Insecticidal activity and behavioral disorders by pyrifluquinazon against Trialeurodes vaporariorum and Bemisia tabaci

Pyrifluquinazon is known to act as a feeding inhibitor in several insect species. In this study, we investigated the effect of pyrifluquinazon on the whiteflies, Trialeurodes vaporariorum and Bemisia tabaci. Pyrifluquinazon showed high insecticidal activity (>90%) against adult T. vaporariorum and B. tabaci at 12.5 ppm to 50 ppm. However, there was no effect on eggs and nymphs of both species. Pyrifluquinazon showed low insecticidal activity in root and foliar uptake. Control efficacy of pyrifluquinazon was above 90% at 5 days after treatment. In order to investigate the behavioral response of the whiteflies initiated by application of pyrifluquinazon, we tested the contact toxicity and ingestion toxicity. After 1 h of contact, whitefly drop, wing convulsion, and paralysis were observed. Similar phenomenon of whitefly population was observed in test of ingestion toxicity after 3 h. In the choice test, pyrifluquinazon showed repellent activity against both species. These results suggest that pyrifluquinazon cause behavioral disorder rather than direct inhibition of feeding.

Key words: Trialeurodes vaporariorum, Bemisia tabaci, pyrifluquinazon, behavioral disorder, feeding inhibition