Location: Commodity Protection and Quality Research
2018 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. These studies evaluated the feasibility of using organosilicone adjuvants to reduce the amount of water used in application. These studies demonstrated that more of the spray was deposited in the upper canopy. Although promising for tall trees, there is no net gain if the lower nuts are at greater risk. If water is reduced, this will allow more rows to be sprayed with a single tank of insecticide, increasing the number of acres sprayed per day.
Under Sub-objective 1A2, experiments evaluated the correlation between almond damage and the capture of navel orangeworm in phenyl propionate traps during the growing season. Phenyl propionate is attractive to navel orangeworm in the presence of mating disruption, while pheromone lures are not. This is important because the use of pheromone lures as a monitoring tool has diminished in many places as mating disruption has increased.
Under Sub-objective 1B2, Tephritid fruit flies are major pests of fresh fruit, and are difficult to control with postharvest treatments. Trapping populations in the field reduces the reliance on postharvest treatments to guarantee that Tephritid-free fruit is marketed. Species from genus Anastrepha, including the Mexican fruit fly and the Caribbean fruit fly, are major pests of citrus across the Americas. The Anastrepha pheromone lure developed by ARS was used to bait traps deployed in field studies conducted in: Miami, Florida; Mission, Texas; Guatemala City, Guatemala; and Tapachula, Mexico. A synthetic analog of trimedlure, the “standard” Mediterranean fruit fly attractant, was used to bait traps deployed in: Miami, Florida; Sarasota, Florida; and Hilo, Hawaii. The analog was highly attractive and an ARS patent is being drafted. Novel food-based lures attractive to all Tephritid species, were used to bait traps deployed in: Miami, Florida; Mission, Texas; Guatemala City, Guatemala; and Hilo, Hawaii. These lures were commercialized. These studies were conducted with the following collaborators: USDA-Animal and Plant Health Inspection Service; Food and Agriculture Organization; International Atomic Energy Agency; and California Department of Food and Agriculture.
Under Sub-objective 1B3, experiments were conducted to examine the effect of hours of emission on the effectiveness of mating disruption targeting navel orangeworm. An experiment in April and May of 2017 found no difference in pheromone trap suppression between an aerosol mating disruption system that emitted for 12 hours a night (i.e., the entire time of darkness) and one that emitted for the last eight hours of the night. A second experiment, from May to August, found no difference in trap suppression for the last six hours of the night and treatments ending one or two hours earlier. A third experiment, conducted in October, compared mating disruption for 12 hours with either mating disruption from six p.m. to midnight or midnight to six a.m. The all-night treatment performed as well or better than the partial night treatments in all cases, whereas the performance of the two six-hour treatments varied by nighttime temperature. This variable result indicates that during cooler periods, all-night emission may be necessary for adequate control of navel orangeworm. A fourth experiment found no difference between the number of males trapped in the untreated control block and the three mating disruption blocks one night after treatment was stopped, indicating no carryover effect.
Under Sub-objective 1D1, a mathematical tool was developed for analysts in Animal and Plant Health Inspection Service (APHIS), Plant Protection and Quarantine (PPQ), Phytosanitary Issues Management (PIM), and Center for Plant Health Science and Technology (CPHST) to evaluate new and existing systems approaches. A team of ARS, APHIS, and university experts evaluated mathematic approaches to describe the experimental results. Brown marmorated stink bug (BMSB), Halyomorpha halys, is an insect of concern to some countries that import California sweet cherries. The removal and/or mortality of BMSB as cherries are harvested, cleaned, packed, fumigated, and shipped was evaluated to meet the requirements of quarantine security. Post-embryonic life stages of BMSB (first-fifth instar and adult) were removed from fruit that is dunked or soaked, as part of commercial protocols for cleaning and packing California cherries. This research can be provided to regulators and trading partners to quantify the reduction in risk of BMSB as sweet cherries are moved from production areas through packing operations to export markets.
Under Sub-objective 1D2, industry data were used to identify risk factors for insect damage in pistachios. A database for the years 2007-2017 was created and the information used to calculate the doubling time for damage (10 days) under high pressure. This information establishes a baseline for each county in the San Joaquin Valley that can be used to assess the efficacy of new strategies for control. Further analysis will concentrate on identifying factors associated with increased damage. The ultimate goal is to help maintain and/or increase crop quality, which will ensure that American pistachios remain competitive in a world market.
