Benefits and costs of early learning in foraging predatory mites Amblyseius swirskii

Abstract: Learning, changed behavior following experience, is ubiquitous in animals, including plant-inhabiting predatory mites (Phytoseiidae). Learning has many benefits but also incurs costs (it requires energy), which are only poorly understood. Here, we addressed learning, especially its costs, in the generalist predatory mite Amblyseius swirskii, which is a biocontrol agent of various herbivorous insects and mites but also able to survive and reproduce on pollen. The goals of our research were (1) to scrutinize if A. swirskii is able to learn during early life in foraging contexts and, if so, (2) to determine the costs of early learning. In the experiments, we used one difficult-to-grasp prey, i.e. thrips, and one easy-to-grasp prey, i.e. spider mites. Our experiments show that A. swirskii is able to learn during early life. Adult predators attacked prey experienced early in life (i.e. matching prey) more quickly than they attacked unfamiliar (non-matching) prey. Furthermore, we observed both fitness benefits and operating (physiological) costs of early learning. Predators receiving the matching prey produced the most eggs, whereas predators receiving the non-matching prey produced the least. Thrips-experienced predators needed the longest for total development. Our findings may pave the way to enhance A. swirskii’s efficacy in biological control, by priming young predators on a specific prey early in life.Extended abstract