Effect of KK‐42 on growth, development, molting, and metamorphosis of the european corn borer, Ostrinia nubilalis (Hübner)

Abstract

(1 -benzyl-5-I(E)-2,6-dimethyl-l ,S-heptadienyll imidazole), administered by feeding, delayed the growth and development ot nondiapause-bound and diapause-bound Ostrinia nubilaiis larvae and increased the length of the instar. At doses of 80-240 ppm, 62-1 00% ot nondiapause-bound fourth instars precociously pupated or remained as fourth instars, while 52-100% of diapausebound fourth instars did not molt to the fifth instar. Injection of these nondiapause-and diapause-bound KK-42-fed fourth instars with ecdysone elicited a molt and resulted in the production of larval-pupal intermediates. When mature fourth instar controls were similarly injected, they molted into normal fifth instars. These results support the view that KK-42 delaydinhibits ecdysteroid production. Both eupyrene and apyrene spermiogenesis were prematurely initiated in nondiapause-bound fourth instars that were fed on mediuni containing 160 ppm KK-42. Fenoxycarb, a potent juvenile hormone mimic, rescued nondiapause-bound fourth instars from precocious pupation. All fenoxycarbtreated larvae either molted to the fifth instar or remained as fourth instars and eventually died. These results support the view that treatment with KK-42 inhibits jH production. When KK-42 treatment was begun in the third instar, a considerable number of nondiapause-bound and some diapause-bound third instars precociously molted to the fifth instar. There was a correlation between weight and the incidence of precocious molting in that third instars destined to skip the fourth instar attained a weight, as pharate fifth instars, of two to three times more than pharate fourth instar ccntrols. Similarly, fourth instars that were destined to undergo precocious pupation attained a weight, as pharate pupae, that was approximately two times more than pharate fifth instar controls. More potent analogues of

Insecticidal and Anti-juvenile Hormone Activities of Precocene II against the Grasshopper Euprepocnemis plorans plorans Charp. Orthoptera: Acrididae.

“…These data have validated the reported antiecdysteroid activity of other anti-JH compounds in some insects. The imidazole compound KK-42 was found to delay/inhibit the ecdysteroid production in O. nubilalis and S. gregaria [110,111]. Another imidazole SDIII had been reported to exert strong anti-JH and anti-ecdysteroid actions on B. mori [112].…”

Growth-Inhibitory Activity of 1-Benzyl-5[E]-2, 6-Dimethyl-1, 5-Heptadienyl Imidazole (KK-42) on Spodoptera litura

“…The antiecdysteroidal activity of KK-42 has been observed in Bombyx mori (Kadono-Okuda et al, 1987b) and the European corn borer, Ostrinia nubilalis (Gelman et al, 1995). The effect was reversed on feeding the treated insects with ecdysone, suggesting a delay/inhibition of ecdysteroid production.…”

Analysis of precocious metamorphosis induced by application of an imidazole derivative to early third instar larvae of the silkworm,Bombyx mori

“…In Manduca sexta, it has been demonstrated that a threshold head capsule size exists for metamorphosis (Nijhout, 1975). Recently it has been reported that when KK-42 is applied to third or fourth instar larvae of the European corn borer, Ostrinia nubilalis, a combination of reduced JH levels, inhibited ecdysteroid synthesis, and the resulting increase in weight gain is responsible for precocious metamorphosis (Gelman et al, 1995).…”