DEVELOPMENT OF IRRADIATION TREATMENTS FOR HIGH IMPACT SPECIES
Tropical Crop and Commodity Protection Research
2012 Annual Report
1a.Objectives (from AD-416):
The primary objective of this project is to assess the effects of ionizing radiation on invasive species including light brown apple moth and spotted winged drosophila.
1b.Approach (from AD-416):
The artificial diet developed for pink bollworm will be used to rear light brown apple moths, and test insects will be treated in diet or in apples. Spotted wind drosophila will be reared on artificial diet or in blueberries. The goal is to find a dose that prevents reproduction, either by preventing development to the adult stage or sterilizing the adults or their progeny. Dose-response tests with all pest life stages will consist of five to eight doses at 30 to 50 Gy increments within a range from 60 to 250 Gy. In each test a control group will not be irradiated. Irradiation treatment will be conducted at a commercial x-ray facility. After irradiation, data will be taken on pupation, adult emergence and/or female fertility, and development of all individuals will be followed until death. Once doses that cause sterility or prevent adult emergence are identified for the most tolerant stage of each species, large-scale confirmatory tests will be conducted using naturally or artificially infested plant material.
The goal of this agreement is to assess the effects of ionizing radiation on invasive species including light brown apple moth and spotted winged drosophila which will contribute directly to objective 1 of the in-house project.
Postharvest irradiation can be used to control quarantine pests in traded commodities. In 2006, USDA APHIS approved first-ever generic radiation treatments of 150 Gy for tephritid fruit flies and 400 Gy for other insects. Generic treatments make irradiation the perfect technology for new invasive pests as treatments are immediately available without further research. Light brown apple moth, Epiphyas postvittana (LBAM) and spotted wing drosophila, drosophila suzukii (SWD) are recent invasive pests introduced to California with the potential to spread widely in North America. A major concern with LBAM and SWD is trade restrictions on fruits and vegetables imposed by importing countries, such as Canada and Mexico. The LBAM fifth instar is the most radiotolerant stage in fruit and a dose of 150 Gy was shown to provide quarantine control. The SWD late pupa is the most tolerant stage in fruit and dose-response studies suggest a dose of 60 Gy will sterilize the adult and provide quarantine control. Large-scale studies irradiating SWD on sweet cherries at 60 Gy are underway.