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United States Department of Agriculture

Agricultural Research Service

Research Project: Pre and Postharvest Treatment of Tropical and Other Commodities for Quarantine Security, Quality Maintenance, and Value Enhancement

Location: Tropical Crop and Commodity Protection Research

2012 Annual Report

1a. Objectives (from AD-416):
The long term goals of our research program are to develop and protect U.S. export markets for fresh tropical commodities with emphasis on expanding and diversifying agriculture and agricultural exports in Hawaii and other states by providing environmentally sound, economically viable systems, treatments, or processes that control quarantine pests, ensure product quality and food safety, and increase product value while safeguarding the agriculture of other states. Our research will address three objectives over the next 5 years: (1) Develop new or improved postharvest treatments, including alternatives to methyl bromide, for tropical fruit, vegetable, and ornamental crop exports to ensure security against quarantine pests and to meet quarantine requirements of U.S. trading partners; (2) Develop new or improved postharvest treatments for tropical 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 tropical 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):
The approach is to develop quarantine treatments, such as low dose irradiation and hypobaric treatments, and other mitigation techniques for fresh tropical commodities and ornamental crops. Quarantine irradiation treatments will be developed for light brown apple moth, papaya mealybug, and green scale. Optimum hypobaric treatment parameters for controlling Caribbean fruit fly, Mediterranean fruit fly, oriental fruit fly, and melon fly will be determined. We will establish the tolerance of tropical fruit to any new or modified quarantine treatments, including the quality of diverse assortments of tropical fruit following irradiation treatment. To expand markets for high-value specialty fruit, we aim to develop postharvest disease control and packaging strategies to extend shelf-life. Also, preharvest practices that reduce the incidence of quarantine pests that limit exports will be investigated, such as non-chemical alternatives to control thrips on orchids, essential oil formulations for control of waxy insects on ornamental crops, and biological control of white peach scale on papayas.

3. Progress Report:
This research project develops preharvest and postharvest treatments or systems to control quarantine pests, while retaining the quality and shelf-life of tropical crops. The project supports the expansion and diversification of U.S. exports of fresh tropical crops, while protecting U.S. agriculture from pest incursions. An irradiation treatment (150 Gy) was developed for light brown apple moth eggs and larvae to supply Hawaii and California with a quarantine treatment alternative if other countries or states impose restrictions on exported fresh produce. Similar phytosanitary irradiation treatments are under development for spotted wing drosophila and European grapevine, two new invasive fruit pests. Irradiation is also an option for quarantine control of stored products pests such as the rice weevil. Radiation treatment at 120 Gy sterilized rice weevil and prevented further damage from feeding. Also, a radiation dose of 70 Gy prevented reproduction in queens of the little fire ant, an increasingly common hitchhiker pest on Hawaii produce. The quality of irradiated produce determines market acceptance. Export approval for high-value mixed fruit boxes would diversify markets for tropical fruit growers. The quality of bananas, papayas, mangos and lychees following radiation treatment was similar for single-fruit versus mixed-fruit combinations. However, the highest dose (800 Gy) tended to cause peel scald, especially on bananas. A second study was performed using irradiated mixtures of banana, papaya, dragon fruit and pineapples. In research on rambutans, optimal temperature (10°C) and packaging systems were identified to maintain fruit quality during export. Modified atmosphere packaging with Peakfresh® film provided the best quality under constant (10°C) or fluctuating temperatures typical during postharvest handling. For ornamental crops, a survey of thrips on orchids in Maui showed that the main species was a light colored variant of Western flower thrips similar to a pesticide-resistant variant spreading on Hawaii Island. We documented the efficacy of insecticides used to control this pest, and in separate trials, demonstrated a biological control approach. We used a common tree species, Macaranga tanarius, to introduce large numbers of anthocorid predators into a greenhouse. The predators controlled the high population of thrips within 3 weeks. In other biocontrol research, federal and state permits were received for the white peach scale parasitoid Encarsia diaspidicola, and field releases into papaya orchards are planned for the fall. For controlling mealybugs and scales, bioassays were used to optimize the efficacy and stability of essential oil emulsions as contact insecticides. We were able to lower the concentration of an expensive emulsifier ingredient without reducing efficacy or stability. For coffee berry borer (CBB) control, we showed that a low percentage of clove oil added to the alcohol in beetle traps dramatically increases CBB trap catch. Field research to determine effective concentrations of Beauveria bassiana for control of CBB is continuing, and differences in efficacy will be correlated with yield increases.

4. Accomplishments
1. Postharvest irradiation treatment controls light brown apple moth. The invasive light brown apple moth, Epiphyas postvittana, was recently established in California, and trade restrictions on host fruits and vegetables have been imposed by importing countries. Irradiation is a postharvest quarantine treatment option for exported commodities such as fruits and vegetables to prevent movement of viable light brown apple moth. ARS scientists in Hilo, HI, determined the effects of irradiation on egg, larval, and pupal development, and adult reproduction in light brown apple moth. The 5th instar was the most tolerant stage found in fruit. In large scale validation tests, a radiation dose of 150 Gy applied to 5th instars resulted in no adult emergence in more than 35,000 treated individuals, which meets the zero tolerance requirement for market access. This information will facilitate trade of commodities that are hosts of LBAM.

2. Cold treatment stops coffee berry borer. Green coffee is shipped around the world for custom blending and roasting and such shipments carry the risk of spreading coffee berry borer. ARS scientists in Hilo, HI, tested the freezing tolerance of coffee berry borer at three different temperatures. Counting all life stages, more than 15,000 insects were evaluated. A temperature of -15°C for 48 hours provided 100% control of all life stages. We used these data in a mathematical model to determine the length of freezing time required for various levels of quarantine security. Hawaii state regulators are using this information to implement a freezing treatment protocol which allows coffee growers in the infested area to ship green coffee to other islands without the need for methyl bromide fumigation.

3. Postharvest practices identified to maintain quality of exported rambutans. Peel browning and postharvest decay are major limitations to rambutan shelf-life and export to distant markets. ARS scientists in Hilo, HI, determined optimal temperature and packaging systems to maintain rambutan fruit quality during shipping and handling. The research showed that precise temperature control during all phases of postharvest handling is critical for quality assurance of this tropical fruit. However under fluctuating temperatures typical in the postharvest chain, modified atmosphere packaging with Peakfresh® film was the best package for preserving rambutan quality. Adoption of a new or improved packaging system for rambutans will expand exports and benefit the industry without requiring a change in field practices to reduce postharvest problems that have constrained export and marketing.

Review Publications
Follett, P.A., Phillips, T., Armstrong, J., Moy, J. 2011. Generic phytosanitary radiation treatment for tephritid fruit flies provides quarantine security for bactrocera latifrons. Journal of Economic Entomology. 104:1509-1513.

Ma, H., Pan, Z., Li, B., Atungulu, G.G., Olson, D.A., Wall, M.M., Mchugh, T.H. 2011. Properties of extruded expandable breadfruit products. Journal of Food Science and Technology. 46(1):326-334. DOI: 10.1016/j.lwt.2011.09.007.

Chang, C.L., Follett, P.A. 2012. Resveratrol modifies tephritid fruit fly response to nutritional and radiation stress. International Journal of Radiation Biology. 88(4):320-326.

Follett, P.A., Wall, M.M. 2011. Phytosanitary irradiation for export of fresh produce: commercial adoption in Hawaii and current issues. Journal of Radioanalytical and Nuclear Chemistry. 81(8):1064-1067.

Last Modified: 06/23/2017
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