Further Development for Testing the Effects of Pesticides on Wolf Spiders

Based on preliminary guidelines of the "Biologische Bundesanstalt für Land- und Forstwirtschaft" (BBA, Germany) for testing the effects of pesticides on wolf spiders (genus Pardosa, Lycosidae, Araneae), two test series were carried out with the pesticides Karate (a.i. λ-cyhalothrin) and a noname product. At start of the test the pesticides were applied onto spiders and a sand substrate with an application apparatus. Thereafter, the mortality, the behavior, and the feeding rate were observed up to 14 days. Ninety-eight percent of the tested individuals belonged to the species Pardosa amentata. The results of the Karate experiments indicated a considerably higher reaction for males than for females. The aggression of the spiders proved to be a stress factor when the vessel was inhabited by more than one spider and caused higher mortality in individuals treated with pesticides. Spiders raised from cocoons in the laboratory were in general less sensitive than animals collected in the field and accustomed to laboratory conditions. Experiments performed with the noname pesticide in different seasons revealed that the sensitivity of the animals was influenced by their age. The parameters of mortality, behavior, and feeding rate proved to provide data adequate for evaluating the lethal and sublethal effects of the substances examined, The results suggest that the test method may be improved by (i) using spiders raised from cocoons in laboratory, (ii) using fine gauze to prevent the escape of food flies, (iii) testing in the same season when application of the pesticide is planned in the field, (iv) using one animal per test vessel to avoid cannibalism and intraspecific stress, (v) providing additional feedings to avoid cannibalism, and (vi) assessing effects of chemicals on both sexes separately. Summarized, the modified test method is suggested as an adequate method for testing the effects of pesticides on wolf spiders (Pardosa sp.). Use of the test during the registration proceeding is proposed as part of the testing program for effects of pesticides on beneficial arthropods.