Tasty but Protected—First Evidence of Chemical Defense in Oribatid Mites
- 324 Downloads
Oribatid mites (Acari, Oribatida) represent one of the most abundant and speciose groups of microarthropods in the decomposer food webs of soils, but little is known of their top-down regulation by predators. Oribatids are relatively long-lived and have numerous morphological defensive adaptations, and so have been proposed to live in ‘enemy-free space’. Most also possess a pair of large exocrine oil glands that produce species-specific mixtures of hydrocarbons, terpenes, aromatics, and alkaloids with presumably allomonal functions, although their adaptive value has never been tested empirically. We developed a protocol that discharges the oil glands of the model oribatid species, Archegozetes longisetosus. and offered ‘disarmed’ individuals as prey to polyphagous Stenus beetles (Staphylinidae), using untreated mites as controls. Stenus juno fed on disarmed mites with behavioral sequences and success rates similar to those observed when they prey on springtails, a common prey. In contrast, mites from the control group with full glands were almost completely rejected; contact with the gland region elicited a strong reaction and cleaning behavior in the beetle. This is the first evidence of an adaptive value of oribatid mite oil gland secretions for chemical defense. The protocol of discharging oil glands should facilitate future studies on top-down control of oribatid mites that aim to differentiate between morphological and chemical aspects of defensive strategies.
Key WordsOribatida Archegozetes longisetosus Stenus juno Oil glands Enemy-free space
MH is funded by the German Science Foundation (DFG-Forschungsstipendium HE4593/3-1). GR was supported by the Austrian Science Funds (FWF), projects P18486-B16 and P21819-B16.
(MP4 8884 kb)
- Alberti, G., Heethoff, M., Norton, R. A., Schmelzle, S., Seniczak, A., and Seniczak, S. 2011. Fine structure of the gnathosoma of Archegozetes longisetosus Aoki (Acari: Oribatida, Trhypochthoniidae). J. Morphol., in press. doi: 10.1002/jmor.10971.
- Betz, O., Koerner, L., and Gorb, S. 2009. An insect’s tongue as the model for two-phase viscous adhesives? Adhesion 3:32–35.Google Scholar
- Eisner, T. 2003. For Love of Insects. Harvard University Press, Cambridge.Google Scholar
- Eisner, T., Alsop, D., and Meinwald, J. 1978. Secretions of opilionids, whip scorpions, and pseudoscorpions, pp. 87–99, in S. Bettini (ed.), Arthropod Venoms, Handbook of Experimental Pharmacology. Springer, Berlin.Google Scholar
- Heethoff, M. Laumann, M., and Bergmann, P. 2007. Adding to the reproductive biology of the parthenogenetic oribatid mite, Archegozetes longisetosus (Acari, Oribatida, Trhypochthoniidae). Turk. J. Zool. 31:151–159.Google Scholar
- Heethoff, M., Laumann, M., Weigmann, G., and Raspotnig, G. 2011. Integrative taxonomy: Combining morphological, molecular and chemical data for species delineation in the parthenogenetic Trhypochthonius tectorum complex (Acari, Oribatida, Trhypochthoniidae). Front. Zool. 8:2.PubMedCrossRefGoogle Scholar
- Mollemann, F. and Walter, D. E. 2001. Niche segregation and can-openers: Scydmaenid beetles as predators of armoured mites in Australia, pp. 281–288, in R. B. Halliday, D. E. Walter, H. C. Proctor, R. A. Norton and M. J. Colloff (eds.). Acarology: Proceedings of the 10th International Congress. CSIRO Publishing, Melbourne.Google Scholar
- Norton, R. A. 2007. Holistic acarology and ultimate causes: examples from the oribatid mites, pp. 3–20, in J. B. Morales-Malacara, V. Behan-Pelletier, E. Ueckermann, T. M. Perez, E. G. Estrada-Venegas and M. Badii (eds.). Acarology XI: Proceedings of the International Congress. Sociedad Latinoamericana de Acarologia, Mexico.Google Scholar
- Norton, R. A. and Macnamara, M. C. 1976. The common newt (Notophthalmus viridescens) as a predator of soil mites in New York. J. Entomol. Soc. Georgia 11:83–88.Google Scholar
- Oudemans, A. C. 1916. Notizen über Acari, 25. Reihe (Trombidiidae, Oribatidae, Phthiracaridae). Arch. f. Naturgesch. 6:1–84.Google Scholar
- Raspotnig, G. 2010. Oil gland secretions in Oribatida (Acari), pp. 235–239, in M. W. Sabelis and J. Bruin (eds.). Trends in Acarology. Springer, Dordrecht.Google Scholar
- Raspotnig, G., Norton, R. A., and Heethoff, M. 2011b. Oribatid mites and skin alkaloids in poison frogs. Biol. Lett. in press. doi: 10.1098/rsbl.2010.1113.