Project : USDA ARS

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Research Project: Systematics of Beetles, Flies, Moths and Wasps with an Emphasis on Agricultural Pests, Invasive Species, Biological Control Agents, and Food Security

Location: Systematic Entomology Laboratory

2025 Annual Report

Objectives
Objective 1: Conduct integrative taxonomic research that incorporates adult, immature, and molecular data to develop new and improve existing classifications of agriculturally important insects, create biosystematic databases, determine host plants, and analyze phylogenetic relationships based on next-generation sequencing, comparative morphological and bioinformatics analyses, and modern illustration methods. [NP304, C1, PS1A; C2, PS2B; C3, PS3A and 3B; C4 PS4A and 4B] Objective 2: Generate molecular and morphological diagnostic tools that will allow stakeholders and beneficiaries (e.g. Animal and Plant Health Inspection Service, Department of Homeland Security, state departments of agriculture, foreign and domestic biological control laboratories, researchers, and citizens worldwide) to accurately identify and rank agriculturally important insects. [NP304, C1, PS1A; C2, PS2B; C3, PS3A; C4 PS4A and 4B] Objective 3: Curate and expand through fieldwork and acquisitions the U. S. National Insect Collection to support morphological and molecular research by U.S. scientists and stakeholders worldwide and enhance pest insect diagnostics. [NP304, C3, PS3A; C2, PS2B; C3, PS3A; C4 PS4A and 4B] Objective 4: Provide expert/authoritative identifications for early detection of potentially invasive or novel insect pests intercepted by APHIS or Homeland Security personnel at U.S. ports, and generate research associated with specimens submitted by ARS researchers for biological control research with U.S. state departments of agriculture and U.S. university scientists. [NP304, C1, PS1A; C2, PS2B; C3, PS3A and 3B; C4 PS4A and 4B]

Approach
Parasitoid and phytophagous wasps (Hymenoptera) are a species-rich and biologically diverse group of insects critical to managing pests of agriculture and natural resources. Of the various types of natural enemies, parasitoid wasps are most frequently used to control pest insects. Phytophagous wasps include plant pests and species used to control weeds. We propose to acquire and analyze morphological and molecular character data (and other biosystematic and natural history data) for beneficial and pest chalcidoid, ichneumonoid, and cynipoid wasps to (1) discover and describe new taxa, as well as discover and report new natural history data; (2) generate phylogenies to estimate evolutionary relationships and dates of divergence for lineages, and predic host range for species; (3) propose new taxonomic concepts based on hypotheses of evolutionary relationships and make corresponding nomenclatural changes; (4) redescribe taxa to reflect changes in how they are defined or report new diagnostic character states; and (5) develop tools for identifying taxa. The aforementioned will be generated through phylogenomic research on Chalcidoidea, Ichneumonoidea, Ceraphronoidea, Platygastroidea and Cynipoidea, resulted in revised classifications and species delimitations. We also propose to (1) increase access to the National Insect Collection through digitizing the Hymenoptera type collection and providing that data online, as well as the Hymenoptera ethanol collection; (2) provide authoritative identifications of hymenopterans for USDA-ARS, USDA-APHIS, and other state and federal researchers and action agencies; and (3) curate selected wasp groups in the National Insect Collection (NIC) at the Smithsonian Institution National Museum of Natural History (NMNH).

