Browsing by Author "Gullickson, Matthew"

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    Spotted-wing Drosophila: Investigating the Efficacy of Innovative and Alternative Management Techniques
    (2020-01) Gullickson, Matthew
    Spotted-wing drosophila (Drosophila suzukii; SWD) established recently in North America as an invasive insect pest of small and soft skinned fruit, responsible for significant economic losses nationwide and locally in Minnesota. Female SWD use a heavily sclerotized and serrated ovipositor to deposit eggs in ripening and ripe fruit. Larvae then emerge and develop within the flesh which results in unmarketable fruit at harvest. Consequently, there is a zero-tolerance threshold for larvae in fresh fruit. Current management strategies are often limited to regular applications of broad- spectrum insecticides, primarily organophosphates, spinosads, and pyrethroids. Weekly sprays may have deleterious ecological impacts to beneficial, non-target species including pollinators. Additionally, frequent spraying can contribute to insecticide resistance and may even fail to adequately protect fruit from infestation. Organic pesticide application for SWD management is particularly difficult for growers due to fewer chemical options and increased cost compared to conventional products. Since the arrival of SWD and the subsequent increase of insecticidal sprays, it has been a significant challenge for producers to balance economics as well as pest and pollinator management goals. Weekly conventional insecticide rotations in primocane raspberries can still result in widespread infestation likely due to high SWD populations, immigration by new individuals, and/or inadequate spray penetration in the dense plant canopy. Frequent applications of broad spectrum insecticides continues to be the most prevalent management strategy, but pesticide resistance is a concern. Resistance has already been reported for one of the only effective insecticides labeled for organic production systems, underscoring the need to diversify management strategies. Responding to the critical need for additional management tools and chemical alternatives, the goal of this research was to investigate the efficacy of novel chemical controls and physical exclusion on SWD in primocane raspberry fruit. For our first set of experiments, we conducted a series of laboratory bioassays to test twenty-five potential pesticide treatments. We measured the effects of these treatments on SWD adult mortality, oviposition, larval and pupal development, and adult emergence. This information was used to guide a follow up study testing thirteen of the most promising treatments on SWD mortality and infestation in the field. Results showed that the broad spectrum conventional and organic controls provided the best SWD control, however botanical products provided some protection against infestation. Additionally, there is increasing interest in using physical exclusion and high tunnel production as a pest management tool, particularly since many growers already use high tunnels for season extension and improved fruit quality. Our second set of experiments investigated how plastic-covered, enclosed tunnels affected fruit yield and quality, as well as SWD infestation. We collected data on yield, proportion of marketable and unmarketable fruit, berry size, total soluble solids (°Brix), proportion of infested fruit, and the microclimate characteristics inside of the plots. The objective of these experiments was to improve integrated pest management strategies for SWD and provide recommendations for both organic and conventional growers for sustainable management of this invasive pest.