INVESTIGATING AVOIDANCE RESPONSE AGAINST CHEMICAL CONTAMINATION UNDER PHOTOTACTIC STIMULATION USING L. terrestris

Earthworms are the essential organisms of the soil habitat. They are not dominant under the world of ground. Still, their large population ranks them one of the significant workhorses to the total biomass, and their activities are such that they are necessarily outstanding in maintaining soil fertility in many ways. Therefore, it’s been a long time to recognize their importance for the agricultural industry. However, they usually react to the existence of toxic chemicals and escape away from harmful and irritating substances. Earthworm avoidance response to soil contaminated with hazardous substances has been proposed as a potential tool for assessing soil toxicity with low-test effort. Avoidance migration of the earthworm species L. terrestris was studied with bifenthrin, deltamethrin, glyphosate, gamma-cyhalothrin, and lambda-cyhalothrin under a light stimulation with constant exposure of 24 hours in a pair of choice chambers filled with contaminated soil. Our experimental parameters of latent time and FLD time were defined and analyzed accordingly. The results indicated that L. terrestris showed consistent reluctancy to move toward the contaminated soil. The greatest avoidance response was demonstrated to bifenthrin with the following order to lambda-cyhalothrin, gamma-cyhalothrin, deltamethrin, and glyphosate. A highly linear relationship existed between the parameters of lag time and FLD time difference% with R2 0.767. More study might be needed for elucidating L. terrestris capability of differentiating each chemical compound including the underlying mechanism.