The biological effects of the insect growth regulators; pyriproxyfen and diflubenzuron on the mosquito Aedes aegypti.

The biological effects of two insect growth regulators (IGRs), pyriproxyfen and diflubenzuron against larvae of the mosquito Aedes aegypti (L.) have been evaluated. Mosquitoes were collected from Jeddah governorate, west of the Kingdom of Saudi Arabia and maintained in the laboratory. According to IC50 values obtained (concentrations which inhibit the emergence of 50% of adults), diflubenzuron (0.00036 ppm) proved to be more effective by 11.4 fold of pyriproxyfen (0.0041 ppm). In addition to the delayed lethal action, larval treatment with the two IGRs, pyriproxyfen and diflubenzuron led to pronounced reduction in the reproductive potential of mosquito adults that emerged from these treatments. Pyriproxyfen caused a 33.2% decrease in egg production compared to 25.5% for diflubenzuron. The reduction in egg hatchability was by 40.6 and 36.2% for pyriproxyfen and diflubenzuron, respectively, with up to 4 fold higher reduction rates than in the control tests. These results shed light on the extended biological effects of IGRs on mosquitoes and encourage further testing of IGRs for wider use in the control of Ae. aegypti and other important disease vectors in Arabia and the world.