Uptake of Metepa and Its Effect on Two Species of Mosquitoes (Anopheles quadrimaculatus, Aedes aegypti) and House Flies (Musca domestica)

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Abstract
P32-labeled metepa was rapidly absorbed from glass surfaces by both mosquitoes (Anopheles quadrimaculatus Say and Aedes aegypti(L.)) and house flies (Musca domestica L.). House flies and quadrimaculatus absorbed approximately 7 μg per insect during a 4-hour exposure on surfaces treated at 10 mg/ft2 whereas aegypti picked up 2.5 μg. This uptake resulted in a severe reduction of mating ability in mosquitoes, coupled with 99% sterility, in house fly and aegypti males. Metepa was found to be quite volatile on glass surfaces and highly sorptive on masonite. Under similar conditions quadrimaculatus absorbed 27 mmg from masonite treated at 100 mg/ft2 and 7600 mμg from glass treated at 10 mg/ft2. After 3 days of feeding on treated food, the amounts of the chemosterilant absorbed, expressed in μg-equivalents of p32 metepa, were 3.0,3.7, and 1.7 in quadrimaculatus, house flies, and aegypti, respectively. These dosages caused sterility in all species without reducing male vigor. Exposure of mosquito larvae from the third instar through pupation in water treated at 10 ppm resulted in low metepa uptake and very little induced sterility. The distribution of metepa in the insects was rapid and apparently nonselective. Excretion was rapid in insects exposed to residual deposits of 10 mg/ft2. Insects exposed to treated larval medium and food retained a high percentage of their original radioactivity, over prolonged periods; this activity undoubtedly represented detoxified metepa, however.

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