Abstract

Social learning enables naive individuals to learn where, when, what, or how to eat; with whom to mate or fight; It has been studied in vertebrates, mulloscks, crustaceans, colonial insects such as bees, bumblebees, termites, ants and in a noncolonial insect (the cricket, Nemobius sylvestris Bosc). It has not yet reported in mites. We test social learning ability of the naïve immatures of the predatory mite Neoseiulus californicus (Acari: Phytoseiidae) by smelling adults' predation. Every 24 h, newly laid eggs of predatory mites were collected and the immature predators reared on pollen subjected to one of two experiments. In the first experiment immature predators were near (not physical contact) to their conspecific adults preying on Tetranychus urticae (TSSM) (called experienced predators) and could smell adults' predation. In the second experiment immature predators were far from conspecific adults (called naïve predators) and no smell adults' predation. After 24h starvation in the first day of their adulthood, predator females (40 even-aged N. californicus females as replicates per experiment) were tested on their aggressiveness, defined as latency to attack, against three mobile immatures of TSSM. All experienced (but 90% of naïve) predators attacked TSSM within 8h experimental period. Thirteen percent of the naïve predators but none of the experienced predators died within the aggressiveness test with TSSM. Experienced predators attacked TSSM after 37± 6 (SE) min whereas naïve predators attacked TSSM after 136±22 (SE) min. Experienced predators attacked TSSM more than three times earlier than naïve predators do (F= 18, P< 0.01). Our study provides supporting evidence for social learning in noncolonial predatory mite, N. californicus. Socially acquired information due to smelling of the adults' predation cause avoiding the cost of forgoing activities by shortening the latency to attack.