The relationship between the degree of infestation with Bactrocera oleae Rossi (Diptera: Tephritidae) and the volatiles released by the olive canopy

Abstract

The olive fruit fly, Bactrocera oleae (Rossi), is the most economically important pest of the olive tree; the fly prefers some cultivars over others, although the reason for this is still unclear. Current research results indicate that volatile compounds of the olive tree have a greater influence on the fly's attraction to a host plant than the physical parameters of the olive fruit. Therefore, the aim of the study was to investigate the relationship between the degree of the olive fruit fly infestation and the volatiles released by the olive leaves and fruits of three cultivars with similar physical fruit parameters, grown in the same olive grove. Lastovka, Frantoio and Leccino cultivars were studied, HS-SPME/GC–MS was performed to determine the profile of volatiles in leaves and fruits and to investigate the relationship between volatiles and the olive fruit fly infestation. Frantoio was the olive cultivar with the highest infestation by the olive fruit fly (39.66 %), followed by Leccino (24 %) and Lastovka (5 %). Among total number of volatiles identified in the study (55), more were detected in the fruits (37) than in the leaves (26). Saturated hydrocarbons and terpenes were the most abundant volatile groups in the fruits, while terpenes were found the most abundant in the leaves. The amounts of (E)-4,8-dimethylnona-1,3,7-triene and heneicosane were highest in the olive fruits of all cultivars tested. Heneicosane and eicosane were mainly released from ripe fruits and strongly correlated with the degree of infestation with the olive fruit fly. In addition, henicosane was the most abundant volatile compound in ripe fruits, along with 2,6-di-tert-butyl-4-methyl-phenol. Therefore, the results of the study suggest that fruit-derived volatiles have the greatest impact on the attraction of the olive fruit fly. The use of plant volatiles as attractants could be an effective tool for the sustainable control of olive trees to reduce the damage caused by the olive fruit fly while avoiding negative impacts on the environment and biodiversity.