Research Project: Next-Generation Approaches for Monitoring and Management of Stored Product Insects

Location: Stored Product Insect and Engineering Research

2022 Annual Report

Objectives
Objective 1: Expand genomic resources for stored product insects and use functional genomics to find new gene targets or pathways for biorational control, identify genes that insects use to detect and respond to sensory cues, and improve nutritional content of stored product insects as food sources for humans and livestock. Subobjective 1A: Improve genomic resources for stored product insects. Subobjective 1B: Use functional genomics to identify genes that insects use to respond to pheromones and kairomones. Subobjective 1C: Genetic research to improve insects as animal feed. Subobjective 1D: Investigate molecular responses that allow insects to recover after exposure to insecticides and oral RNAi. Objective 2: Improve monitoring strategies for stored product insects through the identification of new attractants, improve understanding of insect response to traps and attractants, and develop and evaluate remote sensing and imaging technologies for detection of stored product insects and other quality issues. Subobjective 2A: Identify new semiochemicals that can be used as attractants or repellents for stored product insects and evaluate factors that impact active spaces around traps and packages. Subobjective 2B: Develop remote sensing and imaging for rapid detection of stored product insect infestations and other grain quality issues that occur during storage. Objective 3: Improve and develop new pest management tools and strategies for stored product insects in bulk grain storage and food facilities that focus on preventing infestations and reducing risks associated with insecticides. Subobjective 3A: Develop tools that exclude insects from infesting products, bulk storage facilities, and food processing plants. Subobjective 3B: Develop and use long-term monitoring data to improve pest management practices. Subobjective 3C: Optimize use of aerosols for treatment and management of stored product insects. Subobjective 3D: Evaluate efficacy of reduced-risk insecticides for pest management, grain protection, and residual surface treatments. Subobjective 3E: Investigate the impacts of behavior-based integrated pest management (IPM) tactics on insect behavior.

Approach
Whole and processed durable grain-based commodities are susceptible to infestation by a community of stored product insects throughout the distribution chain, which can cause considerable economic losses for the food industry. Additional issues such as phosphine resistance, the phase-out of methyl bromide fumigation, and a growing demand by consumers and producers to reduce pesticide inputs necessitate the development and expansion of alternate approaches to pest management. We propose to develop systems-level pest management tactics that reduce chemical residues that come into direct contact with food, develop new prevention and exclusion techniques to keep insects from infesting facilities and packaged goods, optimize behavior-based management strategies, and develop automated techniques to detect insect infestations. Genomic resources will also be an integral component as these tools can be used to reduce the emergence of insecticide resistant populations, identify genes involved in response to chemical cues associated with food and conspecifics, and improve mass rearing of insects for human and animal consumption. Ultimately, innovative tools and strategies based on research in the areas of genomics, behavior, biology, and ecology will be developed for management of postharvest pests to minimize grain commodity losses and maintain quality at all stages of the marketing chain.

