EFFECTS OF DIAZINON ON MACROINVERTEBRATES AND INSECT EMERGENCE IN OUTDOOR EXPERIMENTAL CHANNELS

Effects of diazinon on macroinvertebrates were assessed in three outdoor experimental channels from mid-May to mid-September, 1980. One channel served as a control and two channels as low and high treatments. Three dosing regimes were employed. The low and high treatment channels were continuously dosed for 12 wk to nominal concentrations of 0. 3 and 3 mu g/l, then increased to 6 and 12 mu g/l for 4 wk, then the high treatment was increased to 30 mu g/l with the low treatment channel returned to ambient. Diazinon concentrations did not reach the intended levels during the latter two dosing regimes. Tolerance of macroinvertebrates to diazinon were as follows: flatworms, physid snails, isopods and chironomids most tolerant; leeches and the amphipod Crangonyx less tolerant; the amphipod Hyalella, mayflies, caddisflies and damselflies sensitive.