Abstract: The enzymatic determinations in vitro were used to demonstratethe relationship between hydrolases activity and pathogenicity of Coelomomyces indi sa for the fourth instar larvae of Culex tritaeniorhynchus. The results showed that carboxylesterase, acetylcholinesterase and glutathione S-transferase activities of themosquito larvae infected with C. indies were lower than that of normal larvae. Especially, the glutathione S-transferase activity decreased more markedly. It is suggested that the decrease of hydrolases activity was attributed to the lesion and destruction of the cells by the fungus toxin, which might have influence upon the metabolism and detoxication of the endogenous and ectogenous substrates.

Key words: Culex tritaeniorhynchus, Coelomornyccs indica, hydrolase