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Hopper, Keith R. - One of the best experts on this subject based on the ideXlab platform.

Shirley, Xanthe A. - One of the best experts on this subject based on the ideXlab platform.

Woolley, James B. - One of the best experts on this subject based on the ideXlab platform.

Keith R. Hopper - One of the best experts on this subject based on the ideXlab platform.

  • The defensive aphid symbiont Hamiltonella defensa affects host quality differently for Aphelinus glycinis versus Aphelinus atriplicis
    Biological Control, 2018
    Co-Authors: Keith R. Hopper, Kristen L. Kuhn, Kathryn Lanier, Joshua H. Rhoades, Kerry M. Oliver, Jennifer A. White, Mark K. Asplen, George E. Heimpel
    Abstract:

    Endosymbiont interactions with hosts have important effects on fitness, including the fitness of many pest and beneficial species. Among these interactions, facultative endosymbiotic bacteria can protect aphids from parasitoids. Aphis craccivora and Acyrthosiphon pisum can harbor the symbiotic bacteria Hamiltonella defensa and its bacteriophage APSE. Infection by H. defensa defends these aphids against some but not all parasitoid species in the hymenopteran family Braconidae. Here, we report results on the effect of H. defensa on parasitism of these aphids by species in the other major lineage of aphid parasitoids, Aphelinus species in the family Aphelinidae. Parasitism of aphids infected with H. defensa/APSE by two Aphelinus species did not differ from that of uninfected aphids. While Aphelinus atriplicis showed no difference in fitness components between infected and uninfected aphids, Aphelinus glycinis actually produced more adult progeny and larger female progeny on infected than on uninfected aphids. Aphelinus glycinis may increase host quality for itself by changing the titer of nutritional versus protective bacteria in such a way that aphids infected with H. defensa can be made more suitable for parasitoid development than uninfected aphids. Our results and reasoning suggest that these Aphelinus species may be less prone to harm by H. defensa/APSE that affect eggs because they have anhydropic, heavily chorionated eggs, which may not absorb toxins during embryogenesis.

  • host specificity of Aphelinus species collected from soybean aphid in asia
    Biological Control, 2017
    Co-Authors: Keith R. Hopper, George E. Heimpel, Kathryn Lanier, Joshua H. Rhoades, Kim A Hoelmer, William G Meikle, Robert J Oneil, David G Voegtlin, James B. Woolley
    Abstract:

    Abstract The soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), is native to Asia where it is an occasional pest of soybean, Glycine max (L.). Aphis glycines was found during 2000 in North America and since then has spread throughout much of the area where soybean is grown. In Asia, A. glycines seldom reaches damaging levels; however in North America, it has become the most important insect pest of soybean, decreasing yields and incurring large control costs. Field surveys and exclosure experiments in China showed that natural enemies can limit soybean aphid abundance. A project to find, evaluate, and introduce Asian natural enemies into North America was initiated in 2001, with an emphasis on parasitoids. To ensure that introductions of exotic parasitoids would have minimum impact on non-target species, we tested host specificity of all candidates for introduction. Here we report results of experiments on host specificity of 13 populations in seven species from three species complexes in the genus Aphelinus (Hymenoptera: Aphelinidae). In no-choice laboratory experiments, four species had broad host ranges and one species had an intermediate host range. However, two species, Aphelinus glycinis and Aphelinus rhamni , had narrow host ranges, being restricted to some species in the genus Aphis . We also report the results of experiments on the mechanisms of host specificity in the parasitoid species with intermediate to narrow host ranges. Most of this host specificity can be explained by differences in the behavior of females when they encountered different aphid species. Females of these species rarely approached, stung, oviposited or host fed on aphids outside the genus Aphis . Even within the genus Aphis , Aphelinus glycinis and Aphelinus rhamni parasitized primarily Aphis glycines and closely related species. From these results, we conclude that Aphelinus glycinis and Aphelinus rhamni are excellent candidates for introduction into the North America to control Aphis glycines .

  • host specificity of Aphelinus species considered for introduction to control diuraphis noxia
    Biological Control, 2017
    Co-Authors: Keith R. Hopper, James B. Woolley, Kathryn Lanier, Joshua H. Rhoades, Dominique Coutinot, Guy Mercadier, Nathalie Ramualde, Marie Roche, John M Heraty
    Abstract:

