Effect of selected pesticides on phyllosphere microbial diversity in mulberry (Morus alba L.)

Abstract

Phyllosphere microbes are associated with diverse microbial communities and these microorganisms influence plant health, nutrient cycling and degradation of agrochemical residues. With this contest, the present study was undertaken to evaluate the effect of recommended pesticides, viz., diafenthiuron, abamectin, dimethoate, cyanopyrafen and azadirachtin on the diversity and composition of phyllosphere bacteria associated with mulberry. The results of the experiment were revealed based on morphological and molecular identification of culturable bacterial isolates. A total of 52 bacterial isolates were identified from the phyllosphere of mulberry. Pesticide application resulted in a marked shift in the bacterial community of phyllosphere, with treated leaves showing dominance of Bacillota (Firmicutes), mainly represented by Bacillus cereus, B. thuringiensis and B. subtilis. In contrast, leaves without pesticide application exhibited higher diversity of Proteobacteria represented by Acinetobacter, Brevundimonas and Sphingomonas. The investigation has thrown light on the influence of pesticide toxicity on phyllosphere microbes, where chemical stress favours spore-forming Bacillus species while suppressing non-spore forming Proteobacteria.