Functional characterization of cultivable gut bacterial communities associated with rugose spiralling whitefly, Aleurodicus rugioperculatus Martin

Gut symbiotic bacteria provide protection and nutrition to the host insect. A high reproductive rate and dispersal ability of the rugose spiralling whitefly help this polyphagous species to develop and thrive on many horticultural crops. In this study, we isolated the cultivable gut bacteria associated with rugose spiralling whitefly and demonstrated their role in the host insect. We also studied the influence of antibiotics on the rugose spiralling whitefly oviposition. A total of 70 gut bacteria were isolated from the second nymphal stage of rugose spiralling whitefly reared on coconut, banana, and sapota using seven growth media. From the 70 isolates, chitinase, siderophore (51), protease (44), and Glutathione-S-Transferase producers (16) were recorded. The activities of chitinase, siderophore, protease, and Glutathione-S-Transferase in the gut bacterial isolates of rugose spiralling whitefly ranged from 0.07 to 3.96 µmol–¹ min–¹ mL–¹, 10.01 to 76.93%, 2.10 to 83.40%, and 5.21 to 24.48 nmol–¹ min–¹ mL–¹ μg–¹ protein, respectively. The16S rRNA gene sequence analysis revealed that bacterial genera associated with the gut of rugose spiralling whitefly included Bacillus, Exiguobacterium, Acinetobacter, Lysinibacillus, Arthrobacter, and Pseudomonas. Based on the susceptibility of the gut bacteria to antibiotics, 11antibiotic treatments were administered to the host plant leaves infested with the nymphal stages. The antibiotics were evaluated for their effect on rugose spiralling whitefly oviposition. Among the antibiotic treatments, carbenicillin (100 µg mL–¹) + ciprofloxacin (5 µg mL–¹) significantly reduced the oviposition (13 eggs spiral–¹) and egg hatchability (61.54%) of rugose spiralling whitefly. Disruption of chitinase, siderophore, protease, and detoxification enzyme producers and elimination of these symbionts through antibiotics altered the host insect physiology and indirectly affected whitefly oviposition. In conclusion, gut bacteria-based management strategies might be used as insecticides for the effective control of whiteflies.