No abstract

Earthworms are particularly important soil macroinvertebrates and are often used in assessing the general impact of pesticide pollution in soil. The present study was conducted in order to investigate the toxicity of three insect growth regulators (IGRs) buprofezin, lufenuron, and triflumuron, at different application rates and exposure times toward mature earthworms Aporrectodea caliginosa. The effects of these pesticides on the growth rate in relation to the activities of acetylcholinesterase (AChE) and glutathione S-transferase (GST) as biochemical indicators were evaluated to elucidate the mechanisms of action. Toxicity studies indicated that lufenuron was the most harmful pesticide to mature earthworms, followed in descending order by buprofezin and triflumuron. A reduction in growth rate in all pesticide-treated worms was dose-dependent over the 28-day exposure period, which was accompanied by a decrease in AChE and GST activities. Relationships between growth rate, AChE, and GST provided strong evidence for the involvement of pesticidal contamination in the biochemical changes in earthworms, which can be used as a bioindicator of soil contamination by pesticides.

Terrestrial snail, Monacha cantiana was used as a bioindicative organisms to assess the ecotoxicological effect in El Behira governorate. Five districts (El-Dalengat, Kom Hamada, Damanhour, Shoubrakhet and Etay El-Baroud) were selected for the animals collection during winter and spring seasons of 2008/2009. AChE activity was observed at a highest value (71.65 mole/mg protein/min) in Damanhour district which considered a control zone. Lactic dehydrogenase (LDH) is an indicative criteria of exposure to chemical stress, was showed the lowest inhibition (13.7 IU/ mg protein) in Etay El-Baroud. On the other hand, from the family of enzymes with important roles in the biotransformation of xenobiotics substances, glutathione-S-transferase (GST) was chosen. It recorded significantly decreasing in activity of snails collected from El-Dalengat, Damanhour and Etay El-Baroud districts, respectively, with values (63.01, 73.54, and 87.99%) compared with control. The terrestrial snail was an efficient bioindicator that accumulate bioavailable contaminants as a diagnosis tools for toxicological responses.