Integrating Circadian Activity and Gene Expression Profiles to Predict Chronotoxicity of Drosophila suzukii Response to Insecticides

Abstract

Native to Southeast Asia, Drosophila suzukii (Matsumura) is a recent invader that infests intact ripe and ripening fruit, leading to significant crop losses in the U.S., Canada, and Europe. Since current D. suzukii management strategies rely heavily on insecticide usage and insecticide detoxification gene expression is under circadian regulation in the closely related Drosophila melanogaster, we set out to determine if integrative analysis of daily activity patterns and detoxification gene expression can predict chronotoxicity of D. suzukii to insecticides. Locomotor assays were performed under conditions that approximate a typical summer or winter day in Watsonville, California, where D. suzukii was first detected in North America. As expected, daily activity patterns of D. suzukii appeared quite different between ‘summer’ and ‘winter’ conditions due to differences in photoperiod and temperature. In the ‘summer’, D. suzukii assumed a more bimodal activity pattern, with maximum activity occurring at dawn and dusk. In the ‘winter’, activity was unimodal and restricted to the warmest part of the circadian cycle. Expression analysis of six detoxification genes and acute contact bioassays were performed at multiple circadian times, but only in conditions approximating Watsonville summer, the cropping season, when most insecticide applications occur. Five of the genes tested exhibited rhythmic expression, with the majority showing peak expression at dawn (ZT0, 6am). We observed significant differences in the chronotoxicity of D. suzukii towards malathion, with highest susceptibility at ZT0 (6am), corresponding to peak expression of cytochrome P450s that may be involved in bioactivation of malathion. High activity levels were not found to correlate with high insecticide susceptibility as initially hypothesized. Chronobiology and chronotoxicity of D. suzukii provide valuable insights for monitoring and control efforts, because insect activity as well as insecticide timing and efficacy are crucial considerations for pest management. However, field research is necessary for extrapolation to agricultural settings.

Seasonal Monitoring forDrosophila suzukii(Diptera: Drosophilidae) in California Commercial Raspberries

“…2). The increased male capture in the vacuum samples may be because of differences in D. suzukii activity by sex, as male D. suzukii were found to be more active in laboratory activity bioassays (Hamby et al 2013) and research observations in Japan described females as more "passive" (Kanzawa 1939). It is unsurprising that time of year would impact the sex ratio of trap captures, as D. suzukii may overwinter as mated females and males exhibit greater mortality at cold temperatures (Kanzawa 1936(Kanzawa , 1939Dalton et al 2011).…”

Trapping system comparisons for and factors affecting populations of Drosophila suzukii and Zaprionus indianus in winter‐grown strawberry

“…30 Wooded perimeters may serve as a refuge for flies during the overwintering period in temperate regions but also daily for flies seeking cooler temperatures and higher relative humidity. 55,56 Just over a quarter of the Florida strawberry field perimeter was woodland or partial-woodland, and we recommend focusing trap placement in these areas.…”

Invasion biology of spotted wing Drosophila (Drosophila suzukii): a global perspective and future priorities

“…Hamby et al (2013) found that detoxification gene activity has daily rhythmic patterns in SWD, with the highest activity at Fig. 9 Age-specific oviposition by SWD at 21°C.…”