PATHOGENICITY OF AN ENTOMOPATHOGENIC FUNGUS AGAINST MANGO FRUIT FLIES UNDER CONTROLLED CONDITIONS

Abstract

Zunain Fatima, Shahbaz Ahmad

Management of the insect pests is mainly done through synthetic insecticides which have resulted in residual effects in fruits as well environmental hazards. The current research was conducted to examine the biopesticidal impact of an entomopathogenic fungus Beauveria bassiana on two species of mango fruit flies, namely Bactrocera dorsalis and Bactrocera zonata. Virulence of the fungus was assessed at three dose rates under laboratory conditions. Three dosages of B. bassiana isolate viz. 3 × 108, 6 × 108, and 9 × 108 conidia/ml, were assessed for their larvicidal efficacy. The bioassays were conducted in an incubator set at 30°C with 65% relative humidity and devoid of lighting. The mortality of the introduced larvae was recorded 5 and 10 days’ post-exposure to the respective dosages. Results of mortality bioassays revealed that maximum mortality (50%) of B. dorsalis was due to 9 × 108 conidia/ml whereas the minimum mortality (38%) was noted at 3 × 108 conidia/ml by exposure period of 10 days. In case of B. zonata, the highest mortality (41%) was noted down at the highest conidial dose rate i.e. 9 × 108 conidia by exposure period of 10 days whereas the lowest mortality value (33%) was noted at 3 × 108 conidial/ml dose of B. bassiana. Outcomes of mycosis revealed that maximum mycosis (85.34%) was recorded at 9 × 108 conidial/ml dose by exposure period of 10 days in case of B. dorsalis whereas the comparatively low mycosis (67.56%) was enumerated at 3 × 108 conidial/ml. Similarly, maximum sporulation maximum (152.31 conidial/ml) was recorded at dose rate of 9 × 108 conidia and the lowest (110.65 conidia/ml) at dose rate of 3 × 108 conidia. Comparatively low values of mycosis and sporulation were recorded in case of B. zonata. Overall results disclosed that mortality, mycosis and sporulation responses were found dose as well as exposure period dependent and B. dorsalis showed comparatively more susceptibility towards B. bassiana compared with B. zonata. Further research is warranted to assess the efficacy of these entomopathogenic fungi in controlling fruit flies within both controlled laboratory environments and natural field conditions. This necessitates the evaluation of more virulent strains and isolates of entomopathogenic fungi, the development of appropriate formulations, and the standardization of application methods.