title: Food stress causes sex-specific maternal effects in mites.
abstract: Life history theory predicts that females should produce few large eggs under food stress and many small eggs when food is abundant. We tested this prediction in three female-biased size-dimorphic predatory mites feeding on herbivorous spider mite prey: Phytoseiulus persimilis, a specialized spider mite predator; Neoseiulus californicus, a generalist preferring spider mites; Amblyseius andersoni, a broad diet generalist. Irrespective of predator species and offspring sex, most females laid only one small egg under severe food stress. Irrespective of predator species, the number of female but not male eggs decreased with increasing maternal food stress. This sex-specific effect was probably due to the higher production costs of large female than small male eggs. The complexity of the response to the varying availability of spider mite prey correlated with the predators' degree of adaptation to this prey. Most A. andersoni females did not oviposit under severe food stress, whereas N. californicus and P. persimilis did oviposit. Under moderate food stress, only P. persimilis increased its investment per offspring, at the expense of egg number, and produced few large female eggs. When prey was abundant, P. persimilis decreased the female egg sizes at the expense of increased egg numbers, resulting in a sex-specific egg size/number trade-off. Maternal effects manifested only in N. californicus and P. persimilis. Small egg size correlated with the body size of daughters but not sons. Overall, our study provides a key example of sex-specific maternal effects, i.e. food stress during egg production more strongly affects the sex of the large than the small offspring.
authors.affiliation: Arthropod Ecology and Behavior Group, Division of Plant Protection, Department of Crop Sciences, University of Natural Resources and Life Sciences, Peter Jordanstrasse 82, Vienna 1190, Austria andreas.walzer@boku.ac.at.
authors.forename: Andreas
authors.initials: A
authors.lastname: Walzer
authors.affiliation: Arthropod Ecology and Behavior Group, Division of Plant Protection, Department of Crop Sciences, University of Natural Resources and Life Sciences, Peter Jordanstrasse 82, Vienna 1190, Austria.
authors.forename: Peter
authors.initials: P
authors.lastname: Schausberger
mesh_terms: D000818:Animals; D049628:Body Size; D005260:Female; D005508:Food Deprivation; D008297:Male; D008925:Mites / Q000502:physiology*; D010058:Oviposition / Q000502:physiology; D010063:Ovum; D011235:Predatory Behavior / Q000502:physiology; D012098:Reproduction / Q000502:physiology; D012727:Sex Characteristics; D040102:Tetranychidae / Q000502:physiology
keywords: Egg size/number trade-off; Environmental stress; Phytoseiid mites; Sex-specific effects; Trans-generational effects