Efficacy of Beauveria bassiana and Metarhizium anisopliae (Ascomycota: Hypocreales) against Bactrocera cucurbitae (Coquillett) (Diptera: Tephritidae) under controlled and open-field conditions on bitter gourd

Bactrocera cucurbitae (Coquillett) (Diptera: Tephritidae) is the most destructive pest of bitter gourd. Conventionally, it is controlled by chemical insecticides despite their hazardous impacts. Entomopathogenic fungi are considered as eco-friendly and safer alternative of chemical. This study aimed to evaluate the efficacy of Beauveria bassiana and Metarhizium anisopliae against B. cucurbitae on bitter gourd. The study revealed that B. bassiana and M. anisopliae were efficient against B. cucurbitae in controlled as well as field conditions. Both mode of application (i.e., contact and oral) were found to be effective; however, high efficacies of them were observed through contact application (73.43 and 59.72%), respectively. Pathogenicity of both fungi increased with increase in concentration and time intervals. Under field conditions, significantly low fruit infestations and significantly a high population reduction of B. cucurbitae were observed at 30 DAT when both fungi were applied with 108 CFU/ml concentrations. Beauveria bassiana and M. anisopliae had the potential to be used against B. cucurbitae; however, the former showed high efficiency comparatively.