Project : USDA ARS

ARS Home » Pacific West Area » Hilo, Hawaii » Daniel K. Inouye U.S. Pacific Basin Agricultural Research Center » Tropical Crop and Commodity Protection Research » Research » Research Project #438421

Research Project: Postharvest Protection of Tropical Commodities for Improved Market Access and Quarantine Security

Location: Tropical Crop and Commodity Protection Research

2024 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 three broad objectives over the next 5 years: Objective 1: Develop new or improved postharvest treatments or technologies for fresh tropical commodities that mitigate risks associated with quarantine pests and improve quality and shelf-life. • Sub-objective 1A. Develop quarantine irradiation treatments for western flower thrips, tropical nut borer, and the semi-slug Parmarion martensi. • Sub-objective 1B. Evaluate ethyl formate fumigation for thrips control in ornamentals. • Sub-objective 1C. Determine the quality and shelf life of fresh commodities subjected to quarantine irradiation treatment. Objective 2: Develop new preharvest methods for the monitoring and control of phytosanitary and quarantine pests and commodity quality improvement. • Sub-objective 2A. Develop oviposition deterrents for behavioral control of oriental fruit fly and spotted wing drosophila. • Sub-objective 2B. Identify trail pheromone components of little fire ant for improved management in Hawaii. • Sub-objective 2C. Determine preharvest factors that increase aflatoxin prevalence in macadamia nuts. Objective 3: Develop risk management systems and systems approaches to control tropical plant pests and decrease the intensity or need for commodity treatments. • Sub-objective 3A. Evaluate predator breeding stations for augmentative biological control of coffee berry borer in coffee. • Sub-objective 3B. Conduct classical biological control of coffee berry borer using the adult parasitoid Phymasticus coffea. • Sub-objective 3C. Develop a multi-component system for determining chemical and sensory quality associated with coffee berry borer (CBB) damaged coffee and other coffee defects.

Approach
Obj 1A: Quarantine irradiation treatments for western flower thrips, tropical nut borer, and the slug Parnarion martensi will be developed. Dose response data will be generated for mortality, fecundity and fertility. Irradiation treatments will be submitted to USDA APHIS and the IPPC for approval. 1B: Ethyl formate fumigation for postharvest thrips control in ornamentals will be developed, including orchids. Efficacy trials will be conducted with nymph and adult stages using fumigation across concentrations and times. Preliminary data show thrips can be controlled at very low ethyl formate concentrations without loss of orchid quality. 1C: The quality & shelf life of fresh commodities subjected to quarantine irradiation treatment will be determined, particularly for breadfruit. Fresh breadfruit will be irradiated and evaluated for physical, chemical & sensory attributes. If quality is negatively impacted at phytosanitary doses, then combination treatments with hot water or 1-MCP will be tested. Obj 2A: Oviposition deterrents for behavioral control of oriental fruit fly and spotted wing drosophila will be developed. Chemical odors will be extracted from fruits and fungi and screened for attraction or antagonism to fruit flies using field cage tests or GC-EAD & GC-MS analysis. Oviposition deterrents might reduce insecticide spraying. 2B: Trail pheromone components of little fire ant will be identified. Potential candidates will be extracted from venom sac/Dufour’s glands of LFA workers and trails created on epiphytic moss. Bioactivity will be determined via behavioral, chemical and electrophysiological techniques. Pheromones with toxic baits could improve discovery, worker recruitment, and delivery to nests workers. 2C: Preharvest factors increasing aflatoxin in macadamia nuts will be determined. Samples from fields and processor will be evaluated for insect damage & aflatoxins. A prototype in-line fluorescence detector for contaminated nuts will be developed. Aflatoxin detection in immature or insect-damaged nuts can allow mitigation via preharvest insect control, timely harvests, & postharvest sorting. Obj 3A: Predator breeding stations will be evaluated for augmentative biological control of coffee berry borer (CBB) in coffee. Sleeve cages and artificial berries will be used to quantify predation rates in flat bark beetle predators of CBB. Breeding stations will be evaluated for their ability to multiply & augment predators. Increased predators in coffee farms should result in lower CBB populations. 3B: Classical biological control of CBB using the parasitoid Phymasticus coffea will be conducted. P. coffea will be imported from Colombia & tested in quarantine against native and exotic scolytine prey to determine host range. If P. coffea shows no significant nontarget effects, release permits will be obtained. 3C: A system to determine chemical & sensory quality of CBB-damaged coffee will be developed. Methods for volatiles analysis will be developed to distinguish damaged from undamaged beans. If volatile and sensory analyses are effective in differentiating CBB damaged coffee the methodology will be applied to detect other coffee defects.

