Location: Commodity Protection and Quality Research
2016 Annual Report
Objectives
Objective 1: Develop practical, systems-based strategies, for management of pests of fresh fruit and high valuable durable commodities (e.g., navel orangeworm in almonds, pistachios and walnuts, mealybugs on table grapes, codling moth in walnuts, tephritid fruit flies in fruit) through all aspects of production, distribution, and marketing that enhance production and commodity quality.
Subobjective 1A: Characterize the biotic and abiotic factors that affect the insecticides used to control navel orangeworm in tree nuts in order to optimize their efficacy and minimize non-target impacts on human health and environmental quality.
Subobjective 1B: Characterize and optimize semiochemical strategies for monitoring and control of key dipteran and lepidopteran pests in the context of minimizing preharvest and post-harvest chemical treatment requirements.
Subobjective 1C: Characterize and optimize control strategies, utilizing the physiology of key lepidopteran, coleopteran and dipteran pests, in the context of minimizing preharvest and post-harvest chemical treatment requirements.
Subobjective 1D: Develop an overall metric of treatment efficacy, via combining the individual contributions from preharvest and post-harvest processes, to evaluate systems-based strategies for insect control in fresh and durable commodities.
Objective 2: Develop new treatment technologies or modify existing protocols for post-harvest treatment of pests, such as the Indianmeal moth and the red flour beetle, with the objective of minimizing negative effects to the environment and food quality, while maintaining the positive sensory qualities and marketability of these commodities.
Subobjective 2A: Develop technologies to reduce, or eliminate, atmospheric emissions from ventilation effluent following post-harvest fumigations.
Subobjective 2B: Develop treatments for novel post-harvest applications involving fresh and durable commodities.
Subobjective 2C: Improve semiochemical-based strategies for controlling stored product insect pests in post-harvest scenarios.
Objective 3: Develop treatment technologies for action agencies that require alternatives to methyl bromide for phytosanitary and quarantine treatment of pests such as the codling moth, spotted wing drosophila, and Fuller rose beetle. Conduct research to support USDA-APHIS negotiations with trade partners as well as research on the fate and transport of post-harvest agrochemicals, thereby enhancing the competitiveness of U.S. agriculture in the global marketplace.
Subobjective 3A: Develop post-harvest treatments for quarantine purposes that minimize reliance on post-harvest methyl bromide (MeBr) fumigations.
Subobjective 3B: Obtain sorption and depuration data related to post-harvest fumigations to serve as physicochemical basis for regulation related to nontarget human ingestion and inhalation exposures.
Subobjective 3C: Identify agrochemical use strategies and novel technologies to ensure foodstuff residues are compliant with importer regulations.
Approach
The first objective has four subobjectives focusing on navel orangeworm, fruit fly, Indianmeal moth, and assorted pests through production, packing and shipping as well as damage prediction. These goals will be attained using a collaborative and multidisciplinary research approach combining chemical analysis, insect physiology, population dynamics, damage prediction and assessment of natural enemies. These elements will then be integrated into a systems approach that can be applied from the field through all channels in production and export.
The second objective, which has three subobjectives, is focused on the development of new technologies and/or modifications of existing protocols for post-harvest treatment of insects such as Indianmeal moth and red flour beetle. Particular emphasis will be placed on reducing fumigant emission into the atmosphere and the development of new fumigation protocols that retain commodity quality. Strategies employing semiochemicals instead of fumigants will be investigated for control of Indianmeal moth in warehouses.
The final objective has three subobjectives and is focused on control of quarantine pests in recently harvested commodity in storage. Sorption and depuration data will be obtained to help quantify nontarget human exposure in order to improve worker safety. These strategies ensure that foodstuff residues are compliant with importer regulations.
