Clove-derived eugenol induces strong avoidance behaviour in the invasive fruit fly, Drosophila suzukii

Abstract

The success of invasive species often relies on sensory adaptations that allow them to exploit new environments. Unlike most of its relatives, the spotted-wing drosophila (Drosophila suzukii) lays eggs in ripening fruit, making it a serious and rapidly spreading agricultural pest worldwide. Spice plants produce volatiles that repel many insects, presenting potential sources of behavioural modulators for D. suzukii. Here, we examined whether volatiles from clove (Syzygium aromaticum) affect adult behaviour and offspring performance in D. suzukii. Behavioural assays revealed strong aversion: adults avoided grapes treated with clove extract, and gravid females laid significantly fewer eggs on treated fruit in both no-choice and choice assays. Clove exposure also reduced fitness, resulting in slower larval growth, lower adult weight, decreased emergence rate, and shortened lifespan. Gas chromatography–mass spectrometry analyses identified eugenol as the predominant volatile. Synthetic eugenol elicited strong avoidance across multiple host fruits, including apple, banana, blueberry, guava, mango, orange, papaya, raspberry, strawberry, and tomato. Molecular docking and single-sensillum recordings indicated that eugenol binds most strongly to DsuzOR88a and DsuzOR69aA odorant receptors. Cheminformatic screening of 1000 eugenol analogues revealed several structural variants predicted to interact strongly with OR88a, providing additional candidate repellents. By integrating behavioural, analytical chemistry, electrophysiology, and cheminformatics, our study shows that clove, through its major volatile eugenol, modulates host choice and reduces offspring performance in D. suzukii. These results highlight the ecological role of plant-derived volatiles in insect–plant interactions and support eugenol as a promising natural compound for sustainable fruit pest management.