Location: Tropical Crop and Commodity Protection Research
2018 Annual Report
Objectives
The long-term goals of our research program are to develop and protect U.S. export markets for fresh tropical commodities. An emphasis is placed 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 increase product value while safeguarding the agriculture of other states. Our research will address four broad objectives over the next 5 years:
Objective 1: Develop new or improved postharvest treatments or technologies for fresh tropical commodities to ensure security against quarantine pests, including new irradiation treatments for western flower thrips, and various ants on fresh fruits.
Sub-objective 1A. Develop quarantine irradiation treatments for western flower thrips, coffee berry borer, rough sweetpotato weevil, and red imported fire ant.
Sub-objective 1B. Develop a quarantine cold treatment for melon fly in citrus.
Sub-objective 1C. Determine the effectiveness of hypobaric treatments against surface pests.
Objective 2: Develop new or improved postharvest treatments or systems (such as hypobaric storage and modified atmospheres) to improve quality and extend shelf life of tropical horticultural crops subjected to quarantine treatment.
Sub-objective 2A. Determine hypobaric storage conditions that retain quality and extend storage life of fresh tropical fruit.
Sub-objective 2B. Develop combination treatments of modified atmosphere packaging and irradiation to retain quality of exported fresh papaya.
Objective 3: Develop or improve preharvest methods for surveillance, detection, and control of invasive tropical plant pests of quarantine significance, such as coffee berry borer.
Sub-objective 3A. Study the ecology of Cathartus quadricollis and other predatory flat bark beetles and explore ways to increase their role in suppressing coffee berry borer populations in coffee.
Objective 4: Develop multiple-component systems approaches to decrease the severity of or need for commodity treatments.
Sub-objective 4A. Quantify systems approaches for quarantine security of melon fly.
Approach
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 treatment will be developed for rough sweetpotato weevil, in sweet potato, western flower thrips, red imported fire ant, and coffee berry borer. Optimum hypobaric treatment parameters for maritime shipment of tropical fruits to preserve quality and extend shelf life will be determined. We will establish the tolerance of tropical fruits to any new or modified quarantine treatments.To expand markets for high-value tropical specialty fruit, we will develop postharvest disease and packaging strategies to extend shelf life. Integrated pest management strategies for coffee berry borer will focus on understanding the population dynamics and ecology of predatory flat bark beetles and improving rear-and-release systems. A cold treatment will be developed for melon fly in citrus. Also, a systems approach will be developed for melon fly control in covered tomatoes using mass trapping, protein baits and sanitation.
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.
In laboratory cage and open field tests, gold and green cultivars of kiwifruit were shown to be poor hosts for melon fly, Mediterranean fruit fly and oriental fruit fly, with limited natural infestation in these fruits. Infestation of Jazz apples by oriental fruit fly and melon fly was similarly poor, and growth and development on apples was slow.
Postharvest irradiation treatments may help kiwi and apple exporters overcome quarantine restrictions during fruit fly outbreaks. In fruit quality research, green and gold cultivars of kiwifruit showed good tolerance up to 600 gray (Gy), which is the highest dose that fruit might experience during a phytosanitary irradiation treatment. Sensory quality was slightly reduced at 800 Gy. For apples, the differential tolerance of five cultivars to potential x-ray disinfestation for codling moth showed that ‘Royal Gala’ was the most susceptible cultivar. Flesh browning increased after longer pretreatment storage times (10 weeks), and as dose increased above 500 Gy. Internal ethylene concentration decreased as the dosage increased for all storage times.
Modified atmosphere packaging (MAP) creates a low oxygen environment that may increase radiation tolerance in quarantine insect pests. A study with spotted wing drosophila infesting sweet cherries in several types of commercial MAP bags showed that the efficacy of the approved quarantine irradiation treatment will not be compromised by the low oxygen environment.
A thyme and oregano oil extract embedded in methyl cellulose or chitosan films was shown to provide control of rice weevil, and Aspergillus and Penicillium molds in packaged rice.
Predator breeding stations were developed to augment biological control of the coffee pest, coffee berry borer (CBB). Evaluation of station performance on coffee farms and in the laboratory showed that 1000s of predatory beetles are produced and dispersed from stations that started with 100 adults.
