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
McCulloch John B; Owen Jeb P
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 unmate...
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
Jacobson, Alana L.; Nault, Brian A.; Vargo, Edward L.; Kennedy, George G.
Knowledge of the relative influence of population- versus species-level genetic variation is important to understand patterns of phenotypic variation and ecological relationships that exist among and within morphologically indistinguishable cryptic species and subspecies. In the case of cryptic species groups that are pests, such knowledge is also essential for devising effective population management strategies. The globally important crop pest Thrips tabaci is a taxonomically difficult group of putatively cryptic species. This study examines population genetic structure of T. tabaci and reproductive isolation among lineages of this species complex using microsatellite markers and mitochondrial COI sequences. Overall, genetic structure supports T. tabaci as a cryptic species complex, although limited interbreeding occurs between different clonal groups from the same lineage as well as between individuals from different lineages. These results also provide evidence that thelytoky and arrhenotoky are not fixed phenotypes among members of different T. tabaci lineages that have been generally associated with either reproductive mode. Possible biological and ecological factors contributing to these observations are discussed. PMID:27690317
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
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.