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. Formerly 5320-43000-015-00D (12/10).
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 to supply Hawaii and California with a quarantine treatment alternative if other countries or states impose restrictions on exported fresh produce. In avocado research, skin puncture resistance was a major factor determining the infestability of Sharwil avocado by oriental fruit fly, indicating that fruit firmness measurements may be a practical part of a systems approach for export. Low-chill blueberry cultivars showed a wide range of susceptibility to oriental fruit fly, and planting of resistant cultivars may help minimize damage and crop loss. Hypobaric treatment research using the Metabolic Stress Disinfection and Disinfestation (MSDD) system showed that fruit flies inside fruit are difficult to kill, but that surface pests can be controlled. Export approval for high-value mixed fruit boxes would diversify markets for tropical fruit growers. The quality and ripening of summer-harvested mixed-fruit combinations were compared to single fruit types after quarantine irradiation treatment. A banana, papaya, mango combination had similar quality to irradiated single commodity boxes. For longans, optimal temperature (10°C) and packaging systems (clamshells, modified atmosphere packaging, or microperforated bags) were identified to maintain fruit quality during export. However under fluctuating temperatures, typical during postharvest handling, clamshells were the best packaging system for longans. In biocontrol research, a petition to release the white peach scale parasitoid Encarsia diaspidicola was approved by the Hawaii Dept. Agric., and an environmental assessment was prepared by USDA-APHIS and published for public comment. For ornamental crops, a pest survey on orchids in Maui showed that the predominant species was a light colored variant of Western flower thrips similar to a pest-resistant variant also discovered on Hawaii island. A survey of flowering plants in Hawaii showed that a pioneer tree species, Macaranga tanarius, produced large numbers of anthocorid predators (thrips enemies) on its flowers, and was not infested with any pest species of thrips. Therefore, Macaranga may be acceptable as companion plants for orchids. Bioassays were done to identify factors affecting the efficacy and stability of essential oil emulsions designed to function as contact insecticides for waxy insects (mealybugs and scales). Emulsion size affected the ability of the mixtures to remove insect wax. Field research for coffee berry borer (CCB) control established the persistence and efficacy of spray applications of Beauveria bassiana. Initial results suggest that naturally occurring Beauveria is common in coffee fields and reduces insect pressure on the crop, and that sprays of a commercial Beauveria strain also are having an effect on CCB populations.
1. Availability of commercial Beauveria products for control of coffee berry borer. Beauveria basiana is an insect-killing fungus which is the most important natural enemy of the coffee berry borer. ARS scientists in Hilo, HI characterized the genetic diversity of locally occurring strains of B. bassiana. These research results and other information were used by regulators in public meetings to document the environmental safety of this generalist insect pathogen, leading to the introduction and use of commercial Beauveria products for control of this new, extremely damaging pest in Hawaii.
2. Low-chill blueberry susceptibility to fruit flies. Low chill blueberries grow in Hawaii but are susceptible to fruit flies. ARS scientists in Hilo, HI tested 15 cultivars of low-chill blueberries in the laboratory for their susceptibility to tephritid fruit flies. Cultivars varied widely in their susceptibility to oriental fruit fly and Mediterranean fruit fly infestation and certain cultivars were not preferred. This information will aid in development of pest management recommendations as planting of low-chill blueberry cultivars expands to areas with subtropical and tropical fruit flies. Planting of fruit fly resistant cultivars may result in lower infestation levels and less crop loss.
3. Postharvest practices for exporting longans. Peel browning and postharvest decay are major limitations to longan shelf-life and export to distant markets. ARS scientists in Hilo, HI determined optimal temperature and packaging systems to maintain longan 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, clamshell containers were the best package for preserving longan quality. Adoption of a new or improved packaging system for longans will expand exports and benefit the industry without requiring a change in field practices in order to reduce postharvest problems that have constrained export and marketing.
Galarza, L., Neumann, G., Follett, P.A. 2010. Response of white peach scale to metabolic stress disinfection and disinfestation (MSDD) treatment. Hawaiian Entomological Society Proceedings. 42:49-52.