Location: Invasive Insect Biocontrol & Behavior Laboratory
2020 Annual Report
Objectives
OBJECTIVE 1: Develop semiochemicals (pheromones, kairomones including plant volatiles, and other attractants and repellents) of significant landscape pests (such as brown marmorated stink bug and exotic scarabaeids) and their natural enemies (e.g., parasitoids and spiders) for monitoring and management.
Sub-objective 1.A: Identify and synthesize volatiles and secretions from ornamental landscape pests or their plant hosts that are important in host- or mate-finding behavior, as components for biologically based control strategies.
Sub-objective 1.B: Develop effective strategies for using synthesized semiochemicals to reduce plant damage due to ornamental landscape insect pests.
OBJECTIVE 2: Develop and genomically characterize effective microbial and arthropod natural enemies as biocontrol agents, including bacteria (e.g., Bacillus thuringiensis [Bt]; Chromobacterium spp.), baculoviruses, and other entomopathogens, against insect pests of landscape plants (such as European and Asian gypsy moth, brown marmorated stink bug, and winter moth).
Sub-objective 2.A: Discover additional environmental isolates of C. subtsugae and related species, and characterize their insecticidal properties.
Sub-objective 2.B: Make phylogenetic and pathogenic comparisons of soil and phylloplane populations of Bt.
Sub-objective 2.C: Evaluate and develop viral pathogens as potential control agents for selected lepidopteran pests in unmanaged urban forest landscapes.
Sub-objective 2.D: Compare the floral and extrafloral resources of native and exotic urban landscape plant species for their ability to support natural enemies.
Sub-objective 2.E: Use molecular gut-content analysis to identify brown marmorated stink bug egg predators.
OBJECTIVE 3: Employ new technologies to characterize genomes and transcriptomes, characterize gene expression patterns, and develop RNAi-based molecular biopesticides for control of insect pests of landscape plants, especially brown marmorated stink bug and gypsy moth.
Sub-objective 3.A: Characterize and generate draft reference genome for brown marmorated stink bug (BMSB) and gypsy moth.
Sub-objective 3.B. Develop RNAi-based microbial biopesticides targeting brown marmorated stink bug (BMSB) and European and Asian gypsy moth.
Approach
This highly interdisciplinary project combines concepts and methodologies from analytical and synthetic organic chemistry, insect chemical behavior, insect pest-pathogen genomics, and microbial and insect ecology to develop multiple strategies for managing key insect pests of urban landscapes, orchards, and surrounding forest remnants. Integrated pest management approaches to be developed will include: (1) discovery and deployment of insect- and plant-derived attractants and repellents; (2) conservation of parasitic and predatory insects and spiders through selection of host plants for their ability to support natural enemies and thereby to promote effective biocontrol of pests; (3) pest-specific microbial controls including bacteria (e.g., Bacillus thuringiensis strains and Chromobacterium spp.) and baculoviruses; and, (4) plant genetic resistance using molecular-based gene discovery. Research will target insect pests that cause major damage to woody plants, including key landscape and forest genera, as well as fruit-bearing trees. The combination of semiochemical approaches, biological controls, molecular techniques, and crop resistance will offer a range of non-chemical tactics useful to integrated pest management for major pests of urban landscapes and associated orchard and forest ecosystems.
Progress Report
Objective 1. Develop semiochemicals of significant landscape pests and natural enemies for monitoring and management.
ARS scientists in Beltsville, Maryland, identified Brown Marmorated Stink Bug (BMSB) aggregation pheromone mimics structurally close to both pheromone molecules. These compounds were tested in the field in cooperation with ARS scientists in Kerneysville, West Virginia, and displayed modest attractiveness to BMSB. A synthetic mixture was devised containing both pheromone components and mimics.
