Flat Mites of the World

Flat Mites of the World provides a portal to a variety of keys, images, and fact sheets to help support identification of this diverse, potentially destructive group of mites.

In Flat Mites of the World Edition 2, you will find interactive keys, fact sheets, descriptions, and images to aid in the identification of flat mites (Acari: Trombidiformes: Tetranychoidea: Tenuipalpidae) from the United States and around the world. Please note that this tool is a work in progress! The newest edition of the tool, updated as of May 2013, will help identify the 38 genera of flat mites present throughout the world, including specific diagnostics for 20 species of Raoiella, 19 species of Brevipalpus, 3 species of Cenopalpus, Dolichotetranychus floridanus, Tenuipalpus pacificus, T. crassulus, and a closely related new species T. nr crassulus. The genus Raoiella is of major concern to quarantine world-wide due to the rapid spread of one species, the red palm mite (RPM), R. indica Hirst. The genus Brevipalpus is the most commonly intercepted genus of Tenuipalpidae in quarantine world-wide, but it is also the most complicated and by far the most diverse genus in the family. The three most important species in the family world-wide, Brevipalpus californicus, B. obovatus and B. phoenicis, though still consistently confused and misidentified, can be identified using this tool, and the Brevipalpus phoenicis species complex has been further separated into seven cryptic species. Dolichotetranychus is increasingly diverse genus of monocot-associated flat mites. Here we present diagnostics for an economically important species associated with pineapple across the world, D. floridanus. Tenuipalpus is a hugely diverse and complicated genus. Tenuipalpus pacificus is the name most commonly applied, correctly or incorrectly, to species in the genus Tenuipalpus intercepted on orchids across the world. We provide diagnostics for T. pacificus, based on type material. A recent incursion in the USA of an unidentified Tenuipalpus mite near T. crassulus sparked our interest in providing diagnostics for these two flat mite species associated with succulent plants.

Exotic species of flat mite pose a significant threat to USA’s biosecurity both as plant pests and as vectors of plant disease; however, the available diagnostics do not allow accurate and reliable identification of species. This tool is aimed at enhancing our diagnostic capabilities for key taxa and to ultimately allow plant protection and quarantine services to develop rapid solutions to serious biosecurity threats. The necessity to accurately and efficiently identify intercepted flat mites will increase as globalization increases. Flat Mites of the World provides a portal to a variety of keys, images, and fact sheets to help support identification of this diverse, potentially destructive group of mites.

This tool is designed to help identify any flat mite to the taxonomic level of genus, and in some cases to species, without the need for expertise in the group. Target users include USDA-APHIS pest survey specialists, ports of entry inspectors, other inspection personnel, students, and scientists. The “Is it a flat mite?” page provides information on how to distinguish a flat mite from other members of the spider mite superfamily Tetranychoidea.

Slide mounted mites: A flat mite looks very different alive under a stereoscope compared to after it has been squashed flat and slide mounted. Often the 3D shape of the mite is lost in the process.

Microscopy for mites: When dealing with mites, we are interested mainly in the morphology of surface structures, and DIC offers better interpretation of these features than phase contrast does.

The key is designed for users with limited knowledge about the group to identify flat mites to genus (and to identify critical genera to species). All characters are best observed using DIC (differential interference contrast) on a compound microscope. Ideally the user should have access to a compound microscope with a magnification capacity of 1000X (10X eyepiece + 100X oil objective) with DIC. The microscope images provided in the key were taken using DIC, mostly at 1000X. We highly recommend the use of DIC over Phase Contrast for identifying mites as the optical properties of DIC allow a more accurate interpretation of mite morphology. Please see the “DIC VS Phase Contrast” page for more information.

• Resource Title: Flat Mites of the World.

  File Name: Web Page, url: http://idtools.org/id/mites/flatmites/index.php