Chronic Effects on Emergence Ratio and Development Rate of Chironomus yoshimatsui Exposed to Carbendazim in a Sediment-water Exposure System

Carbendazim is the hydrolysate of benomyl and thiophanate-methyl, which are the active ingredients of pesticides, in the environment. Carbendazim has been detected in environmental water and sediment in Japan, and there is concern that it may have chronic effects on benthic organisms living in aquatic environments. In this study, the Japanese native chironomids Chironomus yoshimatsui were exposed to carbendazim from the first instar larval stage to emergence using a sediment-water system prepared by spiking carbendazim into the sediment. During exposure, the emergence ratio and development rate of C. yoshimatsui were measured. As a result, the no-observed-effect concentration based on the sediment concentration （ NOEC sed ） of carbendazim for C. yoshimatsui was 3.07 mg kg -1 , which was 170 times higher than the highest concentration of 0.018 mg kg -1 in the Japanese environmental sediment. Therefore, it is necessary to consider the results of this study when evaluating the toxicities of benomyl and thiophanate-methyl in sediment in the future.