Laboratory evaluation of insect growth regulators against the spotted wing drosophila, Drosophila suzukii

Abstract

Drosophila suzukii (Diptera: Drosophilidae) is an invasive species that causes great damages to many stone and small fruits, resulting in reduced fruit production and high economic losses. The concern about this pest has led to the research of a wide range of possible control methods. However, the main control strategies are still based in insecticide applications. The efficacy of different insect growth regulators (IGRs), which have better ecotoxicological profile than conventional pesticides, was evaluated to test their feasibility for the control of this pest. When adult flies fed for three days on artificial diet surface-treated with lufenuron, cyromazine or pyriproxyfen, no adult offspring developed. However, adult offspring production progressively recovered when flies were transferred to non-treated diet. When adult flies fed continuously for 19 days on surface-treated artificial diet, lufenuron, cyromazine and pyriproxyfen completely suppressed the production of viable offspring while azadirachtin and tebufenozide reduced offspring production by more than a half compared to the untreated control. Nevertheless, these were transient non-permanent effects since viable offspring was produced shortly after females fed on treated diet were transferred to non-treated diet. The results observed in additional choice and egg-transfer assays indicate a vertical transmission of lufenuron and cyromazine from treated females to their offspring whereas the effect of pyriproxyfen seems to be related to the feeding of larvae on treated diet, although effects on reproductive processes cannot be discarded. In addition, choice assays showed no repellent effect on oviposition by lufenuron, cyromazine and pyriproxyfen.