Integrated Lethal and Sub-Lethal Effects of Chlorfluazuron and Triflumuron on Pieris Brassicae

Abstract

The biological effects of insect growth regulators may include direct mortality as well as disruption of development and larval growth. This study integrated mortality, concentration–response, developmental duration, head capsule width and body length data from a laboratory investigation of chlorfluazuron and triflumuron against Pieris brassicae (Linnaeus, 1758). Both compounds produced high mortality of second-instar larvae, with mortality increasing with concentration and exposure duration. At 120 h, chlorfluazuron mortality was 73–100% across 1–7%, while triflumuron mortality was 63–100%. Probit analysis showed 120-h LC50 values of 0.542 ppm for chlorfluazuron and 0.758 ppm for triflumuron. Sublethal exposure was associated with altered developmental duration and reduced head capsule width and body length. The integrated pattern indicates that IGR activity against P. brassicae cannot be characterized adequately by mortality alone. The results provide a laboratory basis for future field studies of IGR-based management of this crucifer pest.