Free-living mesostigmatic mites in Australia: their roles in biological control and bioindication
F. Beaulieu A C D and A. R. Weeks BA School of Integrative Biology, University of Queensland, St. Lucia, Qld 4072, Australia.
B Centre for Environmental Stress and Adaptation Research (CESAR), Department of Genetics, University of Melbourne, Parkville, Vic. 3010, Australia.
C Present address: Eastern Cereal and Oilseed Research Centre, Agriculture and Agri-Food Canada, Ottawa, ON K1A 0C6, Canada.
D Corresponding author. Email: beaulieufr@agr.gc.ca
Australian Journal of Experimental Agriculture 47(4) 460-478 https://doi.org/10.1071/EA05341
Submitted: 6 December 2005 Accepted: 26 May 2006 Published: 9 March 2007
Abstract
The taxonomy, biology and ecology of free-living mesostigmatic mites in Australia and their current and potential use in biological control and bioindication is reviewed. Most current research on free-living Mesostigmata in Australia focuses on species with an established role in the biocontrol of crop pests, such as members of the family Phytoseiidae. Three introduced species and at least seven native species of Phytoseiidae are presently used for the control of phytophagous mites in Australia. The introduced phytoseiids are mostly specific to spider mites and have been selected for resistance to some of the common pesticides. Native species provide the advantage of being generalist feeders and are capable of using alternative food in the absence of mite pests. Therefore they can persist more effectively in the environment and contribute to the control of several pests. The reduced and selective use of pesticides, accompanied by scouting services, has allowed the successful control of phytophagous mites by native species in several Australian tree crops, especially grapevine and citrus. In soils, Mesostigmata are extremely abundant, species-rich and play significant ecological roles. They feed on a broad range of invertebrates, including phytophagous pests that spend part or most of their lives on or in the soil or root systems. However, the majority of mesostigmatic mite species are unknown in Australia. Nevertheless, recent research indicates that many species are habitat-specific, and that they may be sensitive to agricultural practices and other land management systems. Mesostigmata have great potential for biological control of pests, and as indicators of soil quality and sustainable agricultural practices. However, the current paucity of research and information on the taxonomy, life-history and ecology of native species in natural and managed landscapes will continue to hinder their use in biological control and as bioindicators.
Additional keywords: agroecosystems, community structure, ecological indicators, insect pests, species diversity.
Acknowledgements
We thank Jennifer Beard, Adrianne Kinnear, Stewart Learmonth, Graham Osler, Geoff Waite and Irene Vänninen for additional information on Australian Mesostigmata, and Bruce Halliday, Maurizio G. Paoletti, Heather Proctor, Andrea Ruff, Linda Thomson and David Walter for comments on a previous version of the manuscript. We also thank David Walter for providing scanning electron micrographs of mites.
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[Verified 4 February 2007]
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measured the time required for slide-mounting and identifying Mesostigmata (mainly phytoseiids) collected from leaf samples. It takes ~150 h to process ~600 specimens, representing 76 named and undescribed species. This represents 15 min per specimen. Although this would take substantially more time for an inexperienced worker, the processing time decreases significantly with an increase in samples and specimen numbers from a given site; once the most common species of a local fauna are recognised, it may not even be necessary to slide-mount specimens, as some can be identified directly under a stereomicroscope. Mesostigmatic mites are characterised by a broad range of morphological characters, many of which vary among taxa. Body size, the position, numbers and shape of setae (‘hairs’) of shields and appendages, the texture of ventral and dorsal shields, cheliceral teeth, and the shape of primary and secondary sexual characters can be useful characters to sort specimens into species-level taxa or ‘recognisable taxonomic units’ (morphospecies). Some publications are excellent for the sorting of families and the learning of morphological characters (e.g. Walter 2001). Despite their small size, given similar infrastructure (i.e. identification tools, appropriate microscopes) and taxonomic experience, mesostigmatic mites can be as easy to identify and may not require substantially more time for specimen preparation than common, diverse insect groups such as flies, beetles or ants.
