Studies on several microsomal enzymes in two strains of Tribolium castaneum (tenebrionidae, coleoptera)

Abstract

1. Levels of cytochrome P450 in Tribolium castaneum (Herbst) CTC-12 strain is higher in larvae (4-fold) and adults (3-fold) compared with the respective developmental stages of the susceptible CSbb line. Similar but less dramatic quantitative differences regarding cytochrome b 5 were observed in both strains. In CTC-12 adults levels twice that of CSbb were detected. 2. Microsomal oxidative activity measured by the rate of aldrin epoxidation is more than twice higher in larvae of CTC-12 vs that found in CSbb. Yet such a difference was not detected in adults. Epoxide hydrase activity is more than five times higher in CTC-12 than in the CSbb strain. 3. Cytochrome P450 in larvae and adults of CTC-12 and CSbb strains were induced considerably by dietary phenobarbital. Larval cytochrome b 5 levels and epoxide hydrase activity are inducible to a certain degree by the drug. 4. The relevance of the above findings to the resistance acquired by T. castaneum to insecticides is discussed.