Laboratory evaluation of four insecticides on the mosquito Culiseta longiareolata (Macquart) (Diptera Culicidae)

The efficacy of four insecticides belonging to different groups, synthetic pyrethroid (lambdacyhalothrin), carbamate (Marshal) , fungicide (Topas) and insect growth regulator (Neemrich) as well as their joint action were tested against 3rd larval instar of Culiseta longiareolata . Based on concentration mortality data LC50 and LC90 values, results obtained showed that LC50 values as observed were 0.09, 2.3 , 9.0and 25.0 ppm for lambdacyhalothrin , Marshal , Neemrich and Topas, respectively. The results showed that all mixtures consisted of a 1:1 (v/v) ratio of the LC25 of each compound indicated potentiating effect .The highest potentiating effect was achieved by a mixture of co-toxicity factor equaled+100 (lambdacyhalothrin + Neemrich). The lowest potentiating effects were obtained from mixtures of Marshal + Topas and Topas+Neemrich (co-toxicity factor equaled+40) .The tested insecticides completely inhibited the emergence of adults till 0.0078,0.0625,0.25 and 1 ppm for lambdacyhalothrin , Marshal , Topas and Neemrich , respectively ,and the emergence of adults was inversely proportional to the concentration.