Project : USDA ARS

ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Systematic Entomology Laboratory » Research » Research Project #438801

Research Project: Systematics of Acari and Hemiptera: Plant Pests, Predators, and Disease Vectors

Location: Systematic Entomology Laboratory

2023 Annual Report

Objectives
New Objective 1: Conduct integrative systematic research of molecular (including Ag100Pest data) and morphological data to: determine species boundaries; recognize, describe, and illustrate new and invasive species; develop identification keys; hypothesize phylogenetic relationships among the respective groups for the purpose of stabilizing classification and providing predictive relationships of species; and investigate host associations and specificity of Acari (mites), Aphidomorpha (aphids), Membracoidea (leafhoppers and treehoppers), Aleyrodomorpha(whiteflies), Coccomorpha (scale insects), and Heteroptera (true bugs) that are pests of or beneficial to U.S. agriculture. [NP304, C1 PS1A; C2 PS2B; C3 PS3A and 3B] New Objective 2: Develop web-searchable electronic databases, tools, and images of mites, aphids, whiteflies, scale insects (Sternorrhyncha), leafhoppers (Auchenorrhyncha), and true bugs (Heteroptera) in the U.S. National Insect and Mite Collection and obtained through field exploration. This includes developing web-based resources to improve technology transfer of research products and disseminating this information to a broad group of stakeholders (e.g., quarantine, conservation, and biological control personnel). The proposed products will include searchable databases and expert systems of certain mites and hemipteran families. [NP304, C1 PS1A; C2 PS2B; C3 PS3A and 3B] New Objective 3: Provide authoritative identifications of specimens submitted by stakeholders worldwide and manage and curate assigned portions of the U.S. National Insect and Mite Collection, including all taxa in the hemipteran suborders Heteroptera, Auchenorrhyncha, Sternorrhyncha, and Coleorrhyncha, which involve more than one and a half million specimens housed in more than 3,000 insect drawers and mounted on hundreds of thousands of microscope slides, and the Acari with more than 360,000 microscope slide containing over a million specimens. [NP304, C1 PS1A; C2 PS2B; C3 PS3A and 3B]

Approach
Morphological characters will be identified through the examination of specimens using dissecting, DIC, Phase Contrast, CLSM, TT-SEM and Cryo SEM. Use of Cryo-SEM in mite taxonomy is revealing remarkable new character systems that were previously unknown and allowing researchers to re-evaluate poorly understood morphological characters that are difficult, if not impossible, to evaluate based on traditional slide-mounted preparations. This technique not only greatly expands the array of morphological characters available, offering them in greater detail, but it also provides valuable behavioral characters, especially with respect to understanding mite feeding behavior. Cryo-SEM will be used to confirm the intricate details of certain morphological characters visible with light microscopy, especially those of the tarsi and empodia. The novel characters available with Cryo-SEM (e.g., tegument texture and tarsal morphology) will be investigated and assessed using a minimum of 5 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. TT-SEM and CLSM technologies will be used to further the morphological studies. Although the research will focus primarily on morphological and ecological characters of 4 tetranychid genera and 4 eriophyid genera, these data sets will be augmented with molecular data (COI, 18S, 28S, EF-1') as an exploratory avenue for systematic research in these taxa. We will collaborate with Dr. Ashley Dowling and his team at the University of Arkansas who have expertise in molecular characterization of mites. Character information will include the external and internal morphology of mounted flat mites, adults and immatures, combined with the molecular data and analyzed using TNT and MrBayes. Live specimens used for Cryo-SEM studies will be solicited from colleagues and/or brought into the laboratory from domestic and/or foreign fieldwork following standard quarantine regulations and evaluated for morphological characters. In addition, some slide-mounted specimens will be borrowed from or examined at various institutions worldwide, especially the type specimens located in Canada, Brazil and Australia. More than half of the type specimens located at the National Mite Collection (Beltsville, MD) have been studied under DIC and Phase Contrast microscopy. Additional specimens will be collected from regions that are poorly represented in accessible collections, including Australia, South America, India and China. Methods of preparation and preservation will follow those previously described for slide mounting and Cryo-SEM.

