EVALUATION OF COLD TREATMENT AGAINST MEDITERRANEAN FRUIT FLY IN ´TAROCCO´ ORANGES

Abstract

Citrus intended for export to some overseas markets requires post-harvest treatment to eliminate the presence of insect pests that are of quarantine significance. Several importing countries allow fresh citrus from competing regions if it has undergone cold treatment. Cold treatment involves storage of fruits at low temperature for specified periods to ensure their freedom from insects. This paper addresses the effectiveness of cold treatment against Medfly (Ceratitis capitata Wiedemann) infestation in 'Tarocco' oranges. In large scale disinfestations tests a static trial with simulation of transport was simultaneously carried out using a set of three different full equipped van containers with bottom air delivery system under a 14 day 1.5°C cold treatment schedule. The containers were loaded with cartons of 'Tarocco' oranges from a grove located in a typical blood orange production area. Infested fruits, containing the most tolerant Medfly stage (third instar), were packaged and stuffed inside containers, randomly distributed on three different levels and among boxes containing non-infested fruits. At the end of cold treatment all infested fruits were removed and dissected to determine the number of survivors and dead larvae, then the temperature was set at 15°C to simulate shelf-life. After 1 week shelf-life, fruits were inspected for visible blemishes and decay. In order to evaluate the effect of cold treatment on the fruit quality, initially (just before loading into the container) and after cold treatment plus 1 week shelf-life, physicochemical and sensory parameters were determined. Experiments provided 100% larval mortality. Very low incidence of fruits with light chilling injury was found. Cold-treated 'Tarocco' oranges had good appearance, no substantial quality differences and did not exhibit excessive level of decay.