Extended effect of Bacillus thuringiensis H-14 on Culex pipiens adults surviving larval treatment

Three Bacillus thuringiensis H-14 preparations (a laboratory prepared and two commercial formulations namely, Tecknar and Vectobac) were assayed against third instar Culex pipiens larvae in order to trace their toxic activity on larval treatment. The LC50 values were 0.002, 0.02 and 0.04 ppm. respectively. The laboratory strain was tested on the development of Culex pipiens. Larval mortality, pupation, adult emergence and sex ratio showed significant differences as compared to the non-treated group. Toxic action on the treated larvae with laboratory strain of B. thuringiensis H-14 revealed drastic effect on larval mid-gut epithelium and resulted in extended pathological activity in adults, which survived larval treatments. Nervous and reproductive systems were found to be the most damaged systems in female adults.