The estimation of pesticides toxicity with the help of zootest method

Abstract

The following article is the result of biotesting of ecotoxicological danger of pesticides, which are used in gardening. Ten pesticide preparations were selected for the research, six of them are fungicides: flint-star, chorus, score, stroby, topsin-M and median-extra and four of them are insecticides: bi-58, calypso, mospilan and actara. Toxicity of pesticides was identified through analyzing ten times dilution (1:10) of the recommended solution specified by the manufacturer. Not less than three days old tap water served as control. Daphnia, Ostracoda and Danio were selected as test objects. After 1, 2, 3, 4, 5, 24 and 72 hours of exposure the number of dead animals was visually determined and the percentage of survival of testers was calculated. The toxicity of the pesticide preparations was considered as proven if the percentage of test organisms mortality rate was ≥50%. The scale of pesticide toxicity degree was developed, including the percentage of test organisms mortality during certain exposure time (up to 24 or 48 hours). It can be used to define its acute and toxic effect. According to the biotesting results, flint-star and score are the most toxic among the examined pesticide preparations fungicides for aquatic ecosystems, as they showed ultrahigh and high levels of toxicity for zootests. Carp fishes of the genus Danio showed greater sensitivity to the influence of fungicides and lower to insecticides, while for aquatic crustaceous Daphnia and Ostracoda these features were not detected. The sensitivity of the tested test objects to insecticides decreased in an order: Ostracoda sp.→Daphnia sp.→Danio sp. Comparing the sensitivity of aquatic crustaceous in the process of the pesticides biotesting, it was found out that Ostracoda sp. is more sensitive test object than Daphnia sp. Under the same conditions of biotesting, an absolute immobilization of ostracods is two times higher than the immobilization of Branchiopoda.