ATLA::Alternatives to Laboratory Animals

Volume 31, Number 6

Carbaryl-induced behavioural and reproductive abnormalities in the earthworm Metaphire posthuma: a sensitive model.

Shrawan K. Gupta and Prem N. Saxena

Cell Biology Division, Industrial Toxicology Research Centre, P.O. Box 80, M.G. Road, Lucknow 226 001, India

SUMMARY

Carbaryl, an N-methyl carbarnate insecticide, is used in India to control foliar insects, but, due to soil contamination, it also adversely affects non-target organisms such as earthworms. This paper deals with the toxic effects of carbaryl on the behavioural and reproductive profiles of the earthworm, Metaphire posthuma. Locomotion and geotaxis were significantly affected, even after a 20-minute exposure to 0.125 ppm carbaryl. The hatching of cocoons was altered at 0.5 ppm, whereas cocoon production was retarded even at 0.125 ppm carbaryl. No cocoon production was observed at 2.0 ppm carbaryl. Sperm head abnormalities were reported even at the lowest test concentration of 0.125 ppm. Wavy head abnormalities were observed at 0.125 ppm carbaryl, whereas at 0.25 ppm and 0.5 ppm, the sperm heads became amorphous and the head nucleus was turned into granules deposited within the wavy head. It is concluded that the earthworm could be used as an ecosystem model for the initial toxicity testing of environmental pollutants.

Keywords: behavioural toxicity, carbaryl, earthworm, environmental pollution, Metaphire posthuma, reproduction toxicity