Location: Commodity Protection and Quality Research
2019 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
Under Sub-objective 1A, field studies were conducted to assess insecticide coverage in almonds and pistachios by ground and air. These studies evaluated the feasibility of using organosilicone adjuvants to reduce the amount of water used in application, as well as improve coverage in the upper canopy. Coverage in the upper canopy significantly improved with this class of adjuvant and this finding has value for mature orchards with tall trees. Differences among organosilicone adjuvants, as well as their ability to consistently decrease the amount of water used in application, are being evaluated. If these findings are confirmed, insecticide coverage will increase and more rows can be sprayed per tankful, improving timing and reducing application cost.
Also under Sub-objective 1A, research was continued examining phenyl propionate (PPO) and other lures attractive to both sexes of navel orangeworm as alternatives to the male-only pheromone lures for monitoring in the presence of mating disruption, where pheromone lures should capture no moths. Experiments demonstrated that the degree to which traps are open-sided profoundly influences the number of moths captured, the degree to which pheromone synergizes PPO, and the variability, measured using standard error, involved with the trap. Experiments and outreach to technology transfer partners seek to develop a commercially acceptable open-sided trap, and also examine the possibility that the standard delta trap with PPO-only may provide sufficient detection and have the advantage of less variability (lower standard error). PPO lures have been commercialized by two manufacturers.
Under Sub-objective 1B, experiments to optimize use of an aerosol formulation have been completed, published in the peer-reviewed literature, and incorporated into a cooperator’s current practice. Additional related research is currently examining whether hand-applied dispensers for navel orangeworm can, unlike mating disruption for other crops and pests, be hung at head level rather than higher in the tree. If this practice can be adopted without loss of crop protection, the economy of labor could cause this form of mating disruption to be more widely adopted in parts of the almond and pistachio industries.
Under Sub-objective 2B, postharvest treatments were developed to control key insect pests that impact commodities intended for domestic markets. Efficacy of propylene oxide was evaluated against eggs of postharvest insect pests (dried fruit beetle, red flour beetle, Indianmeal moth, tobacco moth, cigarette beetle, codling moth, and navel orangeworm). Lepidopteran eggs were more susceptible than coleopteran eggs. Propylene oxide alone or in combination with carbon dioxide was toxic to eggs of all the insect species tested. Generally, coleopteran eggs were more propylene oxide-tolerant than lepidopteran eggs, and carbon dioxide did not affect the toxicity toward either. This research contributes to the ability of industry to supply domestic and international consumers with disinfested commodity, thereby enhancing the competitiveness of U.S. agriculture.
Under Sub-objective 2C, research is focused on quantifying how long the ability of almond moth males to find females is lost after exposure to mating disruption dispensers. The results will help illuminate the relative effectiveness of pure mating disruption versus attract-and-kill strategies for this pest.
Accomplishments
1. Control of invasive and quarantine horticultural pests. It is a constant challenge to both protect U.S. market share and expand markets. A series of quarantine trials were conducted using the procedures and methodology developed by an ARS scientist in Parlier, California. U.S. market share was protected using a variety of methods, including postharvest methyl bromide fumigation to control codling moth in Japanese plum exports to Japan (valued at $10 million); brown marmorated stinkbug was controlled with ethyl formate fumigation to retain market access for U.S. automobiles to Australia and New Zealand (with a projected annual value of $8 billion annually); warehouse beetle was controlled in dried distillers grain exports to Thailand (valued at $250 million annually); spotted wing drosophila was controlled with ozone fumigation in table grape exports to Australia (valued at $180 million annually); and bean thrips was controlled with postharvest phosphine fumigation to retain market access for fresh citrus to Australia (with a projected annual value of $20 million). Within the U.S., the spread of Asian citrus psyllid was controlled by the postharvest ethyl formate fumigation of trailer loads in the grove to limit movement from quarantine zones. This research directly resulted in market retention or expansion and served as the basis for technical interaction between industry, USDA Foreign Agricultural Service, USDA Animal and Plant Health Inspection Service, U.S. Environmental Protection Agency, and respective counterparts in foreign governments.
2. Importance of trap characteristics for performance of lures for navel orangeworm under mating disruption. The navel orangeworm is the principal insect pest of almonds, pistachios, and walnuts, which were worth approximately $6.6 billion in unprocessed form in 2017. A new technology, mating disruption, is currently used on approximately 500,000 of the over 1.58 million acres of almonds, pistachios, and walnuts in California, but mating disruption drastically decreases the efficacy of the pheromone lures currently used in monitoring traps. An ARS scientist in Parlier, California, conducted research on the influence of trap design on the efficacy of phenyl propionate, a potentially useful attractant unaffected by mating disruption. Traps with open sides (wing traps) were more effective than traps with closed sides (delta traps) and delta traps could be modified by cutting openings in the side to improve performance. Follow-up with commercial trap producers is underway to produce a form of the modified trap that is acceptable to the industry. Improving information on pest population density will enable ranch managers to improve control of this pest.
