Heather R. Mattila

Recent work has demonstrated considerable benefits of intracolonial genetic diversity for the productivity of honeybee colonies: single-patriline colonies have depressed foraging rates, smaller food stores and slower weight gain relative to multiple-patriline colonies. We explored whether differences in the use of foraging-related communication behaviour (waggle dances and shaking signals) underlie differences in foraging effort of genetically diverse and genetically uniform colonies. We created three pairs of colonies; each pair had one colony headed by a multiply mated queen (inseminated by 15 drones) and one colony headed by a singly mated queen. For each pair, we monitored the production of foraging-related signals over the course of 3 days. Foragers in genetically diverse colonies had substantially more information available to them about food resources than foragers in uniform colonies. On average, in genetically diverse colonies compared with genetically uniform colonies, 36% more waggle dances were identified daily, dancers performed 62% more waggle runs per dance, foragers reported food discoveries that were farther from the nest and 91% more shaking signals were exchanged among workers each morning prior to foraging. Extreme polyandry by honeybee queens enhances the production of worker–worker communication signals that facilitate the swift discovery and exploitation of food resources.

1. Each autumn in northern regions, honeybee colonies shift from populations of short‐lived workers that actively rear brood to broodless populations of long‐lived winter bees. To determine if dwindling pollen resources trigger this transition, the natural disappearance of external pollen resources was artificially accelerated or delayed and colonies were monitored for effects on the decline in brood‐rearing activity and the development of populations of long‐lived winter bees. 2. Delaying the disappearance of pollen resources postponed the decline in brood rearing in colonies. Colonies with an extended supply of pollen reared workers longer into October before brood rearing ended than control colonies or colonies for which pollen supply was cut short artificially in autumn. 3. Colonies with extended pollen supply produced more workers throughout autumn than colonies with less pollen, but the development of the population of long‐lived winter bees was delayed until relatively later in autumn. Colonies produced similar numbers of winter bees, regardless of the timing of the disappearance of pollen resources. 4. Mean longevity of autumn‐reared workers was inversely related to the amount of brood remaining to be reared in colonies when workers eclosed. Consequently, long‐lived workers did not appear in colonies until brood rearing declined, which in turn was controlled by the availability of pollen. 5. Dwindling pollen resources provide a powerful cue that initiates the transition to populations of broodless winter bees because it directly affects the brood‐rearing capacity of colonies and indirectly indicates deteriorating environmental conditions associated with the approach of winter.

Each fall, honey bee (Apis mellifera L. (Hymenoptera: Apidae)) colonies in northern temperate regions rear a population of long-lived winter bees that maintains a broodless nest throughout the winter and resumes brood-rearing activities in the spring. Pollen supply in colonies is closely tied to this phenomenon; winter bees sequester large reservoirs of pollen-derived nutrients in their bodies and the brood-rearing capacity of colonies is dictated by the availability of pollen. We determined the effects of manipulating pollen supply during the fall on the number of winter bees present in colonies by spring, their mass and protein content before and after winter, and their capacity to rear brood during the spring. Colonies were either supplemented with or partially deprived of pollen during the fall, while a third group of colonies was not manipulated (control). We found that the performance of winter bees was not enhanced by supplementing colonies with pollen in the fall, nor did worker function suffer if pollen supply was restricted. Similar numbers of winter bees survived to spring in colonies and workers had similar physiology and brood-rearing efficiencies. These results suggest that beekeepers would not benefit by investing in fall pollen supplements to maximize colony growth in early spring.

Honey bee queens mate with many males, creating numerous patrilines within colonies that are genetically distinct. The effects of genetic diversity on colony productivity and long-term fitness are unknown. We show that swarms from genetically diverse colonies (15 patrilines per colony) founded new colonies faster than swarms from genetically uniform colonies (1 patriline per colony). Accumulated differences in foraging rates, food storage, and population growth led to impressive boosts in the fitness (i.e., drone production and winter survival) of genetically diverse colonies. These results further our understanding of the origins of polyandry in honey bees and its benefits for colony performance.

Honey bee (Apis mellifera L.) colonies in temperate climates often deplete winter pollen stores because of intense brood rearing activity in the spri