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Thesis (Ph. D.)--University of Adelaide, Dept. of Crop Protection, 1997. / Includes bibliographical references (leaves 175-191).

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No description available.

Bibliography: leaves 175-191. Trissolcus basalis (Wollaston) is a solitary endoparasitoid of the eggs of many pentatomid bugs. It is a quasi-gregarious scelenoid and aggressively defends host patches. In the Adelaide (S. Aust.) region its most abundant host is the native horehound bug, Agonoscelis rutila (Fabricius). This study of patch defence draws together important areas of research in parasitoid behavioural ecology, including the theories of adaptive superparasitism, sex ratio decisions, foraging behaviour and contest resolution.

Bibliography: leaves 175-191. / xx, 191 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Trissolcus basalis (Wollaston) is a solitary endoparasitoid of the eggs of many pentatomid bugs. It is a quasi-gregarious scelenoid and aggressively defends host patches. In the Adelaide (S. Aust.) region its most abundant host is the native horehound bug, Agonoscelis rutila (Fabricius). This study of patch defence draws together important areas of research in parasitoid behavioural ecology, including the theories of adaptive superparasitism, sex ratio decisions, foraging behaviour and contest resolution. / Thesis (Ph.D.)--University of Adelaide, Dept. of Crop Protection, 1997

Currently, there is little known about stink bug (Hemiptera: Pentatomidae) eggs, their natural enemies, and their susceptibility to insecticides. A survey of stink bug egg parasitoids was conducted in row crops and vegetables in eastern Virginia. Parasitization was highest in Euschistus servus (Say) with 89.7% and 49.2% of egg masses and individual eggs parasitized, respectively, followed by Acrosternum hilare (Say), with nearly half of all individual eggs parasitized. The most common parasitoid was Telenomus podisi Ashmead (Hymenoptera: Scelionidae). Laboratory egg-dip bioassays and field applications of acephate, lambda-cyhalothrin, spinosad, and thiamethoxam, were carried out to determine efficacy against nonparasitized E. servus and A. hilare eggs, and T. podisi embryos developing in E. servus eggs. Results showed that eggs of both species were susceptible to insecticides, that there was little difference among insecticides, but there was generally greater mortality in field-treated versus dipped eggs. Developing T. podisi were generally more susceptible to insecticides than stink bugs. Scanning electron microscopy was used to investigate oviposition sites as possible sites of insecticide movement into eggs. Oviposition wounds and holes made by a tungsten probe were similarly sealed by a "scab", so it was not clear whether these wounds allow for increased insecticide movement into parasitized eggs. Differences in chorion permeability of non-parasitized and parasitized eggs were compared by immersing them in solutions containing different ¹⁴C-ammended insecticides at field application rates for 0, 30, 120 or 240 minutes. Results showed that insecticide movement into the egg increased significantly with immersion time for both acephate and λ-cyhalothrin, but there were no significant differences between nonparasitized and parasitized eggs. Neither immersion time nor egg status was significant for thiamethoxam. A model was constructed that predicts amount of insecticide entering the egg at any given time. An 8-week survey for the brown marmorated stink bug, Halyomorpha halys (Stål) was conducted in Beijing and five other cities in China. Incidence of egg parasitism was recorded. Results showed that H. halys utilized at least four different plants throughout the summer, and insects were found in Nanjing, Kunming, and Xi'an. Parasitization of eggs was noted, and the parasitoids were identified as Trissolcus halyomorphae Yang (Scelionidae: Hymenoptera) by K.A. Hoelmer (USDA-ARS). / Ph. D.

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<p>Diss. (sammanfattning) Umeå : Umeå universitet, 1992, härtill 8 uppsatser</p> / digitalisering@umu

