Herbicides can potentially impact feeding behavior of beneficial predators in agricultural systems and subsequently compromise integrated pest management efficacy. We measured variation in feeding behaviors of an agriculturally abundant wolf spider, Pardosa milvina, when exposed to soil with field-relevant concentrations of five commonly used herbicides. Tested herbicides included atrazine, S-metolachlor, rimsulfuron, mesotrione, glyphosate, a mixture of all five herbicides, and a distilled water control. Spiders were housed individually in containers with topsoil previously sprayed with a recommended herbicide dosage or water control. Tested spiders were collected from two adjacent fields: one kept under continuous crop rotation for over twenty years and sprayed with various combinations of all these herbicides while the other was an alfalfa field with no pesticides applied for the last 12 years. Adult males and females from each plot were exposed to the seven treated soil substrates (N=1,214, n=43). Spiders were maintained on these treated substrates for 14 days and fed crickets (Gryllodes sigillatus). Their predatory behaviors toward an individual cricket were observed on untreated substrates. Individual spiders from each herbicide treatment were standardized for hunger then presented a cricket one week and two weeks after initial treatment exposure. We found no significant differences in prey capture latency for spiders across herbicide treatments during the first week of exposure, but large differences emerged by the second week. We also found large sex and collecting site differences in prey capture efficiency and weight change across treatments. Mesotrione and rimsulfuron-treated spiders showed the greatest weight loss between the first and second week of exposure while atrazine, glyphosate and s-metalachlor treated spiders gained more weight than the control group. Our results show that some herbicides can significantly reduce or increase feeding responses in this important agriculturally abundant predator and should be considered in integrated pest management decisions