Progress Report
The goal of Objective 1 is the development of practical systems-based strategies for improved pest control. Under subobjective 1A, field experiments conducted in almonds indicated that the break point for insecticide coverage occurs above 12 feet in the canopy and was confirmed by chemical analysis of nut samples and bioassay. Current studies are comparing two different nozzles and their ability to cover targets placed at a height of 14-16 feet in the canopy. There are ongoing studies analyzing differences in the egg and adult toxicity of selective insecticides to navel orangeworm. Trapping is a common method used to both monitor population dynamics and assess the success of insecticide treatments. Companion studies focused on trapping, either through improving the lure used, determining the best trap array and number of traps necessary, or establishing trap efficacy, using a male moth trap. These traps vary in design and glue type used, and the relationship between the number of moths visiting a trap and the number actually captured were established and described by an equation. With this equation serving as a foundation, research can proceed on the linkage between the number of males trapped and both treatment efficacy and the damage determined at harvest.
Under subobjective 1B, improving pheromone trap efficacy was addressed by evaluating traps placed in arrays. A previous study suggested that groups of navel orangeworm pheromone traps placed in an array would more accurately predict navel orangeworm population density than individual traps. This hypothesis was tested in almond using 10-acre plots to compare trap counts with infestation shortly after harvest. The association between the mean number of males per trap and nut infestation was greater when arrays of five traps were used than when single traps were used. Increasing the size of the arrays above five did not change the findings, but further tests are underway to confirm that five traps are the optimal number. Research is continuing on methods to maximize the efficacy of mating disruption as well as evaluate other nonchemical technologies for insect control.
Under subobjective 1C, several chemical lures were developed for both the Mediterranean fruit fly, a pest of nearly all types of fresh fruit, and several species from genus Anastrepha, including the Mexican fruit fly and the Caribbean fruit fly. Novel food-based lures were developed using formulations of trimethyl amine, ammonium acetate, and putrescine, incorporated in a cellulosic matrix. More than 20 structural analogs (similar structure but differing in one component) of trimedlure, the “standard” Mediterranean fruit fly attractant, were synthesized and formulated in polymer matrices. The aggregation pheromones of both the Mexican fruit fly and the Caribbean fruit fly, epianastrephin and anastrephin, were synthesized and formulated in polymer matrices for mating disruption studies and in cellulosic matrices for attract-and-kill studies. In collaboration with the Animal and Plant Health Inspection Service (APHIS) trapping studies in grove and orchard systems are underway in Hawaii for the Mediterranean fruit fly, in Texas for the Mexican fruit fly, and in Florida for the Caribbean fruit fly.
The goal of subobjective 1D is developing benchmarks to evaluate the success of systems-based strategies. Processor databases are an untapped resource that can be used for a greater understanding of the relationship between insect population density and damage. A pistachio research database for the years 2007-2015 was established. This information will be used to determine the pattern of damage, so that high-risk areas can be identified for either further study or more coordinated insect control. These data will also be used to establish the relationship between harvest date and damage, and to determine the rate of navel orangeworm damage over the course of the harvest. Ultimately, this study will help establish new recommendations for insect control as well as establish baseline values to evaluate future management schemes.
The mathematical framework for a tool to evaluate new as well as existing systems approaches was developed for the Animal and Plant Health Inspection Service Plant Protection and Quarantine, Phytosanitary Issues Management, and Center for Plant Health Science and Technology. Tracking standard industry processes of harvesting, packing, and distribution, data was collected for the removal and/or control of spotted wing drosophila in table grapes, Asian citrus psyllid in fresh citrus, and brown marmorated stink bug in sweet cherries. In the next phase of research a team of ARS, APHIS, and University experts will evaluate various mathematical approaches to describe the experimental results and ultimately establish a final model.
The goals of Objective 2 are to develop new technologies or modify existing protocols for postharvest treatments of insect pests. Under subobjective 2A the absorption rate of fumigants was calculated using different commodities and temperatures to ensure that the minimum amount of chemical is used. Negative impacts to air quality can be minimized, or eliminated, by absorbing the fumigants with activated carbon. The end-products of tree nut and tree fruit production (hulls for example) were evaluated for their potential to sorb (adsorb or absorb) methyl bromide from ventilation effluent following postharvest chamber fumigations. Experiments were also conducted to determine other methods to eliminate methyl bromide using aqueous solutions of thiosulfate as well as by electrolysis. Aqueous solutions of thiosulfate were costly and the cheaper process of electrolysis successfully broke down >80% of methyl bromide very efficiently. Developing cost-effective methods to eliminate methyl bromide emissions may help ensure its continued use because of minimal environmental impact.
