Location: Systematic Entomology Laboratory2018 Annual Report
ARS is interested in performing research to increase and enhance the understanding of the systematics of aphids, leafhoppers, plant bugs, thrips, and termites important to agriculture, ornamentals, and the environment. Our Project Plan has four main objectives: Objective 1: Determine species boundaries; recognize, describe, and illustrate new and adventive species; develop identification keys; define relationships among the respective groups; and investigate host use and specificity of leafhoppers, true bugs, aphids, scale insects, and related groups that are pests of, or beneficial, to U.S. agriculture. Objective 2: Develop accurate species concepts for aphids using a holistic approach based on morphological and molecular data. Objective 3: Compile, organize, and post on web electronic databases and images of primary types of important aphids, leafhoppers, termites, thrips, and true bugs. Objective 4: Provide expert identifications of specimens submitted by stakeholders worldwide and manage assigned portions of the U.S. National Insect Collection.
ARS will undertake the taxonomic research on agriculturally and economically important aphids, leafhoppers, plant bugs, termites, and thrips, using both morphological and molecular data to create species concepts and develop hypotheses about relationships. This information will be used to develop comprehensive revisions, including generic and species diagnoses and descriptions, illustrations of adults and diagnostic characters using light and electron microscopy, and dichotomous identification keys that will facilitate accurate identification. This information will be made available through publications, including hard-copy books, online pdf files, websites, and other media. Timely, accurate identifications of aphids, bugs, leafhoppers, termites, and thrips submitted by APHIS/PPQ, other state and Federal agencies, and a wide range of researchers will be provided. Large portions of the United States National Collection of Insects will be maintained and expanded.
Progress was made on all objectives, which fall under NP304 (Crop Protection & Quarantine): Thirty-four valid and synonymized world-wide aphid species of Rhopalosiphum were compared using advanced statistical analysis on 1,030 individual aphids to reassess previously proposed synonymies. It was found that the analysis (linear discriminant analysis) works well for wingless adults (apterae) but poorly for winged adults (alatae), which are morphologically similar. Analyses confirmed many of the proposed aphid synonymies are valid, which will help stabilize the nomenclature and species concepts within this aphid genus. The world-wide literature search of the Neuropterida/Sternorrhyncha (predator/prey) resulted in 2,500 citations. The Sternorrhyncha reference database has been designed and its layout determined. Taxonomic name combinations from other Sternorrhyncha databases have been assessed to avoid duplication of references. Completed measurements for 90 species of Heteroptera as scheduled, to further research on additional plant bug pests. The Phenacoccus scale insect project was completed and has been submitted for publication as two separate but related papers. These papers describe the spread of this species from the United States into Asia and the Mediterranean, where it is causing severe damage to cotton and other commodities. Results included genetic characterization of populations from the native and invasive range, a review of known geographical distributions, and an assessment of relationships with close – morphologically similar – relatives that will aid in proper identification of the pest. One hundred and eighty-two specimens of whiteflies from Panama have had their DNA extracted and have been slide mounted; 20% of these have been tentatively identified. These collections will be used in a phylogenetic analysis of whiteflies and an evaluation of host-use evolution (specialists vs. generalists) for this group. Completed revisions have been made on two manuscripts relating to the phylogeny and higher taxonomic classification of Diaspididae; both manuscripts are in review. Between the two studies, phylogenies were reconstructed using DNA data for ~1,500 individuals from ~400 species, sampled from around the globe. The taxonomy of Diaspididae was tested from the family-level down to (select) species, allowing for a revision of tribes and laying the groundwork for subsequent revisions of genera. These studies have also resulted in the discovery of about 70 new species. Completed drafts of Stegaspine immatures for port identifiers and researchers investigating the phylogeny of leafhoppers and treehoppers; images still required. Images of 450 membracid and 318 mirid type specimens of the USNM were digitally captured and edited (3,097 images of dorsal and lateral habitus and the type labels of each); due to a lack of technical support, we were not able to capture all mirid types. Concerted efforts within the projects resulted in 1,099 “Urgent” identifications (<24 hour turn-around), 540 “Prompt” identifications, and 2,230 “Routine” identifications of Hemiptera as of 13 June 2018. These identifications had major regulatory and quarantine ramifications in protecting American agriculture.
1. Protection of plants by describing and reporting their associated plant bugs. A number of species plant bugs were studied for their agricultural and scientific significance. The first report of an invasive plant bug from the Palearctic region was provided. In addition, a cryptic new species of plant bug from South America (that is a potential new biocontrol agent of the invasive water hyacinth) was described. Numerous papers on Heteroptera, which included descriptions of new genera and species and related information, empowered APHIS quarantine and state extension efforts by reporting new distribution and host plant records for plant bug pests in the USA and Mexico. Therefore, this greatly aided in regulatory decision-making for protecting U.S. agriculture.
