Chemosterilization of Culex pipiens fatigans Wiedemann by exposure of aquatic stages. I. Sterilization potential of certain aziridinyl compounds.

The sterile-male technique has been considered to be a promising tool for the control of mosquito populations. Many chemosterilants are known to sterilize insects effectively in the same way as ionizing radiations. The sterilizing activity of 8 alkylating aziridinyl compounds has been assessed on the tropical house-mosquito, Culex pipiens fatigans Wiedemann. The chemosterilants employed for larval and pupal treatments were apholate, metepa, tepa and 5 diaziridinyl alkoxyphosphine oxides. In general, metepa was least toxic to the various life stages of C. p. fatigans during the treatment. Apholate was toxic only in pupal treatments while tepa was less toxic in pupal treatments and more toxic in larval treatments. Diaziridinyl compounds were moderately toxic in both larval and pupal treatments. The tepa and apholate treatments caused certain structural and moulting abnormalities in pupae and adults and also induced abnormalities in eggs and larvae.Among the polyaziridinyl compounds, non-toxic doses of apholate could produce about 100% sterility with larval treatment. Tepa was inferior to apholate, and metepa was least effective in larval treatment. Among the diaziridinyl compounds, the methyl ester was most promising. For pupal treatment, tepa was more effective than apholate and metepa at non-toxic doses, inducing almost complete sterility. The propyl and isopropyl esters of the diaziridinyl compounds also induced very high sterility in pupal treatments.