Topical and injection toxicities of some pyrethroids in the housefly, Musca domestica L.
1985 Volume 36 Issue 1 Pages 31-38
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1985 Volume 36 Issue 1 Pages 31-38
The comparative toxicities of some synthetic pyrethroids in the housefly, Musca domestica L. (Lab-em-7-em strain), were studied over 24hr (injection) and 48hr (topical). Results indicated that the housefly was very susceptible to knockdown (KD) by the synthetic pyrethroids although the 24 and 48hr topical LD_<50> values showed little difference from that of fenitrothion, the comparative OP insecticide used in the tests. The most toxic compound in topical application was cypermethrin while fenvalerate was most toxic in injection. In the topical application treatments, α-cyano substituted compounds were more effective both at kill and at KD than non-substituted compounds, except for S-5439 and fenvalerate where the reverse situation was predominant. The relationship between the topical and injection LD_<50> values suggested that some of the synthetic pyrethroids (i.e. phenothrin, cyphenothrin, cypermethrin and S-5439), as well as fenitrothion, could penetrate the housefly cuticle more easily than lindane, permethrin, fenvalerate and fenpropathrin. The general order of toxicity of the tested insecticides, based on the 24 and 48hr LD_<50> s was as follows : cypermethrin>>cyphenothrin≥fenpropathrin≥fenitrothion>fenvalerate≥S-5439≥lindane≥permethrin>phenothrin. Fenitrothion had very little or no KD effects in the housefly.
