Effects of novaluron ingestion and topical application on German cockroach (Blattella germanica) development and...

Insect growth regulators disrupt insect development and reproduction. Chitin synthesis inhibitors (CSIs) allow the insect to grow normally, but because chitin is an essential component of the cuticle, formation of a new cuticle and ecdysis are prevented and the insect dies. CSIs can also kill embryos by disrupting their normal development. We evaluated the potential utility of novaluron in bait formulations against the German cockroach (Blattella germanica L.).

The minimum novaluron intake that interfered with molting and reproduction was assessed by exposing nymphs and adult females to novaluron. Results showed that 1 day of feeding on 0.1% novaluron was sufficient to disrupt molting in nymphs and prevent adult females from developing viable oothecae. The long-term effects on gravid females were investigated by feeding females 0.1% novaluron for different 5-day intervals during successive stages of gestation. Results demonstrated that gravid females fed novaluron during any period of gestation were able to produce viable eggs. To determine if ingestion of novaluron affected mating success and fertility of adult males, males were fed novaluron and then allowed to mate with untreated virgin females. Males that fed on novaluron successfully mated, and the females produced viable oothecae. Finally, direct comparisons revealed that novaluron is equally effective by ingestion and topical application.

Novaluron caused mortality in nymphs and interfered with ootheca production in adult females, but only before they formed an ootheca. It successfully reduced German cockroach populations in cages and has potential to be incorporated in cockroach baits.