Progress Report
Isometopine progress: The predatory mirid subfamily Isometopinae currently contains about 33 genera and 173 species worldwide. So far for this study three new genera and approximately 45 new species have been recognized for the Western Hemisphere. Completed habitus images for about half the species, written keys to genera and about one fourth of the species and have described about one fourth of the known species. Completed several collaborative research projects, including a revision of the tribe Hallodapini with the descriptions of 6 new species, a new genus and 3 new species from Argentina, a revision of a Neotropical stilt bug genus with descriptions of 2 new species, the description of a new oxycarenid from Mexico, and the first report of a plant bug in the United States. The “raindrop” Darnini—9 genera and 44 described species—is severely understudied. We have scored the data matrix for 673 morphospecies, begun genitalic dissections, and obtained habitus images of 385 morphospecies (about 1,500 images). We have about 500 additional Brazilian specimens that I have partially sorted to morphospecies and photographed, and still need to score for characters add to the matrix. We have recently obtained 352 Colombian specimens to add to the study. Throughout adhoc telework, I have also worked on projects that did not require regular access to the collections and equipment on site involving descriptions of new Auchenorrhyncha species and their immature stages. Using my Membracoidea of the World Database, a 230-page world generic checklist of membracoid families Cicadellidae, Myserslopiidae, and Archijassidae was prepared and submitted for a book chapter. Amplification has been attempted for all aspidiotine samples; sequencing has been completed for approximately one-half of samples/loci. Troubleshooting and sequencing of the remaining specimens is currently in progress. Additionally, substantial progress has been made sequencing a Ultraconserved Elements (UCE) dataset and constructing a corresponding morphological dataset for a family-level, fossil-calibrated phylogenetic analysis of scale insects. In lieu of coding a morphological matrix for specimens of Aspidiotinae, efforts have instead focused on building a morphological matrix to complement a UCE-based molecular matrix for family-level phylogenomic analysis. The dataset currently comprises 164 taxa and 175 characters and is approximately 80% complete. Mites (ACARI) in the families Eriophyidae, Phytoptidae and Diptilomiopidae (Eriophyoidea); Tenuipalpidae (Brevipalpus) and Tetranychidae (Tetranychoidea) were acquired and mounted for studies under the Differential Interference Contrast(DIC) microscope, tabletop Scanning Electron Microscope(SEM). The material for the cryo-scanning electron microscope was lost due to Dewar failure. Several genera in the family Eriophyidae were mounted and studied. Several genera in the order Acariformes (Parasitengona) were reviewed and safe for further molecular studies. A couple of specimens in the Mesostigmata were collected and saved for molecular study. In collaboration with the University of Florida, Butantan Institute (Brazil), and the Floral Nursery and Plants Research Unit at the National Arboretum a revision of literature search of plant feeding mites (Acari: Eriophyidae) and Parasitengona mites associated with diseases (fungi and viruses) has been compile. As of 21 June 2023, made 440 urgent identifications of Acari; 150 urgent identifications of Auchenorrhyncha; 210 urgent identifications of Heteroptera; and 315 urgent identifications of Sternorrhyncha.

Accomplishments
1. Collaborative research on Heteroptera at U.S. Natural History Museum. An ARS scientist at the Natural History Museum, Washington, D.C., completed several collaborative research projects, including a revision of the ant-mimetic plant bug tribe Hallodapini with a researcher at the American Museum in New York and the Natural History Museum, Basel, Switzerland, and descriptions of 6 new species; a new genus and 3 new species of a Neotropical stilt bug genus with a colleague at the Museo de La Plata, Argentina, several of which are potential pests of tomatoes and other solanaceous crops; the description of a new oxycarenid seed bug from Mexico, with a colleague in Wyoming, and the first U.S. report of a plant bug with colleague at the University of Connecticut that is a potential pest of ornamental century plants. These works all contribute to our knowledge of the biodiversity of the New World fauna and give us a greater capability to identify economically important and potentially invasive species.

2. Catalog of the Leafhoppers of The World at the U.S. Natural History Museum. The first 1758-2020 catalogue is a 230-page list of valid genera, their synonyms, and their distributions, complied by an ARS scientist at the Natural History Museum, Washington, D.C., which has been submitted for publication. The updated database also enables preparation of subsequent catalogues of leafhopper subfamilies. It the authoritative source for the valid names and higher taxon of 3,035 genera of the world and thus critical to using the correct genus-species combinations to communicate about domestic and invasive species.

3. Description of Auchenorrhyncha species and immature stages at the U.S. Natural History Museum. Described new Auchenorrhyncha species and immature stages. Completed and published 5 papers on different groups of treehopper immatures and made substantial progress on forthcoming installments in project, with manuscripts describing 1 new genus and 8 new species, on the immatures of the treehopper tribe Polyglyptini, and the immatures and life history of a USA species described in 2019 by an ARS scientist at the Natural History Museum, Washington, DC. Insects intercepted at ports are often in the immature stage (nymph or eggs), yet almost no immatures have been described before this project by an ARS scientist. Immature morphology can indicate erroneous assumptions of relationship among species and contribute to identifications of species intercepted at U.S. ports of entry.

4. Studies of several published studies on species in the family Eriophyidae. Several published studies on species in the Eriophyoidea associated with viruses were done in collaboration with the U.S. National Arboretum, the Rose Rosette Disease program and the University of Florida. An ARS scientist, along with Penn State University researchers, reported an eriophyid mite with possible biocontrol effect on tree of Heaven. These works involved an analysis of the genus-virus associations and the impact on several fruit trees and ornamentals, including lychee, citrus, avocado, and berry trees. As part of the study and identification service of the Tetranychoidea mites four new species of mites in the Parasintegona that are of medical/veterinary importance and some plant-feeding mites in the Tetranychoidea (Acari) were described; these findings were done in collaboration with scientist from the Smithsonian Institution, Peru, and Brazil. ARS mite scientist at Beltsville in collaboration with Butantan Institute scientists described several new species of mites and their association with different virus diseases. A spider mite species associated with a native agriculture plant in the Americas was described. A Peruvian researcher and Australian scientist worked with an ARS scientist at Beltsville in the comparison of this new species that will impact South American native flora.

U.S. DEPARTMENT OF AGRICULTURE

Systematic Entomology Laboratory: Beltsville, MD