COMPARATIVE TOXICITY OF DELTAMETHRIN AND CIS-PERMETHRIN ON FIRST INSTARS OF TRIATOMA-INFESTANS (HEMIPTERA, REDUVIIDAE)

We evaluated the toxicity of deltamethrin and cis-permethrin at 3 temp eratures on instars of Triatoma infestans (Klug). After treatment, tem perature had an important effect on LD(50)s of both insecticides, whic h tended to decrease when temperature decreased. How ever, the effect of temperature on LT(50)s was small. Cis-permethrin was slightly more lethal than deltamethrin only at 26 degrees C. Lethal action of deltam ethrin was faster than cis-permethrin at all temperatures assayed. The toxicity of both pyrethroids was affected by the age and the nutritio nal state of the nymphs. We evaluated sublethal effects on blood meal ingestion and moulting. Only deltamethrin yielded a substantial decrea se in the number of moulted nymphs.