The recent invasion of spotted-wing drosophila (Drosophila suzukii; SWD) is a significant threat to local small fruit production in Minnesota and throughout temperate fruit producing regions world-wide. Mature female SWD pierce the skin of ripening and ripe fruit in order to deposit eggs. Larvae hatch from the eggs within 12 to 72 hours and destructively feed on the interior of the fruit, resulting in soft, unmarketable fruit at harvest. A recent economic analysis showed that conservative estimates of 20% yield loss to raspberry producers corresponds to a statewide loss of $2.2 million annually in Minnesota (Digiacomo, 2019). Increasing numbers of raspberry growers are halting production--tilling plants under as they struggle to manage this pest. Current management strategies are limited to frequent applications of broad spectrum insecticides, the majority of which are synthetic and can’t be used in organic systems. Presently, there is a need for additional management strategies, understanding how these strategies may work together in an IPM program, and studies on the economic viability of these practices. Botanical products such as volatile organic compounds (VOCs; e.g. essential oils) and their role in plant-insect interactions could provide an alternative pest management strategy that could be implemented without additional equipment investment from growers. SWD is known to locate hosts via visual and olfactory cues, suggesting that plant VOCs could mask the scent of SWD host fruit, while also decreasing the use of broad spectrum insecticides which negatively impact the environment, human health, pollinators and other beneficial insects. We propose a research project to study the field implementation of botanical repellents for organic management of spotted-wing drosophila (Drosophila suzukii) in small fruit. We hypothesize that growers could artificially apply VOCs on or around small fruit crops as a natural deterrent for SWD without harming beneficial insects or pollinators. The objectives of this proposed project are to assess the efficacy of botanical VOCs (the individual compound lavender oil, as well as the commercially available organic approved Ecotrol Plus and Sporan products) on SWD infestation in blueberry and raspberry crops. The results of the proposed project will guide future research and result in recommendations for both organic and conventional growers for sustainable management of SWD.
Project objectives from proposal:
Small fruit producers and researchers will both benefit from the outcomes of this research. Learning outcome 1: organic and small fruit producers will learn basic SWD management techniques such as monitoring, identification, biology, and behavior of SWD. Learning outcome 2: organic and small fruit producers will learn how to integrate botanical repellents into their current pest management plans for SWD. Learning outcome 3: Researchers will learn about the efficacy of botanical repellents to prevent SWD infestation in fruit crops. Action outcome 1: organic and small fruit producers will implement appropriate science-based IPM techniques to reduce infestation by SWD and improve marketable fruit yield. Action outcome 2: This research will be used to guide future applied research on SWD behavior and IPM in order to provide additional control strategies for producers. Action outcome 3: Having additional pest management options will lead to an increase in production of small fruit, the supply of local small fruit, and the profits for growers while reducing the amount of pesticide applied to the fruit.