• S. Geetha
• J. Kannadasan
• G. Chandrasehar

Earthworms are hermaphrodite, bilaterally symmetrical, segmented worms [2]. They are systematically classified under the phylum Annelida belonging to the class Oligochaeta [4]. The climate changes will have direct effects to all ecosystems, including the soil ecosystems. In ecotoxicological investigations, temperature is an important factor, since it can act as a stressor and induce the physiological status of organisms, besides affect the fate and transport of pollutants present in the environment. However, most of the ecological studies investigations neglected the possible effects of temperature and focused solely on the effects of toxicants on organisms. Considering the temperature can contribute to the toxicity of pollutants, it is of massive importance to scrutinize whether the change in the exposure temperature will impact the durability of the toxic effects present in soil ecosystems. Therefore, in the present study the toxicity effect and biomass change of Dimethoate 30% EC to earthworms was assessed under different exposure temperatures (20°C and 25°C). The results showed that changes in temperature led to variation in biomass and LC50. Namely, exposure to the concentration at different temperatures lead to different toxicity responses. Increase in temperature is caused increasing the toxicity, whereas decreasing the biomass change. To assess the influence of temperature on the acute toxicity of Dimethoate 30% EC on Earthworm (Eisenia fetida), a laboratory study was conducted under two different temperature conditions viz., 20 ± 1 °C and 25 ± 1 °C. Earthworms were exposed to five different concentrations of 25, 50, 100, 150 and 200 mg Dimethoate 30% EC / kg dry artificial soil. Test concentrations were prepared using deionised water and applied to the artificial soil in which earthworms were exposed. This experiment set up was maintained for 14 days separately under two different temperature conditions. Observation on mortality and biomass change were made on Day 14 after treatment. Earthworms were assessed for mortality and body weights were assessed on day 0 and day 14. The results of the experiment showed that there was a temperature response toxic effect and biomass change noticed on the earthworm. The LC50 of Dimethoate 30% EC on day 14 was determined to be 83.165 mg/kg dry artificial soil incubated in 20 ± 1 °C and 64.80 mg/kg dry artificial soil incubated in 25 ± 1 °C. The 14-day No-Observed-Effect Concentration (NOEC) with respect to biomass was determined to be 50mg /kg dry artificial soil for both 20 ± 1 °C and 25 ± 1 °C. The LC50 values of Dimethoate 30% EC were significantly high at higher temperature range tested (25±1°C). It is concluded that the temperature has a pronounced effect on toxicity of Dimethoate 30% EC on earthworm.

Earhworms, Eisenia fetida, Dimethoate 30% EC, Temperature, Toxicity.

"Effect of Temperature on Acute Toxicity of Dimethoate 30%EC on Earthworm, Eisenia fetida ", International Journal of Emerging Technologies and Innovative Research (www.jetir.org), ISSN:2349-5162, Vol.11, Issue 6, page no.f309-f319, June-2024, Available :http://www.jetir.org/papers/JETIR2406535.pdf

"Effect of Temperature on Acute Toxicity of Dimethoate 30%EC on Earthworm, Eisenia fetida ", International Journal of Emerging Technologies and Innovative Research (www.jetir.org | UGC and issn Approved), ISSN:2349-5162, Vol.11, Issue 6, page no. ppf309-f319, June-2024, Available at : http://www.jetir.org/papers/JETIR2406535.pdf