Effects of solid and aqueous dietary diflubenzuron ingestion on some biological parameters in synthetic pyrethroid-resistant German cockroach, Blattella germanica L. (Blattodea: Ectobiidae)

Abstract

Cockroaches, widespread pests found in metropolitan areas, are known as vectors ofvarious disease agents, including viruses, fungi and antibiotic-resistant bacteria, as wellas causing allergies in humans. Insect growth regulators have been used in pest man-agement for several decades. These insecticides disrupt insect development and repro-duction. Chitin synthesis inhibitors interfere with chitin biosynthesis in insects, causingabortive moulting and mortality, as well as inhibiting egg fertility, and larval hatching ininsects. In this research, we evaluated the various effects of diflubenzuron, a chitinsynthesis inhibitor, on synthetic pyrethroid-resistant German cockroach (Blattella ger-manicaL. Blattodea: Ectobiidae), including ootheca production, oothecal viability,ootheca incubation time, the number of nymphs emerging from the ootheca and survi-vorship of nymphs. The cockroaches were fed diets that contained diflubenzuron,which was added to solid bait (impregnated fish food) and ingestible aqueous bait(impregnated cotton). Three concentrations (0.5%, 1% and 2%) were used in the exper-iments. As a result, diflubenzuron treatment led to ootheca production ranging from60% to 100%; statistically, no difference was found between the treatment and thecontrol groups. The number of nymphs emerging from the first and second oothecawas reduced by 40%–100% in the diflubenzuron-treated groups compared with thecontrol. Nymphs exposed to diflubenzuron-impregnated solid bait and ingestible aque-ous bait experienced mortality exceeding 92.1% and 66.27% within 15 days, respec-tively. In conclusion, diflubenzuron is a potential insecticide for use in cockroach baitsto controlB. germanica, as it caused high nymphal and embryonic mortality in the syn-thetic pyrethroid-resistant population and decreased the number of nymphs emergingfrom the ootheca.