Chemosterilization of Male House Flies by Fumigation

A closed fumigation system with circulating atmosphere saturated with vapors of tepa, thiotepa (tris (l-aziridinyl) phosphine sulfide), hempa, thiohempa (hexa-methylphosphorothioictriamide), bis (l-aziridinyl)- N methyl-phosphinothioic amide, or bis (l-azilidinyl)- N -methylphosphinothioic amide was used to stetilize male Musca domestica L. Chemical and physical characteristics of the chemosterilant affected the fumigation period required for 50 or 95% sterilization (ST50 and ST95), but the vapor pressure of a sterilant was not directly proportional to its effectiveness. On the other hand, an increase in ambient temperature or in the treatment period invariably increased sterility. The uptake of hempa or thiohempa by treated flies was similar to the injection dose needed for the same degree of sterility, and each compound was metabolized to a different extent during the fumigation period. The closed fumigation system is safe to the operator, and the procedure is rapid and economical both in use of sterilant and in handling of insects. For mass treatments, the equipment could be easily scaled up.