Effect of the presence of carbendazim on imidacloprid degradation in a biological organic mixture

Abstract

ABSTRACT The biological organic mixture (BOM) is a major component of a biopurification system (BPS), which provides an ample substrate for many microbes. Fungi present in BOM predominantly degrade pesticides through co-metabolism. We assume that the application of fungicides could have an impact on the fungal growth as well as the depuration ability of the BPS. This study is conducted to evaluate the efficiency of BOM in degrading imidacloprid in the presence of carbendazim, a commonly used fungicide. Both pesticides degraded at a faster rate when treated separately with the BOM, but their half-lives increased when applied in combination. The applied quantity of carbendazim (100 times of field recommended dose) was degraded within 60 days of the experiment. Approximately 75% of applied imidacloprid was dissipated within first 15 days of the experiment. Although carbendazim degraded at a faster rate, it had a negative impact on imidacloprid degradation during the experiment. Imidacloprid residue did not produce a negative effect on carbendazim degradation. Microbial and major soil enzyme activities were suppressed when BOM was exposed to the combination of pesticides in comparison to their single applications. Application of carbendazim was lethal to fungal population and may be the reason behind the increased persistence of imidacloprid in BOM.