Bio efficacy of Indigenous isolates of Beauveria bassiana against different Stages of Bactrocera zonata (Guava Fruit fly)

Background Pakistan is the world’s leading producer of guava, with 0.0585 million hectares under cultivation, yielding a total production of 0.56 million tons guava annually. However, various biotic and abiotic constraints limit global guava yields. Among the biotic factors, the fruit fly, Bactrocera zonata poses a significant challenge in Pakistan. The indiscriminate use of chemical insecticides to control these pests has caused significant environmental and regulatory concerns, highlighting the need for ecologically safe and environmentally friendly alternatives. In this context, native isolates of entomopathogenic fungus, Beauveria bassiana have been isolated and their efficacy was evaluated against different stages of Bactrocera zonata. Results Susceptibility of the fruit fly varied significantly with the spore concentration. The indigenous isolate, FMB-BB-FF 04, demonstrated high virulence against the 3 ^rd instar larvae, pupa and adult causing up to 98% mortality at 14 days after treatment (DAT) at the highest spore concentration tested (1 ×10 ⁸ conidia/mL). Furthermore, horizontal transmission of fruit fly adult was tested achieving highest mortality rates when both male and female were inoculated. While comparatively higher mortality was recorded in treatments with inoculated females than treatments with non-inoculated females. FMB-BB-FF 02 and FMB-BB-FF 04 exhibited high mortality, suggesting its potential as a bio‑pesticide in fruit fly management programs. Conclusions Based on virulence, and efficacy, FMB-BB-FF 04, showed significant potential as a biocontrol agent for managing guava fruit fly. The present study identified an effective native isolate and demonstrated its in vitro efficacy. Thus, it could be integrated into fruit fly management programs in guava cultivation as an efficient biological control agent.