Resumo
The beetle Alphitobius diaperinus (Panzer), considered a worldwide pest in the poultry industry, is difficult to control and it is a vector for pathogens. The objective of this study was to evaluate the biological control of the lesser mealworm, by strains of fungi Beauveria bassiana, Cladosporium sp. and Trichoderma sp. Larvae and adults of the A. diaperinus were inoculated with suspensions of conidia in the concentration of 10(7) conídia.mL-1. The B. bassiana isolate caused higher insect mortality as compared to Cladosporium sp. and Trichoderma sp. isolates, with the larvae being more susceptible than adults. The entomopathogenicity of B. bassiana was further evaluated with 200 larvae and 200 adults of A. diaperinus inoculated with suspensions 10(6), 10(7), and 10(8) conidia.mL-1, and observed for ten days. Larvae mortality started at the fourth day at the lowest concentration, and the adult mortality was only observed on the sixth day at the concentration of 10(8) conidia.mL-1.
Resumo
The beetle Alphitobius diaperinus (Panzer), considered a worldwide pest in the poultry industry, is difficult to control and it is a vector for pathogens. The objective of this study was to evaluate the biological control of the lesser mealworm, by strains of fungi Beauveria bassiana, Cladosporium sp. and Trichoderma sp. Larvae and adults of the A. diaperinus were inoculated with suspensions of conidia in the concentration of 10(7) conídia.mL-1. The B. bassiana isolate caused higher insect mortality as compared to Cladosporium sp. and Trichoderma sp. isolates, with the larvae being more susceptible than adults. The entomopathogenicity of B. bassiana was further evaluated with 200 larvae and 200 adults of A. diaperinus inoculated with suspensions 10(6), 10(7), and 10(8) conidia.mL-1, and observed for ten days. Larvae mortality started at the fourth day at the lowest concentration, and the adult mortality was only observed on the sixth day at the concentration of 10(8) conidia.mL-1.
Resumo
This work aimed at the evaluation of the in vitro susceptibility of Amblyomma cajennense nimphs and adults to isolates of Beauveria bassiana and Metarhizium anisopliae fungi. Three isolates of M. anisopliae (959, 319 e E9) and two of B. bassiana (986 e 747) were used. Conidia suspensions were made from fungi grown up in a rice culture medium and each test consisted of four treated groups (10(5), 10(6), 10(7), 10(8) conidia/ ml) plus a control group. Viability of individuals was assessed 15 days after treatment or after adult ecdisis. Significative differences were found for all treatments and for all stages studied. A large reduction in the viability of ticks was observed, and this effect increased as conidia concentration raised. Based upon the results obtained, it can be concluded that all isolates tested presented an in vitro lethality for the biological stages of A. cajennense evaluated, suggesting a potential use in the biological control of this tick species.
O trabalho teve por objetivo verificar a mortalidade in vitro de ninfas e adultos de Amblyomma cajennense frente à ação de isolados dos fungos Beauveria bassiana e Metarhizium anisopliae. Foram avaliados três isolados de M. anisopliae (959, 319 e E9) e dois de B. bassiana (986 e 747). As suspensões de conídios foram preparadas a partir de fungos produzidos em meio de arroz, e cada bioensaio foi constituído de quatro tratamentos nas concentrações 10(5), 10(6), 10(7), 10(8) conídios/ml e um grupo-controle. A análise constou da observação do percentual de mortalidade, 15 dias após o tratamento ou após a ecdise de adultos. Foram observadas diferenças significativas entre os tratamentos quanto à mortalidade para todos os isolados e todos os instares. Nos grupos tratados houve aumento considerável na mortalidade à medida que se aumentava a concentração de conídios na suspensão. Conclui-se que todos os isolados testados causaram mortalidade em testes in vitro sobre esses estádios evolutivos, sugerindo o controle do A. cajennense pela ação desses fungos.