Progress Report
This research project develops pre-harvest 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 and value-added tropical crops, while protecting U.S. agriculture from pest incursions. This is the fourth-year report for the project 2040-43000-018-000D “Postharvest Protection of Tropical Commodities to Improve Market Access and Quarantine Security”. In support of Sub-objective 1A, ARS researchers in Hilo, Hawaii, developed phytosanitary irradiation treatments to support the export of Hawaii-grown fruits and vegetables to the continental United States. Irradiation treatment at 150 Gy and 400 Gy, the generic doses commonly used for Hawaii produce and for fruit internationally, prevented any reproduction in the semi-slug Parmarion martensi which can infest exported sweet potato tropical fruits. This suggests that irradiation treatments aimed at disinfestation of quarantine insect pests will also control hitchhiking slugs. The 150 Gy dose also deactivated a zoonotic nematode, Angiostrongylus cantonensis, that can infect P. martensi, thus reducing health risks and preventing the spread of the nematode. The western flower thrips, Frankliniella occidentalis, is a major pest of horticultural crops, causing direct damage and transmitting plant diseases, and is a quarantine pest of concern in many countries where it does not occur. Preliminary studies showed that an irradiation dose of 250 Gy could prevent reproduction and thus irradiation is a phytosanitary treatment option. Large-scale tests with F. occidentalis are underway to confirm this dose with high confidence so that it can be accepted by the IPPC for use internationally. Under Sub-objective 1B, ARS researchers continued to develop ethyl formate fumigation as a postharvest treatment to reduce shipment rejections of ornamental crop exports from Hawaii to the continental United States due to insects. Thrips cause most of the rejections in exported cut orchid flowers. Dose response tests revealed that one hour ethyl formate fumigation of 7.42 gh/m3 at 23 degrees C was effective at controlling western flower thrips and melon thrips. Ethyl formate fumigation had no noticeable effect on flower color and shelf life. Scale-up confirmatory fumigation trials are on-going using 1 m3 fumigation chambers. For Sub-objective 1C, Ma’afala breadfruit were coated with carnuba wax to extend shelf-life following X-ray radiation as a quarantine treatment. Radiation had no effect on fruit firmness, weight loss or internal color when breadfruits were treated with doses ranging from 200 to 800 Gy. However, coated and radiated fruit retained green skin color and firmness following treatment and storage at 13 degrees C for 10 days, when compared to unwaxed irradiated fruit. This indicated that softening and browning of radiated breadfruit can be mitigated with carnuba wax treatment. In support of Sub-objective 2A, ARS researchers identified oviposition deterrents for spotted wing drosophila, oriental fruit fly, and melon fly (a regular U.S. patent application serial no. 18/477,665 has been filed under a CRADA). When used as a push component in a push-pull management approach for spotted wing drosophila, spraying the oviposition deterrent on raspberries resulted in significant reduction in spotted wing drosophila oviposition under very high spotted wing drosophila pressure in the field. Progress on Sub-objective 2B, continued on research to identify the chemical components of the little fire ant (LFA) trail pheromone. LFA is a nuisance pest in many agricultural crops in Hawaii that can inflict a painful sting. Adding trail pheromone to little fire ant baits may help recruitment of workers to toxic baits and improve the efficacy of the baits. Chemicals in the Dufour’s gland of the workers of little fire ants were extracted and behaviorally tested for elicitation of trailing behavior. In laboratory bioassays, chemicals in the Dufour’s gland elicited trailing behavior from the workers of little fire ant. Studies are on-going to determine key trail pheromone component. ARS researchers have also started to investigate faster acting insecticides to improve LFA bait as the current commercial bait (developed to target red imported fire ant) takes too long to kill LFA workers (greater than 25 days) within the nests. In support of Sub-objective 2C, field sampling of macadamia nuts and laboratory analyses for aflatoxins (AF) indicated that insect damage was positively correlated with higher levels of AF in commercial orchards. ARS researchers conducted a field study to determine whether tropical nut borer (TNB) damage, specifically, was correlated with aflatoxin incidence in macadamia orchards, but no clear relationship was evident, possibly due to unsuitable (dry) environmental conditions for Aspergillus species to develop and produce AF at the time of the experiment. For Sub-objective 3A, ARS researchers developed a predator breeding station consisting of a screened and sheltered enclosure containing food (cracked corn and cornmeal) and a membrane lure with attractants (quadrilure and fungal volatile blend) to augment predator numbers in