ARS scientists in Beltsville, Maryland, continued to evaluate methyl benzoate and its analogs as insecticides, with efficacy against bed bugs, mosquitoes, thrips, white flies, nematodes, and some stored product insect pests demonstrated under laboratory conditions. ARS scientists in Beltsville, Maryland, also continued to develop the controlled-release dispenser for optimization of spotted wing drosophila (SWD) attraction and application of attract-and-kill strategy to manage SWD population.
Objective 2. Develop microbial and arthropod natural enemies as biocontrol agents of native and exotic pests of landscape plants.
In conjunction with European Biocontrol Laboratory (EBCL) scientists in Montpellier, France, Invasive Insect Biocontrol and Behavior Laboratory (IIBBL) scientists sequenced and characterized what appears to be a novel species Serratia isolated from cadavers of the tephritid parasitoids Psyttalia lounsburyi and P. ponerophaga. Phylogenetic analyses based of whole genome alignments indicated that the isolates were conspecific, and most closely related to S. marcescens, S. nematodiphila, and S. ureilytica. Functional characterization of this species' gene content was performed to determine details of its quorum sensing mechanisms, among other capabilities.
Genomic analysis of crystal forming Bacillus wiedmannii revealed a gene for a potential mosquitocidal toxin. These bacteria were found to be endemic to hardwood forests in central Maryland, and were associated with earthworm castings.
Objective 3. Employ new technologies to characterize genomes and transcriptomes, characterize gene expression patterns, and develop RNAi-based molecular biopesticides for control of insect pests of landscape plants, especially brown marmorated stink bug and gypsy moths.
An Indian isolate of a novel alphabaculovirus from the brown tussock moth was identified in the IIBBL insect virus collection, and its genome was sequenced. Analysis of the genome sequence revealed that it is most closely related to alphabaculoviruses of gypsy moth, suggesting that it may have biocontrol potential for gypsy moth outbreaks.
In collaboration with ARS scientists in Byron, Georgia, IIBBL scientists sequenced and assembled the genome of a bacterium associated with the pupal soil cell of the pecan weevil that inhibits the entomopathogenic fungus Beauveria bassiana. Phylogenetic analysis of the bacterium based on genomic alignment methods revealed that it was conspecific with the nematode symbiont and entomopathogen Serratia nematodiphila.
ARS scientists in Beltsville, Maryland, prepared a revised genomic assembly of the European gypsy moth, Lymantria dispar dispar (LDD) and collaborations with Canadian scientists of Natural Resources Canada and the Université Laval have resulted in updated assemblies of two Asian gypsy moth subspecies: L. dispar asiatica (LDA) and L. dispar japonica (LDJ). It was determined that 69% of LDD is composed of repetitive DNA, while LDA and LDJ were both 67% repetitive DNA. Gene finding was performed using RNA-Seq data generated by ARS scientists in Beltsville, Maryland, who also developed a pipeline specifically for use with insect species. A total of 70,739 peptides of at least 100 aa residues was identified for LDD, 59,982 for LDA, 59,422 for LDJ, and 36,230 for Ld652 (a gypsy moth cell line derived from LDD ovary tissue). These protein sequences are being refined and annotated using homologous sequences identified in various reference species and will eventually be utilized in metabolic pathway analyses to compare and contrast these four taxa for functional content.
Accomplishments
1. Assembly and annotation of the brown marmorated stink bug genome. ARS scientists in Beltsville, Maryland, led an international consortium of 57 scientists belonging to 31 institutions that has sequenced, assembled, and annotated the genome of the brown marmorated stinkbug Halyomorpha halys (Stål). The stinkbug is a highly mobile worldwide invasive pest that can attack a wide range of important crops, and causes particularly serious damage to fruit crops. The annotation of the stinkbug genome revealed an expanded set of genes encoding taste receptors, as well as genes involved in detoxification and digestion, which are probably key to the extreme breadth of the stinkbug’s dietary preferences. Researchers will use the gene sequences and their annotations to guide genetic knockdown or knockout experiments to assess the role of particular genes in the physiology of this formidable pest. This information, along with the gene sequences, will allow the development of RNA interference based biopesticides, or other control strategies, that are more specific for the stinkbug than conventional insecticides.
