Single and combined toxicity of the pesticides abamectin and difenoconazole on soil microbial activity and Enchytraeus crypticus population

Abstract

Besides being toxic to enchytraeids, pesticides may also affect microbial communities, which are the main diet of enchytraeids. This study aimed to analyze the individual and combined effects of the insecticide Kraft® 36 EC (abamectin) and the fungicide Score® 250 EC (difenoconazole) to soil microbial communities and Enchytraeus crypticus populations. The abamectin and difenoconazole effects to the microbial community metabolism, as revealed by qCO2 increase in the first two periods of exposure, might indicate an acute effect of pesticides, which might result in lowered microbial biomass once microorganisms spend more energy in detoxification processes than in microbial growth. E. crypticus juvenile production was not affected at the different conditions tested. However, the importance of microorganisms on the enchytraeids diet was ratified. Besides, it is important to emphasize that only one recommended dose of the pesticides was tested in this study. Hence, other situations (e.g. pesticides over application or a slower process of pesticides degradation) may result in a different scenario of effects and should be further investigated.