Residual effect of lambdacyhalothrin on Triatoma infestans.
Insecticidal residual effect and triatomine infestation rates in houses of a community fumigated with lambdcyhalothrin (Icon) are reported. No mortality was observed in 5th-instar Triatoma infestans nymphs in 72-hr exposure test on three different surfaces, one month after fumigation for a dose of 31.5 mg am/m2. However, during post-exposure observation a mortality of 60% was recorded for those insect exposed on sprayed woodboard. The results observed with mud-containing treated walls, were markedly poorer (0% of mortality). Twelve month after spraying 40% of mortality was observed on first-instar T. infestans nymphs in 72-hr exposure test on woodboard, but lower mortality rates were observed in mud-containing materials. When the effect of deltamethrin (109 mg ai/m2) and lambdcyhalothrin (94 mg ai/m2) was compared, the former did not appear to be superior at similar loads. Both have showed a mortality rate of 30% on 5th-instar T. infestans nymphs three months post-fumigation. The dose utilized in the field fumigation was enough to get a significant (p < 0.0001) control of triatomine domestic infestation, since it was sufficient to keep 95% of the houses uninfested throughout 21 months following treatment, when compared with baseline situation. A remarkable knock-down effect on adult and nymphs forms of the insect and a high in situ mortality were observed as a result of its application, even at very low doses.
Instituto de Investigaciones en Ciencias de la Salud, Universidad Nacional de Asunción, Paraguay.
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D000818:Animals; D005651:Fumigation; D007300:Insect Control; D007306:Insecticides; D009570:Nitriles; D010239:Paraguay; D010573:Pesticide Residues; D011722:Pyrethrins; D014224:Triatoma
D007306:Insecticides; D009570:Nitriles; D010573:Pesticide Residues; D011722:Pyrethrins; C017180:decamethrin; C037304:cyhalothrin