Food imprinting revisited: early learning in foraging predatory mites

Abstract

Learning is a ubiquitous phenomenon in foraging animals, allowing behavioural optimisation in variable environments. Food imprinting is a specific form of learning restricted to the early stages of life and with long lasting consequences. However, since coining of the term four decades ago, the uniqueness of food imprinting has been largely questioned due to a putative mechanistic similarity with associative learning. Here, we demonstrate food imprinting in the predatory mite Neoseiulus californicus , which primarily feeds on spider mites but may use thrips as alternative prey. Brief (24 h) exposure to thrips (contact without feeding) early in life resulted in shorter attack latencies and consistently higher predation rates on thrips during adulthood. Predation and oviposition rates were positively correlated but oviposition did not differ between naive and experienced females. Our results suggest that food imprinting is indeed special because, unlike associative learning, it occurred without reinforcement, was restricted to a sensitive phase and persisted into adulthood. Food imprinting seems particularly advantageous when prey species availability varies little within generations and a given prey is difficult to ingest for young small but not older larger life stages. Food imprintability could be used to improve the efficacy of biocontrol agents such as N. californicus .