Review Publications
Hebert, F.O., Freschi, L., Blackburn, G., Beliveau, C., Dewar, K., Boyle, B., Gundersen, D.E., Sparks, M., Cusson, M., Hamelin, R.C., Levesque, R.C. 2019. Expansion of LINEs and species-specific DNA repeats drives genome expansion in Asian gypsy moths. Scientific Reports. 9:16413.
Sparks, M., Gundersen, D.E., Bansal, R., Oppert, B.S., Poelchau, M.F., Childers, C., Rhoades, J.H., Velamuri, A.S., Benoit, J.B., Chao, H., Blackburn, M.B., Johnston, J. 2020. Brown marmorated stink bug, Halyomorpha halys (Stål), genome: underpinnings of polyphagy, insecticide resistance potential and biology of a top worldwide pest. BMC Genomics. https://doi.org/10.1186/s12864-020-6510-7.
Dou, X., Zhang, A., Jurenka, R. 2019. Functional identification of fatty acyl reductases in female pheromone gland and tarsi of the corn earworm, Helicoverpa zea. Insect Biochemistry and Molecular Biology. https://doi.org/10.1016/j.ibmb.2019.103260.
Larson, N.R., Strickland, J.A., Shields, V., Zhang, A. 2020. Controlled-release dispenser and dry trap developments for Drosophila suzukii detection. Frontiers in Ecology and Evolution. https://doi.org/10.3389/fevo.2020.00045.
Dos Santos, E.R., Ecker, A., Trentin, L.B., Da Silva, L.A., Borges, M., Ribeiro, B.M., Mowery, J.D., Harrison, R.L., Ardisson-Araujo, D.M. 2019. An iflavirus found in stink bugs (Hemiptera: Pentatomidae) of four different species. Virology. 534:72-79.
Morrison III, W.R., Larson, N.R., Brabec, D.L., Zhang, A. 2019. Methyl benzoate as a putative alternative, environmentally-friendly fumigant for the control of stored product insects. Journal of Economic Entomology. 112(5):2458-2468. https://doi.org/10.1093/jee/toz179.
Larson, N., Zhang, A., Feldlaufer, M.F. 2019. Fumigation activities of methyl benzoate and its derivatives against the common bed bug (Hemiptera: cimicidae). Journal of Medical Entomology. https://doi.org/10.1093/jme/tjz138.
Su, J., Zhao, B., Zhang, A., Bu, X., Chen, J., Yan, Z., Wang, S. 2019. Pore-ridged nanostructures on the surface of trichoid sensilla of the male Bombyx mori: Aerodynamic trapping, sensing, and transporting of the pheromone molecules. Arthropod Structure and Development. S1467-8039(18)30167-1.
Guo, T., Mehan, S., Gitau, M.W., Wang, Q., Kuczek, T., Flanagan, D.C. 2017. Impact of number of realizations on the suitability of simulated weather data for hydrologic and environmental applications. Stochastic Environmental Research and Risk Assessment (SERRA). 32(8):2405-2421. https://doi.org/10.1007/s00477-017-1498-5.
Farrar, R.R., Gundersen, D.E., Kuhar, D.J., Blackburn, M.B. 2020. Insecticidal activity of Chromobacterium phragmitis, a recently described bacterium from tidal marshes. Journal of Entomological Science. 55(1):98-104.
Thomas, G.C., Dohmen, E., Hughes, D.T., Murali, S.C., Poelchau, M.F., Glastad, K., Anstead, C.A., Ayoub, N.A., Batterham, P., Bellair, M., Childers, C., Duan, J.J., Gundersen, D.E., Handler, A.M., Hunter, W.B., Scully, E.D., Hackett, K.J., et all. 2020. Gene content evolution in the arthropods. Genome Biology. 21:15. https://doi.org/10.1186/s13059-019-1925-7.
