Prenatal chemosensory learning by the predatory mite Neoseiulus californicus.

Prenatal or embryonic learning, behavioral change following experience made prior to birth, may have significant consequences for postnatal foraging behavior in a wide variety of animals, including mammals, birds, fish, amphibians, and molluscs. However, prenatal learning has not been previously shown in arthropods such as insects, spiders and mites.We examined prenatal chemosensory learning in the plant-inhabiting predatory mite Neoseiulus californicus. We exposed these predators in the embryonic stage to two flavors (vanillin or anisaldehyde) or no flavor (neutral) by feeding their mothers on spider mite prey enriched with these flavors or not enriched with any flavor (neutral). After the predators reached the protonymphal stage, we assessed their prey choice through residence and feeding preferences in experiments, in which they were offered spider mites matching the maternal diet (neutral, vanillin or anisaldehyde spider mites) and non-matching spider mites. Predator protonymphs preferentially resided in the vicinity of spider mites matching the maternal diet irrespective of the type of maternal diet and choice situation. Across treatments, the protonymphs preferentially fed on spider mites matching the maternal diet. Prey and predator sizes did not differ among neutral, vanillin and anisaldehyde treatments, excluding the hypothesis that size-assortative predation influenced the outcome of the experiments.Our study reports the first example of prenatal learning in arthropods

The effects of prenatal learning on residence preference of predatory mite protonymphs.

<p>Mean (± SE) proportion of <i>N. californicus</i> protonymphs preferentially residing in the vicinity of spider mites matching the type in their maternal diet. Protonymphs originated from mothers fed on neutral, vanillin- or anisaldehyde-flavored spider mites and were given a binary choice between dead spider mites matching the maternal diet and non-matching spider mites (<i>n</i> = 24 for each of the six choice situations).</p

Body length and width (µm; mean ± SE) of spider mites fed on bean plants (<i>P. vulgaris</i>) flavored with vanillin or anisaldehyde or non-flavored (neutral).

<p>Treatment did not affect the length and width in any of the life stages: larva, nymph or adult female (ANOVAs: <i>p</i>>0.05 for each measurement).</p