Lethality of triatomines (Hemiptera: Reduviiae), vectors of Chagas' disease, feeding on blood baits containing synthetic insecticides, under laboratory conditions Letalidade de triatomíneos (Hemiptera: Reduviidae), vetores da doença de Chagas, alimentados sobre iscas de sangue contendo inseticidas sintéticos, em condições de laboratório

Abstract

A laboratory study was conducted to test the toxicity of synthetic insecticides added to defibrinated sheep blood kept at room temperature and offered as food to the following triatomine species: Triatoma infestans, Panstrongylus megistus, Triatoma vitticeps, Triatoma pseudomaculata, Triatoma brasiliensis and Rhodnius prolixus. The insecticides used, at a concentration of 1g/l, were: HCH, DDT, Malathion and Trichlorfon, and the lethalithy observed at the end of a 7-day period varied according to the active principle of each. HCH was the most effective by the oral route, killing 100% of the insects, except P. megistus (95.7%) and T. pseudomaculata (94.1%). Trichlorfon killed the insects at rates ranging from 71.8% (T. vitticeps) to 98% (R. prolixus). Malathion was slightly less efficient, killing the insects at rates from 56.8% (T. vitticeps) to 97% (T.brasiliensis). DDT was the least effective, with a killing rate of 10% (T. vitticeps) to 75% (T.brasiliensis). Since the tests were performed at room temperature, we suggest that baits of this type should be tried for the control of triatomines in the field.Ensaiou-se, em laboratório, o efeito tóxico de inseticidas sintéticos, adicionados ao sangue de carneiro desfibrinado, mantidos em temperatura ambiente, oferecidos como fonte alimentar às seguintes espécies de triatomíneos: Triatoma infestans, Panstrongylus megistus, Triatoma vitticeps, Triatoma pseudomaculata, Triatoma brasiliensis e Rhodnius prolixus. Os inseticidas usados, na concentração de 1g/l, foram: HCH, DDT, Malathion e Triclorfon e a letalidade observada, ao fim de 7 dias variou, de acordo com o princípio ativo. HCH foi o mais efetivo por via oral, matando 100% dos insetos, exceto P. megistus (95,7%) e T. pseudomaculata (94,1%). Triclorfon eliminou entre 71,8% (T. vitticeps) e 98% (R. prolixus). Malathion ficou ligeiramente abaixo, matando entre 56,8% (T. vitticeps) e 97% (T. brasiliensis). DDT foi o menos efetivo, matando entre 10% (T. vitticeps) e 75% (T. brasiliensis). Como os testes foram feitos em temperatura ambiente, espera-se que iscas desse tipo possam ser usadas no controle de triatomíneos no campo.

Keywords

• Trypanosomiasis
• Triatomines
• Vector control
• Blood feeding
• Insecticides
• Lethality rate