Browsing by Subject "insecticide"

Now showing 1 - 3 of 3
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    Hormetic and Transgenerational Effects in Spotted-wing Drosophila (Diptera: Drosophilidae) in Response to Three Commonly-Used Insecticides
    (2022-03-14) Deans, Carrie; Hutchison, William; dean0179@umn.edu; Deans, Carrie; University of Minnesota Hutchison Lab
    Although insecticide formulations and spray rates are optimized to achieve lethal exposure, there are many factors in agricultural settings that can reduce the effective exposure of insect pests. These include weather patterns, timing of application, chemical degradation/volatilization, plant structural complexity, and resistant populations. While sub-lethal exposure to insecticides can still have negative impacts on pest populations, they can also lead to stimulatory, or hormetic, responses that can increase the fitness of surviving insects. Sub-lethal concentrations may also produce increased tolerance in the offspring of surviving adults through transgenerational effects. Sub-lethal effects are pertinent for the invasive fruit pest spotted-wing Drosophila, Drosophila suzukii Matsumura, because its small size, diurnal movement patterns, and utilization of hosts with complex plant structures, such as caneberries and blueberries, make effective insecticide applications tenuous. In this study, we measured spotted-wing Drosophila survivorship, reproductive performance, and offspring tolerance in flies exposed to sub-lethal concentrations of three commonly-used insecticides (zeta-cypermethrin, spinetoram, and pyrethrin). We found some evidence for hormesis, with survival effects being sex- and concentration-dependent for all insecticides. Males were far more susceptible to insecticides than females, which in some cases exhibited higher eclosion success and reproductive rates when exposed to sub-lethal doses. We did not observe significant transgenerational effects at sub-lethal concentrations, despite trends of increased offspring viability for zeta-cypermethrin and spinetoram. More research, however, is needed to fully understand the role that sub-lethal effects may play in pest population dynamics, insecticide efficacy, and the development of genetic resistance.
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    Hydrolysis and Photolysis of Neonicotinoid Insecticides
    (2018-08-16) Todey, Stephen A; Fallon, Ann M; Arnold, William A; arnol032@umn.edu; Arnold, William A.; University of Minnesota, Department of Civil, Environmental, and Geo- Engineering and Department of Entomology
    Data for the hydrolysis of neonicotinoid insecticides as a function of pH and for photolysis under natural and simulated sunlight.
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    Managing Halyomorpha halys: Effects of cold tolerance, insecticides, and linguistic uncertainty
    (2017-06) Cira, Theresa
    Managing pests effectively and efficiently requires knowledge about their biology. Likewise, clear communication about scientific research pertaining to management is needed for managers to make well-informed decisions. My research pertains to the biology of the brown marmorated stink bug, Halyomorpha halys and communication between scientists about insecticidal categorization. Halyomorpha halys is an exotic invasive species in North America. Many horticultural and agricultural plants in North America are at risk for economic damage due to the highly polyphagous nature of this species. Additionally, H. halys has become a serious nuisance pest in human-made structures in some areas when, in preparation for winter, they aggregate in sheltered structures. Therefore, factors such as cold and insecticides, which affect H. halys distribution and ability to cause crop injury are of particular interest to develop management plans. I first conducted several studies of cold tolerance on H. halys in North America. I found that H. halys exhibits a chill-intolerant cold tolerance strategy, that season, sex, and acclimation location affect cold tolerance (i.e., supercooling points), and that laboratory assays of lethal temperature were able to accurately forecast winter mortality in the field. Second, I studied H. halys diapause in more depth. I present a protocol for rearing diapausing H. halys in the laboratory that exhibit similar cold tolerance (i.e., supercooling points and lower lethal temperatures) as individuals with field-induced diapause. I found that H. halys diapause confers greater cold tolerance than a non-diapausing state, and appears to be necessary to survive overwintering. Additionally, I showed diapausing H. halys actively feed for at least three weeks post-diapause induction, but feeding is mediated by temperature and adult age. Third, I investigated and critiqued the current paradigm for determining insecticidal efficacy on H. halys. I highlighted important sublethal effects of insecticides on feeding that can significantly reduce crop injury without the necessity of high direct mortality to H. halys. Lastly, using an interdisciplinary lens I examined linguistic uncertainty as it pertains to categories and descriptors of insecticides. I demonstrated the presence and consequences of linguistically uncertain terms associated with insecticides and encouraged entomologists to more adequately acknowledge and address these uncertainties in future research.