Effects of pesticide formulations containing cypermethrin or tebuconazole, individually and in mixture, on the earthworm Eisenia fetida

Abstract

The use of pesticides has increased considerably over the past few decades to maximize crop yields. This resulted in the presence of a range of toxic compounds in ecosystems, which may interact with each other, potentially enhancing adverse impacts on wildlife and ecosystem services. The objective of this study was to evaluate potential effects induced by chronic exposure to a mixture of pesticide formulations extensively used in agriculture: one containing cypermethrin (Sherpa 100 EC – SHP) and used as insecticide, the other containing tebuconazole (Spekfree 430 SC – SKF) and used as fungicide. In laboratory experiments, the earthworm Eisenia fetida was exposed for 28 days to the following treatments: control, double recommended field dose (2× FD) and quadruple recommended field dose (4× FD) of SHP or SKF, and mixtures of both formulations in a full factorial design. Effect criteria were mortality, reproduction, growth, respiration rate, and the activity of glutathione S-transferases (GST) and acetylcholinesterase (AChE). No significant effects on the life-cycle parameters of E. fetida, AChE activity or GST activity were observed. Therefore, chronic exposure to levels above the recommended field application doses of SHP and SKF are not expected to cause significant negative effects to the evaluated parameters in Eisenia fetida.