McCulloch John B
Full Text Available Abstract Background The northern fowl mite (NFM; Ornithonyssus sylviarum is a blood-feeding ectoparasite of birds and a major pest of poultry in the United States. Mite populations spread rapidly in commercial flocks, reach peak burdens of >70,000 mites per bird and have developed resistance to many pesticides. Despite decades as a pest in the United States, the reproductive biology of NFM remains unclear. Based on karyotypes, the NFM has haplodiploid sex determination, which suggests unmated females could produce male offspring (arrhenotoky. Thus, unmated females could disseminate to a new host and initiate an infestation by producing and mating with sons (oedipal mating. Methods We used small capsules to isolate and recover NFM on host chickens. Mites in capsules could blood feed, develop and reproduce, but could not contact other mites. Individual larvae were matured in isolation to produce known, unmated females. We evaluated reproduction of (I previously mated females (i in isolation, or (ii paired with a male, and (II unmated (virgin females in isolation. In each treatment we recorded the number and sexes of offspring produced over time. Results Mated NFM produced female and male offspring in isolation, or when paired with a male. When paired with a male, females produced a female-biased sex ratio of the offspring (F:M ratio ~5:1. Unmated, female NFM produced exclusively male offspring when in isolation. When paired with their sons that had developed to maturity, the "virgin" females were able to mate and subsequently produce female offspring. Conclusions This study found that females with immediate access to sperm produced mostly female offspring. Virgin female NFM initially produced only male offspring and subsequently used oedipal mating to produce female offspring. Using this reproductive system NFM could successfully colonize new hosts as immature, or unmated females. The strong female-biased sex ratio of NFM populations suggests a
Microarthropod species were classified according to life-history tactics and feeding guilds. Twelve life-history tactics were distinguished, based on well-defined life-history traits like the type of reproduction (thelytoky, arrhenotoky, sexual reproduction), oviposition (semelparity, iteroparity), development, synchronization (of the life cycle with environmental conditions), and dispersal (phoresy, anemochory). Examples are given of the distribution of these tactics among microarthropod spe...
W. R. Lourenço
Parthenogenesis, a rare phenomenon in Chelicerates, apart from mites, is reviewed in scorpions, notably Tityus serrulatus Lutz & Mello from Brazil, Tityus columbianus (Thorell) from Colombia and Tityus metuendus Pocock from Peru and Brazil. Thelytokous parthenogenesis (with all-female broods) is most often observed. The only known exception to this is T. metuendus in which arrhenotoky (all-male broods) has been observed. In the present paper, current ideas regarding parthenogenesis in scorpio...
W. R. Lourenço
Full Text Available Parthenogenesis, a rare phenomenon in Chelicerates, apart from mites, is reviewed in scorpions, notably Tityus serrulatus Lutz & Mello from Brazil, Tityus columbianus (Thorell from Colombia and Tityus metuendus Pocock from Peru and Brazil. Thelytokous parthenogenesis (with all-female broods is most often observed. The only known exception to this is T. metuendus in which arrhenotoky (all-male broods has been observed. In the present paper, current ideas regarding parthenogenesis in scorpions are summarized. The notion of geographic parthenogenesis ('parthénogenèse géographique', coined by Vandel in 1928, is discussed. This rule is tentatively exemplified by a new case of parthenogenesis reported in a scorpion of the genus Tityus C. L. Koch, inhabiting 'Pico da Neblina' in Brazil / Venezuela.
Trials for the evaluation of the effectiveness of the sterile insect technique for the suppression of greenhouse whitefly, Trialeurodes vaporariorum (Westwood), both in cage and in greenhouse conditions are described. The results show a significant reduction of the reproductive capacity of the untreated whitefly populations interacting with sterile insects. Untreated whiteflies, co-existing in a mixed population together with sterile insects, attained less than the half (44%) of their potential reproductive capacity. This trend was also evident in the cage test where the untreated whitefly population, crossed with the sterile whiteflies, increased without exceeding 2/3 of the density recorded in the control cages. These results may be based on 2 joint sterile insect technique effects: primarily a drastic reduction of the progeny of normal untreated females, when mating with sterile males, carriers of dominant lethal mutations, and secondarily a progressive reduction of the females in the population due to an increasing rate of unsuccessful matings resulting in a condition of forced arrhenotoky. No deleterious effects, on plant health and fruit quality, were observed on plants exposed to high sterile whitefly pressures
Farrokhi, S; Ashouri, A; Shirazi, J; Allahvari, H; Huigens, M E
Trichogramma species (Hymenoptera: Trichogrammatidae) are haplo-diploid egg parasitoids that are frequently used as biological control agents against lepidopteran pests. These wasps display two reproductive modes, including arrhenotoky (bisexuality) and thelytoky (unisexuality). Thelytokous forms are often associated with the presence of endosymbiotic Wolbachia bacteria. The use of thelytokous wasps has long been considered as a way to enhance the efficacy of biological control. The present study investigates the potential of a thelytokous Wolbachia-infected and an arrhenotokous uninfected Trichogramma brassicae Bezdenko strain as inundative biocontrol agents by evaluating their functional response towards different egg densities of the factitious host, the Angoumois grain moth, Sitotroga cerealella (Olivier) (Lepidoptera: Gelechiidae). The results revealed a type II functional response for both strains in which parasitism efficiency decreases with host egg density because of an increasing host handling time. A model with an indicator variable was used to compare the parameters of Holling's disc equation in different data sets. It was demonstrated that the two strains did not differ in host attack rate. However, the Wolbachia-infected strain did have an increased host handling time when compared to the bisexual strain. Some applied aspects of the findings are discussed. PMID:21062211