Progress Report
Objective 1: ARS researchers recently released a chromosome-scale assembly of the Indianmeal moth to National Center for Biotechnology information (NCBI) and completed a re-assembly of the red flour beetle genome resulting in full recovery of all ~200 Mb of genome for the first time. Previous assemblies were between 160 and 170 Mb in size and did not include repetitive regions. We also sequenced the genome of a red flour beetle that had been recently caught from the field for comparison to determine if inbreeding had impacted gene content and sequence. Significant progress was also made for field sampling for lesser grain borers and other stored product insects, and we completed an intensive analysis of a three year population genomics study on lesser grain borer from insects caught at three different food facilities in and around Manhattan, Kansas. Although the three habitats are independent and grain is not readily moved between them, the populations were genetically similar. In addition, we developed a next-generation sequencing assay to assess diet of field-caught lesser grain borers and identified several alternative food sources used by dispersing individuals. Behavioral responses of lesser grain borer, red flour beetle, rice weevil, red-legged ham beetle, and larger grain borer to whole maize, whole wheat, wheat flour, and/or country ham volatiles have been assessed in various bioassays. In addition, antennal responsiveness of Indianmeal moth males and females (mated and unmated) was assessed over their lifespan using a new electroantennogram system to determine times when they are most/less responsive to their own sex pheromone. The transcriptomes of all developmental stages of lesser mealworm and greater mealworm were obtained and analysis of gene expression across these different life stages is in progress. In addition, assembly and analysis of microbial sequence from colonies with reduced and normal growth was completed and the unit is collaborating with researchers in Stoneville, Mississippi, to generate transformed yellow mealworm lines for large larvae/pupae. Our unit’s work on insects as food was recently included under a new ARS Grand Challenges Synergies program. As part of that project, we are using sequencing to identify potential pathogens in insects (as they may contribute to the health of farmed insects and also impact food safety) and developed a collaboration with Food and Drug Administration (FDA). Mortality and recovery were assessed for three different types of insecticide treated netting containing either 0.3% alpha-cypermethrin, 0.4% deltamethrin, or 8.3% Etofenprox. There was minimal efficacy on mortality of adult beetles exposed to the alpha-cypermethrin netting at exposure times up to 60 minutes. However, work investigating the sublethal effect on progeny production on the alpha-cypermethrin netting and the feasibility of using the netting as a physical barrier is continuing. Work investigating the use of netting in conjunction with fumigation in grain bins for bulk storage and in collaboration with other ARS researchers at Manhattan, Kansas, is also ongoing for summer 2022. We also recently hired a post-doc who is studying when insects recover over a 24 hour time period to identify mechanisms of recovery after insecticide exposure. Experiments on feeding dsRNA to red flour beetle larvae were also completed, and data are being compiled and analyzed. Objective 2: Our researchers have developed a protocol to quickly weaken and inoculate grain with any fungus to rapidly perform tests on microbial volatiles in the laboratory or field. We have also screened microbial volatiles for behavioral response by cigarette beetle, rice weevil, and red legged ham beetle in the wind tunnel. We were able to evaluate the active space around pitfall traps and found attraction at short ranges. We have evaluated lesser grain borer, red flour beetle, rice weevil, and Indianmeal moth using an electronic nose (MSEM) to remotely detect grain quality issues. Data collection has been optimized by evaluating whether a charcoal filter is necessary, whether sampling from the top or bottom of the grain mass is required, among other factors. Data separation is being optimized using algorithms such as principal component analysis, non-metric dimensional scaling, and neural networks. In addition, the unit was also awarded funds to support a post-doctoral fellow to develop programs for insect image identification. Objective 3: We found that regardless of how long-lasting insecticide netting was deployed at warehouses, dispersal to commodities was decreased by 93-95%, while progeny production was decreased by 99% in commodities protected by netting compared to unprotected controls. Three factsheets were developed (focusing on direct mortality, behavioral effects, or deployment methods and location) in collaboration with Kansas State University, University of Nebraska-Lincoln, and Arkansas State University. We also evaluated the incorporation of spinosad and methoprene, alone or in combination, into packaging materials on the lesser grain borer, rice weevil, and warehouse beetle. Spinosad alone or in combination with methoprene had >90% mortality on rive weevil adults after 14 days of exposure on polymer packaging and 100% mortality of lesser grain borer adults was observed. We further advanced our knowledge of the effect of methoprene packaging on four new stored product species, including sawtoothed grain beetle, Angoumois grain moth, rice weevil and the lesser grain borer. The sawtoothed grain beetle and lesser grain borer were highly susceptible, and egg-to-adult emergence was <1%. We also gathered and organized data to examine species distribution models for the larger grain borer under climate change conditions and began analysis on long-term monitoring data in response to fumigations. We conducted experiments examining the effects of diet and insect density on diapause in the warehouse beetle and the effect of density and the amount of diet on carrying capacity in red flour beetles, which can impact population growth and modeling datasets. Researchers were also awarded funds to support a post-doctoral fellow to develop analysis programs for predicting the impacts of climate change scenarios on future distributions of stored product insects. We evaluated a pyrethrin + methoprene aerosol insecticide at 4 and 16 micron (small and large particles) on adults of eight species of stored product insect inside an aerosol flow chamber. We observed that increasing the particle size increased the mortality among all species. Additional studies and collaborations are underway to model the flow of aerosol particles of different sizes in the flow chamber to determine their impact efficiency on surfaces in correlation to material deposition and insect mortality. We also evaluated and developed a high-performance liquid chromatography (HPLC) method to detect methoprene deposition from a cylinderized pyrethrin + methoprene aerosol application in a semi-field facility. We found that petri dishes containing flour, acting as an absorber, could be placed at various locations within the room to collect the aerosol particles as they were deposited throughout the space and provide a better estimation of the distribution of particles throughout a given space (compared to current methods). We evaluated the efficacy of beta-cyfluthrin and spinosad applied to concrete, metal and painted concrete surfaces stored in an empty grain bin and storage warehouse, compared to laboratory control, over a 12-month period on rice weevil and lesser grain borer adults. Both species were highly susceptible to both insecticides throughout the duration of the study. Bioassay areas stored in the empty grain bin demonstrated the greatest reduction in 7 days mortality, while arenas stored in the lab had maintained the highest mortality rates among both species. In attract-and-kill interception traps, we found the optimal dose of pheromone was a single lure, though two and three lures were also tested and compared to a negative control with no lure. In both a wind tunnel and release-recapture assay, a single lure was most attractive for both red flour beetle and lesser grain borer, two species with very different life histories.

