Physiological and behavioral responses of pea aphid Acyrthosiphon pisum to the non-consumptive effects (NCEs) from the ladybird Harmonia axyridis

Abstract Non-consumptive effects (NCEs) refer to the ecological impacts of predators beyond direct consumption, encompassing alterations in prey behavior, physiology, and reproduction. However, several key questions regarding NCEs, such as the individual behavioral feedback pattern within prey, remain unresolved. The study aimed to understand how the presence of ladybird-induced NCEs influences individual aphid behavior, feeding patterns, and reproductive capabilities. In this study, by introducing a single red aphid into populations of green ones of varying sizes, with a specific focus on tracking the behavior of individual aphids, we investigated the NCEs that induced by ladybirds (Harmonia axyridis) on pea aphids (Acyrthosiphon pisum). Experimental setups included observation chambers for behavioral analysis, tracking marker configurations, and experiments assessing feeding and offspring dynamics. The findings reveal that NCEs can significantly mediate aphid behavior, particularly increasing individual moving speed and distance, while concurrently impacting feeding and reproductive capacities. Moreover, the study suggests that chemical factors, such as hydrocarbons (from ladybird footprints) and E-β-farnesene (EBF, an aphid alarm pheromone), are crucial for ladybird-aphid interactions mediated by NCEs; EBF can broaden the scope of NCEs, while hydrocarbons can prolong effect duration of it. The influence of NCEs on aphid individual behavior and population-level responses has practical implications for pest management strategies. Overall, this investigation provides insights into the complex relationship of predator-prey dynamics, offering a nuanced perspective for developing more effective and sustainable pest control strategy.