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Introduction

Invasive Mite Identification:
Tools for Quarantine and Plant Protection

David Evans Walter
Colorado State University, Fort Collins and The University of Alberta, Edmonton

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PLEASE SEND COMMENTS & CORRECTIONS FOR FUTURE UPDATES TO DAVE WALTER: dew@ualberta.ca

About mites
Taxa covered and relationships between the 9 tools

About mites

After the insects, mites (the subclass of the Arachnida named Acari or Acarina) are the most diverse and difficult group of arthropods encountered in quarantine. Like insects, but unlike their arachnid relatives (spiders, scorpions and the like), the feeding ecologies of mites go well beyond predation to include herbivory and parasitism. The Acari includes a host of plant parasites that can devastate crops by their feeding or by transmitting plant pathogens. Domestic and wild animals also are infested by an often bewildering diversity of parasitic mites, including those that cause debilitating disease and deformity. Even other arthropods are not immune, as the worldwide spread of the honeybee parasite varroa has demonstrated. Social insects and those that bore in timber are especially rich in associated mites and for most of these mites we have no idea what their potential impact may be if they are introduced into new areas.

Because mites are tiny (mostly less than 1 mm in length as adults and many less than 0.25 mm); highly diverse; omnipresent in crops, soil, timber products, warehouses and other human habitations, and on animals, they present a major challenge to quarantine. This is especially true since there are very few people who have studied mites broadly and who can give taxonomic support to quarantine officers. Even innocuous mites (which will always be the vast majority of mite intercepts) can be difficult to identify with a level of certainty that will allow for prompt regulatory decisions.

Taxa covered and relationships between the 9 tools

These keys are designed to provide support to quarantine workers at three levels: training in mite anatomy and identification, preliminary identification (sorting non-actionable from potentially actionable mites), and advanced taxonomic support. The keys range in complexity from Is it a mite?, at a very basic introductory level, to species level treatments (e.g., Stratiolaelaps). The nine keys are interrelated, each treating taxa at various taxonomic levels:

Is it a mite?: introductory, to aid in distinguishing mites from other taxa

Major Mite Taxa: covers major groups of taxa at order, suborder, cohort, and superfamily levels; two of the covered taxa are the orders Mesostigmata and Endeostigmata

Mesostigmata: family, subfamily, and genus level treatments of taxa with commonly encountered species of quarantine concern; two of the covered taxa are the genera Phytoseiulus and Stratiolaelaps

Phytoseiulus: species level treatment of this genus in the order Mesostigmata

Stratiolaelaps: species level treatment of this genus in the order Mesostigmata

Endeostigmata: commonly misidentified genera (and one family)

Exotic Mite Pest Families: families (and two subfamilies) with commonly encountered species of quarantine concern; the two covered subfamilies are Bryobiinae and Tetranychinae

Bryobiinae: genus level treatment of this subfamily in the superfamily Tetranychoidea

Tetranychinae: genus level treatment of this subfamily in the superfamily Tetranychoidea

Additionally, an illustrated glossary with more than 700 terms defined is provided. I hope that these works will prove successful in supporting quarantine activities and welcome any suggestions for their improvement or correction.

Dave Walter