Characterization of culturable gut bacterial isolates from wild population of melon fruit fly (Bactrocera cucurbitae) and assessing their attractancy potential for sustainable pest management

Abstract

The melon fruit fly, Bactrocera cucurbitae (Coquillett) poses a serious threat to cucurbit production worldwide. Its management by conventional means remains difficult due to their proclivity to oviposite in fruit. In view of the increasing environmental safety concerns, use of biocontrol agents for sustainable pest control holds immense potential. Given this, the study intended to identify the cultivable bacteria inhabiting the intestinal tract of adult male and female melon fruit flies (Bactrocera cucurbitae) separately from field-collected population, and to assess the attractiveness of these bacteria to the fly. All selected bacterial isolates were identified and characterized based on morphological, biochemical and 16S rRNA gene sequence. Bacterial community identified in the gut of B. cucurbitae predominantly composed of Enterobacteriaceae followed by Staphylococcaceae, Enterococcaceae, Bacillaceae and Brucellaceae. Further, the laboratory bioassay was employed to examine the attractiveness of the supernatant as well as whole culture broth of 10 different species of bacteria to B. cucurbitae adults. Among these, Klebsiella oxytoca and Citrobacter freundii followed by Bacillus cereus were found highly attractive to fruit flies. The field experiment using supernatant of two bacteria demonstrated that the K. oxytoca was significantly more attractive to female flies followed by C. freundii.