Oviposition-deterrent effect of linalool - a compound of citrus essential oils - on female Mediterranean fruit flies, Ceratitis capitata (Diptera: Tephritidae)

BACKGROUND Linalool is a natural scent, found in essential oils (EOs) of several plants. It is widely used as a fragrant, also possessing toxic, oviposition-deterrent and repellent properties against many insect species. Ceratitis capitata (medfly) is one of the most notorious insect pests for international fresh fruit production. Despite the available information on the repellent effects of EOs on herbivorous insects, possible oviposition-deterrent effects of linalool against C. capitata remain unknown. OBJECTIVES AND RESULTS We tested whether different linalool concentrations, application methods on fruit hosts and time since application elicited oviposition-deterrence on medfly, from bitter oranges, apples and nectarines, under constant laboratory conditions. We also tested possible repellent properties of linalool on adult medflies in field conditions. Females drilled fewer oviposition stings and deposited fewer eggs per fruit in all linalool-treated hosts. Spraying and topical-droplet application were the most efficient methods on bitter oranges, although spraying was the least effective method in apples. Bitter oranges and nectarines that were offered to females immediately post-exposure to linalool received more oviposition stings and eggs than those offered 3 days post-exposure to linalool solutions. Conversely, apples tested 3 days following linalool application received significantly more oviposition stings and eggs than those tested immediately and 1 day post-exposure. More adults in total, and more females, were captured in traps located on untreated-control than on linalool-treated trees, especially in citrus hosts. CONCLUSION Linalool has a potential future use in environmentally friendly control strategies against C. capitata. (C) 2020 Society of Chemical Industry