Location: Commodity Protection and Quality Research
2017 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 Subobjective 1A, field studies were conducted to assess insecticide coverage in almonds and pistachios. At least two years of field data are necessary to improve the precision of our estimates of both the amount of insecticide deposited on target and the duration of control of a particular insecticide. This information can then be used to optimize insecticide application and ultimately reduce both the number of sprays needed for control as well as reduce damage. These studies have been expanded to evaluate the role played by adjuvants (chemicals added to the spray tank to improve insecticide retention on target and enhance spreading) in improving toxicity and/or the duration of control.
Separate studies were conducted under Subobjective 1B to optimize semiochemical strategies for monitoring insect pests. Chemical lures were developed for several fruit fly species (Mexican fruit fly and the Caribbean fruit fly). Novel food-based lures, which are attractive to all fruit fly (Tephritid) species, were made by formulating mixtures of chemicals in a cellulosic matrix. The aggregation pheromones of both the Mexican fruit fly and the Caribbean fruit fly were synthesized and formulated in both 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 Texas for the Mexican fruit fly, and in Florida for the Caribbean fruit fly.
Under Subobjective 1B, replicated small-plot assays were used to compare three aerosol mating disruption treatments for control of navel orangeworm in almonds, pistachios and walnuts. These treatments occurred during the last 4, 6, or 8 (current standard) hours before dawn. The outcome measured was the suppression of males captured in pheromone traps, with fewer males captured indicating greater suppression. These treatments were also compared to trap capture in a section of orchard that was not using mating disruption. All three mating disruption treatment times significantly reduced the number of males captured, but there was no significant difference among the three treatments. This finding suggests that the traps can be turned on later in the evening, which will use less chemical, enabling mating disruption treatments to be administered in a more cost-effective manner and increasing the adoption of this alternative technology.
Under Subobjective 1D, a mathematical tool was developed to assist analysts belonging to three units within APHIS, Plant Protection and Quarantine Unit (PPQ), Phytosanitary Issues Management Unit (PIM), and Center for Plant Health Science and Technology Unit (CPHST), in evaluating new, as well as existing systems approaches for insect control. Data were collected for the removal of Asian citrus psyllid (ACP) in fresh citrus. Using a retrospective analysis and the application of Bayesian probability statistics, the removal and/or mortality of ACP was demonstrated using contemporary packing procedures. The key steps in ACP removal/and or mortality were found to be commercial wax driers, soaking, and passing the fruit over rollers. This research directly resulted in the retention of exports from California to Australia, and has also served as the basis for the domestic quarantine policy for organic citrus growers.
Under Subobjective 1D, pistachios were chosen as a model system to determine if industry data can be used to identify risk factors for increased insect damage. A pistachio research database for the years 2007-2015 was created and this information was used to establish the relationship between harvest date and damage for the counties producing pistachios. It was determined that the doubling time for navel orangeworm damage to pistachios is two weeks. Ultimately, this information will help establish new recommendations for insect control as well as establish baseline damage values to evaluate future management schemes to improve control.
Research conducted under Subobjective 2A established that the negative impacts to air quality from fumigation can be minimized by scrubbing the ventilation effluent with a sorbent. Activated carbon (AC) sorbents from walnut and almond shells as well as peach and prune pits were prepared using different methods of pyrolysis, activation, and quenching. Each source and preparation was evaluated for its performance on tests where methyl bromide-containing airstreams were directed through a columnar bed of the sorbent. Activated carbon sorbents from prune pits received the greatest number of doses prior to breakthrough and had the highest capacity, approximately 12 to 14% by mass, outperforming a commercially-marketed AC derived from coconut shells.
Under Subobjective 2B, postharvest treatments were developed to control key insect pests that impact the quality, safety, and distribution of commodity intended for domestic markets. Sulfuryl fluoride fumigation protocols were developed to control stored product pests. Sulfuryl fluoride and ethyl formate fumigation protocols were developed to control brown marmorated stink bug in vehicle exports. Results support the finding that for fumigation success, time is a more dominant variable than dose. This research contributes to the ability of industry to supply domestic consumers with an optimal commodity.
Under Subobjective 2C, the infestation of stored products at the processor was addressed. In order to improve noninsecticidal control of the Indianmeal moth (a major processing and warehouse pest) using pheromones, modified assays were used to examine the hypothesis that a non-attractive sex pheromone formulation would disrupt mating at higher population densities, compared to 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 disruption, and examining whether females were mated rather than the number of males captured in a monitoring lure. Initial results suggest that the non-attractive formulation can disrupt at higher population densities, but results to date are not statistically significant and further replication is in progress.
Under Subobjective 3A, a new postharvest treatment using ethyl formate was developed for citrus to eliminate mites from the genus Brevipalpus, including two California species B. lewisi and B. Californicus, and the Asian citrus psyllid. A new fumigation treatment using methyl bromide was developed to eliminate codling moth from California plum exports to Japan. A systems-approach to eliminate black widow spider from California table grape exports to the European Union and Australia was developed using a combination of ozone and cold-treatment lasting six days. These results were presented to APHIS Phytosanitary Issues Management (PIM) to support negotiations with foreign governments to facilitate specialty crop export.
Under Subobjective 3B, in order to reduce human exposure to fumigants, novel experimental procedures and modeling techniques were used to trace fumigant residues over the course of fumigation, storage, and marketing. These experiments were designed in collaboration with the United States Environmental Protection Agency (USEPA), California Department of Food and Agriculture, and the Food and Drug Administration. Results were presented to these agencies from the perspective of worker exposure and environmental impacts.