    Diuraphis noxia, the Russian wheat aphid, has become a major pest of wheat and barley since first being detected in the western USA in 1986. However, it is rarely a pest in Eurasia, its area of origin, and research has shown that natural enemies can limit its abundance there. Among the most important of natural enemies of D. noxia in Eurasia are parasitoids in the genus Aphelinus. Here we report results on host specificity of ten populations of seven species from two species complexes in the genus Aphelinus. Host specificity was not related to host plant species or the phylogenetic relatedness of the aphids or the parasitoids. While some species had very broad host ranges and others had intermediate host ranges, Aphelinus hordei had a very narrow host range, being restricted primarily to species in the genus Diuraphis, and especially D. noxia. We also report the results of experiments on the mechanisms of this host specificity. Most of the host specificity of A. hordei can be explained by differences in the behavior of females when they encountered different aphid species. Females of A. hordei rarely approach, sting, oviposit or host feed on aphids outside the genus Diuraphis, and they oviposit most frequently in D. noxia. From these results, we conclude that A. hordei is an excellent candidate for introduction into the USA to control D. noxia.

  • Revision of the asychis species group of Aphelinus (Hymenoptera: Aphelinidae)
    Journal of Hymenoptera Research, 2017
    Co-Authors: Xanthe A. Shirley, James B. Woolley, Keith R. Hopper
    Abstract:

    Aphelinus (Hymenoptera: Aphelinidae) is a genus of parasitoid wasps that has a long history of use in biological control programs against aphids. Past research shows that species delimitation within Aphelinus is greatly complicated by lack of comprehensive literature and the existence of cryptic species complexes. One of these complexes is the Aphelinus asychis species group. Through the development of a morphological character set, a revision of the Aphelinus asychis species group was conducted. Two new species, Aphelinus sinensis sp. n., and Aphelinus kazakhstanensis sp. n., are described, and the two existing valid species within the asychis group, Aphelinus asychis and Aphelinus semiflavus are redescribed and lectotypes are designated for Aphelinus semiflavus and Aphelinus brevipennis (a junior synonym of A. semiflavus). We also provide a key for identifying species in the asychis group

  • Variation in genome size and karyotype among closely related aphid parasitoids (Hymenoptera, Aphelinidae)
    Comparative Cytogenetics, 2017
    Co-Authors: Vladimir E. Gokhman, Kristen L. Kuhn, James B. Woolley, Keith R. Hopper
    Abstract:

    : Genome sizes were measured and determined for the karyotypes of nine species of aphid parasitoids in the genus Aphelinus Dalman,1820. Large differences in genome size and karyotype were found between Aphelinus species, which is surprising given the similarity in their morphology and life history. Genome sizes estimated from flow cytometry were larger for species in the Aphelinus mali (Haldeman, 1851) complex than those for the species in the Aphelinus daucicola Kurdjumov, 1913 and Aphelinus varipes (Forster,1841) complexes. Haploid karyotypes of the Aphelinus daucicola and Aphelinus mali complexes comprised five metacentric chromosomes of similar size, whereas those of the Aphelinus varipes complex had four chromosomes, including a larger and a smaller metacentric chromosome and two small acrocentric chromosomes or a large metacentric and three smaller acrocentric chromosomes. Total lengths of female haploid chromosome sets correlated with genome sizes estimated from flow cytometry. Phylogenetic analysis of karyotypic variation revealed a chromosomal fusion together with pericentric inversions in the common ancestor of the Aphelinus varipes complex and further pericentric inversions in the clade comprising Aphelinus kurdjumovi Mercet, 1930 and Aphelinus hordei Kurdjumov, 1913. Fluorescence in situ hybridization with a 28S ribosomal DNA probe revealed a single site on chromosomes of the haploid karyotype of Aphelinus coreae Hopper & Woolley, 2012. The differences in genome size and total chromosome length between species complexes matched the phylogenetic divergence between them.

Georgina Alins - One of the best experts on this subject based on the ideXlab platform.

  • Woolly apple aphid Eriosoma lanigerum Hausmann ecology and its relationship with climatic variables and natural enemies in Mediterranean areas.
    Bulletin of Entomological Research, 2014
    Co-Authors: Jaume Lordan, Ferran Gatius, M. José Sarasúa, Simó Alegre, Georgina Alins
    Abstract:

    A multilateral approach that includes both biotic and climatic data was developed to detect the main variables that affect the ecology and population dynamics of woolly apple aphid Eriosoma lanigerum (Hausmann). Crawlers migrated up and down the trunk mainly from spring to autumn and horizontal migration through the canopy was observed from May to August. Winter temperatures did not kill the canopy colonies, and both canopy and root colonies are the source of reinfestations in Mediterranean areas. Thus, control measures should simultaneously address roots and canopy. European earwigs Forficula auricularia (Linnaeus) were found to reduce the survival of overwintering canopy colonies up to June, and this can allow their later control by the parasitoid Aphelinus mali (Haldeman) from summer to fall. Preliminary models to predict canopy infestations were developed.