Chemical Ecology of Oviposition Dynamics inDrosophila suzukii(Diptera: Drosophilidae)

Abstract

Massive economic damage by spotted-wing drosophila (SWD), Drosophila suzukii, results from their unique egg laying behavior wherein a gravid fly pierces a ripening fruit to lay a number of eggs. Gravid SWD flies employ a complex suite of behaviors to find a fruit with the optimum firmness and chemistry. We investigated chemosensory cues potentially contributing to the oviposition behavior of SWD. In a series of experiments, we studied how the fruit ripeness and the underlying volatile chemistry influence oviposition. We tested the comparative attraction of three common fruits implicated in oviposition and determined raspberries to be most attractive in the trap choice assays that strictly measured olfactory preference. Since SWD oviposit in ripening fruits and appear to avoid the overripe fruit, we further evaluated the effect of ripeness on gravid fly attraction. Overripe fruits were significantly more attractive compared to the ripe fruits. The trap choice assays were repeated in an olfactory T-maze paradigm that provided a complex odor environment, potentially experienced by the gravid flies, and the results were mostly comparable. Since our behavioral paradigms indicated a clear olfactory preference for specific ripeness stages (ripe and overripe), we analyzed the constituent volatile odorants from the three ripening stages, revealing discrete odor profiles. Finally, we quantified the total soluble sugars and carbon dioxide concentrations from field-collected raspberries in underripe, ripe, and overripe conditions, revealing that the overripe stage is the most sugar-rich. Together, our results indicate unique chemosensory adaptations in gravid SWD flies for successfully exploiting optimal oviposition resources.

Drosophila Infestations of California Strawberries and Identification of Drosophila suzukii Using a TaqMan Assay

“…These results suggest that the preference for oviposition on ripe fruit has evolved in the lineage leading to D. suzukii [17]. In addition, these authors indicated that D. suzukii is attracted to overripe rotten fruit mostly for feeding, and ripe fruit are mostly selected for oviposition [17], which is also in agreement with findings of Mori et al and Littler et al [18,19].…”

Sugar sensation and mechanosensation in the egg-laying preference shift of Drosophila suzukii

“…Estimates vary with the fruit, the cultivar, and the ripening stage. Different studies have arrived at different conclusions about relative levels of sugar in ripe v. overripe fruit (15, 16, 44, 45). In any case, sugar concentrations are typically measured in entire, homogenized fruits.…”

Fine-mesh exclusion netting reduces Drosophila suzukii (Diptera: Drosophilidae) infestation and improves organic fall-bearing raspberry yields

“…For raspberry production, spinosads are recommended as one of the few effective organic pesticides for D. suzukii , and as such, they see frequent usage despite their high price (Beers et al 2011, Goodhue et al 2011, Van Timmeren et al 2019). Compounding these issues, raspberries are at especially high risk of D. suzukii infestation compared to other susceptible fruits (Lee et al 2011, 2016, Burrack et al 2013, Poyet et al 2015, Littler et al 2022). To counteract D. suzukii damage, both conventional and organic raspberry growers have implemented significant mitigation tactics.…”