Under subobjective 2B new methods for phosphine fumigations were developed to control phosphine-resistant strains of stored product pests. Fumigation methods employing sulfuryl fluoride and ethyl formate were developed to control brown marmorated stink bug in almond, walnut, and pistachio stores. Propylene oxide fumigations were developed to control viruses of strawberries.
Under subobjective 2C infestation of both stored products and infestation at the level of the processor were addressed. The Indianmeal moth is a major processing and warehouse pest, and research to improve its control is critical. If mating disruption can control Indianmeal moth in processing facilities and warehouses, substantially less insecticides will be needed. This benefits the processors because consumers want fewer insecticides used to protect commodities in processing and storage. It is necessary to establish a theoretical model for the mechanism of mating disruption that will be used to control this insect. Laboratory-based wind tunnel assays were used to select candidate pheromone formulations for pilot-scale studies and these experiments are ongoing.
Research was conducted on two interrelated subobjectives under Objective 3. Under subobjective 3A several quarantine treatments were developed to eliminate spotted wing drosophila from California apricot exports to Australia, eliminate codling moth from California nectarine exports to Japan, eliminate bean thrips from California citrus exports to Australia, and a treatment with ozone, a generally recognized as safe compound, was developed to eliminate black widow spider from California table grape exports to the European Union. These results were presented to APHIS Phytosanitary Issues Management to support negotiations with foreign governments to facilitate specialty crop exports.
Under subobjective 3B, studies using novel experimental procedures and modeling techniques were conducted to determine the efficacy, fate, and transport of fumigants over the course of fumigation, storage, and marketing. The fumigants studied were methyl bromide treatments of fresh fruit (citrus, table grapes, and stone fruit), phosphine treatments of fresh fruit (citrus, table grapes, and stone fruit), sulfur dioxide treatment of table grapes, sodium metabisulfite treatment of table grapes, and phosphine treatment of grains. This research was conducted in collaboration with the United States Environmental Protection Agency, California Department of Food and Agriculture, and the Food and Drug Administration. Results on worker exposure and environmental impact were presented to these government action agencies.
Accomplishments
1. Developing new technology to ensure compliance with maximum residue levels for export crops. The export of California tree nuts to the European Union has an estimated value of $2.5 billion annually. An ARS scientist in Parlier, California, developed novel analytical methodologies to quantify and decrease levels of residues on tree nuts in order to comply with the maximum residue levels for almonds and walnuts established by the European Union. These methodologies included the use of gas chromatography-mass spectrometry to quantify residues of phosphorous acid as well as development of a new method to quantify residues of propylene oxide and its halohydrins. The transfer of this method to European Union chemists and regulators directly resulted in the establishment of temporary phosphorous acid maximum residue levels for tree nuts through March 2019, thereby preserving the export of California tree nuts until a permanent import tolerance can be established. This research also serves as a key basis for technical interaction between California industry, USDA-Foreign Agricultural Service, USDA-Animal and Plant Health Inspection Service, U.S. Environmental Protection Agency, and respective counterparts in foreign governments, with the ultimate goal of protecting export markets.
2. The assessment of the field performance of pheromone lures for navel orangeworm. Navel orangeworm is the principal insect pest of almonds and pistachios in California, with a farm gate value over $5 billion per year. An ARS scientist in Parlier, California, compared both the field performance of different lures for navel orangeworm and the effect of age on these lures. Pheromone lures are a recently adopted technology used to monitor this insect pest and improve its control, and growers are still learning the best way to use them. This research demonstrated that one lure was more effective than other lures when stored at low temperature (-20°C) for up to two years, and chemical analysis indicated that efficacy was linked to the proportion of the pentaene component of the lure. Storage conditions affected lure performance, and the finding that performance is linked to the proportion of the pentaene emitted from the lure will help manufacturers produce a more effective product.
