Culturable epiphytic bacteria isolated from Teleogryllus occipitalus crickets metabolize insecticides.

Abstract

The development of insecticide resistance is attributed to evolutionary changes in pest insect genomes, such as alteration of drug target sites, upregulation of degrading enzymes, and enhancement of drug excretion. Beyond these well-known mechanisms, symbiotic bacteria may confer insecticide resistance to host crickets. The current study was designed to screen all possible culturable bacterial groups found living in and on the bodies of Teleogryllus occipitalis crickets. We recovered 263 visible bacterial colonies and cultured them individually. After identifying the colonies based on morphology and phylogenetic analysis, we shortlisted 55 bacterial strains belonging to 28 genera. Of these 55 bacterial strains, 18 degraded at least 50% of the original amount of 400 mg/L chlorpyrifos (CP) after 24 hr of coculture. Six of these strains degraded more than 70% of the original amount of 400 mg/L CP. Three strains had antagonistic effects on Bacillus thuringiensis growth. Additionally, the ability of the isolates to degrade glyphosate, phoxim, and esfenvalerate was assessed. We also detected extracellular hydrolase enzyme activities in these isolates. We propose that epiphytic bacterial strains play multiple roles in cricket biology, one of which contributes to chemical and biological pesticide resistance.