Effects of honey-bee alarm pheromone compounds on the behaviour of Varroa jacobsoni

Abstract - In a simultaneous choice test, bees killed by freezing were more attractive to Varroa than bees stung to death by other bees. The smell of the sting apparatus proved to be repellent for Varroa. In addition, 6 out of 9 alarm pheromone compounds were significantly repellent. Next to isopentyl-acetate, which showed no effect, 1-octanol is the most quantitatively important alarm pheromone compound of Apis mellifera. With that substance, Varroa showed the strongest repellent effect in both olfaction and chemo-contact perception tests. An amount of 0.5 μl 1-octanol, present in 1 sting apparatus, injected into dead bees caused significantly more mites to leave these bees after only 30 s than water injected into control bees. 1-octanol is obviously an important chemical trigger for Varroa to leave a bee which is stung or just contaminated with alarm pheromone during robbing.