Fate of Diflubenzuron in Southwestern Corn Borer Larvae (Lepidoptera: Pyralidae)1

Abstract

The penetration and metabolism of diflubenzuron were examined in nondiapausing (NDL) and diapausing (ElL) larvae of Diatraea grandiosella (Dyar). Penetration of diflubenzuron into NDL was about twice that of EIL, with times for 50% disappearance of topically applied radiocarbon of 360 and 744 min, respectively. Both NDL and EIL degraded diflubenzuron; only 56% of the injected dose was the parent compound by 16 h. The major metabolite in the organic extract at 16 h was 4-chloroaniline, comprising 21 and 30% of the dose in NDL and EIL, respectively. Other metabolites isolated from both larval types included N-[[(4-chloro-2-hydroxyphenyl)amino]carbonyl]-2,6-difluorobenzamide, N- [[(4-chloro-3-hydroxypheny1)amino]carbony1]-2,6-difluorobenzamide, 2,6-difluorobenzamide, 2,6-difluorobenzoic acid, and 4-chlorophenylurea. Unidentified radiocarbon, probably conjugates, was present in the aqueous extract; this material comprised 9% in NDL and 3% in EIL at 16 h. Degradation of diflubenzuron by D. grandiosella was appreciably greater than that reported for other lepidopterans.