Progress Report
Coleoptera research focused on generating beetle genomic DNA extractions, sequencing genomes, and analyzing data. Nearly 200 leaf beetle genomes were sequenced while another 50 genomes were obtained from public repositories to generate a robust molecular phylogeny. The first manuscript draft is written, and these data were presented by an ARS Postdoctoral Fellow at the International Congress of Entomology in August 2025. Longitarsus genetic data were also generated, and the analyses started. The first phylogenomic study and revision at the generic-level classification of Cossoninae (Coleoptera: Curculionidae) is underway for more than one third, 100 of 275, of the currently known world genera. This research will improve our ability to address prevention and control of non-native agriculturally important beetle species using genomic data. A comprehensive synopsis of baridine flower weevil from the US and Canada is progressing with an illustrated key to all 61 genera and more than 400 species in the United States that will be used to identify this critical group of plant feeding beetles. Progress on the West Indian flea beetle genera project includes a compiled and substantially edited chapter providing information for all 59 genera occurring in the West Indies. The database containing all 396 West Indian valid flea beetle species has been edited and original descriptions for all the species are examined. Classification of West Indian Monoplatina was completed. Diptera research focused on analyses of the evolutionary relationships among the genera of Tephritidae (true fruit flies) progressed. Samples of additional genera were collected and sequenced. Preliminary analyses supported many previously recognized relationships but also revealed some surprising new results. An identification tool for Anastrepha, the largest and most economically important fruit fly group in the tropical Americas was further enhanced. Molecular studies were completed that help to define cryptic species within the fraterculus pest complex. COI barcodes, useful identification of all life stages, were obtained for more than 1200 fruit fly specimens. Manuscripts including a molecular phylogenetic analysis of 239 species of Anastrepha and revision of another poorly known genus were submitted for publication. To assess species diversity in agromyzid leafmining flies, more than 1000 specimens were identified using DNA barcoding and morphological analysis. Over 100 species were found, including 15 new to science. One of these presumptive species has traditionally been identified as the globally invasive pest species Liriomyza sativae but instead represents a closely related and currently undescribed species. Analysis of geographic variation in nominal L. sativae found that the new species is present along with true L. sativae in the vegetable growing regions of California. While true L. sativae is a highly damaging pest of dozens of crops, the host use of the new group is unknown. Species-specific traits are being characterized in preparation for a formal description. Population genomic structure within the invasive polyphagous pest L. trifolii was assessed with phylogenomic population data to explore cryptic species and host-plant associated divergence. These results offer insights on the evolution of host-use patterns and specialization in Liriomyza pest species. Lepidoptera scientists focused on conducting integrative taxonomic research to develop new and improve existing classifications of Lepidoptera that are agricultural pests, forest pests, pollinators, and key components of food webs, and that are essential to agriculture and biosecurity. Research included the Erebidae, prominent moths, snout moths, and twirler moths. A novel phylogenomics-based classification of Prominent moths created eight new subfamilies and a new tribe, provided extensive caterpillar images, and the current global classification of the Erebidae, the largest family of Lepidoptera, was reviewed. In the twirler moths, we described four new species of the polyphagous leaf-tier moths, clarified relationships and updated the classification among genera in three subfamilies based on a phylogenetic study. In the snout moth family, we described two new species that feed on ornamentals, one new sugarcane boring species, and provided new evidence on the establishment and spread of a lantana biological control agent worldwide. We provided diagnostic tools for identification of the lantana leafroller and related species worldwide, the new sugarcane borer species from Mexico, and aquatic moth caterpillars of southeast Asia that are intercepted at U.S. ports. We curated the entire snout moth grass-feeding subfamily collection and incorporated southeast Asia material for the cogongrass biological control project. We accessioned two American moth collections (Metzler, Sullivan) of ~20,000 and ~150,000 specimens, respectively, curated four recently accessioned collections (Albu, Townes, Metzler, Janzen) and processed and labeled ~30,000 specimens from the Janzen material. Lepidoptera scientists completed all identifications intercepted at all ports-of-entry into the U.S. and entered the data into the ARM database (Urgents: 877; Prompts: 72; Routines: 441), and those submitted to the laboratory by universities and agricultural extension agencies. In partnership with APHIS and SCINet, we developed a dashboard in R for analyzing/visualizing data and metadata associated with intercepted pests. Hymenoptera research focused on hundreds of various species of parasitic wasps associated with: stink bugs that eat major food crops in the U.S. and infest homes; pest flies that eat strawberry, blackberry, and other fruit, as well as beneficial flies that parasitize snails and slugs; herbivorous and wood-boring insects in forests worldwide that feed on trees and kill them; plant-feeding insects in grasslands adjacent to crop fields; invasive spiders in Europe; and fire ants that disturb livestock. Along with clarifying identification, new biological attributes and host records were discovered for wasps important to agriculture and natural resources. Correct identification of biological control agents, as well as an understanding of their biological role in mitigating pestiferous species populations, is essential for making rearing and quarantine decisions in the protection of U.S. agricultural interests worldwide. Lastly, collaborative projects with other scientists in Brazil, Mexico, Thailand, and the U.S. have resulted in the most extensive and complete estimates of evolutionary relationships for Braconidae and several groups within that family.

