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

The agricultural pest Drosophila suzukii differs from most other Drosophila species in that it lays eggs in ripe, rather than overripe, fruit. Previously we showed that changes in bitter taste sensation accompanied this adaptation (Dweck et al., 2021). Here we show that D. suzukii has also undergone a variety of changes in sweet taste sensation. D. suzukii has a weaker preference than D. melanogaster for laying eggs on substrates containing all three primary fruit sugars: sucrose, fructose, and glucose. Major subsets of D. suzukii taste sensilla have lost electrophysiological responses to sugars. Expression of several key sugar receptor genes is reduced in the taste organs of D. suzukii. By contrast, certain mechanosensory channel genes, including nompC, are expressed at higher levels in the taste organs of D. suzukii, which has a higher preference for stiff substrates. Finally, we find that D. suzukii responds differently from D. melanogaster to combinations of sweet and mechanosensory cues. Thus, the two species differ in sweet sensation, mechanosensation, and their integration, which are all likely to contribute to the differences in their egg-laying preferences in nature.