Primer effects of a brood pheromone on honeybee behavioural development

Abstract

Primer pheromones are thought to act in a variety of vertebrates and invertebrates but only a few have been chemically identi¢ed. We report that a blend of ten fatty-acid esters found on the cuticles of honeybee larvae, already known as a kairomone, releaser pheromone and primer pheromone, also act as a primer pheromone in the regulation of division of labour among adult workers. Bees in colonies receiving brood pheromone initiated foraging at signi¢cantly older ages than did bees in control colonies in ¢ve out of ¢ve trials. Laboratory and additional ¢eld tests also showed that exposure to brood pheromone signi¢cantly depressed blood titres of juvenile hormone. Brood pheromone exerted more consistent e¡ects on age at ¢rst foraging than on juvenile hormone, suggesting that the primer e¡ects of this pheromone may occur via other, unknown, mechanisms besides juvenile hormone. These results bring the number of social factors known to in£uence honeybee division of labour to three: worker^worker interactions, queen mandibular pheromone and brood pheromone.

Regulation of behavioral maturation by a primer pheromone produced by adult worker honey bees

“…These results suggested that the worker inhibitory factor was either a nonvolatile ''contact'' pheromone, a behavior, or both, with old bees having greater inhibitory potency than younger bees. The possibility that the worker inhibitory factor might be a pheromone gained strength with the discovery that two other honey bee primer pheromones, queen mandibular pheromone (QMP) and brood pheromone (BP), also play a role in regulating worker behavioral maturation (11,12). In addition, Pankiw (13) recently reported that a hexane extract of foragers delays age at onset of foraging.…”

“…Exposure to QMP and BP was controlled in these experiments because both can affect age at onset of foraging (11,12). Instead of a live queen each colony was given a commercially available plastic strip (Bee Boost, PheroTech, Vancouver, Canada) containing the five-component QMP blend (2) that releases one queen equivalent per day.…”

“…Two doses of EO were used: 0.21 and 2.1 mg of EO per g of sugar candy. Doses were based on the effects of BP in another study that used the same form of treatment (12). EO constitutes 21% of the 10-component BP (17), and the doses of BP used in ref.…”

“…This was done by comparing GC͞MS profiles of 2-methylpentane extracts from nurses and foragers. 2-Methylpentane was chosen because we were particularly interested in fatty acid esters, given that BP affects behavioral maturation and is composed of 10 fatty acid esters (12). Nurses and foragers were of unknown age, collected from a typical colony in the field headed by a naturally mated queen.…”

Variation in honey yield per hive of Africanized bees depending on the introducing time of young queens

“…The higher the food flow, the better the queen is feeded, stimulating it to increase the egg laying rate and, consequently, offspring production, colony population size and number of forage workers (LE CONTE et al, 2001 ;. The offspring stimulate the foraging for food resources in general, thus the amount of pollen and nectar (honey) collected by a colony of Apis mellifera depends on the amount of forage workers and the offspring (eggs, larvae and pupae) present in this colony, and these two variables depends on the population size of the colony .…”