3. Improving application coverage for control of navel orangeworm using adjuvants. The navel orangeworm is the principal insect pest of almonds and pistachios (over 1.25 million acres) in California, valued at over $7 billion in 2018. Adjuvants are chemicals used to enhance the activity of insecticides by increasing penetrance, spreadability, adherence to substrate, and/or stability. An ARS scientist in Parlier, California, assessed the effect of adjuvants belonging to the organosilicone family, applied by ground and by air, on the initial deposition of insecticides and duration of control in the field. It is challenging to protect nuts in the upper canopy of trees and these trials demonstrated improved coverage with organosilicone adjuvants both by ground and air. Applications by air provided excellent coverage in the upper canopy and they are a viable choice for many orchards with tall trees. This information on improving coverage in the upper canopy will increase application efficacy by ground and air, while increased adoption of air application will improve treatment timing, thereby increasing the quality of almonds and pistachios grown in California.
4. Fumigation with phosphine does not harm citrus quality. Fumigation with methyl bromide may not be possible in the future. A replacement is urgently needed to maintain the export of citrus to countries that require a quarantine treatment, and this treatment must also maintain the quality of the fruit. ARS researchers in Parlier, California, tested the tolerance of mandarins, navel and Valencia oranges, lemons and grapefruit to phosphine fumigation and found that quality is not adversely affected by the treatment. This quarantine treatment was superior to both methyl bromide fumigation and cold treatment that sometimes damaged the peel surface of the citrus. This research gives confidence in the ability to control insect pests and continue citrus exports in the absence of methyl bromide.
5. Development of a lure for fruit flies belonging to the genus Anastrepha. Tephritid fruit flies, including Mexican and Caribbean fruit fly, are major pests of citrus across the Americas and have the potential to disrupt trade. Trapping populations in the field reduces reliance on postharvest treatments. The Anastrepha pheromone lure developed by ARS researchers in Parlier, California, was tested in field studies in Miami, Florida; Mission, Texas; Guatemala City, Guatemala; and Tapachula, Mexico, and a novel matrix to release the Anastrepha pheromones was also developed. These studies were in collaboration with USDA-Animal and Plant Health Inspection Service, Food and Agriculture Organization of the United Nations (FAO), International Atomic Energy Agency, and California Department of Food and Agriculture. A synthetic analog of trimedlure, the industry standard lure, was used to bait traps deployed in field studies in Miami and Sarasota, Florida and Hilo, Hawaii. The analog was highly attractive to the flies and an ARS patent was filed (Serial Number 16/101,805). Adoption of this product will increase the ability to trap fruit flies in the field, thereby improving control.
6. Evaluating methyl bromide and phosphine chamber fumigations for postharvest control of fruit fly. Oriental fruit fly and Mediterranean fruit fly pose a risk to the movement of sweet cherries from production areas through packing operations and transport to export markets. Laboratory results from trials were transferred to Animal and Plant Health Inspection Service Plant Protection and Quarantine (APHIS PPQ), Plant Epidemiology and Risk Analysis Laboratory, and Center for Plant Health Science and Technology (CPHST) to evaluate the relative contribution of different postharvest treatments toward an overall systems approach. A team of ARS, APHIS PPQ, and University experts evaluated mathematic approaches to describe the experimental results, and produced a publication entitled “Quantifying a Systems Approach for Mitigating the Risk of Oriental Fruit Fly, Bactrocera dorsalis, in Cherry Fruit: Probabilistic Model Descriptions”. This research will be provided to domestic regulators and trading partners to quantify the reduction in risk/threat of Oriental fruit fly and Mediterranean fruit fly, thereby protecting U.S. market share and expanding new markets.
7. Using industry data to identify pistachio factors associated with navel orangeworm infestation. Navel orangeworm damage is a cause for concern because of lost product and aflatoxin contamination. Pistachio processor gradesheets (162,000) from the period 2007-2017 were compiled and used by ARS researchers in Parlier, California, to identify nut factors contributing to navel orangeworm damage. The percent of nut split at harvest, harvest date, percent of dark staining of the shell and percent of shell defect, were correlated with insect damage. Damage curves and an overall damage model were calculated using this dataset. This information will be distributed to pistachio producers and processors to help focus on production practices that can reduce these risk factors. This in turn will help maintain and/or increase crop quality, which will help ensure that U.S. pistachios remain competitive in the world market.
8. Minimizing the impact of fumigation on air quality. Finding cost-effective techniques for eliminating methyl bromide emissions into the atmosphere may help ensure that the continued use of fumigants is accompanied by minimal environmental impact. Scientists in Parlier, California, conducted studies on removing fumigant from commodities using activated carbon sorbent, and sorbents from walnut and almond shells as well as peach and prune pits were prepared using different methods of pyrolysis, activation, and quenching. Activated carbons from prune pits were the most effective and had the highest capacity, outperforming a commercially-marketed activated carbon derived from coconut shells. The methyl bromide-laden activated carbon was utilized as an electrode and electrolytic reduction was evaluated as a means to destroy the sorbed methyl bromide.
