Insecticidal effect of diflubenzuron against cockroaches

Abstract

Laboratory tests were conducted to evaluate the potential activity of diflubenzuron, an insect growth regulator, to control cockroaches. In first-instar nymphs of Blattella germanica, 100% mortality was obtained with filter-paper harborages treated with a water suspension of 20ppm or more active ingredient (a.i.) concentration. However, the nymphs fed on animal-food powder containing 100ppm a.i. were not killed completely. The effects of diflubenzuron residually applied to harborages were also demonstrated against first-instar nymphs of Periplaneta americana as well as against final-instar nymphs of B. germanica. Topical applications to final-instar nymphs of B. germanica were also effective. The age of the greatest sensitivity of first-instar nymphs of P. americana was about 4 days before ecdysis, and that of final-instar nymphs of B. germanica was from 3 to 6 days before their final ecdysis at 26℃, during which a single-day exposure to treated harborages was enough to kill them all. The exposure of parent cockroaches to treated harborages showed substantial ovicidal effect in B. germanica.