Under Sub-objective 2A, activated carbon sorbent was evaluated to reduce the negative impact of postharvest chamber fumigations on air quality. Activated carbon 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, prepared by steam activation or carbon dioxide activation coupled to water quenching, outperformed a commercial product derived from coconut shells. 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.
Under Sub-objective 2B, postharvest treatments were developed to control key insect pests of commodity intended for domestic markets. Phosphine fumigations were developed to control phosphine-resistant strains of stored product pests, including: red flour beetle, lesser grain borer, rice weevil, and navel orangeworm. A new phosphine treatment was developed to control warehouse beetle, a pest of concern to countries that import Dried Distillers Grains (DDGs) from the U.S., and models of the duration-mortality response predicted greater than 99 percent mortality when headspace concentrations of phosphine [PH3], are maintained at levels equal or greater than 0.8 mgL-1 (500 parts per million by volume [ppmv]) and equal or less than 1.5 mgL-1 (1,000 ppmv) for equal or greater than 120 hours. This research aims to ensure that domestic consumers receive an optimal commodity.
Under Sub-objective 2C, in order to improve non-insecticidal control of the Indianmeal moth (a major processing and warehouse pest) using pheromones, modified assays evaluated whether a non-attractive sex pheromone formulation would disrupt mating at higher population densities than an attractive formulation. The planned assays were modified by varying the number of male-female pairs released rather than the number of pheromone dispenser point sources used for mating disruption, and also examined whether females were mated, an indicator of success, rather than the number of males captured in a monitoring lure. The results to date are not statistically significant and further replication is in progress in order to determine if the hypothesis is valid.
Under Sub-objective 3A, several quarantine treatments were developed to control key insect pests. Results were presented to APHIS Phytosanitary Issues Management (PIM) to support negotiations with foreign governments to facilitate specialty crop export. Cold treatment schedules were developed for: bean thrips in fresh citrus exports to Australia; Brevapalpus mites in fresh citrus exports to Australia; spotted wing drosophila in stone fruit exports to New Zealand and Australia; brown marmorated stinkbug in fresh fruit exports to New Zealand and Australia; and phyloxera in table grape exports to Australia. This research supports the U.S. Government’s goal of retaining and expanding export markets, including President Obama’s National Export Initiative, Executive Order 13534.
Under Sub-objective 3B, the efficacy, fate, and transport of fumigants was traced throughout fumigation, storage, and marketing. Experiments were designed in collaboration with the U.S. Environmental Protection Agency, California Department of Food and Agriculture, and the Food and Drug Administration. Results were presented to these action agencies from the perspective of worker exposure and environmental impacts. Sorption and depuration processes were reported for: methyl bromide treatments of fresh fruit; propylene oxide fumigation of tree nuts; phosphine treatments of fresh fruit; ethyl formate treatment of citrus in field bins; pyrethrin fog treatments of citrus in field bins; sulfur dioxide treatment of table grapes, blueberries, and fresh figs; and metabisulfite treatment of table grapes, blueberries, and fresh figs.
Under Sub-objective 3C, using the modeling techniques from Sub-objective 3B, a user program was developed to predict the residue levels of propylene oxide. Users enter critical parameters, including: 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. This increases the likelihood that product will arrive at the destination in compliance with country-specific maximum residue level tolerances, thereby avoiding rejection which is costly.
Accomplishments
1. Establishing the toxicity of adjuvants to navel orangeworm. Adjuvants are chemicals used to enhance the activity of insecticides by increasing their penetrance, spreadability, adherence to substrate, and/or stability. Neither their intrinsic toxicity to the eggs and adults of navel orangeworm, nor their contribution to the duration of insecticide control have been examined. An ARS scientist in Parlier, California, in collaboration with scientists at the University of Illinois, in Champaign, Illinois, assessed six adjuvants in the laboratory, and also assessed two adjuvants in the field. Two classes of adjuvants were identified that increased egg and adult mortality and these effects will be quantified further. Field experiments also demonstrated that differences in the initial deposition of insecticides depended on the adjuvant used. This information will be used to improve control of navel orangeworm, the principal moth pest of almonds and pistachios in California (over $7 billion value), by increasing application efficacy and thereby increase the quality of almonds and pistachios grown in California.
