Sublethal effects of nine insecticides on Drosophila suzukii and its major pupal parasitoid Trichopria drosophilae

Abstract

BackgroundAlthough the pupal parasitoid Trichopria drosophilae is employed in conservative and augmentative biocontrol of Drosophila suzukii infestations, current pest management strategies mostly rely on multiple insecticide applications. In this context, the aim of the study was to investigate the baseline toxicity of nine insecticides on D. suzukii larvae and their multiple sublethal effects (LC10) on immature stages of the pest feeding on contaminated diet and T. drosophilae developing within the intoxicated host.ResultsChlorpyriphos and azadirachtin showed the lowest and the highest LC10, which values were 9.78×1013 and 1.46×103 times lower than their recommended label field rate, respectively. Among tested insecticides, imidacloprid, malathion and dimethoate were the only treatments that did not affect the juvenile development time of D. suzukii, while spinosad and the organophosphates chlorpyriphos and dimethoate did not influence fly pupal size. No sublethal effects were recorded on T. drosophilae degree of infestation (DI) and juvenile development time. On the contrary, cyazypyr and dimethoate negatively affected the success of parasitism (SP) and the number of progeny of the pupal parasitoid, in association with malathion for the first parameter and spinosad for the fertility. Compared to the untreated control, more female progeny emerged following azadirachtin exposure, while dimethoate caused the opposite effect. Imidacloprid, lambda‐cyhalothrin and spinetoram decreased hind tibia length of emerged parasitoids.ConclusionThis study provides new insights on the (eco)toxicological profile of nine insecticides and new information needed to support the deployment of T. drosophilae in the field within the sustainable management techniques against D. suzukii.This article is protected by copyright. All rights reserved.

Effects of eight insecticides on Drosophila suzukii and its major pupal parasitoid Trichopria drosophilae

“…For two pupal parasitoids of D. suzukii, the sensitivity to dry residues of eight commercial insecticides was higher for P. vindemmiae than for T. anastrephae, resulting in a signi cant reduction in parasitism for the former species (Schlesener et al 2019). Sublethal doses of Cyazypyr and dimethoate negatively affected the success of parasitism and the number of progeny of T. drosophilae (Lisi et al 2023). The results of our study were consistent with those of these previous reports.…”

“…In addition to the increased mortality caused by indirect contact with drugs, the long-term, trans-generation effects of sublethal doses of pesticides on parasitic wasps should also be considered when assessing the safety of pesticides (Costa et al 2014;Lisi et al 2023). Treating host larvae or pupae with insecticides can affect the parasitic behavior of parasitoids and the emergence of the next generation.…”

Compatibility of Bioinsecticides with Parasitoids for Enhanced Integrated Pest Management of Drosophila suzukii and Tuta absoluta

“…Several bioinsecticides have been tested on D. suzukii and T. absoluta, with spinosad, azadirachtin, and pyrethrins among the most common active ingredients targeting both insect pests. While commonly used bioinsecticides mainly target D. suzukii adults, they can also affect pest immature stages and/or natural enemies because of their broad-spectrum action [10,27,28]. Avermectins, essential oils, and microbial-based biopesticides are additional tools for managing T. absoluta in organic contexts [18,[29][30][31].…”

“…Various studies have shown the non-target impact of insecticides with different origins and Mechanisms of Action (MoA) towards key natural enemies of D. suzukii [28,36] and T. absoluta [37][38][39]. However, the potential compatibility of biopesticides with Ganaspis kimorum Buffington (Hymenoptera: Figitidae) and Necremnus tutae Ribes & Bernardo (Hymenoptera: Eulophidae), which are among the most important larval parasitoids of D. suzukii and T. absoluta, respectively, is still poorly investigated.…”

Insecticidal Activity of Bacillus cereus against the Spotted Wing Drosophila

“…Spotted wing Drosophila, D. suzukii, is one of the most destructive polyphagous pests in soft-skinned fruits, including blueberries, strawberries, cherries, and raspberries (Karageorgi et al, 2017;Lisi et al, 2023;McIntosh et al, 2022;Vijayan et al, 2022). It is endemic to East Asia, and currently widespread throughout the Americas and Europe as an invasive species that is notoriously di cult to control (Kwadha et al, 2021).…”