In coffee quality research related to CBB infestation, an automated head space, gas chromatography, mass spectroscopy method was developed for the study of volatiles in green coffee beans exhibiting various levels of visible damage by CBB. The relative concentrations of eight prominent volatiles were determined as potential markers for CBB damage. Volatile profiles of green coffee beans were differentiated from undamaged samples at three levels of damage.
Four cultivars of mango fruit were stored under hypobaric conditions, 2.7 Kilopascals (kPa) and 13 degrees Celsius (C), to confirm previous trials. Mango storage life was extended by 7-10 days under low pressures when compared to control fruit, 100 kPa, 13 degrees C.
Ethyl formate fumigation may help Hawaii ornamental crop growers overcome shipment rejections to the mainland and abroad due to quarantine restrictions. Ethyl formate fumigation was effective at killing various stages of western flower thrips and melon thrips that cause the most rejections of cut orchid flower exports from Hawaii.
Identification of the recruitment trail pheromone in little fire ant might help improve baits for this noxious pest. The epiphytic moss growing on branches of infested macadamia nut trees was identified as a source of pheromone components. In the field, little fire ant workers exhibited trail following behavior to chemicals laid on natural trails. In the laboratory, workers readily formed trails on the invisible line drawn with hexane extract of epiphytic moss which contained the natural trail of little fire ant.
Non-nutritive sugars were investigated as an alternative method for control of Hawaii’s fruit flies. Erythritol ingestion increased mortality of adult flies in a dose-dependent manner. Adult flies of different ages (0- and 7-day old) fed with 0.5 moles (M) sucrose + 2.0M erythritol solution invariably died within 6-10 days, while flies fed with 0.5M sucrose alone showed high survival over the 2-week experimental period.
Accomplishments
1. Modified atmosphere packaging (MAP) and insect radio-tolerance. MAP is used to prolong the shelf life of fresh produce. The use of MAP during phytosanitary irradiation is restricted by the USDA Animal and Plant Health Inspection Service (APHIS) and prohibited by the International Plant Protection Convention (IPPC) because the low oxygen environment it creates may increase the radiation tolerance of pest insects, reducing the effectiveness of phytosanitary irradiation treatments. ARS scientists in Hilo, Hawaii, showed that MAP did not reduce the efficacy of irradiation treatments against spotted wing drosophila in sweet cherries. Studies with melon fly and Mediterranean fruit fly in papayas and oriental fruit fly in mangos also showed that MAP did not reduce the efficacy of irradiation at approved doses. Restrictions of the use of MAP are a disincentive to the use of irradiation technology, particularly for highly perishable commodities like sweet cherries. A petition will be submitted to eliminate current regulatory restrictions so that this method may be used to prolong the shelf life and benefit producers and consumers.
2. Quarantine treatment for fresh kiwifruit cultivars. Disinfestation of fresh commodities with X-ray radiation is an effective and accepted quarantine treatment for export markets. ARS scientists in Hilo, Hawaii, collaborated with scientists at the New Zealand Institute of Plant and Food Research to determine the tolerance of green and gold kiwifruit varieties to ionizing radiation in a commercial facility. Both cultivars maintained quality following treatment at doses effective for controlling invasive fruit flies and other insect pests. The results will support adoption of x-ray quarantine treatment by the New Zealand kiwifruit industry to overcome quarantine barriers in the event of a fruit fly incursion.
3. Spotted wing drosophila (SWD) monitoring tools. Early detection of SWD is important for application of timely field control measures. For this purpose, it is especially important to detect SWD before they damage fruit, so growers can confidently delay insecticide spraying until traps capture SWD in the field. Commercial lures developed by ARS scientists in Hilo, Hawaii, and novel food baits were compared for their efficacy in the early detection of SWD. Commercially available lures and bread-dough fermenting bait were effective in detecting SWD prior to fruit damage in blueberry orchards. One of the commercial lures captured SWD at the same week that SWD start to damage fruit in raspberry orchards. This lure was cleaner, easier to service, more specific and longer lasting than bread-dough bait and thus was recommended as an early detection tool for SWD in the northeastern U.S.