9. Control of quarantine insect pests of stone fruit using methyl bromide. Spotted wing drosophila fruit flies are a major problem for the export of stone fruit from California to Australia and Japan. An optimized postharvest methyl bromide treatment schedule for control of spotted wing drosophila in California apricots, nectarines, and peaches was developed by ARS researchers in Parlier, California, to support exports to Australia. A kinetic model of sorption was applied to the measurements of methyl bromide and associated exposures across the fumigation trials. Additional postharvest chamber fumigation with methyl bromide was used to control codling moth in Japanese plum exports from California to Japan. Results were presented to the Animal and Plant Health Inspection Service Phytosanitary Issues Management (PIM) to support negotiations with foreign governments to facilitate agricultural exports valued at $30 million annually.
10. Determining the efficacy, fate and transport of fumigants. Worker exposure to fumigants is an ongoing concern at the local, state, and national level. Novel experimental procedures and modeling techniques were developed by ARS researchers in Parlier, California, in collaboration with the U.S. Environmental Protection Agency (EPA) and California Department of Pesticide Regulation, to assess the efficacy, fate, and transport of fumigants over the course of treatment, storage, and marketing. Results were presented to these government action agencies from the perspective of worker exposure and environmental impacts to support registration activities. Data on sorption and depuration processes were reported for phosphine treatments of citrus, table grapes, stone fruit, pears, apples, tomatoes, lettuce, pomegranate, blueberries, and figs. Research demonstrated that workers were exposed to less phosphine, relative to an equally efficacious treatment using methyl bromide. The EPA used the results to support a “non-food” use designation for postharvest phosphine fumigation of fresh fruits and vegetables with an associated 10 parts per billion residue tolerance.
11. Predicting methyl bromide and propylene oxide levels in commodities upon arrival in a foreign market. From a worker safety perspective, it is important to be able to predict the level of fumigant outgassing from a commodity upon arrival. Using a database based on extensive testing, a user program was developed by ARS researchers in Parlier, California, and cooperating agencies, to predict the residue levels of methyl bromide and propylene oxide upon arrival in a foreign market. The user-entered parameters are: fumigation temperature, applied dose of fumigant, duration of post-fumigation incubation, temperature of post-fumigation incubation, storage temperature and duration, expected trans-oceanic shipping time to destination, and estimated temperature during shipment. The program yields a prediction of expected residue levels, thereby increasing the likelihood that product will arrive at the destination in compliance with country-specific maximum residue level (MRL) tolerances. Compliance with these MRL tolerances is essential for U.S. market retention as well as increased exports.
Review Publications
Walse, S.S., Tebbets, J.S., Leesch, J.G. 2019. Postharvest methyl bromide fumigation of Japanese plums to control codling moth (Lepidoptera: Tortricidae). Journal of Asia Pacific Entomology. 22(3):807-815. https://doi.org/10.1016/j.aspen.2019.04.011.
Siegel, J.P., Strmiska, M.M., Walse, S.S., Niederholzer, F.J., Giles, K.D. 2019. Evaluating insecticide coverage and determining its effect on the duration of control for navel orangeworm (Amyelois transitella Walker) (Lepidoptera: Pyralidae) in California almonds. Pest Management Science. https://doi.org/10.1002/ps.5413.
Guedes, R.C., Cervantes, F.A., Backus, E.A., Walse, S.S. 2018. Substrate-mediated feeding and egg-laying by spotted wing drosophila: waveform recognition and quantification via electropenetrography. Journal of Pest Science. 92(2):495-507. https://doi.org/10.1007/s10340-018-1065-y.
Preto, C., Bellamy, D., Walse, S.S., Zalom, F.G. 2018. Predicting larval stage distribution of Lobesia botrana (Lepidoptera: Totricidae) at three constant temperatures. Journal of Economic Entomology. 112(2):585-590. https://doi.org/10.1093/jee/toy374.
Burks, C.S., Thomson, D.R. 2019. Optimizing efficiency of aerosol mating disruption for navel orangeworm (Lepidoptera: Pyralidae). Journal of Economic Entomology. 112(2):763-771. https://doi.org/10.1093/jee/toy417.
Guedes, R.N., Cervantes, F.A., Backus, E.A., Walse, S.S. 2019. Electropenetrography of spotted wing drosophila (Drosophila suzukii) on pesticide-treated strawberry. Journal of Pest Science. https://doi.org/10.1007/s10340-019-01124-6.
Siegel, J.P., Strmiska, M.M., Niederholzer, F.J., Giles, K.D., Walse, S.S. 2018. Evaluating insecticide coverage in almond and pistachio for control of navel orangeworm (Amyelois transitella) (Lepidoptera: Pyralidae). Pest Management Science. 75(5):1435-1442. https://doi.org/10.1002/ps.5265.