Under Subobjective 3C, in order to investigate off-gassing of the fumigants and support U.S. exports, sorption and depuration processes were reported for fresh fruit (cherries, peaches, and plums), table grapes, and phosphine treatment of grains. The phosphine research resulted in the USEPA pursuing a “non-food use” registration for this fumigant. Novel methodologies were developed to both quantify and then decrease levels of residues on food stuffs to comply with maximum residue levels (MRLs) for specialty crops exports. A gas chromatography-mass spectrometry method was developed to quantify residues of propylene oxide and its halohydrins in tree nut exports to the European Union. A liquid chromatography-mass spectrometry method was developed to quantify residues of phosphorous acid in tree nut residues to the European Union. A gas chromatography-mass spectrometry method was developed to quantify residues of sulfur dioxide in blueberries to support the establishment of domestic and international food tolerances. The research critically supports goals of APHIS and the Foreign Agricultural Service, respectively, to ensure the safe trade of agricultural products and to increase U.S. food and agricultural exports to $200 billion by end-year 2017.
Accomplishments
1. Ozone fumigation for spider control in California table grape exports. Black widow spiders, particularly the adult females, are cited as a pest of concern by several countries that import table grapes from California. This is a valuable export market and the export of table grapes from California to the United Kingdom is valued at $20 million annually. ARS scientists in Parlier, California developed a novel chamber fumigation for postharvest control of black widow spider in fresh table grapes. The ozone-based treatment results in over 96% mortality of adult female black widow spiders and provides, for the first time, an opportunity to control this pest using a pesticide that is Generally Recognized as Safe (GRAS) and potentially compliant with organic marketing strategies. The ARS research served as a key basis for technical interaction between industry, USDA-Foreign Agricultural Service, USDA-Animal and Plant Health Inspection Service, and respective counterparts in foreign governments, thereby ensuring the export of table grapes.
2. A lure for monitoring navel orangeworm in almonds in the vicinity of mating disruption. Mating disruption for navel orangeworm, used in an increasing proportion of almond and pistachio orchards, is a least-toxic pest management alternative that decreases population of and damage from this pest, but also makes detection with pheromone lures more difficult in both the treated block and neighboring blocks. ARS scientists in Parlier, California demonstrated that combination phenyl propionate/pheromone lures attract similar numbers of adults compared to pheromone lures in the absence of mating disruption, and more adults than either lure type alone in the presence of mating disruption. Data from the current study demonstrate a field life of six weeks for phenyl propionate dispensers, and indicate that the number of adults captured was similar across different intensities of mating disruption in experimental plots. Data from monitoring sites 0.6 to 2.8 miles from large commercial mating disruption blocks indicated that phenyl propionate/pheromone combination traps detected navel orangeworm under conditions in which traps baited only with pheromone were partially or completely suppressed. These findings indicate that phenyl propionate/pheromone combination traps will be useful for monitoring for navel orangeworm, the key insect pest of the $7.8 billion almond and pistachio industries, in areas in which mating disruption is commonly used.
3. Field validation of a new product for mating disruption of navel orangeworm. Mating disruption is a technology that can reduce the use of insecticides used to control navel orangeworm in almonds and pistachios. One barrier to its widespread adoption is its cost, due in part to a lack of competition among suppliers, because only two companies had products registered for use in California in 2016. ARS scientists in Parlier, California conducted extensive field studies evaluating a new mating disruption product in almonds and pistachios, and their research demonstrated that this product was effective and their data were used to support the registration of this product in California for the 2017 field season. As a result of this work, there are now three mating disruption technologies available for control of navel orangeworm, providing the almond and pistachio growers with greater choice. This technology will both help control navel orangeworm and reduce the use of insecticides, ensuring nut quality and consumer acceptance of these two commodities.
Review Publications
Jain, A., Paz, J., Obenland, D.M., Rodriguez, K., Prakash, A. 2017. Effect of phytosanitary irradiation on the quality of two varieties of pummelos (Citrus maxima (Burm.) Merr.). Scientia Horticulturae. 217:36-37. doi:10.1016/j.scienta.2017.01.029.
Burks, C.S. 2017. Combination phenyl propionate/pheromone traps for monitoring navel orangeworm (Lepidoptera: Pyralidae) in almonds in the vicinity of mating disruption. Journal of Economic Entomology. 110(2):438-446. doi: 10.1093/jee/tow318.
Bagchi, V., Siegel, J.P., Demkovich, M., Zehr, L., Berenbaum, M. 2016. Impact of pesticide resistance on toxicity and tolerance of hostplant phytochemicals in Amyelois transitella (Lepidoptera: Pyralidae). Journal of Insect Science. 16(1):62. doi: 10.1093/jisesa/iew063.
Higbee, B.S., Burks, C.S., Carde, R.T. 2017. Mating disruption of the navel orangeworm (Lepidoptera: Pyralidae) using widely spaced, aerosol dispensers: is the pheromone blend the most efficacious disruptant? Journal of Economic Entomology. doi:10.1093/jee/tox185.
Picot, A., Ortega-Beltran, A., Puckett, R.D., Siegel, J.P., Michailides, T.J. 2016. Period of susceptibility of almonds to aflatoxin contamination during development in the orchard. European Journal of Plant Pathology. 148(3):521-531. doi: 10.1007/s10658-016-1108-2.
Guedes, R.C., Walse, S.S., Throne, J.E. 2017. Sublethal exposure, insecticide resistance, and community stress. Current Opinion in Insect Science. 21:47-53. doi:10.1016/j.cois.2017.04.010.
Walse, S.S., Tebbets, J.S., Leesch, J.G. 2017. Postharvest fumigation of California table grapes with ozone to control Western black widow spider (Araneae: Theridiidae). Postharvest Biology and Technology. 134:1-4. doi:10.1016/j.postharvbio.2017.07.012.
