Larvicidal Effects of New Organophosphorus Schiff base compounds against Dengue Fever Vector Aedes aegypti (Diptera; Culicidae)

Abstract

Mosquitoes are the most important medical insect, that transmits diseases, such as dengue fever and malaria. The biological effects of new Organophosphorus Schiff base compounds (2-Furalidenediphenylphosphate-1-phenylsemicarbazide OPSL₁) and 2-methoxybenzalidenediphenylphosphate-1-phenylsemicarbazide OPSL₂) against the mosquito larvae of Aedes aegypti was evaluated at different concentrations using WHO standard susceptibility test with some modifications. A laboratory bioassay was conducted to assess the larvicidal activity under controlled laboratory conditions, late 3rd or early 4th instar larvae were exposed to various concentrations – ranging from 150 ppm to 1200 ppm of the tested compounds. Mortalities were observed to increase with the increase in concentrations. The results showed that OPSL₂ revealed significantly high activity against   Ae. aegypti  with (LC50 = 600.6 ppm) compared to the  OPSL₁, with LC50 = 642.9 ppm respectively. Further investigations would be required to evaluate the new active Organophosphorus compounds responsible for larvicidal efficacy in the future.