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Irradiating Insect Pests

By: , Posted on: May 18, 2017

peter follett

Could you begin by introducing your main research aims and activities?

Along with my colleagues at the US Department of Agriculture Agricultural Research Service, I work to develop new or improved postharvest quarantine treatments so that Hawaiian farmers can safely export high-quality, fresh agricultural products to the US mainland and other countries. Due to its mild climate, diverse tropical and subtropical agricultural crops and habitats, reliance on imported fresh produce, and popularity as a travel destination, Hawaii has acquired a wide variety of invasive insect pests from around the Pacific Rim. Many of these pests, such as the Mediterranean fruit fly, are not established in mainland US, and therefore quarantine treatments are required by law to prevent their spread in host commodities (fruit, vegetable or ornamental crops) exported to the continental US or elsewhere. Postharvest treatment of fresh commodities with heat, cold, chemical fumigants or irradiation aims to kill any insect pests or hitchhikers and prevent their spread to new areas. It’s estimated that new invasive pests cost American farmers US $120 billion annually, and are a major threat to agriculture as well as urban and natural ecosystems.

In what ways does phytosanitary irradiation differ from other types of food irradiation?

Food may be irradiated for several reasons: to reduce food-borne pathogens such as Escherichia coli, Listeria and Salmonella; to inhibit sprouting in tuber and bulb crops such as potatoes, onions and garlic; to extend shelf life by deactivating spoilage organisms; and to control quarantine insect pests in fresh commodities or stored products to reduce contamination and losses. I mostly work in the latter area, developing postharvest, phytosanitary treatments to control insects in fresh and durable commodities. Irradiation is an alternative technology to fumigation, particularly to methyl bromide fumigation. This is the most common method of disinfesting commodities but has been shown to damage the stratospheric ozone layer.

How widespread is the current use of phytosanitary irradiation?

Hawaii has been a leader in the use of irradiation to export fresh fruits and vegetables, having conducted pilot studies in the 1990s and opened two commercial irradiators in 2000 and 2013. These are designed specifically to treat fresh agricultural products like fruit, vegetables, herbs and flowers. Currently, Hawaii is shipping 10 types of fresh fruit and vegetables to the US mainland using irradiation to control quarantine pests, and the state has approvals for 15 more. Interest from foreign countries in exporting irradiated fresh produce took off in 2006 after the approval of the first ever generic irradiation treatments. During the past eight years, India, Mexico, Pakistan, South Africa, Thailand and Vietnam have all established bilateral agreements with the US for the use of phytosanitary irradiation, and are exporting increasing volumes of fruit (13.6 million kg in 2014) using generic radiation treatments. Other parts of the world are following suit. Australia is exporting an increasing number of fruits and vegetables to New Zealand and Malaysia using irradiation quarantine treatment.

What are the negative effects, if any, of phytosanitary irradiation?
Technically speaking, there are no shortcomings. All insect pests can be controlled by irradiation, and most fresh horticultural commodities can tolerate irradiation treatment without injury at the low doses required to control insects. For this reason, irradiation is superior to other postharvest quarantine

treatment technologies. Furthermore, irradiation is probably the most thoroughly studied food processing technology, with hundreds of nutritional and toxicological studies during the past 60 years on a variety of foods. Numerous major health and science organisations have reviewed the literature and

endorsed, approved or supported the safety and benefits of food irradiation. Irradiation is approved in more than 60 countries around the world for a wide variety of food products.

What are your hopes for the future of phytosanitary irradiation?

For countries that have already approved use of phytosanitary irradiation, fresh produce exports should steadily increase. Consumers should see a wider variety of produce available in the marketplace as countries such as India, South Africa, Thailand, Mexico and Vietnam export increasing volumes of irradiated tropical fruits – including mango, rambutan, guava and dragon fruit – to major markets and gain market penetration. Other countries should come aboard soon given recent successes. The sky’s the limit!

About the book

Irradiation for Quality Improvement, Microbial Safety and Phytosanitation of Fresh Produce

Irradiation for Quality Improvement, Microbial Safety and Phytosanitation of Fresh Produce presents the last six and a half decades of scientific information on the topic. This book emphasizes proven advantages of ionizing irradiation over the commonly used postharvest treatments for improving postharvest life of fresh fruits and vegetables to enhance their microbial safety. This reference is intended for a wide range of scientists, researchers, and students in the fields of plant diseases and postharvest diseases of fruits and vegetables. It is a means for disease control to promote food safety and quality for the food industry and can be used in food safety and agriculture courses.

Visit to and use discount code STC317 at checkout and save up to 30% on your very own copy!

About the author

peter follettDr. Peter Follett is a Research Entomologist with the USDA Agricultural Research Service (ARS) in Hilo, Hawaii, where he coordinates research efforts to develop new or improved postharvest treatments to control quarantine pests that restrict the export of tropical fruits and vegetables. He has authored or co-authored 180 scientific publications and is recognized internationally as an expert in the areas of postharvest entomology and commodity quarantine treatment. His research on the radiobiology of more than three dozen insect pests was used to develop first-ever generic irradiation treatments, which are now used worldwide and have helped expand international trade in tropical fruits and vegetables. Dr. Follett received the Entomological Society of America (ESA) Distinguished Achievement Award in Horticultural Entomology, the USDA Secretary’s Group Honor Award for Excellence, and the Federal Laboratory Consortium (FLC) Award for Excellence in Technology Transfer for his accomplishments in phytosanitary irradiation research and commodity quarantine treatment development.

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