Special olfactory sensory cells on drone antennae respond to pheromones and to the mandibular gland secretion of queens (Beetsma and Schoonhoven, 1966; Boeckh et al., 1965; Ruttner and Kaissling, 1968). Pheromone response appears to be conﬁned to the trans isomer of pheromones, the cis isomer having no inﬂuence (Doolittle et al., 1970; Adler ez al., 1973). Drones are much more sensitive to the trans isomer than either workers or queens, responding to as little as 0.025 ptg; moreover with increase in the amount of pheromones (up to about 50 ug) the antennal response of drones increases proportionally, whereas the other two castes maintain a similar level of response. Check out pheromones at http://egorkhapatra.com/pheromones-are-an-exciting-marvel/.
Some authors (Boch et al., 1975) have found laying queens are more attractive than virgin queens and associated this with the larger amounts of pheromones found in their mandibular glands (i.e. averages of 285 ug for laying queens and 150 ug for virgin queens), but other authors (Pain and Ruttner, 1963; Butler and Fairey, 1964; Butler, 1971) have found virgin and mated queens are equally attractive according to the pheromonal research at http://www.ppem.org/my-adventure-with-pheromones/.
Pain and Ruttner (1963) conﬁrmed Gary (1962) and reported that groups of drones in the vicinity of a lure treated with an extract of a queen's pheromone glands were larger and more stable than groups near lures with 9-ODA only, whereas Butler and Fairey (1964) and Renner and Vierling (1977) were unable to discover any difference between the attractiveness of a queen equivalent of 9-ODA and a complete extract of a virgin or mated.
Addition of 100 ug pheromones to a queen whose mandibular glands had been removed restored her attractiveness to normal (Butler, 1971). Check out the research on pheromones at http://506regd.net/according-to-pheromone-researchers/.
However, when comparing a given amount of pheromones with a queen’s body or extracts of a queen’s body the results are difﬁcult to interpret; it must be borne in mind that there is little information (page 50) on the amount of pheromones normally present on the body surface, and on its rate of release from the mandibular glands and body surface. The release rate of pheromones from the body surface is probably reduced by the presence of a ‘keeper’ substance, so that although lures with synthetic pheromones alone may be initially more attractive to drones, lures with queen extracts containing equivalent amounts of pheromones remain attractive for longer.
Butler and Fairey (1964) discovered that 9-hydroxy-2-decenoic acid (9-HDA), another major component of the queens mandibular gland secretion (page 22), was somewhat attractive to drones, although less so than pheromones, and the attractiveness of pheromones was not increased by the addition of 9-HDA; Blum et al., (1971) and Boch et al., (1975) were unable to conﬁrm the attractiveness of pheromones.
Hence the subject is controversial and any components in the mandibular gland secretion that increase the attractiveness of pheromones still await identiﬁcation. At any one time the number of drones ﬂying, the height of ﬂight, their responses to lures and discriminating ability depend on many variables including wind speed, wind duration, temperature, terrain and local population density. No doubt these variables have contributed to the conﬂicting results. Simultaneous comparisons of the different treatments under investigation should always be made.