Laboratory investigations were carried out to study the effect of two protease inhibitors on the transmission of W. bancrofti filarial by Culex pipiens and to study the susceptibility interaction between filaria and protease inhibitors. The results
obtained revealed that, infection rates were variable among untreated and treated symbiotic and aposymbiotic Cx. pipiens females resulted from third instar larvae treated with E-64 and EDTA. The survival rate was variable among untreated and
treated symbiotic and aposymbiotic females resulted from third instar larvae treated with E-64 and EDTA. Protease inhibitor (E-64) caused inhibition of the parasite development and transmission by means of ceasing catalytic activity- responsible for parasite migration-caused by parasitic larval stages inside the mosquito vector.