Accomplishments
1. Critical research in beetles. In Coleoptera (beetles), scientists at the National Museum of Natural History, Washington DC discover, document, and classify pestiferous flea beetles, metallic wood boring beetles, and weevils. These beetles are plant feeders that belong to three hyper diverse groups (9,900 flea beetles, 4,150 metallic wood-boring beetles, and 62,000 weevil species), many of which are serious pests and feed on crops destroying valuable plants costing to U.S. economy millions of dollars annually; the emeral ash borer, alone, costs American taxpayers billions, annually, in tree damage. ARS researchers in Beltsville, Maryland, in collaboration with researchers from Brazil, Czech Republic, and Argentina made significant progress towards our baseline understanding of the species that occur in two major trade partner areas – the West Indies and Brazil. Research resulted in the final complete information on the almost 400 species of flea beetles of the West Indies and of the more than 6,000 species and 562 genera of leaf beetles from Brazil. In addition, in collaboration with the U.S. Forest Service and the Animal Plant Health Inspection Service (APHIS) the scientists inferred the most comprehensive phylogeny based on 10 DNA markers for 302 species. These resources are necessary to prevent the incursion of non-native plant feeding species that may negatively impact our crops, food supply and safety. Phylogenetic trees help serve as a kind of roadmap to quaranteen officers, biocontrol workers, and extension entomologists, helping predict and understand potential new agricultural pests, pollinators, or biological control agents of weeds.

2. Original research revealed new families and species of moths. Noctuoidea is the largest superfamily of Lepidoptera, with over 50,000 described species, including the fall armyworm and corn earworm, together which cause billions of dollars in damage globally each year. Yet the relationships among the six currently recognized noctuoid families are poorly resolved, leading to difficulty in the identification of pests. When compiling genomic data for one of these families, the Notodontidae, or Prominent Moths, ARS scientists in Beltsville, Maryland discovered that one of its component subfamilies was in fact an entirely distinct lineage outside the family and possibly the sister group to all the remaining noctuoid families. Grass-feeding moth identities in the U.S. after more than a hundred years. A grass feeding species of moth was correctly identified in the U.S. after more than 100 years of confused identity. Another species, described in 1794 from St. Croix, was erroneously applied to the species in mainland U.S. An ARS researcher located at the National Museum of Natural History, Smithsonian Institution, Washington, D.C., collaborated with researchers from Switzerland, England, and Germany to adapt molecular methods to target the barcode gene in hundred-plus-year-old type specimens located in European and American museums, and together with structural characters, fixed the identity of this group of grass-feeding species. Another species described from Bermuda in 1915 is the correct name to be applied to the more widespread North American species. Researchers in other USDA labs will use these revised species, genera and families to increase the accuracy of their work.

3. Advances in braconid systematics. Research on several braconid wasp phylogenomics studies were completed, resulting in clearly circumscribed species used in the biological control of pest flies, beetles and moths . Research on several braconid wasp phylogenomics studies were completed. These wasps are essential biological control agents of pestiferous species, such as the emerald ash borer and Asian longhorn beetle, both of which cause billions of dollars in damage to tree species in America. The studies included hundreds of braconid species and elucidated evolutionary relationships that were previously unknown or ambiguous. New tribes, genera, and species were proposed to reflect the newly recovered relationships. Mitogenome structure was explored for inferring evolutionary relationships within Braconidae and was found to be a valuable source of data for phylogenetic inference. Scientists in other labs depend on reliable phylogenies for their own research. Without such well resolved and strongly supported phylogenies, it is extremely difficult to reliably predict what parasitoids will be useful in biological control. In addition to braconid phylogenomics, ARS scientists in Beltsville, Maryland, collaborated to assess the impact of braconid parasitoids in regulating wheat stem sawfly (WSS) populations sampled from cultivated wheat and a variety of wild grasses in crop fields and adjacent seminatural grasslands. They found higher levels of WSS parasitism in certain wild grasses than in wheat; thus, wild grasses are possibly important for supporting populations of WSS parasitoids. These data are critical for biocontrol workers researching this system, in that additional grasses may be necessary to maintain natural enemy populations.

4. Systematic research on fruit flies. An analysis of the evolutionary relationships within the largest and most economically important group of fruit flies in the American tropics (Anastrepha) was submitted for publication. This genus, composed of over 200 species, are some of the worst pests that destroy citrus, mango, guava and peach, and hugely impact the importation of these fruits into the United States. ARS scientists at the National Museum of Natural History conducted research that included DNA sequences from nearly 300 loci from over 700 specimens representing 239 species. The results provide an evolutionary framework for all types of future comparative biological studies of the group and also help to resolve the cryptic species in the fraterculus cryptic species complex, which includes multiple major pests of Citrus and many other commercial crops. The data will be further analyzed to discover additional molecular markers as well as providing diagnostic guides for port identifiers, extension agents, and biocontrol workers trying to fight the invasion of these flies into the United States.

U.S. DEPARTMENT OF AGRICULTURE

Systematic Entomology Laboratory: Beltsville, MD