Keywords: stream pyrethroids Insecticides Substances: Bifenthrin (OXCDWLBJSLVWHB-LKRLXIKPSA-N) Acrinathrin (YLFSVIMMRPNPFK-WEQBUNFVSA-N) Cyphenothrin (FJDPATXIBIBRIM-UHFFFAOYSA-N) Chlorpyrifos-methyl (HRBKVYFZANMGRE-UHFFFAOYSA-N) Cypermethrin (KAATUXNTWXVJKI-UHFFFAOYSA-N)