2. Improving navel orangeworm mating disruption by using blends. Mating disruption is used to control a variety of lepidopteran pests, and the blend of compounds that works best varies with both the target species and the way in which the mating disruption product is presented. For the navel orangeworm, a major pest of fruits and nuts, mating disruption currently uses a single chemical compound which, by itself, is not attractive. The use of attractive blends for navel orangeworm mating disruption has received little attention because such blends require an unusual compound, which is more expensive to register. An ARS researcher in Parlier, California, in collaboration with university and industry collaborators, found that aerosol dispensers using attractive blends were better at suppressing the ability of males to locate the female sex pheromone than the current single-compound product. A subsequent study using a hand-applied passive dispenser found the same effect. This demonstration that an attractive pheromone blend for navel orangeworm can achieve disruption more efficiently may convince industry and regulatory agencies to find ways to bring a more effective product to market, providing better and more environmentally friendly protection for the California almond and pistachio crops, valued at over $7 billion annually.
3. Optimizing fumigations against spotted wiry drosophila. ARS researchers in Parlier, California, developed novel methyl bromide (MB) chamber fumigations for postharvest control of spotted wing drosophila (SWD), a major pest of fruit, in fresh sweet cherry exports from the Western U.S. valued at $100 million annually. A kinetic model of sorption was developed based on the measurement of MB and how calculated exposures varied across the fumigation trials. The model describes how to manipulate the applied MB dose, fumigation duration, and the load factor so that the resultant exposure is adequate for SWD control across various pulp temperatures when cherries are fumigated in wooden versus plastic bins. These results will be used to optimize quarantine fumigation schedules for control of SWD, which will promote more strategic technical and economic Quarantine Pre-shipment (QPS) use of MB as well as minimize the exposure of workers to MB. The ARS research served as a key 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.
Review Publications
Burks, C.S., Wilk, C. 2017. Effect of storage of pheromone lures for Amyelois transitella: field performance and compound ratios. Florida Entomologist. 100(4):820-822. https://doi.org/10.1653/024.100.0411.
Demkovich, M., Siegel, J.P., Walse, S.S., Berenbaum, M. 2018. Impact of agricultural adjuvants on the toxicity of the diamide insecticides chlorantraniliprole and flubendiamide toward different life stages of navel orangeworm (Amyelois transitella) (Lepidoptera: Pyralidae). Journal of Pest Science. 91(3):1127-1136. https://doi.org/10.1007/s10340-018-0959-z.
Guedes, R.C., Corbett, S.M., Rodriguez, M., Goto, J.J., Walse, S.S. 2018. Pesticide-mediated disruption of spotted wing Drosophila flight response to raspberries. Journal of Applied Entomology. 142(5):457–464. https://doi.org/10.1111/jen.12500.
Rovnyack,, A.M., Burks, C.S., Grassman, A.J., Sappington, T.W. 2018. Interrelation of mating, flight, and fecundity in navel orangeworm (Lepidoptera: Pyralidae) females. Entomologia Experimentalis et Applicata. 166(4):304-315. https://doi.org/10.1111/eea.12675.
Ornelas-Paz, J., Meza, M., Obenland, D.M., Rodriguez, K., Jain, A., Thornton, S., Prakash, A. 2017. Effect of phytosanitary irradiation on the postharvest quality of Seedless Kishu mandarins (Citrus kinokuni mukakukishu). Food Chemistry. 230:712-720. https://doi.org/10.1016/j.foodchem.2017.02.125.
Obenland, D.M., Arpai, M. 2018. Impact of changing wax type during storage on mandarin flavor and quality attributes. Acta Horticulturae. 1194:807-814. https://doi.org/10.17660/ActaHortic.2018.1194.114.
Bush, D.S., Lawrance, A., Siegel, J.P., Berenbaum, M.R. 2017. Orientation of navel orangeworm larvae and adults (Amyelois transitella: Lepidoptera: Pyralidae) toward Aspergillus flavus. Environmental Entomology. 46(3):602–608. https://doi.org/10.1093/ee/nvx068.
