Pesticide-mediated disruption of spotted wing Drosophila flight response to raspberries

Authors: GUEDES, RAUL NARCISO - UNIVERSIDADE FEDERAL DE VICOSA; CORBETT, STEPHEN - CALIFORNIA STATE UNIVERSITY; RODRIGUEZ, MATTHEW - UNIVERSITY OF CALIFORNIA, DAVIS; GOTO, JOY - CALIFORNIA STATE UNIVERSITY; Walse, Spencer

Submitted to: Journal of Applied Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/22/2018
Publication Date: 2/19/2018
Citation: Guedes, R.C., Corbett, S.M., Rodriguez, M., Goto, J.J., Walse, S.S. 2018. Pesticide-mediated disruption of spotted wing Drosophila flight response to raspberries. Journal of Applied Entomology. 142(5):457–464. https://doi.org/10.1111/jen.12500.
DOI: https://doi.org/10.1111/jen.12500

Interpretive Summary: Pesticides are used to control many types of agricultural pests, including the spotted wing drosophila (SWD). This study contributes to our understanding of under-appreciated consequences of pesticide use and how they may contribute to the overall goal of pest control. Specifically, we examined the potential for pesticide treatment to interfere with the ability of SWD to locate a fruit host. Five pesticides (the insecticides malathion, pyrethrins, and spinetoram; and the fungicides fenhexamid and pyrimethanil) were applied at field rates to raspberries, or to SWD adults via contact exposure. The SWD attraction to raspberries was assessed in a series of two-choice flight bioassays. Pesticides exhibited little interference with the release of raspberry volatiles when the berries were treated, where only spinetoram and pyrethrins resulted in mild effects of avoidance and attraction respectively. Nonetheless, SWD adults sublethally exposed to pesticides had their flight-take off seriously impaired, as was their up-wind flight in recognition to fruit volatiles. The impairment was particularly drastic when insecticides were used, although the fungicides also compromised the insect response to the raspberry volatiles. These findings suggest that even the sublethal pesticide exposure can aid in SWD control, and also indicate that pesticides may compromise sampling/trapping strategies used for this pest species.

Technical Abstract: The disruption of chemical communication between insects and host plants may take place due to an interference with the signal-emitting host plant, or the signal-receiving insect, compromising the signal production and emission, or its reception and processing. Anthropogenic compounds in general, and pesticides in particular, may impair the chemical communication that mediates host location by insects. Five different pesticides (the insecticides malathion, pyrethrins, and spinetoram; and the fungicides fenhexamid and pyrimethanyl) were applied per field rates to raspberry fruits, or cages enclosing adult spotted wing drosophila (SWD; Drosophila suzukii), and the attraction to fruit volatiles was evaluated in a series of two-choice flight bioassays. The application of raspberry fruit with pesticides did not statistically affect attraction of unexposed adults, with exceptions being the spinetoram treatment, which led to higher insect avoidance, and the pyrethrins treatment, which resulted in slightly preferential attraction. In contrast, adults sublethally exposed to the pesticides had their flight take-off impaired by the insecticides, but not by the fungicides. Furthermore, all pesticides, and particularly the insecticides, compromised the up-wind capture of adults. Thus, the treatment of fruits with pesticides may indeed interfere with the flight response of SWD to host volatiles, particularly when the insects were previously exposed to pesticides. These findings are suggestive of the potential for sublethal insecticidal exposures to aid pest control, and also provide evidence that pesticide use may compromise sampling/trapping strategies for this pest species that are based on attraction to host volatiles.