Keywords: stream pyrethroids Insecticides Substances: Bifenthrin (OXCDWLBJSLVWHB-LKRLXIKPSA-N) Cyfluthrin (OFHFONYRMVKULH-WNYJFNBPSA-N) Chlorpyrifos-methyl (HRBKVYFZANMGRE-UHFFFAOYSA-N) Cypermethrin (KAATUXNTWXVJKI-UHFFFAOYSA-N)