Lethal concentrations of glyphosate-based herbicide on nymphs of agroecosystem spider predator Phylloneta impressa L. Koch 1881

Abstract

Broad-spectrum herbicides containing glyphosate are one of the most widely used pesticides in the world. They appear to be only slightly toxic to model animals in laboratory experiments. We investigated the lethal effect of the glyphosate-based herbicide to the first nymphal instar of the comb-footed spider Phylloneta impressa L. Koch 1881, which is a common spider predator of agroecosystem pests. Lethal concentrations LC 50 and LC 90 were calculated 24 h after dorsal application of the recommended herbicide dosage in Potter laboratory spray tower. The concentration recommended by manufacturer killed almost 25% of tested spiders. The concentration that would kill 90% of spiders was calculated to be 2.34 times higher than the highest recommended concentration.