Combined postharvest X-ray and cold quarantine treatments against the Mediterranean fruit fly in "Clemenules" mandarins

L Palou,M Alonso,J.A Jacas Miret,M.A Del Rio,A Marcilla

doi:10.5424/sjar/2007054-278

Abstract

In the present work, survival of the Mediterranean fruit fly Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) on artificially infested "Clemenules" clementine mandarins (Citrus reticulata Blanco) was assessed on fruit subjected to integrated quarantine treatments consisting of irradiation with X-rays at doses of 0 (control), 30, 54, and 164 Gy followed by exposure to 1 deg C for 0 (control), 3, 6, 9, or 12 days. Additionally, physico-chemical (rind color, firmness, and physiological disorders, soluble solids concentration, titratable acidity, maturity index, juice yield, and ethanol and acetaldehyde content) and sensory (sweetness, acidity, sensory maturity index, off-flavors, and mandarin-like flavor) fruit quality of "Clemenules" clementines were assessed on X-irradiated fruit exposed to 1 deg C for 0 (control), 6, or 12 days. Complete insect mortality with no negative effects on fruit quality after 7 days at 20 deg C of shelf life was obtained on clementines firstly X-irradiated at 30 Gy and subsequently exposed to 1 deg C for 2 days. This combination of treatments considerably reduced quarantine time if compared to standard cold quarantine treatments (1.1-2.2 deg C for 14-18 days) and therefore showed promise as a potential commercial treatment for Spanish citrus exports.

Highlights

Worldwide plantings and consumption of clementine mandarins have been steadily increasing during the last years
These periods of cold quarantine were established after a re-evaluation of the scientific basis for previous regulatory treatment schedules that was conducted as a consequence of interceptions, in recent years, of live C. capitata larvae in fruit that had been cold-treated during transit (USDA, 2002a, 2004)
When cold quarantine was applied to non-irradiated infested mandarins, the longest period of 12 days at 1°C was needed to achieve complete mortality of C. capitata

Summary

Introduction

Worldwide plantings and consumption of clementine mandarins have been steadily increasing during the last years. Citrus exports from Spain to C. capitata-free countries are subjected to a mandatory cold-based quarantine treatment. In the case of the USA, the Department of Agriculture established a minimum exposure during overseas transit of 14-18 days at 1.1-2.2°C (USDA, 2002b) These periods of cold quarantine were established after a re-evaluation of the scientific basis for previous regulatory treatment schedules that was conducted as a consequence of interceptions, in recent years, of live C. capitata larvae in fruit that had been cold-treated during transit (USDA, 2002a, 2004). Irradiation treatments are known to be effective against fruit flies and other pests of quarantine importance (Burditt, 1994; Hallman, 1999) and they could be one of such viable alternatives for Spanish citrus exports

Methods

Results

Conclusion