Measured Dose of Gamma Hexachlorocyclohexane (γ 666) Required to Kill Flies and Cockroaches,and a Comparison with DDT

Abstract

Summary

1. The approximate LD₅₀ for y 666 in the cockroach (Periplaneta americana) is 4.6 mg per kg when applied to the body surface and 3.4 mg per kg when injected intra-abdominally. These values are not significantly different.

2. An approximate equivalence, similar to that noted above. between surface and injection toxicity for the roach has been reported for DDT. This finding emphasizes the importance of the absorptive capacity of the insect body surface for contact poisons in contributing to the effectiveness of insecticides.

3. The approximate LD₅₀ for y 666 applied to the body surface is 0.4 mg per kg for the newly emerged fly (Musca domestira). For the older adult the LD₅₀ is about 0.8 mg per kg for Musca domestica and 0.6 mg per kg for Calliphora spp. This decrease in sensitivity as the fly ages is leas than that reported for DDT.

4. Gamma 666 is about twice as toxic as DDT for the cockroach (Periplaneta americana), and is distinctly more toxic than DDT for Musca domestica (newly emerged and adult) and Calliphora spp. (adult).

5. Both death and knockdown occur more rapidly after surface application of y 666 to Musca domestica and Periplaneta americana than after DDT.