COMPARATIVE EFFECTS OF IRRADIATION AND HEAT QUARANTINE TREATMENTS ON THE EXTERNAL APPEARANCE OF LYCHEE, LONGAN, ANS RAMBUTAN.

Authors: Follett, Peter

Submitted to: IAEA/FAO Final Research Coordination Meeting on Irradiation as a Phytosanitary Treatment for Food and Agricultural Comodities Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 8/15/2003
Publication Date: 11/20/2004
Citation: Follett, P.A. 2004. Comparative effects of irradiation and heat quarantine treatments on the external appearance of lychee, longan, ans rambutan.. IAEA/FAO Final Research Coordination Meeting on Irradiation as a Phytosanitary Treatment for Food and Agricultural Comodities Proceedings, Vienna, IAEA-Techdoc 1427.

Interpretive Summary: Abstract only.

Technical Abstract: Irradiation was explored as a method to prevent adult emergence in, or to sterilize, mango seed weevil. Mixed-age mango seed weevils in mangoes were irradiated with target doses of 50, 100, or 300 Gy and held for adult emergence. The 300 Gy treatment (dose range 180-310 Gy) did not prevent adult emergence. Emerging adults from the 100 and 300 Gy treatments were lethargic and short-lived, and laid no eggs indicating sterility. An irradiation quarantine treatment (300 Gy) to sterilize mango seed weevil in mangoes has been approved, and an irradiation treatment for control of mango seed weevil and fruit flies in mangoes has been proposed. Approval of this treatment will open U.S. mainland markets to mango exports from Hawaii. Studies were undertaken to determine whether irradiation treatment at 250 Gy, an accepted treatment for disinfestation of fruit flies in spindaceous fruits from Hawaii, would also disinfest fruit of two species of Cryptophlebia. Cryptophlebia illepida (Butler) was determined to be more tolerant of irradiation than Cryptophlebia ombrodelta (Lower), and so C. illepida was the focus for detailed tests. Using the criterion of success in developing to the adult stage, the pattern of tolerance to irradiation in C. illepida was generally eggs125 Gy emerged as adults and produced viable eggs, indicating sterility can be achieved at doses well below 250 Gy. In large scale tests, when 11,256 late instars were irradiated with a target dose of 250 Gy, 951 pupated (8.4%) and none eclosed as adults. Therefore, the irradiation quarantine treatment of a minimum absorbed dose of 250 Gy approved for Hawaii's fruits will effectively disinfest fruits of any Cryptophlebia in addition to fruit flies.