TOXICITY STUDIES ON THE EFFECT OF DICHLORVOS ON BIOLOGICAL SENTINELS

ABSTRACT

Earthworms are beneficial to the health of the soil. In agriculture, there is a gradual increase in the use of chemicals which can lead to unintended consequences. The study was conducted to analyze the toxicity of dichlorvos on biological sentinels. This study was conducted to analyze the acute toxicity of dichlorvos on microorganisms in association with earthworms in the soil.This study methodology involved isolation and characterization of microorganisms using microbiological techniques. Also, weight and length of associated earthworms was obtained and biomarkers present in the soil was analysed such as changes in Glutathione peroxidase (GPX), Catalase, and Glutathione-S-transferase (GST).Organisms isolated include Pseudomonas aeruginosa, Escherichia coli, Bacillus subtilis and Bacillus cereus. The results indicated no significant change in the heterotrophic bacterial count irrespective of the concentration of dichlorvos. Also, the result showed that post exposure, the dichlorvos notably caused a reduction in the length of the earthworms, especially at the 0.6ml/kg treatment group. Also, there was a marked change in the weight of the earthworms. Analysis revealed that there was no statistically significant difference in the mean length of exposed earthworms compared to the control (P>0.05). Many behavioral changes were observed; worms looked sluggish and showed excessive coiling and total mortality was recorded after 14days. In conclusion, there should be a controlled use of dichlorvos because of its effects on soil microbiota.