March 29, 2012
Mites Form Friendly Societies
Predatory mites who stick with familiar individuals are more efficient at finding food
For plant-inhabiting predatory mites, living among familiar neighbors reduces stress. This allows individuals to focus on other tasks and be more productive, in particular while they are foraging. The new study by Markus Strodl and Peter Schausberger, from the University of Natural Resources and Life Sciences in Vienna, Austria, supports the theory that so-called 'social familiarity' reduces the cognitive, physiological and behavioral costs of group-living, leading to increased efficiency in other tasks. Their work is published online in Springer's journal, Naturwissenschaften - The Science of Nature.
Strodl and Schausberger studied whether a familiar social environment during the juvenile phase had any positive effects on the predatory mite's development. Among this species, group-living is brought about by the predators foraging, reproducing and developing spider mite webs, as well as mutual attraction.
In a series of three experiments, the authors showed that familiarity had significant effects on individual grouping and foraging traits of juvenile P. persimilis. In mixed-age groups of familiar and unfamiliar individuals, familiar individuals preferred to stick together.
Life-stage influenced this grouping behavior: larvae were much closer together than older individuals. In groups of individuals of the same age, the distances between individuals were smaller within groups of familiar mites than within groups of unfamiliar mites.
At similar developmental speed and body size at maturity, juvenile mites held in familiar groups foraged more efficiently than juvenile mites held in unfamiliar groups. The authors also identified a sensitive familiarization period during the larval stage, with memory persisting into the adult stage.
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