Lethal and sublethal effects of chronic exposure to insecticide on the wolf spider Tigrosa helluo and Pardosa milvina

Imidacloprid and pyrethroid-based insecticides are among the most widely used in the world. The lethal and sublethal effects of chronic exposure to these compounds in spiders are unknown despite their economic and ecological importance in crop systems. We tested imidacloprid and pyrethroid-based exposure over a 31-day period for the wolf spider Tigrosa helluo and a 15-day period for the wolf spider Pardosa milvina. Dosages varied between 0.5-20x. We found significant sex-based differences in behavior and mortality among Tigrosa. Males showed more paralysis and died earlier than females. Both males and females showed impaired prey capture efficiency. Females lost weight then recovered over time. We also found sex-based differences in avoidance of insecticide-treated substrates. Pardosa showed high mortality but no sex-based differences. Given the widespread application of these insecticides within agricultural systems, our results suggest significant negative effects on ground spider populations showing large sex and species differences in sensitivity