Avermectins, MK-933 and MK-936, for mosquito control.

Two avermectins were shown to be effective as mosquito larvicides or when fed to adult female mosquitoes in sucrose solution or in blood. Larval LC50 values of compounds MK-933 and MK-936, expressed as parts per billion, were found to be 3.94 and 2.42 for Culex pipiens, 5.85 and 2.90 for Anopheles stephensi and 23.4 and 10.4 for Aedes aegypti. When fed to adult females of An. stephensi, Ae. aegypti or Cx quinquefasciatus, MK-933 at 2.8mg active ingredient per litre in sucrose solution caused complete mortality within 60 hours. When female mosquitos engorged blood from mice injected subcutaneously 12 hours previously with MK-933 at 82 mg a.i./kg, mortality rates after 36 hours were 100% for An. stephensi, over 60% for Ae. aegypti and over 50% for Cx quinquefasciatus. Thus the systemic insecticidal effect was greater against anopheline than against culicine female mosquitoes.