Electropenetrography of spotted wing drosophila (Drosophila suzukii) on pesticide-treated strawberry

Authors: GUEDES, RAUL - Universidade Federal De Vicosa; Cervantes, Felix; Backus, Elaine; Walse, Spencer

Submitted to: Journal of Pest Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/13/2019
Publication Date: 5/20/2019
Citation: Guedes, R.N., Cervantes, F.A., Backus, E.A., Walse, S.S. 2019. Electropenetrography of spotted wing drosophila (Drosophila suzukii) on pesticide-treated strawberry. Journal of Pest Science. https://doi.org/10.1007/s10340-019-01124-6.
DOI: https://doi.org/10.1007/s10340-019-01124-6

Interpretive Summary: Spotted wing drosophila, Drosophila suzukii, is an invasive pest of fruits and vegetables that was introduced to the U.S.A. and Europe in 2008 and subsequently spread to the rest of North and South America. Pesticides have been the primary means of controlling spotted wing drosophila, but can have unintended, environmental impacts and negatively affect many biological interactions, including sublethal effects on target (pest) and non-target insects. Consequently, understanding interactions between insects and pesticide-treated hosts is important. Electropenetrography (EPG) is the most rigorous way to study such interactions but has previously been restricted to hemipteroid insect (truebugs). The new technology of AC-DC EPG was used for the first time to monitor interactions between spotted wing drosophila and strawberry fruits treated either with the fungicide fenhexamid or the insecticide spinetoram. Non-probing (walking, grooming, standing still) and feeding were negatively affected by both pesticides, but egg-laying was not affected by pesticides. Feeding was strongly reduced by spinetoram, which also reduced insect lifespan. Fenhexamid fungicide exhibited mild effects on feeding but did not affect lifespan. Thus, EPG of interactions between spotted wing drosophila and strawberry fruits was successful and introduces a new technology for studies of feeding for insects beyond hemipteroid species.

Technical Abstract: Pesticides are ubiquitous in agroecosystems and potentially affect biological interactions, leading to consequences beyond target mortality. Accordingly, understanding intimate insect-host interactions in pesticide-treated hosts is important.Electropenetrography (EPG) is the best method to improve such understanding, but its use has been restricted to feeding activities of hemipteroid insects. Recent improvement in electropenetrograph technology (AC-DC) has made it amenable for use with non-hemipteroid species, such as the invasive spotted wing drosophila, Drosophila suzukii. AC-DC EPG was used herein to monitor interaction between spotted wing drosophila and strawberry fruits treated either with the fungicide fenhexamid or the insecticide spinetoram, in addition to an untreated control. High-resolution EPG was achieved via recognition of three behavioral phases of the insect: non-probing, feeding, and egg-laying. The first two phases were affected by pesticide contamination, but egg-laying was not affected by pesticides. Both pesticides decreased the number of non-probing events, but increased their overall duration, while the opposite took place with feeding, especially in spinetoram-treated strawberry. Regarding feeding activity, both pesticides compromised insect dabbing and ingestion with particularly strong impairment by spinetoram, which also compromised female longevity. Fenhexamid fungicide exhibits mild effects on feeding not affecting longevity, but more subtle effects may accrue, therefore deserving further attention. Thus, electropenetrography of the interaction between spotted wing drosophila and strawberry fruits was successful and opens a new technology for studies of non-hemipteroid feeding.