Comme presque tous les êtres vivants, les insectes et autres arthropodes terrestres évoluent dans des environnements dynamiques et hétérogènes relativement à de multiples facteurs abiotiques incluant le rayonnement ultraviolet (UV). L’absorption de ces photons peut affecter le fitness des individus à travers différents types d’effets physiologiques et comportementaux. Certaines stratégies de lutte intégrée manipulent l’exposition au rayonnement UV en contexte agricole de façon à prendre avantage de son aspect attractif pour de nombreux ravageurs et de leur susceptibilité aux photodommages qu’il induit. Considérant le manque de connaissances sur les conséquences potentielles de telles approches sur les ennemis naturels, j’ai étudié dans cette thèse l’influence du rayonnement UV au fil du cycle de vie de deux espèces de guêpes parasitoïdes d’œufs, Telenomus podisi Ashmead, 1893 et Trissolcus utahensis Ashmead, 1893 (Hymenoptera : Scelionidae), et d’une de leurs punaises hôtes, Podisus maculiventris (Say, 1832) (Hemiptera : Pentatomidae), une espèce prédatrice qui pond des œufs de différents niveaux de pigmentation photoprotectrice. De façon à examiner divers paramètres d’histoire de vie de ces associations hôtes-parasitoïdes ainsi que certains des comportements liés à la recherche et à l’exploitation d’hôtes chez les parasitoïdes, j’ai réalisé une série d’expériences sous exposition naturelle et artificielle au rayonnement UV à l’aide de matériaux transmettant ou absorbant ces photons. Je démontre qu’une exposition réaliste au rayonnement UV peut entraîner des conséquences négatives sur le fitness des punaises et de leurs parasitoïdes d’œufs, et ce qu’ils y soient exposés durant leur développement ou comme adultes. L’exposition soutenue à un rayonnement UV-A de faible intensité a réduit la survie et la longévité des parasitoïdes adultes, tandis que chez les punaises, elle a induit des effets reportés négatifs sur la survie des nymphes jusqu’au stade adulte. Les conséquences immédiates et ultérieures de l’exposition des œufs de P. maculiventris au rayonnement UV ont été atténuées avec l’augmentation de leur niveau de pigmentation, et ce tant pour l’hôte que son parasitoïde. Au niveau comportemental, j’ai décrit comment les microhabitats exposés au rayonnement UV attirent les femelles parasitoïdes tout en réduisant leur activité locomotrice. Néanmoins, un taux de parasitisme élevé a été observé à diverses intensités d’exposition au rayonnement UV sur des plants de soya en cages de terrain, révélant que l’atténuation de ces signaux ne réduit pas nécessairement la performance de mes parasitoïdes. Dans l’ensemble, ces différentes études expérimentales ont révélé des effets similaires du rayonnement UV chez les trois espèces testées. Elles fournissent d’importantes réponses quant aux interactions complexes entre des insectes bénéfiques et un facteur abiotique associé aux changements climatiques et qui agit simultanément comme source de stress et d’information relativement à l’environnement. / Like most living things, insects and other terrestrial arthropods navigate environments that are dynamic and heterogenous with regards to various abiotic factors including ultraviolet (UV) radiation. Absorbing those photons can affect arthropod fitness via different types of physiological and behavioural effects. Some integrated pest management strategies manipulate UV exposure in agricultural settings to take advantage of its attractiveness to pests and of their susceptibility to UV damage. Considering the lack of knowledge on how such techniques could affect natural enemies, I studied the influence of UV radiation throughout the lifecycles of two egg parasitoid species, Telenomus podisi Ashmead, 1893 and Trissolcus utahensis Ashmead, 1893 (Hymenoptera: Scelionidae), and one of their potential stink bug hosts, Podisus maculiventris (Say, 1832) (Hemiptera: Pentatomidae), a predatory species that lays eggs of different photoprotective qualities. To examine various life history parameters in these host-parasitoid associations as well as some of the parasitoids’ host location and exploitation behaviours, I conducted a series of experiments under natural and artificial UV exposure, using UV-transmitting and UV-absorbing materials. I showed that realistic doses of UV radiation can have negative consequences for the fitness of stink bugs and their egg parasitoids, whether they were exposed during their development or their adult stage. Long-term exposure to mild UV-A intensities reduced parasitoid emergence and longevity, while inducing negative carryover effects on stink bug nymph survival to adulthood. Immediate or delayed consequences of exposing P. maculiventris eggs to UV radiation lessened with increasing egg pigmentation levels, both for the hosts and their parasitoids. As for behavioural responses to UV radiation, UV-exposed microhabitats were attractive to foraging female parasitoids but also reduced their walking activity. Nonetheless, high parasitism rates were observed under different intensities of UV exposure on soybean plants in field cages, revealing that UV attenuation does not necessarily impede these parasitoids’ performance. Together, these different experimental studies revealed similar effects of UV radiation on the three species tested. They provide important insight on the complex interactions between beneficial insects and an abiotic factor that is involved in climate change and that can act both as an environmental hazard and a visual cue.