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United States Department of Agriculture

Agricultural Research Service

Research Project: POSTHARVEST TREATMENT OF TROPICAL COMMODITIES FOR QUARANTINE SECURITY, QUALITY MAINTENANCE, AND VALUE ENHANCEMENT

Location: Tropical Crop and Commodity Protection Research

2009 Annual Report


1a.Objectives (from AD-416)
To develop and protect export markets for tropical fruit, vegetable, nut, and ornamental crops, with emphasis on expanding and diversifying agriculture and agricultural exports in Hawaii by providing environmentally sound, economically viable systems, treatments, or processes that control quarantine pests, ensure product quality and food safety, and increase product value. The three broad objectives to be addressed include (1)Develop new or improved postharvest treatments, including alternatives to methyl bromide fumigation, for fruit, vegetable, and ornamental crop imports and exports to ensure security against quarantine pests; (2) Develop new or improved postharvest treatments for fruit, vegetable, nut, and ornamental crops to improve product quality and shelf life, reduce or eliminate postharvest disorders or decay, and enhance product value; and (3) Identify, develop or improve preharvest methods for fruit, vegetable, nut, and ornamental crops that enhance postharvest quality and reduce the incidence of quarantine pests that limit exports.


1b.Approach (from AD-416)
Develop target quarantine pest and host commodity control efficacy and product quality data, respectively, using irradiation, controlled-atmosphere temperature treatment, limonene and oils, ozone fumigation, or radio frequency treatment with commodity quality, microbial, biochemical, physical property, or vitamin analyses to meet Objectives 1 and 2; and measure target pest feeding activity to forecast damage, determine insecticide resistance levels, or develop caffeine-based toxicants to meet Objective 3. Foremrly 5320-43000-009-00D (4/05).


3.Progress Report
Research conducted under this project addresses quarantine pests or quality issues specific to exported tropical commodities vital to the growth of agriculture in the U.S. Pacific Basin. In the area of quarantine treatment research, large-scale irradiation tests are underway to demonstrate the efficacy of a treatment dose of 150 Gy against light brown apple moth, a serious quarantine pest spreading in California and disrupting trade. Blueberry was tested for its susceptibility to fruit fly attack; blueberry appears to be a good host for medfly and oriental fruit fly, an acceptable host for melon fly, and a non-host for solanaceous fruit fly, although there is significant cultivar variation in resistance. Host range studies with the parasitic wasp Encarsia diaspidicola were completed in quarantine and an environmental assessment was prepared; a permit request was submitted to the Hawaii Department of Agriculture for release of the wasp as a biological control agent against white peach scale in papaya. Research was conducted demonstrating that ‘Sharwil’ avocado is a poor host for fruit flies, but hard mature green fruit may rarely be infested by oriental fruit fly and therefore a systems approach is required to export rather than a non-host protocol. The time of harvest within a production season impacted ‘Sharwil’ avocado quality, but not infestability. Late season fruit had higher dry matter and oil contents, and had a shorter shelf life than early and mid-season fruit. Research supports the use of 29% dry matter as a maturity index for marketing high-value ‘Sharwil’ fruit. A provisional patent application was approved for formulations of essential oils designed to control waxy insects such as scales and mealybugs. The stability of formulations was increased when polysorbate 80 was used in place of potassium salts of fatty acids as the emulsifier for the essential oil. Banana moth is an occasional post-harvest pest of many fruits and vegetables. Banana moth males were trapped in papaya plantations to determine the relative attractiveness of different forms of octadecadienal. Jackson sticky traps baited with rubber septa containing 250 mg octadecadienal caught as many males as did traps holding virgin females. Trapping continues for purposes of monitoring seasonality of the pest and to determine whether mating disruption using the octadecadienal attractant is practical. In postharvest studies for longans and rambutans, optimum storage temperatures and packaging systems were established. Research showed that visual quality was maintained, overall disease incidence minimized, and shelf-life extended when fruit were packaged in microperforated bags or clamshell containers and stored at 10°C. Adoption of a better packaging system for specialty fruit will not require a change in field practices but will reduce postharvest quality problems which have been major constraints during export and marketing.


4.Accomplishments
1. Improved methods for evaluating non-host status of horticultural crops for fruit flies. The U.S. requires that quarantine treatments for high risk pests such as fruit flies achieve 99.9968% (probit.
9)mortality at the 95% confidence level by treating a minimum of 93,613 insects with no survivors. It was proposed by ARS scientists at Hilo, HI that the same level of testing should be required during non-host status testing with fruit flies of fruits and vegetables so that its equivalency with postharvest treatments could be demonstrated. Sample size would be determined by the number of insects exposed to fruit or the number of fruit collected to inspect for insects. This recommendation was included in a new North America Plant Protection Organization (NAPPO) Regional Standard for Phytosanitary Measures providing guidelines for determination of host status of a commodity to fruit flies (RSPM No. 30). Incorporating sample size and confidence levels into host status testing protocols along with efficacy will lead to greater consistency by regulatory decision-makers in interpreting results and, therefore, more technically sound decisions on host status.

2. Macadamia nut phytochemicals identified. Off-flavor development (oxidation and rancidity) during storage reduces macadamia nut quality. The presence of phytochemicals in macadamia nuts may protect the kernels from oxidation during storage and marketing, thereby extending shelf-life. In addition, these compounds may contribute to human health. Phytochemical compounds (tocopherols, tocotrienols, and squalene) were measured by ARS scientists at Hilo, HI in different macadamia cultivars to establish whether these compounds enhance the oxidative stability of roasted kernels. Macadamia nuts were a significant source of dietary tocotrienols and squalene, and two cultivars were identified with superior oxidative stability, suggesting that the kernel quality of these cultivars is more stable during storage. Postharvest practices and processing technologies that enhance macadamia nut quality will allow the industry to take full advantage of Hawaii’s name recognition, sustain an established agricultural industry, and expand exports.


5.Significant Activities that Support Special Target Populations
Mentor for Asian-Hawaiian student conducting research on antioxidant activity in quarantine- treated bananas.

Mentor for Asian-American high school student interested in forensic entomology.


Review Publications
Hollingsworth, R.G., Chastagner, G.A., Reimer, N.J., Oishi, D.E., Landolt, P.J., Paull, R.E. 2009. Use of shaking treatments and pre-harvest sprays of pyrethroid insecticides to reduce risk of yellowjackets and other insects on Christmas trees imported into Hawaii. Journal of Economic Entomology., Volume 102. pp. 69-78.

Wall, M.M., Khan, S. 2008. Postharvest quality of dragon fruit (Hylocereus spp.) after x-ray irradiation quarantine treatment. HortScience. 43(7):2115-2119.

Prado, S., Golden, M., Follett, P.A., Daughtery, M., Alameida, R. 2009. Demography of gut symbiotic and aposymbiotic Nezara viridula (L.) (Hemiptera: Pentatomidae). Environmental Entomology. 38: 103-109.

Last Modified: 10/1/2014
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