Independent and joint action of cis- and trans-permethrin in Triatoma infestans (Hemiptera: Reduviidae).

摘要

The toxicity of pure cis- and trans-permethrin or mixtures of the 2 isomers topically applied to 1st, 3rd and 5th instar nymphs of T. infestans at 26deg C was determined. The cis-isomer was more active than the trans-isomer in the 3 stages evaluated. When the 2 isomers were simultaneously applied to 1st instar nymphs, an additive effect was observed. Similar treatments of 3rd and 5th instar nymphs resulted in an antagonistic effect. In 3rd instar nymphs, the cis-isomer was more active than trans-isomer at all the 3 temperatures assayed (16degree C, 26degree C and 36deg C). The toxicity of the cis-isomer was lower at 36deg C than at either 16degree C or 26deg C. Temperature had no significant effect on the toxicity of the trans-isomer within the temperature range assayed. The toxicity of either isomer to 3rd instar nymphs was not affected by pretreatment of nymphs with piperonyl butoxide (an inhibitor of mixed-function oxidases activity) or triphenyl phosphate (an inhibitor of esterase activity), suggesting that these detoxification pathways are not relevant in the metabolism of cis- or trans-isomers.