Accomplishments
1. Microbes as a novel source of attractants for stored product insects. Monitoring for stored product insects inside large food facilities relies on attraction of insects to traps baited with volatiles derived from pheromones or food. In some environments, the efficacy of these baits is low, which could be due to the large number of competing stimuli from the abundant food resources in these facilities. Moldy grain may be attractive to stored product insects as signals an environment rich with moisture and food resources that is suitable for feeding and population growth. Moreover, volatiles derived from moldy grain are not prevalent in many food facilities due to their rigorous sanitation practices. ARS researchers in Manhattan, Kansas, found that many stored product insects, including lesser grain borers and rice weevils, were significantly attracted to fungal contaminated grain over both close and long ranges. Additionally, large numbers of novel volatiles were identified from grain inoculated with Aspergillus flavus. These volatiles are being investigated to determine if their incorporation into traps will increase trap catches in food facilities, which will ultimately provide new attractants for incorporation into baits and lures for monitoring for stored product insects.

2. Improved monitoring and control of invasive stored product insects. Although not established in the United States, the khapra beetle and larger grain borer are of significant concern to stakeholders. The larger grain borer could expand its range northward from Mexico into the southern United States under climate change scenarios, and the khapra beetle is a quarantine species that is routinely intercepted at ports. ARS researchers in Manhattan, Kansas, identified a novel reduced-risk insecticide that induced significant mortality and reduced mobility of larger grain borers when applied to bulk grain. Moreover, the new formulation is more cost-effective compared to existing formulations because it has lower concentrations of the active ingredients but retains the same efficacy. In addition, trap placement and efficacy were optimized for monitoring the khapra beetle. Currently, traps are placed on vertical surfaces, which likely reduces the number of larvae caught in these traps and can cause underestimations in population size. However, applying these traps to rougher surfaces, such as plywood, sheetrock, tile, cement, tape, and netting, improved the climbing ability of larvae and thus, their trap captures. Collectively, these studies provide new methods for monitoring and controlling these invasive insects.

3. Stored product insects as a source of novel digestive enzymes for breaking down gluten. Stored product insects feed heavily on food products enriched with gluten. ARS researchers in Manhattan, Kansas, isolated major digestive proteins from the red flour beetle and determined that a class of proteins called cathepsins was capable of cleaving analogs of gliadin proteins. Gliadins are the major components of gluten. Thus, stored product insects may serve as novel sources of enzymes that can be developed into novel treatment options for treat celiac or other autoimmune diseases.

4. Genome of lesser grain borer provides new insights into insecticide resistance and habitat usage. The lesser grain borer is a major pest of grain worldwide, and phosphine-resistant borer populations threaten the effectiveness of fumigations for pest control, which is a key concern for stakeholders. ARS researchers in Manhattan, Kansas, sequenced the genome of this grain borer to understand its biology and habitat usage. Interestingly, this species lacks a significant expansion of genes related to resistance to contact insecticides compared to other beetle species. The immature larval stage feeds inside grain kernels, reducing its exposure to insecticides and potentially reducing the pressure to evolve detoxification mechanisms against these chemicals. In addition, even though this species has been reported to feed on wood and trees, its genome does not code for any enzymes that can degrade plant cell walls. Therefore, it likely cannot survive while feeding on wood, but rather, it may use wood and trees found in the field for refuge and shelter in agricultural landscapes. Overall, this genome provides a useful tool for studying phosphine- and insecticide-resistance in stored product insects and clarifies some misnomers regarding the biology of lesser grain borer.

5. New integrated pest management tactics for phosphine resistant stored product insects. Phosphine resistant populations of stored product insects are increasing in abundance and distribution around the world. Phosphine is one of the most commonly used fumigants in large warehouses and food facilities for insect control, and the emergence of resistance threatens its efficacy, which has become a key concern of stakeholders. Long-lasting insecticide-incorporated netting (LLIN) and packing material containing insecticides have been effective against several species of stored product insects. ARS researchers in Manhattan, Kansas, evaluated the efficacy LLIN and packaging materials containing four different active ingredients (deltamethrin, permethrin, indoxacarb, and dinotefuran) against phosphine resistant populations of lesser grain borer and red flour beetle. Overall, all compounds caused significant mortality in phosphine resistant strains of both species with the exception of indoxacarb for red flour beetle. The use of bags and netting impregnated with insecticides provides new tools to prevent and reduce infestations of stored product insects, including those that have evolved resistance to phosphine.

