Attack and defense in a gamasid-oribatid mite predator-prey experiment - sclerotization outperforms chemical repellency
2016 - Volume: 56 Issue: 4 pages: 451-461
soil food webs
Oribatid mites represent a diverse group of soil micro-arthropods. They have evolved a broad range of defensive chemical and morphological traits (e.g. sclerotization, ptychoidy, biomineralization). Chemical defense, rather than sclerotization, can provide protection against large predators (staphylinid beetles) and many oribatid mite species are also well protected against gamasid soil mites using morphological traits ("enemy-free-space hypothesis"). However, since predatory mites and staphylinid beetles have different types of attacking and feeding, the adaptive values of chemical and morphological traits might differ accordingly. We used the oribatid model species Archegozetes longisetosus Aoki and the common gamasid mite Stratiolaelaps miles Berlese in a predator-prey experiment. We tested for effects of chemical defense (treatments with and without oil gland secretions) and sclerotization (treatments with unsclerotized tritonymphs and sclerotized adults) in an orthogonal design. In contrast to attacks by large predators, chemical defense was mostly ineffective against gamasid mites. Sclerotization, however, had a positive effect. Hence, in a natural environment with diverse types of predators, the "enemy-free space" seems only realizable by combinations of chemical and morphological protective traits.
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