3. Navel orangeworm adult traps vary in their rate of saturation. Navel orangeworm is the principal insect pest of almonds and pistachios in California, with a farm gate value over $5 billion per year. Two ARS scientists in Parlier, California, compared the field performance of different adult sticky traps for navel orangeworm and calculated the rate that these traps became saturated (no longer trapped moths). There are several different traps available, and they vary in design, surface area, and glue composition. When used with the recently introduced navel orangeworm pheromone, they can effectively monitor the population, but there is considerable variation in the frequency that traps are changed as well as how information on the number of moths recovered is used for management decisions. This study calculated an equation that allows end users to estimate how many moths actually visited the trap and also ranked the traps in terms of their trapping efficiency. This information will increase the ability of orchard managers to incorporate trapping data in their management schemes, ultimately reducing insect damage and increasing commodity quality for both domestic and foreign markets.
An ARS scientist participated as a mentor in the American Chemical Society Project SEED Program. This program provides stipends for high school interns from economically disadvantaged households.
An ARS scientist participated as a mentor for Hispanic Association of Colleges and Universities (HACU) Internship Program. This program provides paid internships for college undergraduate and graduate students attending Hispanic Serving Institutions (HSI’s); i.e., colleges and universities with over 25% Hispanic enrollment.
Review Publications
Walse, S.S., Jimenez, L.R., Hall IV, W.A., Tebbets, J.S., Obenland, D.M. 2016. Optimizing postharvest methyl bromide treatments to control spotted wing drosophila, Drosophila suzukii, in sweet cherries from Western USA. Journal of Asia-Pacific Entomology. 19(1):223-232.
Yang, Y., Yuanqing, L., Walse, S.S., Mitch, W.A. 2015. Destruction of methyl bromide sorbed to activated carbon by thiosulfate and electrolysis. Environmental Science and Technology. 49:4515-4521. doi: 10.1021/es505709c.
Burks, C.S., Yasin, M., El-Shafie, H.A., Wakil, W. 2015. Pests of stored dates. In: Wakil, W., Faleiro, J.R., and Miller, T.A, editors. Sustainable Pest Management in Date Palm: Current Status and Emerging Challenges. The Netherlands: Springer Dordrecht. p. 237-286.
Burks, C.S., Kuenen, L., Daane, K.M. 2016. Phenyl propionate and sex pheromone for monitoring navel orangeworm in the presence of mating disruption. Journal of Economic Entomology. 109(2):958-961.
Kuenen, L.P., Siegel, J.P. 2016. Sticky traps saturate with navel orangeworm in a non-linear fashion. California Agriculture. 70(1):32-38.
Jimenez, L.R., Hall IV, W.A., Rodriguez, M.S., Cooper, W.J., Muhareb, J., Jones, T., Walse, S.S. 2015. Quantifying residues from postharvest fumigation of almonds and walnuts with propylene oxide. Journal of AOAC International. 98(5):1423-1427.
Demkovich, M., Dana, C.E., Siegel, J.P., Berenbaum, M.R. 2015. Effect of piperonyl butoxide on the toxicity of four classes of insecticides to navel orangeworm (Amyelois transitella)(Lepidoptera: Pyralidae). Journal of Economic Entomology. 108(6):2753-2760.
Ampt, E.A., Bush, D.S., Siegel, J.P., Berenbaum, M.R. 2015. Larval preference and performance of Amyelois transitella (Navel orangeworm, Lepidoptera: Pyralidae) in relation to the fungus Aspergillus flavus. Environmental Entomology. 45(1):155-162.
Li, W., Wang, K., Chen, L., Johnson, J.A., Wang, S. 2015. Performance of controlled atmosphere/heating block systems for assessing insect thermotolerance. Biosystems Engineering. 135:1-9. doi: 10.1016/j.biosystemseng.2015.01.006.
Li, W., Wang, K., Chen, L., Johnson, J.A., Wang, S. 2015. Tolerance of Sitophilus zeamais (Coleoptera: Curculionidae) to heated controlled atmosphere treatments. Journal of Stored Products Research. 62:52-57. doi: 10.1016/j.jspr.2015.04.001.
Yokoyama, V.Y., Cambron, S.E., Muhareb, J. 2015. Hessian fly (Diptera: Cecidomyiidae) mortality in export bale compressors and response to a hydrogen phosphide and carbon dioxide gas mixture. Journal of Economic Entomology. 108(1):100-106. doi: 10.1093/jee/tou032.
