot of the 5-day incubated seed under the ground control but not under pseudo-microgravity By this observation it was suggested that

Demographic models reveal the shape of density dependence for a specialist insect herbivore on variable host plants.

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Miller, Tom E X

2007-07-01

1. It is widely accepted that density-dependent processes play an important role in most natural populations. However, persistent challenges in our understanding of density-dependent population dynamics include evaluating the shape of the relationship between density and demographic rates (linear, concave, convex), and identifying extrinsic factors that can mediate this relationship. 2. I studied the population dynamics of the cactus bug Narnia pallidicornis on host plants (Opuntia imbricata) that varied naturally in relative reproductive effort (RRE, the proportion of meristems allocated to reproduction), an important plant quality trait. I manipulated per-plant cactus bug densities, quantified subsequent dynamics, and fit stage-structured models to the experimental data to ask if and how density influences demographic parameters. 3. In the field experiment, I found that populations with variable starting densities quickly converged upon similar growth trajectories. In the model-fitting analyses, the data strongly supported a model that defined the juvenile cactus bug retention parameter (joint probability of surviving and not dispersing) as a nonlinear decreasing function of density. The estimated shape of this relationship shifted from concave to convex with increasing host-plant RRE. 4. The results demonstrate that host-plant traits are critical sources of variation in the strength and shape of density dependence in insects, and highlight the utility of integrated experimental-theoretical approaches for identifying processes underlying patterns of change in natural populations.

Parasitism by Cuscuta pentagona attenuates host plant defenses against insect herbivores.

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Runyon, Justin B; Mescher, Mark C; De Moraes, Consuelo M

2008-03-01

Considerable research has examined plant responses to concurrent attack by herbivores and pathogens, but the effects of attack by parasitic plants, another important class of plant-feeding organisms, on plant defenses against other enemies has not been explored. We investigated how attack by the parasitic plant Cuscuta pentagona impacted tomato (Solanum lycopersicum) defenses against the chewing insect beet armyworm (Spodoptera exigua; BAW). In response to insect feeding, C. pentagona-infested (parasitized) tomato plants produced only one-third of the antiherbivore phytohormone jasmonic acid (JA) produced by unparasitized plants. Similarly, parasitized tomato, in contrast to unparasitized plants, failed to emit herbivore-induced volatiles after 3 d of BAW feeding. Although parasitism impaired antiherbivore defenses, BAW growth was slower on parasitized tomato leaves. Vines of C. pentagona did not translocate JA from BAW-infested plants: amounts of JA in parasite vines grown on caterpillar-fed and control plants were similar. Parasitized plants generally contained more salicylic acid (SA), which can inhibit JA in some systems. Parasitized mutant (NahG) tomato plants deficient in SA produced more JA in response to insect feeding than parasitized wild-type plants, further suggesting cross talk between the SA and JA defense signaling pathways. However, JA induction by BAW was still reduced in parasitized compared to unparasitized NahG, implying that other factors must be involved. We found that parasitized plants were capable of producing induced volatiles when experimentally treated with JA, indicating that resource depletion by the parasite does not fully explain the observed attenuation of volatile response to herbivore feeding. Collectively, these findings show that parasitic plants can have important consequences for host plant defense against herbivores.

Characterisation of Culex quinquefasciatus (Diptera: Culicidae larval habitats at ground level and temporal fluctuations of larval abundance in Córdoba, Argentina

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Marta Grech

2013-09-01

Full Text Available The aims of this study were to characterise the ground-level larval habitats of the mosquito Culex quinquefasciatus, to determine the relationships between habitat characteristics and larval abundance and to examine seasonal larval-stage variations in Córdoba city. Every two weeks for two years, 15 larval habitats (natural and artificial water bodies, including shallow wells, drains, retention ponds, canals and ditches were visited and sampled for larval mosquitoes. Data regarding the water depth, temperature and pH, permanence, the presence of aquatic vegetation and the density of collected mosquito larvae were recorded. Data on the average air temperatures and accumulated precipitation during the 15 days prior to each sampling date were also obtained. Cx. quinquefasciatus larvae were collected throughout the study period and were generally most abundant in the summer season. Generalised linear mixed models indicated the average air temperature and presence of dicotyledonous aquatic vegetation as variables that served as important predictors of larval densities. Additionally, permanent breeding sites supported high larval densities. In Córdoba city and possibly in other highly populated cities at the same latitude with the same environmental conditions, control programs should focus on permanent larval habitats with aquatic vegetation during the early spring, when the Cx. quinquefasciatus population begins to increase.

Within-host spatiotemporal dynamics of plant virus infection at the cellular level.

