Trade‐off between attraction to aggregation pheromones and repellent effects of spike lavender essential oil and its main constituent linalool in the flour beetle Tribolium confusum

Abstract

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.

Behavioral and Antennal Responses of Tribolium confusum to Varronia globosa Essential Oil and Its Main Constituents: Perspective for Their Use as Repellent

“…Five beetles in a stimulation tube were highly attractive to individual T. confusum , confirming earlier results [ 9 ] ( Figure 3 , p < 0.0001). When combining this attractive stimulus with the highly repulsive dose of 5 mg of the essential oil of V. globosa , attractiveness was lost ( p = 0.308).…”

“…Antennal detection, as well as repulsive behavioral responses of T. confusum, to the entire oil, to different degrees to its major components, anethole and caryophyllene, and their mixture were discovered. A similar repellent effect on T. confusum adults had been observed earlier with Lavandula spica essential oil and its main component linalool [9]. In addition to the repellent effect found in the present study, anethole also showed significant toxicity by fumigation against T. confusum and Sitophilus oryzae adults [28], as well as repellency to two Tribolium and two Sitophilus species [29].…”

“…We also found an inhibition of the attraction by T. confusum -produced aggregation pheromones by V. globosa essential oil, similarly to L. spica essential oil and linalool [ 9 ]. A high dose of the essential oil of V. globosa , 5 mg on the filter paper, abolished the attraction of the aggregation pheromone emitted by five conspecifics.…”

“…In addition, behavioral responses depend on the olfactory environment and interactions between odors from different sources, which can modify them [ 7 ]. Especially interactions between different compounds are important to be considered in the development of semiochemical-based pest management strategies, since certain plant volatiles can reduce the attractiveness of pheromones and, inversely, pheromones can reduce repulsiveness of plant volatiles or synergize with attractive plant volatiles [ 8 , 9 ].…”

“…The essential oil of Pistacia lentiscus, for example, has a significant repellant effect on major insect pests of stored food such as Rhyzopertha dominica , Sitophilus zeamais, and T. confusum [ 17 ]. Different essential oils from wooden plant species, such as Croton anisatum and Illicium verum are repellent to Callosobruchus chinensis [ 18 ] and the essential oil of Lavendula spica has a repellent effect on T. confusum [ 9 ].…”