Submitted to: Journal of Entomology and Zoology Studies
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/23/2017
Publication Date: 5/19/2017
Citation: Niogret, J., Epsky, N.D., Gill, M.A., Espinoza, H.R., Kendra, P.E., Heath, R. 2017. Attraction and electroantennographic responses of male mediterranean fruit fly (diptera: tephritidae) to six plant essential oils. Journal of Entomology and Zoology Studies. 5(3):958-964. Interpretive Summary: Exposure to plant essential oils improves of the reproductive success in male Mediterranean fruit flies, the major pest of fruits and vegetables worldwide. Volatile chemicals from these essential oils are suspected to attract males to sites used for mating, and thus may be a source of additional attractants for this pest insect. Therefore, scientists at the Subtropical Horticulture Research Station in collaboration with FHIA scientists in Honduras investigated the attractiveness of several essential oils to sterile males and wild flies in laboratory and field tests, respectively. They also evaluated antennal response to these oils using electroantennography. Ginger root oil and orange oil were more attractive than manuka, cubeb, angelica seed, and tea tree oils. Electroantennographic studies determined the presence of 24 volatile chemicals that elicited positive responses in males, indicating biological activity. Twelve of these chemicals were identified by gas chromatography-mass spectroscopy and were found to include four male pheromone precursors. The amount of emitted a-copaene, a known attractive chemical compound, was not correlated with the fly preferences, suggesting that additional chemicals may play a role in attraction. Male preferences among essential oils were correlated with the emissions of linalool and geraniol, indicating that these two chemicals are potential male attractants that should be investigated further. The results of this research will be used to provide an improved attractant for use by regulatory agencies and growers to detect Mediterranean fruit fly populations, which is a critical component in the areawide management of this pest.
Technical Abstract: Volatile secondary metabolites emitted from plants (and concentrated in plant essential oils) are suspected to attract males of the Mediterranean fruit fly to their calling sites. We investigated the differential attractiveness of various natural essential oils in comparison with trimedlure to (1) sterile males in field cage bioassays conducted in Florida and (2) wild males in field tests conducted in Honduras. All essential oils tended to capture fewer males than trimedlure. However, among the essential oils, ginger root oil, followed by Valencia orange oil, were the most attractive compared to manuka, cubeb, angelica seed, and tea tree oils. With gas chromatographic-electroantennal detection (EAD), 24 volatile chemicals elicited positive responses in males, indicating biological activity. The most attractive oils presented the highest number of EAD active chemicals. Twelve chemicals were identified by gas chromatography-mass spectroscopy (GC-MS), including a- and ß-pinene, camphene, terpinen-4-ol, a-terpineol, ß-caryophyllene, a-copaene, a-humulene, and four male pheromone precursors: ß-myrcene, limonene, linalool, and geraniol. The amount of emitted a-copaene was not correlated with the fly preferences, and experiments with standardized amounts of emitted a-copaene did not alter the fly choices for the tested oils, suggesting that additional chemicals may play a role in attraction. Male preferences among essential oils were correlated with the emissions of linalool and geraniol, indicating that these two chemicals are potential male attractants that should be investigated in future research.