Influence of insect growth regulators on oviposition and transovarial activity in Thrips parvispinus (Thysanoptera:...

Short-spined thrips, Thrips parvispinus (Karny) (Thysanoptera: Thripidae), is an invasive pest of many economically important crops worldwide, particularly ornamentals. Feeding by T. parvispinus affects the aesthetic value and marketability of ornamental plants. Managing T. parvispinus is challenging because of its cryptic feeding behavior, rapid reproduction, and the risk of rapid development of resistance to common insecticides. Insect growth regulators (IGRs) can affect reproduction and elicit transovarial effects in thrips; however, few studies have tested IGRs on T. parvispinus. Thus, the objective of this study was to determine the effects of IGRs (buprofezin, pyriproxyfen, azadirachtin, and novaluron) on oviposition and transovarial activity of adult T. parvispinus after topical and dried-residue exposure. Exposure to the tested IGRs reduced oviposition and larval emergence compared with the nontreated control, although adult survival was not affected. Buprofezin and pyriproxyfen were the most effective compounds, causing a significant reduction in first-instar emergence compared with the other IGRs tested. Exposure to dried residues of azadirachtin and pyriproxyfen reduced oviposition compared with the other tested IGRs. Reduced larval emergence following adult exposure indicates transovarial effects of buprofezin and pyriproxyfen in T. parvispinus. Thus, these insecticides can be integrated into ornamental pest management programs to suppress T. parvispinus populations.