RESUMO
Chagas disease is one of the most important insect-vectored diseases in Brazil. The entomopathogenic fungus Metarhizium anisopliae was evaluated against nymphs and adults of Panstrongylus megistus, Triatoma infestans, and T. sordida. Pathogenicity tests at saturated humidity demonstrated high susceptibility to fungal infection. The shortest estimates of 50% lethal time (LT50 ) for P. megistus varied from 4.6 (isolate E9) to 4.8 days (genetically modified strain 157p). For T. infestans, the shortest LT50 was 6.3 (E9) and 7.3 days (157p). For T. sordida, the shortest LT50 was 8.0 days (157p). The lethal concentration sufficient to kill 50% of T. infestans (LC50 ) was 1.9 × 107 conidia/ml for strain 157p. In three chicken coops that were sprayed with M. anisopliae, nymphs especially were well controlled, with a great population reduction of 38.5% after 17 days. Therefore M. anisopliae performed well, controlling Triatominae in both laboratory and field studies.
Assuntos
Metarhizium/patogenicidade , Panstrongylus/microbiologia , Controle Biológico de Vetores/métodos , Triatoma/microbiologia , Animais , Brasil , Doença de Chagas/prevenção & controle , Galinhas , Abrigo para Animais , Umidade , Insetos Vetores/microbiologia , Ninfa/microbiologiaRESUMO
The growth and autolysis of two strains of the entomopathogenic deuteromycete fungus Metarhizium anisopliae var.anisopliae were evaluated in medium containing casein or glucose as carbon source. Parameters such as economic coefficient and degree of autolysis were determined for each strain. Protease production was determined throughout the growth and autolysis phases of the cultures on medium under conditions of proteaseinduction (in the presence of casein as sole source of carbon and nitrogen). The fungus was shown to utilize casein as a carbon/energy source in a more efficient manner than glucose. The autolysis shown by the strains was intense under both types of growth conditions, reaching up to 62,7 (per cent) of the dry mass produced and started soon after the depletion of the exogenous carbon source. The relationship between the proteolytic activities of the two strains evaluated varied significantly (a maximum of 19.78 on the 5th day and a minimum of 2.03 on the 16th day of growth) during the various growth and autolysis phases, clearly showing that the difference between the growth curves and the difference in the kinetics of enzyme production may decisively affect the process of strain selection for protease production.