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Nicolas Tromas

2014-02-01

Full Text Available A multicellular organism is not a monolayer of cells in a flask; it is a complex, spatially structured environment, offering both challenges and opportunities for viruses to thrive. Whereas virus infection dynamics at the host and within-cell levels have been documented, the intermediate between-cell level remains poorly understood. Here, we used flow cytometry to measure the infection status of thousands of individual cells in virus-infected plants. This approach allowed us to determine accurately the number of cells infected by two virus variants in the same host, over space and time as the virus colonizes the host. We found a low overall frequency of cellular infection (<0.3, and few cells were coinfected by both virus variants (<0.1. We then estimated the cellular contagion rate (R, the number of secondary infections per infected cell per day. R ranged from 2.43 to values not significantly different from zero, and generally decreased over time. Estimates of the cellular multiplicity of infection (MOI, the number of virions infecting a cell, were low (<1.5. Variance of virus-genotype frequencies increased strongly from leaf to cell levels, in agreement with a low MOI. Finally, there were leaf-dependent differences in the ease with which a leaf could be colonized, and the number of virions effectively colonizing a leaf. The modeling of infection patterns suggests that the aggregation of virus-infected cells plays a key role in limiting spread; matching the observation that cell-to-cell movement of plant viruses can result in patches of infection. Our results show that virus expansion at the between-cell level is restricted, probably due to the host environment and virus infection itself.

[The genetic diversity and homology of Anabaena azollae and its host plant (Azolla) based on rapd analysis].

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Chen, Jian; Zheng, Wei-wen; Xu, Guo-zhong; Song, Tie-ying; Tang, Long-fei

2002-01-01

Symbiotic Anabeana azollae and its host plant Anabeana-free Azolla were isolated from 16 Azolla accessions representing different Azolla species or geographic origins.DNA polymorphic fragments were obtained by simultaneous RAPD amplification of both symbiont and host. The UPGMA clusters of Anabeana azollae and its host Azolla were established separately based on Dice coefficient caculation and a coordinated relationship was shown between Anabeana azollae and its Azolla host along both individual genetic divergence,but this genetic homology was reduced among different strains within Azolla species while the obvious mutants of Anabeana azollae were detected in some Azolla tested strains collected from different geographic area in the same host species.

Investigations of entrainment mortality among larval and juvenile fishes using a Power Plant Simulator

International Nuclear Information System (INIS)

Cada, G.F.; Suffern, J.S.; Kumar, K.D.; Solomon, J.A.

1980-01-01

A Power Plant Simulator (PPS) was constructed at the Oak Ridge National Laboratory to examine the component sources of entrainment mortality. This experimental apparatus circulates temperature-controlled water through a closed loop consisting of a pump, a condenser bundle, and vertically adjustable piping. Larval bluegill, channel catfish, carp, largemouth bass, and smallmouth bass and juvenile bluegill and mosquitofish were exposed to different combinations of pump speed and water temperatures in the PPS. Wide differences among species in their sensitivity to pipe and condenser passage were observed. For most of the species tested, short-term conditional mortalities resulting from the physical stresses of pipe and condenser passage increased with ΔT and/or pumping rate. Pump passage was not a major source of physical damage, and no clear relationship was found between pump efficiency and mortality. Susceptibility to physical stresses associated with entrainment was inversely related to the size of the entrained organisms. Delayed mortality frequently occurred among fishes exposed to stresses in the PPS. However, delayed mortality estimates in these experimental groups were significantly greater than corresponding values in handling control groups in only 15 of 64 comparisons. Like short-term mortalities, relatively higher delayed mortalities were often observed for the smaller species tested

Host preference of the hemiparasite Struthanthus flexicaulis (Loranthaceae in ironstone outcrop plant communities, southeast Brazil

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Fabiana Alves Mourão

2016-03-01

Full Text Available Struthanthus flexicaulis is a hemiparasite abundant in ironstone outcrops in southeast Brazil. We evaluated its host preference among species of the plant community, taking into account the abundance and foliage cover of the hosts. The importance of each species in the community and the mortality caused by the parasite were assessed based on a quantitative survey in 10 strips measuring 1m x 50m. The 10,290 individuals belonged to 42 species. Only 15 had a relative abundance in the plant community greater than 1%, of which 12 showed vestiges of parasitism. More than 80% of deaths in the community were associated with parasitism. Non-infected individuals had significantly less mortality rates (7% than those infected (83% (²= 1102.4, df = 1, p < 0.001. The observed infestation was different from the expected both regarding relative host abundance (²= 714.2, df = 11, p<0.001 and foliage cover (²= 209.2, df = 11, p<0.001. Struthanthus flexicaulis preferredMimosa calodendron, a legume attractive to avian seed dispersers. The interaction is maintained and intensified not only by the birds, who deposit innumerous seeds on the hosts branches, but also very likely by the ability of M. calodendron to fix nitrogen, thereby enhancing the mistletoe's development.

Herbivore handling of a plant's trichome: the case of Heliconius charithonia (L.) (Lepidoptera: Nymphalidae) and Passiflora lobata (Killip) Hutch. (Passifloraceae)

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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