Glowska, Eliza; Dragun-Damian, Anna; Dabert, Miroslawa; Gerth, Michael
Wolbachia is the most abundant intracellular bacterial genus infecting a wide range of arthropods and filarial nematodes. Wolbachia have evolved parasitic, mutualistic and commensal relationships with their hosts but in arthropods generally act as reproductive parasites, inducing a wide range of phenotypic effects such as cytoplasmic incompatibility, parthenogenesis, feminization and male-killing. Up to now, the genus has been divided into 14 supergroups successively named A-O. Here, we describe two new Wolbachia supergroups from syringophilid mites (Acari: Cheyletoidea). These obligatory ectoparasites of birds inhabit the quills of feathers in many avian groups. The species of this family reproduce in a haplodiploid mode sensu arrhenotoky and are usually strongly female-biased. Based on the sequences of four protein-coding genes (ftsZ, gltA and groEL and coxA) and the 16S rRNA we identified strains of three Wolbachia supergroups (F and two distinct, yet undescribed ones) in five quill mite species. Our results suggest that in some cases the distribution of the bacteria can be better correlated with the mite's bird host rather than with mite taxonomy as such. The discovery of two new Wolbachia supergroups not only broadens the knowledge of the diversity of this bacterium but also raises questions about potential effects induced in quill mites and transmission mechanisms of the endosymbionts in this peculiar bacteria-quill mite-bird system. PMID:25541519
Variações morfológicas intra e interpopulacionais de Euseius citrifolius Denmark & Muma e Euseius concordis (Chant (Acari, Phytoseiidae Intra and interpopulational morphological variations of Euseius citrifolius Denmark & Muma and Euseius concordis (Chant (Acari, Phytoseiidae
Aloyséia Cristina da Silva Noronha
Full Text Available The determination of morphologic variability within and between populations of phytoseiid mites is important for the precise species identification. Euseius citrifolius Denmark & Muma, 1970 and Euseius concordis (Chant, 1959 are phytoseiids commonly found on different crops in Brazil and other South American countries. The morphologic characterization of populations preliminarily identified as E. citrifolius and E. concordis was done through examination of 10 adult females and 10 adult males of each population and of 2 to 10 adult females and males resulting from crosses between those populations. The plant substrate and collection site of each population were: E. citrijolius: Bauhinia sp. in Arroio do Meio, Rio Grande do Sul, Coffea arabica Linnaeus in Campinas, São Paulo and Terminalia catappa Linnaeus in Petrolina, Pernambuco. E. concordis: Passiflora edulis Sims. i.flavicarpa Deg. in Arroio do Meio, Manihot esculenta (Crantz in Jaguariúna, São Paulo, Hevea brasiliensis Muell. Arg. in Pontes e Lacerda, Mato Grosso, T. catappa in Petrolina and C arabica in Viçosa, Minas Gerais. A comparison of the measurements of different structures of individuals of each population and of type specimens of E. citrifolius and E. concordis confirmed the preliminary identification of the populations. Significant relationships were observed between mean setal lengths and the respective ranges within each population. Females and males of E. citrifolius from Petrolina and E. concordis from Jaguariúna had some of the setae generally shorter than those of other populations of the same species. Measurements of males resulting from heterogamic crosses indicated that E. citrifolius and E. concordis reproduce by pseudo-arrhenotoky.
Insect pests commonly known as whiteflies are Hemiptera belonging to the family of Aleyrodidae Trialeurodes vaporariorum Westwood (greenhouse whitefly) and the B-biotype of Bemisia tabaci Gennadius (=Bemisia argentifolii Bellows and Perring) are pests whose economic importance is constantly increasing within the European agriculture. The B-biotype of B. tabaci, in particular, has become more problematic by causing damage over a wide range, from the temperate climates of Californian squash fields to European greenhouses and field crops. In the absence of valid alternatives, many growers have resorted to intensive application of insecticides to control these pests, creating a severe environmental and health hazard. Several new environmentally safe technologies are currently available and have opened up new opportunities in the integrated pest management (IPM) of whiteflies under greenhouse conditions. In particular, biological or biologically-based control means, including a number of fungi, insects, and compounds have been recently developed. However, the limitation of whitefly population outbreaks in greenhouses is a problem that needs to be solved. The idea to extend the use of sterile insect technique (SIT) to a confined environment against whitefly species is novel, and especially when we consider that the target species undergo arrhenotoky (unfertilised females generate only male progenies). The possibility to join this approach to the Integrated Pest Management (IPM) of the whitefly species in the greenhouse may open new perspectives in the safe application of nuclear technology for pest control. The present work reviews recent advances in research and practice related to the development of SIT for the control of whiteflies in greenhouses. Explanations on whitefly radiation biology, with data on Bemisia spp. radio-sterilisation, methods for whitefly mass rearing and collection, and the definition of a complete SIT procedure tested against the greenhouse