Insecticidal potential of wax-degrading bacteria derived from fermented Ficus extract against Phenacoccus solenopsis Tinsley

Abstract

Aims: Phenacoccus solenopsis is a pest of many agricultural and horticultural crops, causing considerable losses in Asia and other parts of the world. Managing P. solenopsis is challenging due to a waxy covering body and high reproductive potentiality. This study was aimed to explore the potential use of wax-degrading bacteria isolated from fermented Ficus extract against P. solenopsis. Methodology and results: A total of ten isolates of wax-degrading bacteria were isolated from fermented Ficus extract (Ficus FPE) using a selective medium, Davis minimal agar (DMA), which was enriched with mealybug wax. The waxdegrading ability of the bacteria was evaluated through a turbidimetry test using 2, 6-dichlorophenol indophenol (DCPIP). Bacillus sp. 42PB3 demonstrated the highest wax-degrading potential, with 64.78% mealybug wax degraded and 73.85% paraffin wax degraded. The bioassay was conducted with three bacterial concentrations (10 8 , 10 7 and 10 6 ) tested against third-instar nymphs of P. solenopsis on Hibiscus rosa-sinensis by top application technique in completely randomized design (CRD) design with ten replications. The cell suspension and supernatant of Klebsiella pneumonia, Paenibacillus sp. 21F1E3, Bacillus sp. 35F1C1 and Bacillus sp. 42F1B3 isolates caused 70-83% and 60-66% mortality (supernatant) after 168 h post-treatment. Klebsiella pneumonia badly affected the offspring production of the treated mealybug with the lowest number of crawlers (80.2), followed by Paenibacillus sp. 21F1E3 isolate (111). Conclusion, significance and impact of study:In the present study, all tested bacteria isolated from fermented Ficus extract showed varying levels of wax-degrading ability and insecticidal activity against P. solenopsis. These bacterial isolates show promise as an environmentally friendly biocidal agent for managing P. solenopsis, potentially curbing crop losses and ensuring food quality through sustainable pest management practices in the future.