author(s)
Tariq S Alghamdi, Khalid M Alghamdi and Jazem A Mahyoub

abstract
Culex pipiens is a dominant mosquito species in Saudi Arabia and it is responsible for the transmission of several diseases to human. One way to control Cx. pipiens is to use conventional insecticides which have an effective role in reducing mosquito population. However, this control has been accompanied with some public concern and mosquito resistance of insecticides. Therefore, new insecticides have been developed such as Insect Growth Regulators (IGRs) which are safer on human and environment. The present study aims to evaluate two IGRs compound against the Cx. pipiens. Larvae were exposed to several concentrations of Difox flowable and Moskill 4G. The lethal concentration required to kill 50% of larvae was 0.0022 in Difox flowable and 0.1182 ppm in Moskill. As only 0.01 ppm of Difox flowable caused 95 % of adult inhibition compared to 0.5 ppm of Moskill which caused 91%. Moreover, morphological deformations were observed such as contraction of body segments.