Review Publications
Quellhorst, H., Athanassiou, C.G., Morrison III, W.R. 2021. The biology, ecology, and management of the larger grain borer, Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae). Journal of Stored Products Research. 94. Article e101860. https://doi.org/10.1016/j.jspr.2021.101860.
Bandara, H.S., Wijayaratne, L.W., Egodawatta, C.P., Morrison Iii, W.R. 2021. Orientation of Tribolium castaneum (Coleoptera: Tenebrionidae) adults to 4,8-dimethyldecanal, kairomone and botanical oils following ambient, low, or high temperature exposure. Journal of Stored Products Research. 94:101893. https://doi.org/10.1016/j.jspr.2021.101893.
Gerken, A.R., Campbell, J.F., Abts, S.R., Arthur, F.H., Morrison III, W.R., Scheff, D.S. 2021. Long-lasting insecticide treated netting affects reproductive output and mating behavior in Tribolium castaneum (Coleoptera: Tenebrionidae) and Trogoderma variabile (Coleoptera: Dermestidae). Journal of Economic Entomology. https://doi.org/10.1093/jee/toab204.
Hubert, J., Scully, E.D., Sopko, B., Dowd, S.E., Nesvoma, M., Klimov, P., Erban, T. 2021. Interactions of the intracellular bacterium Cardinium with its host, the house dust mite Dermatophagoides farinae, based on gene expression data. mSystems. https://doi.org/10.1128/mSystems.00916-21.
Oppert, B.S., Muszewska, A., Steczkiewicz, K., Šatovic-Vukšic, E., Plohl, M., Fabrick, J.A., Vinokurov, K.S., Koloniuk, I., Johnston, J., Smith, T.P., Guedes, R.C., Terra, W.R., Ferreira, C., Dias, R.O., Chaply, K.A., Elpidina, E.N., Tereshchenkova, V., Mitchell, M.F., Jenson, A.J., Mckay, R., Shan, T., Cao, X., Xiong, C., Jiang, H., Morrison III, W.R., Koren, S., Schlipalius, D., Lorenzen, M.D., Bansal, R., Wang, Y., Perkin, L.C., Poelcheau, M., Friesen, K.S., Olmstead, M.L., Scully, E.D., Campbell, J.F., et al. 2022. The genome of Rhyzopertha dominica (Fab.) (Coleoptera: Bostrichidae): Adaptation for success. Genes. 13(3). Article 446. https://doi.org/10.3390/genes13030446.
Ruiz, K.P., Bruce, A., Cheremond, E., Stratton, C., Murrell, E., Gillette, S.A., Morrison Iii, W.R. 2022. Field trapping and the flight capacity of Eucosma giganteana (Riley) (Lepidoptera: Tortricidae) in response to behaviorally active congeneric semiochemicals in novel Silphium agroecosystems. Insects. 13(4):350. https://doi.org/10.3390/insects13040350.
Scheff, D.S., Campbell, J.F., Arthur, F.H. 2021. Seasonal, Landscape, and Attractant Effects on Lesser Grain Borer, Rhyzopertha dominica (F.), Captures in Northeast Kansas. Agronomy Journal. 12(1)99:3-17. https://doi.org/10.3390/agronomy12010099.
Baliota, G.V., Scheff, D.S., Morrison Iii, W.R., Athanassiou, C.G. 2022. Competition of Prostephanus truncatus with Sitophilus oryzae on maize: The species that gets there first matters. Bulletin of Entomological Research. https://doi.org/10.1017/S000748532100105X.
Gerken, A.R., Morrison Iii, W.R. 2022. Resiliency of, adaptation of, and mitigation of risk to pest management in the postharvest agricultural supply chain in the face of ongoing climate change. Frontiers in Agronomy. 4:918845. https://doi.org/10.3389/fagro.2022.918845.
Hervet, V.D., Morrison Iii, W.R. 2021. Prospects for use of biological control for the food industry in North America. Agronomy. 11:01969. https://doi.org/10.3390/agronomy11101969.
Lampiri, E., Baliota, G., Morrison Iii, W.R., Domingue, M.J., Athanassiou, C.G. 2021. Comparative population growth of the khapra beetle, Trogoderma granarium Everts and the warehouse beetle Trogoderma variabile Ballion on wheat and rice. Journal of Economic Entomology. 115(1):344-352. https://doi.org/10.1093/jee/toab209.
