| Abstract: | The activity of three enzymatic systems of xenobiotic metabolism (cytochrome P-450-dependent monooxygenases, non-specific esterases and glutathione S-transferases) was studied at different stages of development of the Colorado potato beetle (Leptinotarsa decemlineata). Significant sex and ontogenetic differences in the content of cytochrome P-450, position of maxima of CO-difference spectra of the cytochrome P-450 reduced form and substrate specificity of cytochrome P-450 were revealed. The activity of non-specific esterases was shown to increase depending on the age of larvae. The insecticide 1-naphtholenol methylcarbamate which is metabolized by the system of cytochrome P-450-dependent monooxygenases is more toxic in the larvae than at the imago stage, which is correlated with the activity of this system at different stages of ontogenesis. The microsomal monooxygenase inhibitor, piperonylbutoxide, increases the insecticide toxicity in the Colorado beetle imago more than 2-fold. The experimental results testify to different contribution of the detoxication systems to the sensitivity of the Colorado beetle to insecticides at various metamorphosis stages. |
