Imidacloprid alters activity and responses to a visual predator stimulus in Aussie bronze jumping spiders (Helpis minitabunda, Araneae, Salticidae).

Neonicotinoid insecticides can have lethal and sublethal effects on non-target organisms. Sublethal effects may include disrupted motor function, which can be particularly detrimental to active visual hunters like jumping spiders (Salticidae) when searching for prey or mates, or when evading predators. In this study, we tested whether acute exposure to field-recommended concentrations of imidacloprid affects exploration activity, climbing performance or response to visual predator cues in the jumping spider Helpis minitabunda. Insecticide exposure reduced the exploration area, distance travelled, and time spent moving by spiders in an open arena, and also slowed their climbing speed. Responses to a visual predator stimulus were assessed in two phases: initial detection and subsequent response. Insecticide exposure did not affect initial detection, but did reduce subsequent responses of spiders to the stimulus on a video display. Further, the effects of insecticide exposure varied with body condition, with decreased climbing performance in individuals with low body condition compared to individuals with high body condition after exposure. Insecticide exposure also eliminated the positive correlation between body condition and response to the visual predator stimulus shown by control spiders. Spiders showed signs of recovery in their open arena activity and climbing performance when tested again seven days after insecticide exposure. Overall, acute exposure to field-recommended concentrations of imidacloprid compromised the locomotory performance and antipredator response in H. minitabunda. Our study demonstrates that imidacloprid can have large, sublethal effects on the behaviours critical to ecological function of an important arthropod predator.