Abstract: 　Objective] To investigate the possible mechanism underlying the killing of Culex quinquefasciatus larvae by Lagenidium giganteum from the biochemical point of view. [Methods] The activities of alkaline phosphatase(AKP), acid phosphatase(ACP) and esterase(EST) were observed by using calcium cobalt method, lead nitrate method and naphthol method. Results were photomicrographed and analysed quantitatively by image analysis using computer. [Results] The activities of AKP and ACP were decreased while the activities of EST were increased among the infected groups with different infection intensities. [Conclusions] The changes of these enzyme activities might be one of the important mechanisms of action of Lagenidium giganteum against Culex quinquefasciafus larvae.

Key words: Lagenidium giganteum, Culex quinquefasciatus larva, histochemistry