author(s)
VV Waghmare, L Krishna Naik and B Shivanna

abstract
The aim of this study was to evaluate the gut bacteria of chlorantraniliprole-resistant (CRD) and susceptible (CSD) populations of diamondback moth, Plutella xylostella susceptibility to different kinds of antibiotics. The gut bacteria were isolated from chlorantraniliprole-resistant (CRD) and –susceptible (CSD) populations of P. xylostella by simple serial dilution and plating method. Bacterial isolates from both populations were selected based on their colony morphology and tested for antibiotic susceptibility using ten different antibiotics by Kirby-Bauer disk diffusion method. Totally 12 and 13 bacteria were selected from chlorantraniliprole-resistant (CRD) and –susceptible (CSD) populations respectively. Most of the selected gut bacterial colonies were yellow to light pink in colour and were gram negative in reaction. All the bacterial isolates from CRD were sensitive to Cefpodoxime (CPD) and all the isolates were resistant to Cephallexin (CN) except isolate CDK 6 which was found sensitive. All the bacterial isolates from CSD showed sensitivity towards Gentamycin (G), Cefpodoxime (CPD) and Sulfafurazol (S) and almost all the isolates were found resistant to Rifampicin (R) except isolate NDKS 1 whose response was moderately sensitive. The results indicated that, the gut bacteria from both populations were sensitive to Cefpodoxime (CPD) and in overall, the gut bacteria from CRD were more resistant to antibiotics than CSD.