Investigation of the physiological consequences of feeding on methyl eugenol by Bactrocera cacuminata (Diptera: Tephritidae)

Males of many species of fruit flies (Tephritidae: Dacinae) respond to chemical lures of botanical origin. Such lures (e.g., cuelure and methyl eugenol [ME]) have been successfully used in fruit fly population management. The hypothesized role of these chemicals by males is exclusively ecological (pheromonal and/or allomonal), and male response has been classed as pharmacophagy. However, for a response to plant-derived lures to be classified as pharmacophagous sensu stricto, it must be demonstrated that the role of these chemicals is ecological and not primarily metabolic (e.g., nutritional) or associated with host plant recognition. To specifically test the primary metabolic effects of feeding on ME, we investigated the physiological consequences of exposure to ME in the dacine fly, Bactrocera cacuminata (Hering). Our results indicate that feeding on ME does not confer any physiological advantage to B. cacuminata. This is reflected in the lack of any consistent difference over time between ME-fed and non ME-fed flies in terms of overall weight and lipid, carbohydrate and protein reserves. Survival was not significantly influenced by exposure to ME either. These results support the hypothesis that ME use by B. cacuminata could be pharmacophagous.