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Essential oils of aromatic plants and their individual volatile components have been tested in pest management strategies for their toxic and often repellent effects on target insects. When evaluating their possible effects on crucial behaviours of the pest insects, the olfactory environment including intraspecific communication cues has to be considered. We used the flour beetle Tribolium confusum du Val (Coleoptera: Tenebrionidae), a common stored‐product pest, to investigate the influence of oil of spike lavender, Lavandula spica Medik. (Labiaceae), and its main component, linalool, at various doses on olfactory‐guided behaviour. Using four‐way olfactometers, a dose‐dependent repellent effect of L. spica oil and linalool alone was revealed. On the other hand, we confirmed that T. confusum is attracted by conspecifics, by means of an aggregation pheromone and by 10 ng of one of its components, 1‐tetradecene. Twenty‐four hour pre‐exposure to 10 μl of L. spica oil abolished subsequent attraction to 1‐tetradecene and reduced attraction to five conspecifics. Simultaneous exposure to L. spica oil or linalool and five conspecifics reduced the repellent effect of the volatiles in a dose‐dependent manner, whereas simultaneous exposure to 1‐tetradecene at 10 ng abolished the repellent effect of L. spica oil only at a dose of 0.01 mg. These results indicate a dose‐dependent trade‐off between attractive and plant‐derived repellent volatiles, which may influence the effectiveness of such volatiles in their potential use in alternative pest management strategies.

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Essential oils of aromatic plants represent an alternative to classical pest control with synthetic chemicals. They are especially promising for the alternative control of stored product pest insects. Here, we tested behavioral and electrophysiological responses of the stored product pest Tribolium confusum, to the essential oil of a Brazilian indigenous plant, Varronia globosa, collected in the Caatinga ecosystem. We analyzed the essential oil by GC-MS, tested the effects of the entire oil and its major components on the behavior of individual beetles in a four-way olfactometer, and investigated responses to these stimuli in electroantennogram recordings (EAG). We could identify 25 constituents in the essential oil of V. globosa, with anethole, caryophyllene and spathulenole as main components. The oil and its main component anethole had repellent effects already at low doses, whereas caryophyllene had only a repellent effect at a high dose. In addition, the essential oil abolished the attractive effect of the T. confusum aggregation pheromone. EAG recordings revealed dose-dependent responses to the individual components and increasing responses to the blend and even more to the entire oil. Our study reveals the potential of anethole and the essential oil of V. globosa in the management of stored product pests.