Larvicidal and adulticidal effects and ultrastructural changes of larvae midgut epithelium of Musca domestica (Diptera: Muscidae) fed with Bacillus thuringiensis var. kyushuensis.

Introduction: Musca domestica is resistant to many insecticides; hence, biological control is a suitable alternative. Methods: We evaluated the lethality of strain Btk176 towards the larval and adult M domestica and the histopathological effects in the larvae midgut. Results: We observed 99% larval and 78.9% adult mortality within 48 hours of spore ingestion (dosage, 2.4x10(8) CFU/ml). The histopathological effects were consistent with cytotoxicity. PCR analysis showed the presence of the cry1Ba gene. Transmission electron microscopy revealed a bipyramidal parasporal body. Thurigiensin activity was not detected. Conclusions: The serovar, Btk176 might be a potential biocontrol agent for houseflies.