Exploring Agricultural Potentiality of Serratia entomophila AB2: Dual Property of Biopesticide and Biofertilizer

Abstract

Aims: In an attempt to explore novel agents for application in agriculture, the strain Serratia entomophila AB2 was investigated. Study design: Pesticidal, Fertilizing and Toxicological effects. Place and Duration of Study: Department of Botany (Microbiology Unit), Visva-Bharati, Santiniketan, West Bengal, India and M/S Ajay Biotech (India) Ltd., Pune, India, between December 2006 to August 2007. Methodology: Pesticidal activity of the isolate Serratia entomophila strain AB2 was tested against 5 day old larvae of Heliothis armigera, Spodoptera litura, and Plutella xylostella through feeding assay. Fertilizing capacity of the strain was determined by inorganic phosphate and zinc solubilizing experiments. Conventional T-tests were performed to check effect against certainr rhizospheric organisms (Azotobactor chroococcum NCIM 2452, Rhizobium japonicum NCIM 2746, Azospirillum brasiliensis NCIM 5135, Erwinia amylovora MDVB). In animal toxicity experiments, adult male Swiss albino mice (body wt ≈ 25 g) were used to find LD50 within the experimental doses and male Sprague Dawley strain of Swiss albino rat (body wt ≈ 110 g) were used to find out the effect of feed inoculation treatment in liver and blood as general target of intoxication through standard thiobarbituric acid reactive substance (TBARS) and serum glutamic pyruvic transaminase (SGPT) assay. Results: The mortality rate of, lepidopteron larvae tested was determined between 89.5 to 94.3% while LC50 value estimated between 0.44x105 to 1.44x105 CFU (colony forming unit) mL-1 through probit analysis. As a part of fertilizing activity, S. entomophila AB2 was found to solubilize phosphorus and zinc in in-vitro condition. In cross reactivity study with other rhizospheric bacteria, the isolate proved as non reactive. No mortality was recorded with Swiss albino mice and other toxicological data resulted from the experiment with Sprague Dawley strain of Swiss albino rat were found insignificant. Conclusion: The isolate S. entomophila AB2 showed its potential in in vitro conditions for both pesticidal and fertilizing activity. The data generated in this study show much promise of S. entomophila AB2 for its field application in integrated crop management (ICM). These predictors, however, need further work for field validation.