Susceptibility of Aedes aegypti (L.) Larvae to Some Non-conventional Insecticides

摘要

Laboratory trials were conducted to determine the larvicidal activity of the bacterial insecticides (spinosad and vectobac), the insect growth regulators, IGRs (sumilarv and dudim) and the plant extracts of neem [Azadirachta indica] and usher (Calotropis procera) against Aedes aegypti (L.). The toxicity curves showed that the bioinsecticide spinosad proved to be more effective than vectobac against A. aegypti larvae by about 11.1 times. Such a fact was highly pronounced on the basis of LC50 values (concentration which to kill 50% of larvae) which were 0.009 ppm and 0.1 ppm, respectively. According to IC50 values (concentration which to inhibit the emergence of 50 % of adults), the results indicated that mosquito larvae of A. aegypti were more susceptible to the IGR dudim (0.00038 ppm) than sumilarv (0.004 ppm) by about 10.5 folds. The plant extract of neem was also more effective against the present larvae than usher extract, with IC50 of 35 ppm and 66 ppm, respectively. Taking coeffective factor (C.F.) into consideration, the results revealed that the chemical insecticide actellic (pirimiphos-methyl) in combinations with spinosad, dudim and neem extract against the present mosquito larvae produced different levels of potentiation reflected by theinhibition of adult formation.