coffee and macadamia fields. In the laboratory, stocking a breeding station with 100 C. quadricollis resulted in production about 10,000 adults per station over a four-month period at 25 degrees C, demonstrating the station’s potential for multiplying predators in the field. The predator breeding station is being used to augment biological control of the coffee berry borer on several large coffee farms and is being explored similarly for control of tropical nut borer in macadamia nut. In support of Sub-objective 3B, after host specificity testing, environmental and cultural impact assessments were submitted to regulatory authorities for approval for the release of Phymasticus coffea, a parasitoid of the adult coffee berry borer (CBB). P. coffea, originally from Africa, has been introduced against CBB in many coffee-producing countries. The request for field release of P. coffea in Hawaii was approved and permits were received. A requirement upon import of the parasitoid is to rear it for two generations under quarantine containment conditions to ensure there are no hyperparasitoids or other contaminants. The first field release in coffee fields is anticipated for early 2025. Supporting Sub-objective 3C, investigations into the potential impact of CBB infestations on coffee volatiles and cupping quality are ongoing. A sensory panel has been trained to evaluate specialty coffee flavor and aroma, and to identify and differentiate off-flavors and aromas of multiple coffee defects in roasted samples, including CBB damage. A portable electronic nose (e-nose) was not able to differentiate differences in volatile abundance for CBB infested beans but was useful for detecting moldy green coffee beans. In other research, a feasibility study was carried out to evaluate using near-infrared (NIR) spectroscopy to discriminate gamma irradiated vs. non-irradiated Medfly so that SIT sterile release flies could be separated from wild flies in traps in the field. We have collected and analyzed NIR spectra of over one thousand navel orangeworm (NOW) moths reared on four different tree nut diets to develop an algorithm to classify moths based on which orchards they come from. A first pass classifier has been built to identify tropical nut borer (TNB) and coffee berry borer (CBB) from other beetles in a trap using a hyperspectral imaging system and machine learning/AI techniques. Turmeric and ginger have various health benefits, including anticancer, antioxidative, and anti-inflammatory activities. However, their taste is not pleasant due to the presence of bitter compounds. Pineapple juice can mask bitterness and other less pleasant flavor qualities. ARS researchers conducted research to evaluate formulations for a functional beverage that utilizes the flavor masking effect of pineapple juice to deliver the potential health benefits of turmeric and ginger. The results showed that 80% pineapple+10% turmeric+10% ginger low pulp juice could be developed as a healthy beverage, which will benefit the local farmers and distributors of these commodities on Hawaii's Big Island. Macadamia production in Hawaii is threatened by key pests resulting in reduced nut yield and quality, and tree health. Using lure-based traps developed in-house, ARS scientists initiated studies to track the season-long activity with tropical nut borer (TNB) and Cryptophlebia moths across the major growing areas of Hawaii Island, which will aid in the precise timing and integration of pest management activities. A combination of verbenone and methyl salicylate was shown to be an effective repellent against TNB, and preliminary results from mating disruption (MD) experiments show substantially lower moth captures in MD block than in control blocks.

Accomplishments
1. Export procedures for Persian limes from Hawaii. Citrus spp. grown in Hawaii cannot be exported to the continental United States without a quarantine treatment or other mitigation measures to control possible infestations by Oriental fruit fly and Mediterranean fruit fly. A farm on the island of Maui, is harvesting 4,000 ha of Persian limes and will soon exceed local markets for fruit, therefore, an export option was needed. ARS scientists in Hilo, Hawaii, showed that Persian lime is a conditional non-host for both fruit flies. A systems approach was developed based on non-host status and various pre- and postharvest safeguards so that Persian limes can be safely exported from Hawai’i to the continental United States.

2. Quarantine Treatment for Fresh Persian Limes. Disinfestation of fresh commodities with X-ray radiation is an effective and accepted quarantine treatment for export markets. ARS scientists in Hilo, Hawaii, determined the quality of Persian limes following coating with carnauba wax and ionizing radiation at doses suitable for disinfestation of quarantine pests. Wax coating combined with radiation treatment of limes at doses between 150 and 450 Gy ensured marketable visual quality and chemical composition while providing quarantine security for lime exports.

U.S. DEPARTMENT OF AGRICULTURE

Tropical Crop and Commodity Protection Research: Hilo, HI