Developmental Changes in the Microsomal Monooxygenase System and the In Vivo Metabolism of Aldrin in Larvae of the Mexican Bean Beetle (Coleoptera: Coccinellidae)

Abstract

In vivo metabolism of topically applied aldrin and the specific levels of whole body and abdominal microsomal cytochrome P-450, P-420, b5 and creductase were measured during development in the penultimate and last instar of the Mexican bean beetle, Epilachna varivestis Mulsant. There were no significant differences between molting larvae (from the penultimate to the last instar), last-instar feeding larvae and prepupae in these monooxygenase properties for whole-body microsomal preparations, and in respect to in vivo metabolism. Cytochrome P-450, b5, and creductase were higher in the abdominal microsomes of feeding-stage larvae than in whole-body microsomes from the same stage, and cytochrome P-450 and b5 were higher in the abdominal microsomes of feeding-stage larvae than in the abdominal microsomes from prepupae. The molar ratio of P-450 to P-420 was constant (approximately 1) for all microsomal preparations examined. The high tolerance of Mexican bean beetle larvae to topically applied aldrin could not be predicted based on poor penetration or the inability of aldrin to be epoxidized to dieldrin.