Ripening stages and volatile compounds present in strawberry fruits are involved in the oviposition choice of Drosophila suzukii (Diptera: Drosophilidae)

Abstract

Drosophila suzukii (Diptera: Drosophilidae) is an invasive polyphagous pest that causes economic losses in berry production worldwide. Its damage is caused by the ovipositor used to lay eggs into fruits, which also introduces microorganisms that hasten fruit spoilage and serve as food for larvae, leading to non-marketable fruits. Strawberry cultivars more resistant to D. suzukii can help in the management of this pest. Therefore, the aim of this study was to compare the susceptibility of Albion, Monterrey, and San Andreas, worldwide important strawberry cultivars, to D. suzukii harvested at three ripening stages (epidermis with 50%, 75%, and 100% of red surface). Moreover, fruit volatile compounds and their effect over D. suzukii female and male attraction were identified. Free-choice and non-choice bioassays were carried out to check oviposition preference. Fruit trait effects on oviposition preference were determined. Additionally, the volatile organic compounds active in D. suzukii antennas, and their contribution to pest attraction were analyzed. Both, cultivar and ripening stage affected fruit choice in the free-choice bioassay (p < 0.001). More mature fruits (sweeter and less firm) were more oviposited. However, in the no-choice bioassay neither the cultivar nor the ripening stage affected the oviposition choice (p = 0.998). Total amount of volatiles did not explain the oviposition choice, suggesting the relevance of specific volatiles. (±)-Linalool affected D. suzukii females (p = 0.0053) behavior and needs further investigation for being used as an attractant in mass-capture lures, monitoring and toxic baits, and assisting in oviposition control.