4. Multi-choice bioassay for insect attractants. Effective lures and traps are key to early detection of quarantine pests. However, finding an effective lure for the field is often complicated by uncertain bioassay approaches, discrepancies between laboratory and field results, and lengthy behavioral testing. For spotted wing drosophila (SWD), the differences in the background odor in the laboratory and field may have caused the discrepancy in insect attraction to lures. ARS scientists in Hilo, Hawaii, developed a multiple-choice bioassay to rapidly screen for important attractant volatiles by subtracting background odor. Using this method, chemical attractants can be identified in two weeks of laboratory testing rather than two years of laboratory and field trapping experiments. This approach should be applicable to developing food-based attractants for other pest insects.
Review Publications
Wall, M.M., Miller, S., Siderhurst, M.S. 2018. Volatile changes in Hawaiian noni fruit, Morinda citrifolia L., during ripening and fermentation. Journal of the Science of Food and Agriculture. 98:3391-3399. https://doi.org/10.1002/jsfa.8850.
Dunn, D., Follett, P.A. 2017. The Sterile Insect Technique (SIT) – an introduction. Entomologia Experimentalis et Applicata. 164:151-154.
Srimartprom, M., Burikam, I., Limohpasmanee, W., Kongratarporn, T., Thannarin, T., Bunsiri, A., Follett, P.A. 2018. Low-dose irradiation with modified atmosphere packaging for mango against the Oriental Fruit Fly (Diptera: Tephritidae). Journal of Economic Entomology. 111(1):135-140.
Cha, D.H., Powell, T., Feder, J.L., Linn, C.E. 2018. Identification of a new blend of host fruit volatiles from red downy hawthorn, Crataegus mollis, attractive to Rhagoletis pomonella flies from the northeastern United States. Journal of Chemical Ecology. 44(7-8):671-680. https://doi.org/10.1007/s10886-018-0977-6.
Cha, D.H., Loeb, G.M., Landolt, P.J., Linn, C.E., Hesler, S.P. 2018. A multiple-choice bioassay approach for rapid screening of key attractants from complex mixtures of fermentation volatiles. Environmental Entomology. https://doi.org/10.1093/ee/nvy054.
Cha, D.H., Hesler, S.P., Wallingford, A.K., Zaman, F., Jentsch, P., Nyrop, J., Loeb, G.M. 2018. Comparison of commercial lures and food baits for early detection of fruit infestation risk by Drosophila suzukii. Journal of Pest Science. https://doi.org/10.1093/jee/tox369.
Elmquist, D.C., Landolt, P.J., Ream, L.J., Cha, D.H. 2017. Laboratory demonstrations of pheromone-mediated scent-marking, orientation, and mounting behavior in Polistes exclamans Vienick (Hymenoptera: Vespidae). Annals of the Entomological Society of America. 111(1):21-30.
Yee, W.L., Goughnour, R.B., Feder, J.L., Linn, C.E., Cha, D.H. 2017. Comparative responses of Rhagoletis zephyria and R. pomonella (Diptera: Tephritidae) to commercial and experimental sticky traps and odors in Washington State. Environmental Entomology. 46(6):1351-1358. https://doi.org/10.1093/ee/nvx130.
Wallingford, A.K., Cha, D.H., Linn, C.E., Wolfin, M.S., Loeb, G.M. 2017. Robust manipulations of pest insect behavior using repellents and practical application for integrated pest management. Environmental Entomology. 46(5):1041-1050. https://doi.org/10.1093/ee/nvx125.
Nadel, H., Follett, P.A., Parry, C.K., Mack, R. 2017. Postharvest irradiation treatment for quarantine control of the invasive Lobesia botrana (Lepidoptera: Tortricidae). Journal of Economic Entomology. 111(1):127-134.
Roberts, P., Follett, P.A. 2018. Food irradiation for phytosanitary and quarantine treatment. In: Ferreira, I., Antonio, A.L., Cabo Verde, S., editors. Food Irradiation Technologies: Concepts, Applications and Outcomes. Cambridge, UK: Royal Society of Chemistry. p. 169-182.
Cha, D.H., Hesler, S.P., Wallingford, A.K., Zaman, F., Jentsch, P., Nyrop, J., Loeb, G.M. 2018. Comparison of commercial lures and food baits for early detection of fruit infestation risk by Drosophila suzukii. Journal of Pest Science. https://doi.org/10.1093/jee/tox369.
