Effect of heat shock and quarantine cold treatment with a warm temperaturespike on survival of Mediterranean fruit fly eggs and fruit quality in Hawaii-grown 'Sharwil' avocado

The effects of a transient (warming) temperature spike on efficacy of an AP HIS approved quarantine cold treatment, T107 (a), against Mediterranean fru it fly, Ceratitis capitata, was tested on Hawaii grown 'Sharwil' avocados. Avocados infested with late stage eggs were subjected to a warming temperat ure spike (ca. 4.2 degreesC for 1 h) at 6-9 days into the treatment and sub sequently allowed to resume the treatment until conclusion (12 days at < 1. 1<degrees>C, 14 days at < 1.67<degrees>C or 16 days at < 2.2<degrees>C). In sertion of a ca. 4.2 degreesC temperature spike into the treatment at 6-9 d ays had no effect on the efficacy of the quarantine cold treatment when fru it were allowed to resume the treatment to completion. Infested fruit which did not receive a 'heat shock' treatment (recommended to improve fruit qua lity) and subjected to cold treatment for 6-16 days at either < 1.1, < 1.67 or ( 2.2 degreesC (fruit center temperature) had no survivors in the fruit by the 9th day of cold treatment. Infested avocados subjected to a 'heat s hock' treatment for 10-12 h at 38 degreesC prior to cold treatment las abov e) had no survivors in the fruit by the 8th day of cold treatment. Results of this study indicate that a transient (warm) temperature spike of ca. 4.2 degreesC of the type experienced during an in-transit cold treatment of Ha waii grown 'Sharwil' avocados will not compromise the efficacy of the treat ment. This study also reconfirmed that the T107 (a) cold treatment las stat ed in the APHIS treatment manual) is efficacious against Mediterranean frui t fly eggs in 'Sharwil' avocados, and that use of a 'heat shock' to prevent chilling injury during the cold treatment did not extend-survivorship of f ruit fly eggs. Studies on the effects of prolonged (18-28 day) cold storage on fruit quality indicated that avocados can be stored at quarantine cold temperature (pulp, 1.1-2.2 degreesC) for up to 24 days without significant loss of external and internal quality compared to fruit quality at 12-16 da ys storage. Also, shelf life, Gray Flesh discoloration (of internal tissue) , and disease were not affected by the prolonged storage duration. (C) Publ ished by Elsevier Science B.V.