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United States Department of Agriculture

Agricultural Research Service

Related Topics

Research Project: Mite Systematics and Arthropod Diagnostics with Emphasis on Invasive Species

Location: Systematic Entomology Laboratory

2013 Annual Report

1a. Objectives (from AD-416):
The long-term goal of this project is to produce systematic revisions of monophyletic groups of Acari that are important to U.S. agriculture and transfer this information to stakeholders, scientists, and the general public. The project will focus on the mite families Tenuipalpidae (flat mites) and Tuckerellidae (peacock mites) (both superfamily Tetranychoidea), which are of increasing importance on ornamentals and fruit crops in the U.S. Two flat mite genera, Brevipalpus and Raoiella, are affecting thousands of acres of citrus and palms, respectively, across the U.S. and worldwide; and several species of Brevipalpus are strongly linked with the transmission of serious plant viruses. The peacock mites (genus Tuckerella) cause damage to citrus, avocado, tea, and other ornamental and fruit tree crops. Despite their economic importance, these mite genera are in need of rigorous systematic revision, and the tools available for their identification need improvement. An additional goal is to contribute to the currently minimal understanding of the systematics and classification of these taxa through comparative morphological studies. Over the next 5 years the project will focus on the following objectives: (1) Develop accurate species concepts within mite groups using a holistic approach based on morphological and ecological data; (2) Determine and identify adventive species of mites; (3) Evaluate current taxonomic concepts of mites through discovery of new characters for species separation and subsequent systematic relationships; and (4) Process incoming and outgoing arthropod specimens and identifications, and maintain SELIS (Systematic Entomology Laboratory Identification Service), the on-line identification database about agriculturally important arthropods, for use in quarantine conservation, pest management, and other ARS research programs.

1b. Approach (from AD-416):
Morphological characters will be identified through the examination of specimens using dissecting, Differential Interference Contrast (DIC), Phase Contrast, Confocal microscopes and low temperature scanning electron microscopy (LT-SEM). The novel characters available with LT-SEM will be investigated and assessed using a minimum of 10 species from each genus, or more as time and resources permit. The validity of key characters for separating species and genera will be investigated across the family. As part of the data-gathering process, numerous techniques will be used to assess homology and variation in structural characteristics. Measurements and basic statistical data (i.e. range, mean) are often a part of this assessment. Characters will be scored as either discrete or continuous and ordered or unordered, and compiled into a data matrix for analysis. Analyses of the morphological data to construct hypotheses of evolutionary relationships will be conducted using PAUP and MrBayes. MrBayes for Bayesian analyses, and PAUP for parsimony analyses. Although the research will focus primarily on morphological and ecological characters, these data sets will be augmented with molecular data (COI, 18s, 28s, EF-1') obtained from collaborators at the University of Arkansas. Character information will include the external and internal morphology of mounted peacock mites, genus Tuckerella adults and immatures, combined with the molecular data. Identification tools will be developed for users to identify a specific organism among similar organisms and associate a name with that organism. This project will produce traditional dichotomous keys for this purpose, as well as electronic and/or interactive tools that facilitate identifications (e.g., LucID, DELTA). Throughout this project, an additional goal of curating (including remounting and relabelling where needed) and databasing the sections of the collection held in the US National Mite Collection (USNMC) will be met. Mite specimens submitted to the Systematic Entomology Laboratory for identification will be prioritized primarily by importance of their impact, invasive behavior, the number of interceptions, and the commodity involved. The Taxonomic Services Unit is responsible for distributing arthropod specimens submitted for identification to the appropriate SEL research entomologists or collaborators. When the specialists have identified and added their identifications to SELIS, TSU generates a report which is sent to submitters. The TSU coordinates with APHIS, PPQ on a daily basis on various issues relating to identification of specimens intercepted at ports-of-entry or in domestic surveys, especially those specimens with URGENT priority from shipments being detained at ports of entry pending receipt of identification reports from SEL. This objective will result in more than 13,000 identifications (34,000 specimens/year), along with associated biological information, of arthropods annually to customers dependent upon these data for the exclusion of invasive species, assessing potential biological control agents, systematic and biological research, and in support of regulatory programs.