2. A new invasive insect threatens Louisiana’s coastline. The Louisiana coastline is deteriorating, due largely to the loss of marsh grasses that help retain soil and prevent erosion. In 2016, marshes along the coast of Plaquemines Parish took a major hit, as large tracts of common reed (known locally as Roseau cane) died off suddenly. Reeds were discovered to be infested with thousands of tiny, invasive, grass-feeding scale insects. ARS scientists worked closely with researchers from Louisiana State University to identify the invasive scale insect, now dubbed the Roseau cane scale, a species native to Japan. The Smithsonian Institute’s national scale insect collections, which are housed and curated by ARS, played a vital role in the rapid identification of this destructive pest. Roseau cane is the dominant emergent plant in the Mississippi River Delta; it provides habitat for diverse wildlife, reduces wave action, and shelters the coastal region – including a network of oil pipelines – from damaging storm surges and hurricanes. ARS scientists are continuing to work with federal and non-federal partners to study the impact and spread of this invader, and develop strategies for the management of populations now established in the United States. Research efforts will consider both biological and environmental factors contributing toward Roseau cane death in the Mississippi River Delta.
Miller, D.R., Denno, B.D. 2018. John A. Davidson: Coccidologist, artist, teacher and naturalist. Entomologica Bari. 47(2016:5-11).
Miller, D.R., Stocks, I.C. 2017. A new species of Oregmopyga (Hemiptera: Coccidomorpha; Eriococcidae) from the southwestern US and Mexico with keys to species. Proceedings of the Entomological Society of Washington. 119(1):807-822.
Dewer, Y., Abdel-Fattah, R.S., Schneider, S.A. 2018. Molecular and morphological identification of the mealybug pest species, Phenacoccus solani Ferris (Hemiptera: Pseudococcidae), in Egypt. European Plant Protection Organization Bulletin. 48(1):155-159.
Henry, T.J. 2017. Description of a cryptic new species of the plant bug genus Eccritotarsus (Heteroptera: Miridae: Bryocorinae) from Peru, a new biocontrol agent of water hyacinth, Eichhornia crassipes (Pontederiaceae). Proceedings of the Entomological Society of Washington. 119(3):398-407.
Marita, J.M., Rancour, D.M., Hatfield, R.D., Weimer, P.J. 2016. Impact of expressing p-coumaryl transferase in Medicago sativa L. on cell wall chemistry and digestibility. American Journal of Plant Sciences. 7:2553-2569.
Metz, M., Miller, D.R., Dickey, A.M., Bauchan, G.R., Ochoa, R., Skvarla, M.J., Miller, G.L. 2017. Rediscovering digitules in Aphidomorpha and the question of homology among Sternorrhyncha (Insecta: Hemiptera). ZooKeys. 4276(1):139-144.
Henry, T.J. 2017. First record of the Palearctic plant bug Rhabdomiris striatellus (Fabricius) (Heteroptera: Miridae: Mirinae) in North America. Proceedings of the Entomological Society of Washington. 119(4):575-579.
Knight, I.A., Wilson, B.E., Gill, M., Aveles, L., Cronin, J.T., Nyman, J.A., Schneider, S.A., Scott, A., Diaz, R. 2018. Invasion of Nipponaclerda biwakoensis (Hemiptera: Aclerdidae) and associated Phragmites australis dieback in southern Louisiana, U.S.A. Biological Invasions. 20(10):2739-2744. https://doi.org/10.1007/s10530-018-1749-5.
Skvarla, M.J., Miller, G.L., Bauchan, G.R., Lewis, M.L., Foottit, R., Maw, E. 2018. Taxonomy and natural history of a cattail aphid, Rhopalosiphum enigmae Hottes & Frison (Hemiptera: Aphidomorpha: Aphididae), including a new synonymy and notes on ant and parasitoid associates of Rhopalosiphum. Insect Systematics and Diversity. 2(2):1-14.
Henry, T.J., Montemayor, S.I., Knudson, A.H. 2017. Review of the New World Tigava lace bug complex (Hemiptera: Heteroptera: Tingidae), with the description of two new genera and two new species and a key to genera. Dugesiana, Revista de Entomologia. 24(2):269-277.
Favret, C., Meshram, N., Miller, G.L., Nieto Nafria, J., Stekolshchikov, A.V. 2017. A synonymic revision of the Prunus-infesting aphid genus Hyalopterus Koch 1854 (Hemiptera: Aphididae). Proceedings of the Entomological Society of Washington. 119(4):465-474. https://doi.org/10.4289/0013-8718.104.22.1685.