Bruce, A.I., Wilson, A., Ranabhat, S.R., Montgomery, J., Nicholson, S., Harris, K., Morrison Iii, W.R. 2022. A biomass pyrolysis oil as a novel insect growth regulator mimic for a variety of stored product beetles. Journal of Economic Entomology. 115(3):877-887. https://doi.org/10.1093/jee/toac017.
Gourgouta, M., Baliota, G., Morrison Iii, W.R., Domingue, M.J., Athanassiou, C.G. 2021. Comparative capture of Trogoderma granarium and T. variabile in floor traps in single species releases with previously captured conspecific or heterospecific individuals. Journal of Economic Entomology. 114(6):2591-2597. https://doi.org/10.1093/jee/toab174.
Morrison Iii, W.R., Arthur, F.H., Athanassiou, C.G., Lampiri, E., Wilson, L.T., Yang, Y., Wang, J. 2022. Modeling of Sitophilus oryzae (L.) (Coleoptera: Curculionidae) based on historical weather data indicates aeration is effective for management of wheat stored in Greece. Computers and Electronics in Agriculture. 0168-1699. https://doi.org/10.1016/j.compag.2022.106926.
Quellhorst, H.E., Arthur, F.H., Bruce, A., Zhu, K., Morrison Iii, W.R. 2022. Exposure to a reduced-risk insecticide on maize and concrete reduces movement by the stored product pests, Prostephanus truncatus Horn and Sitophilus zeamais Motschulsky. Frontiers in Agronomy. 4:868509. https://doi.org/10.3389/fagro.2022.868509.
Ranabhat, S., Zhu, K., Binghma, G.V., Morrison Iii, W.R. 2022. Mobility of phosphine-susceptible and resistant Rhyzopertha dominica (Coleoptera: Bostrichidae) and Tribolium castaneum (Coleoptera: Tenebrionidae) after exposure to controlled release materials with existing…. Journal of Economic Entomology. 115(3):888-903. https://doi.org/10.1093/jee/toac033.
Van Winkle, T., Ponce, M., Quellhorst, H.E., Bruce, A.I., Albin, C.E., Kim, T., Zhu, K., Morrison Iii, W.R. 2021. Microbial volatile organic compounds from tempered and incubated grain mediate attraction by a primary but not secondary stored product insect pest in wheat. Journal of Chemical Ecology. 48:27-40. https://doi.org/10.1007/s10886-021-01312-8.
Kim, T.N., Bukhman, Y.V., Jusino, M.A., Scully, E.D., Spiesman, B.J., Gratton, C. 2022. Using high-throughput amplicon sequencing to determine diet of generalist Lady Beetles in agricultural landscapes. Biological Control. 170. https://doi.org/10.1016/j.biocontrol.2022.104920.
Khasin, M., Bernhardson, L.F., O'Neill, P.M., Palmer, N.A., Scully, E.D., Sattler, S.E., Funnell-Harris, D.L. 2021. Pathogen and drought stress affect cell wall and phytohormone signaling to shape host responses in a sorghum COMT bmr12 mutant. Biomed Central (BMC) Plant Biology. 21:391. https://doi.org/10.1186/s12870-021-03149-5.
Domingue, M.J., Scheff, D.S., Leva, N., Myers, S.W. 2021. Climbing ability of Trogoderma granarium larvae on artificial household and insecticide-treated materials. Journal of Stored Products Research. 95. https://doi.org/10.1016/j.jspr.2021.101922.
Brabec, D.L., Morrison III, W.R., Campbell, J.F., Arthur, F.H., Bruce, A.I., Yeater, K.M. 2021. Evaluation of dosimeter tubes for monitoring phosphine fumigations. Journal of Stored Products Research. 91. Article 101762. https://doi.org/10.1016/j.jspr.2021.101762.
Agrafioti, P., Brabec, D.L., Morrison III, W.R., Campbell, J.F., Athanassiou, C.G. 2021. Scaling recovery of susceptible and resistant stored product insects after short exposures to phosphine by using automated video-tracking software. Pest Management Science. 77(3):1245-1255. https://doi.org/10.1002/ps.6135.
Asuncion, F.B., Brabec, D.L., Casada, M.E., Maghirang, R.G., Arthur, F.H., Campbell, J.F., Zhu, K., Martin, D.E. 2020. Spray characterization of aerosol delivery systems for use in stored product insect facilities. Transactions of the ASABE. 63(6):1925-1937. https://doi.org/10.13031/trans.14010.