Isolation and identification of volatile compounds from a protein-based food lure: electrophysiological and behavioral responses of Bactrocera oleae adults

Abstract

The olive fly, Bactrocera oleae (Rossi) (Diptera: Tephritidae), is the major insect pest for olive production in the Mediterranean basin and worldwide. Monitoring of its populations is vital for efficient management to avoid yield losses. Olive fly adults are attracted to protein-based food lures. Various protein-based lures are used either for monitoring olive fly populations or for pest management in combination with insecticides. We used two techniques, i.e., dynamic headspace (DHS) and solid-phase microextraction, (SPME) for headspace collection of volatile organic compounds (VOCs) emitted from a commercially available protein-based food lure to identify specific VOCs that attract the olive flies. The collected VOCs were identified with GC–MS and electroantennographically tested with GC–EAD. Both sampling methods isolated a substantial number of VOCs but certain compounds were detected by only one of the two methods. In SPME, more alkyl-substituted pyrazines were detected rather than in DHS. VOCs from various chemical classes provoked electroantennographic responses. Μature mated females gave more responses compared to virgin ones. Both age groups of B. oleae female adults showed electrophysiological responses to 2,5-dimethyl-pyrazine which had lower abundance than the major compound 2,3,5-trimethyl pyrazine. Selected compounds were tested in field trials for attraction of olive fly adults. The highest number of olive fly adults was caught with sticky traps baited with the terpene nonanal. The importance of the collection method in identifying VOCs that might contribute to better monitoring and management of olive fly populations in the field is discussed.