ABSTRACT
From 148 substrate samples collected in peridomestic triatomine-infested habitats of 24 farms in Central Brazil, 31 isolates of Metarhizium anisopliae (Metsch.) Sorok. and 15 isolates of Beauveria bassiana (Bals.) Vuill. were obtained. Most of the isolates were found in substrates that consisted of soil mixed with animal feces or soil only in areas of trees where poultry roost and pig houses. Fungi were detected with an insect bait method using Triatoma infestans (Klug), and combined in vitro and in vivo techniques with modified Chase medium and T. infestans. All isolates were highly virulent to T. infestans third instar nymphs at a relative humidity > 98 percent and temperature of 25 ± 0.5°C. However, activity against nymphs was reduced at 75 percent relative humidity. Results underline the potential of B. bassiana and M. anisopliae as agents for biological control of vectors of Chagas disease. Both species occur naturally in peridomestic habitats of triatomines in Central Brazil and may contribute to control these vectors and to reduce the risk of reinfestation of houses after eliminating domestic vector species.
Foram detectados 31 isolados de Metarhizium anisopliae (Metsch.) Sorok. e 15 isolados de Beauveria bassiana (Bals.) Vuill. em 148 amostras de substratos coletadas em habitats peridomiciliares infestados com triatomíneos de 24 fazendas localizadas no Centro do Brasil. A maioria dos isolados foi encontrada em solos misturados com fezes de animais ou solos de áreas de poleiros e chiqueiros. Os fungos foram detectados com um método de captura utilizando Triatoma infestans (Klug) como isca, e um método combinado in vitro e in vivo, com meio Chase modificado e T. infestans. Os primeiros estudos sobre a atividade dos fungos indicaram que todos os isolados foram patogênicos para T. infestans quando testados em umidade relativa acima de 98 por cento e 25 ± 0,5°C. Porém, a atividade foi reduzida em umidade relativa de 75 por cento. Os resultados ressaltam o potencial de B. bassiana e M. anisopliae como agentes de controle para os vetores da doença de Chagas. As duas espécies ocorrem naturalmente em habitats peridomiciliares de triatomíneos no Centro do Brasil e podem contribuir para o controle desses vetores e reduzir o risco de reinfestação das casas após eliminação de espécies domiciliares.
ABSTRACT
Field tests were carried out during the rainy season of 2001/2002 in São Luís de Montes Belos, Goiás, Brazil, to evaluate the potential of the entomopathogenic fungus, Beauveria bassiana, against peridomestic Triatoma sordida. An oil-water formulation of the isolate CG 14 (Embrapa) was applied in triatomine infested hen houses of four farms at a final concentration of 10(6) conidia/cm2. Numbers of T. sordida decreased over the next 25 days, after application of the fungus, and B. bassiana developed on dead insects in one hen house. A high number of B. bassiana colonies was detected in substrates collected in treated hen houses 24 h after application of CG 14. In the following three months the presence of B. bassiana declined to values found before treatment.
Subject(s)
Ascomycota , Oils , Pest Control, Biological , Triatoma/microbiology , Animals , Brazil , Seasons , Time FactorsABSTRACT
Field tests were carried out during the rainy season of 2001/2002 in São Luís de Montes Belos, Goiás, Brazil, to evaluate the potential of the entomopathogenic fungus, Beauveria bassiana, against peridomestic Triatoma sordida. An oil-water formulation of the isolate CG 14 (Embrapa) was applied in triatomine infested hen houses of four farms at a final concentration of 10(6) conidia/cm². Numbers of T. sordida decreased over the next 25 days, after application of the fungus, and B. bassiana developed on dead insects in one hen house. A high number of B. bassiana colonies was detected in substrates collected in treated hen houses 24 h after application of CG 14. In the following three months the presenceof B. bassiana declined to values found before treatment.
