ABSTRACT
Interest in, and research on, bioactivities of plant essential oils to insects has exploded in the past 15 years, according to a recent bibliometric analysis. However, commercial exploitation of this knowledge is being realized much more slowly although essential oil-based pesticides have begun to establish a market presence at least in the USA. The volatility of essential oils makes them especially suitable as fumigants in protected environments and for protection of stored products, but they also have demonstrated utility for protection of horticultural crops. Many essential oils and their major constituents, monoterpenes and sesquiterpenes, have contact toxicity to insects and mites, but their utility is broadened owing to their sublethal behavioral effects as deterrents and repellents. These bioactivities result from neurotoxicity of the terpenes, with at least two distinct mechanisms of action identified thus far. One intriguing aspect of the toxicity of some essential oils in insects is synergy among particular terpenes within an oil, thus enhancing bioactivity. Although many essential oils display bioactivity against insects when tested in the laboratory, only a few commodity oils – those used extensively in the flavor and fragrance industries – have been developed for use as pesticides. These include certain oils from the families Lamiaceae, Lauraceae, Myrtaceae, and Poaceae. Their potential as protectants for horticultural crops is discussed.190
