Insecticide Toxicity to Drosophila suzukii (Diptera: Drosophilidae) parasitoids: Trichopria anastrephae (Hymenoptera: Diapriidae) and Pachycrepoideus vindemmiae (Hymenoptera: Pteromalidae).

Abstract

Drosophila suzukii (Matsumura) is an important pest of small fruits, which has been causing significant damage to commercial crops in North America, Europe, and South America. This pest is mainly controlled with insecticide applications because of its highly biotic potential and polyphagy. However, studies conducted in crops infested by D. suzukii have shown that this species is attacked by parasitoids that may serve as effective biological controls for this pest. The aim of the current study is to assess the lethal time (LT10 and LT50) and parasitism potential of exposed adults (F0): sex ratio and longevity (F1) of Trichopria anastrephae Lima and Pachycrepoideus vindemmiae (Rondani) when exposed to dry residues of different commercial insecticides. Abamectin, acetamiprid, thiamethoxam, malathion, phosmet, deltamethrin, spinetoram, and spinosad were evaluated. Pachycrepoideus vindemmiae was more sensitive to insecticides than T. anastrephae, showing higher mortality rates in a shorter period of time, as well as a significant reduction in parasitism. Spinosyns (spinosad and spinetoram) and abamectin caused high P. vindemmiae mortality rates, but were harmless to T. anastrephae. Neonicotinoids, organophosphates, and pyrethroids caused high mortality rates regardless of the species. Treatments did not affect D. suzukii offspring longevity and sex ratio (F1). The current study provides information needed for the implementation of D. suzukii management programs focused on the conservation of natural enemies.