Effects Of Ultra-Low Volume Applications of Malathion in Hale County, Texas: III. Effect on Nontarget Animals

Ultra-low volume applications of technical grade malathion were made in 3 Hale County, Texas, towns during 1967 at an application rate of 214 g/ha (3 fl. oz. per acre) of malathion. The treatments were applied to determine if this method of insecticide application would affect arbovirus buildup and transmission through control of the mosquito vector. As part of the overall evaluation, assessment was made of the effect of the insecticide treatments on nontarget insects, fish, and birds in Plainview, the largest treated community. The major impact of the treatments on nontarget insects was on Homoptera and on Hymenoptera (particularly honey bees). Hemiptera, Coleoptera, and Diptera, except for Culicidae, apparently were unaffected. House Sparrows, which represented 93% of the avifauna, were not measurably influenced; no indication of anomaly in mating, aggressiveness or feeding was observed. No adverse effect to the Plainview fishery was authenticated. Although an Ictalurus sp. die-off occurred in one fish pond, the concentration of malathion was considered too low to have been the cause.