Pseudomonas fluorescens Isolates: Effects on Growth and Reproduction of the Earthworm, Eisenia fetida in Artificial Soil

The reproduction toxicity of Pseudomonas fluorescens (PF) isolated from different locations of Tamil Nadu viz., PF 5, PF 18, PF 25 to earthworm, Eisenia fetida (Savigny, 1826) was estimated in a 56-day soil exposure based on OECD 222 (2016) and ISO 11268-2 (2012). Identical test concentration of 106 cfu/kg dry soil was used for all the three strains of PF with four replicates. An untreated control (deionized water) with eight replicates was maintained for comparison. Adult earthworms were exposed to the treated soil and incubated under the test conditions for 28 days. Known quantity of cattle manure was added at weekly interval as food. Food consumption by adult worms per test container was observed and assessed up to 28 days. After 28 days, adult earthworms were sorted from the soil and assessed for mortality and weight loss (sub-lethal effects). Soil (without adult earthworms) was kept in the test container and juveniles/cocoons that produced by the earthworms were allowed to grow for further 28 days. The number of juveniles found in each container was counted at the end of test (56th day). The results of the study indicated that all the validity criteria specified by the guideline were met and no mortality was observed in any of the treatment group and control. Food consumption of earthworms treated with PF strains were on par with control. Biomass change of earthworms and number of juveniles produced by the treatment groups were significantly increased compared to control