THE INFLUENCE OF FORMULATION ON TOXICITY AND AVAILABILITY OF A PESTICIDE (METHOXYCHLOR) TO BLACK FLY LARVAE (DIPTERA: SIMULIIDAE), SOME NON-TARGET AQUATIC INSECTS AND FISH

Abstract

AbstractTwo formulations of methoxychlor were compared with regard to toxicity and availability to aquatic organisms. A particulate formulation was less toxic than an emulsifiable formulation to chironomid larvae, stonefly nymphs, and fish. Similarly the particulate methoxychlor was less rapidly accumulated from water by those same animals than was the emulsified methoxychlor. With black fly larvae, the only filter-feeding animal used, the two formulations were about equal in toxicity, but the particulate formulation was accumulated more readily than emulsified material. Both formulations induced larvae to detach from substrate but emulsifiable methoxychlor acted more quickly. At the time of detachment, larvae exposed to the particulate formulation contained an average of 68 times more methoxychlor than larvae exposed to the emulsion.