The role of peach volatile compounds in relation to the impact of the Mediterranean fruit fly (medfly) Ceratitis capitata

The Mediterranean fruit fly (medfly) Ceratitis capitata is one of the most destructive agricultural pests nowadays causing enormous economic losses in fruit crops of many regions worldwide. Understanding the interaction mechanism fruit-insect is crucial for developing control strategies for such biological pests (Pitts, R. J. and Zwiebel, L. J., 2001). In this study, the relation between the fruits’ tolerance level of different peach cultivars toward the medfly and the volatile composition of ripe fruits of each cultivar has been investigated. Volatile compounds were analyzed by SPME-GC-MS in three cultivars highly attacked by the medfly (Fair time, Flaminia, Sicilia piatta), and in two cultivars little attacked (Percoca romagnola and Doctor Davis). From the factor and multivariate analysis on the main classes of compounds, a different volatile profile has been found for the different cultivars, with the most tolerant cultivar (Percoca romagnola) being clearly different from impacted cultivars. The main differences concerned the composition and relative abundance of esters. The most tolerant cultivars, above all Percoca romagnola, contained higher amounts of hexenyl, hexyl, isoamyl, butyl and isobutyl esters and a lower relative content of methyl esters, some of which are known to act as specific pheromones of the medfly (Warthen, J.D. et al., 1997; Wicker-Tomas, C., 2007). Doctor Davis contained lower levels of aliphatic hydrocarbons. These results let hypothesize a role of some volatile compounds in the interaction fruit-insect and in the selection mechanism of the host.