Postharvest heat and cold treatment to control Ceratitis capitata on cactus pear fruit

In order to work out a quarantine treatment for cactus pear fruit a factorial experimental plan was carried combining postharvest water dips at 20, 50, 54, 58 and 60 degrees C and storage at 1 degrees C for 3, 6 and 10 days. Cactus pear fruit cv 'Rossa' were artificially infested with Med. fly eggs (at least 20 eggs per fruit) then left in the lab at 25 degrees C for 4 days. Treatments took place by dipping the fruit at each water temperature for 2 mm. At each established time fruit was picked and checked for vital larvae and degree of chilling injury (CI). Probit 9 requirements were achieved in all cases when fruit was cold-stored for 10 days. When fruit was kept for 6 days the quarantine requirement was achieved only by dipping the fruit at 58 and 60 degrees C while none dip treatment was effective if fruit was stored for 3 days at 1 degrees C. All Fruit stored for 10 days at 1 degrees C showed severe CI symptoms and when kept for 6 days the same degree of CI was found on fruit dipped in water at 20, 58 and 60 degrees C. No CI was observed after 3 days at 1 degrees C. In conclusion only when fruit was dipped at 50-54 degrees C and stored for 10 days at 1 degrees C the probit 9 condition was attained with acceptable CI symptoms.