Phytosanitary Irradiation Treatments and Equipment

Goals / Objectives
1) Develop a quarantine irradiation treatment for Western flower thrips. 2) Examine the effects of modified atmosphere packaging on radiation tolerance in spotted wing drosophila and other quarantine pests. 3) Test and demonstrate a cabinet x-ray tube irradiator.

Project Methods
1) Western flower thrips, Frankliniella occidentalis, is an actionable pest on multiple crops exported from California to Australia and New Zealand, and a potential cause of pre-clearance shipment rejection. Studies of thrips response to irradiation are limited. We currently have western flower thrips in culture and have begun dose response tests with adult thrips to identify a sterilizing dose. 2) Modified atmosphere packaging (MAP) producing a low oxygen environment is used to prolong the shelf-life of fresh produce. Insects are known to exhibit higher tolerance to radiation in low oxygen environments. APHIS has placed restrictions on the use of MAP bags until research confirms that MAP does not compromise approved irradiation treatments. Recent studies show that radiation tolerance in melon fly is increased in MAP at certain doses, but that the 150 Gy treatment is not compromised. Studies are needed with other pests such as spotted wing drosophila and lepidopteran pests. 3) A cabinet x-ray tube irradiator is an in-line or packing house scale machine that would give growers control over phytosanitary treatment for export markets. This technology is a viable replacement for postharvest fumigation with methyl bromide. A machine was built with TASC funding and will be demonstrated to the sweet cherry and blueberry industries.