3. Progress Report:
Several species of mites in the genera Brevipalpus, Raoiella, Cenopalpus, Dolichotetranychus, Tenuipalpus, and Tuckerella are economically important on fruit trees, ornamental and crop plants. The number of species known in the genus Raoiella increased from 5 to 21 species. Brevipalpus phoenicis is considered the most important mite pest species affecting citrus across the world. However, while studying material from Europe, South America, Australia and the US, we discovered that B. phoenicis has been regularly misidentified, and in fact the most common species on citrus is actually another species that had been erroneously synonymized, Brevipalpus yothersi. This information is essential in the study, management and control of mite pest on crops by farmers, quarantine specialist, extension agents, state and university researchers. Collection of Tuckerella specimens and other associated tenuipalpids had been curtailed due to budgetary constraints in the past and limited travel funds in the present fiscal year. Flat mites such as red palm mites, citrus mites, scarlet flat mite, pineapple red mite, and peacock mites are devastating pests on citrus, oranges, lemons, grapefruit, tea, bananas, coconuts, date palms, olive, eucalyptus, pineapple and ornamental palms. ARS Researchers at Beltsville, MD in collaboration with the Animal Plant Health Inspection Service (APHIS) have developed an on-line lucid identification key with descriptors and numerous images using light microscopy and low temperature scanning electron microscopy. Since its launch there have been over 123,800 visits to the web site with inquiries from 180 countries. This has been a tremendous identification tool for use by farmers, extension agents, state and university researchers, government agencies and APHIS quarantine specialists in the USA and other countries like Australia, South Africa and Canada. The Collection and Taxonomic Service Unit supports with identifications and information on important mite and insect invasive and adventive species the APHIS, state departments and universities in the U.S. In FY 2013, the mite section identified 450 lots with 4664 mite specimens. The Collection and Taxonomic Service Unit for FY 2013 identified 8297 lots with 20,300 arthropod (insect and mite) specimens. It is reasonable to assume that the rate of IDs will remain constant for the rest of this FY 2013. If so, these numbers represented 75% of the total expected for this year.

4. Accomplishments
1. Mite and insect identification service. There are between 3 and 5 million species of mites, and many are economically important agricultural pests that are being transported worldwide with the global trade business. Presently, the identification of flat mites is difficult and highly specialized, but a group of scientists, technicians and technology transfer experts from Agricultural Research Service, Animal Plant Health Inspection Service (APHIS) and the University of Maryland, in collaboration with scientists from almost all the continents around the world, are working together in a careful review and study of flat mites. Scientists using several new microscopy technologies have developed an easy to understand, on-line lucid identification key with descriptors and numerous images of the most economically important species of flat mites, along with numerous data sheets for comparison with other species. Since its launch, there have been over 138,300 visits to the web site with inquiries from more than 190 countries. This has been a tremendous identification tool that is been use by government agencies and quarantine officers in the USA and other countries, including farmers, extension agents, state and university researchers inside the USA and around the world.

Review Publications
Ferragut, F., Navia, D., Ochoa, R. 2013. New mite invasions in citrus: A look towards the early years of the twenty-first century. Experimental and Applied Acarology. 59(1-2):145-164.

Beard, J.J., Ochoa, R., Childers, C.C., Bauchan, G.R., Shepard, M. 2013. Travelling with tea: a Tuckerella’s tale. Experimental and Applied Acarology. 59(1-2):177-202.

Konvipasruang, P., Chandrapatya, A., Amrine, Jr., J.W., Ochoa, R., Bauchan, G.R., Pratt, P.D. 2012. A new species, of Aceria neopaederiae (Acari: Eriophyidae), infesting Paederia foetida L. (Rubiaceae) in Thailand, Hong Kong and Singapore. Systematic & Applied Acarology Special Publications. 17(2):191-201.

Navajas, M., Ochoa, R. 2013. Integrating ecology and genetics to address Acari invasions. Experimental and Applied Acarology. 59(1-2):1-10.

Last Modified: 05/27/2017
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