Larvicidal Activity of some Bacterial Insecticides and Insect Growth Regulators against Mosquito Larvae of Aedes aegypti (L.)

The biological effects of the bacterial insecticides Bacilod, VectoLex and Spinosad as well as the insect growth regulators (IGRs) Baycidal, Sumilarv and Dudim against mosquito larvae of Aedes aegypti have been evaluated. According to LC50 values (concentration which to kill 50% of larvae), the bioinsecticide Spinosad (0.011 ppm) proved to be the most effective compound, followed by Bacilod (0.11 ppm) and VectoLex (0.38 ppm). Taking IC50 values (concentration which to inhibit the emergence of 50% of adults) into consideration, mosquito larvae of A. aegypti were more susceptible to the IGR Dudim (0.00056 ppm) than Baycidal (0.0007 ppm) and Sumilarv (0.0042 ppm) by about 1.25 and 7.5 folds, respectively. Variations in the susceptibility status of the present mosquito larvae may be attributed to the differential mode of action of the test compounds and its effective concentrations. On the other hand, larval treatments with sublethal concentrations of the above insecticides led to a reduction in the egg production and hatchability of eggs produced by mosquito females that developed from surviving larvae.