Imidacloprid Alters Activity and Responses to a Visual Predator Stimulus in Aussie Bronze Jumping Spiders ( Helpis minitabunda , Araneae, Salticidae)

ABSTRACT Neonicotinoid insecticides can have lethal and sublethal effects on non‐target organisms, including arthropod predators that perform key ecosystem functions. 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. However, there was no difference in climbing performance between treated and control spiders 7 days after insecticide exposure, and both treated and control spiders increased their open arena activity after 7 days, which is suggestive of recovery from acute insecticide exposure in treated spiders. 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. Control spiders with high body condition had a stronger response to the visual predator stimulus than control spiders with low body condition, but treated spiders showed no correlation between body condition and response to the visual predator stimulus. Overall, acute exposure to field‐recommended concentrations of imidacloprid compromised the locomotory performance and anti‐predator response in H. minitabunda . Our study demonstrates that imidacloprid can have large, sublethal effects on behaviours critical to the ecological function of an important arthropod predator.