Impact of extreme dry conditions on early shutdown of brood production and “winter bee” population
Due to the extreme hot, dry conditions this summer, there is a growing concern that the honey flow this year may end much earlier than normal. One of the main concerns of an early ending honey flow is how that can impact the colony’s ability to maintain brood production and not prematurely trigger the production of “winter bees” (i.e. diutinus workers). These long lived winter bees typically can live for 20 or more weeks as opposed to “summer bees” which typically only live for six or less weeks during the peak of summer. The survival of the colony over the winter is therefore dependant on the production of adequate numbers of winter bees to survive the entire winter and reactivate brood production in the spring.
In Manitoba, the length of our winters are relatively close to the limits of the typical lifespan of winter bees (e.g. six months). Hence the importance of not allowing the colony to shutdown too early and pushing back the production of winter bees closer to the normal time when they would be produced (e.g. September).
Most years, the production of winter bees coincides with the cessation of flight activity, decreasing day length, and falling temperatures. During that time, the colony typically starts to shutdown brood production and depending on food reserves, the expelling of drones may also start to occur. As brood production declines, so does the amount of brood pheromone in the hive and the time and resources spent nursing brood. This reduction of brood and brood pheromone along with the reduced nursing activity helps to trigger the production of winter bees.
The primary difference between summer and winter bees is the increased amount of stored lipids (i.e. fats) and proteins in the haemolymph (blood) and fat body of winter bees. The other important substance that is found in higher concentrations in winter bees is vitellogenin. This glyco-protein is used in brood food production and in the regulation of foraging. As foraging decreases and brood production begins to shutdown, the level of vitellogenin in the haemolymph and fat body of the worker population starts to increase and so does the number of long-lived workers.
If we have an early end to the honey flow because of drought (i.e. end of July), supplemental feeding may be required to prevent the colonies from shutting down prematurely. For example:
- If nectar foraging appears to be finished before the end of July, feeding sugar syrup or leaving some honey on the colony may be required. It is important not to feed too much syrup to cause the brood chamber to prematurely plug up with feed. Feeding the colony with 20 – 30 lbs (9 – 14 L) of syrup should be sufficient to maintain a single or double brood chamber hive in brood production during the month of August. In September, resume feeding as usual to prepare the colony for winter.
- If there does not appear to be any natural pollen coming into the colony during August & September, feeding pollen or pollen substitute to the colony may be required. Feeding pollen patties or using pollen-supplement feeding stations are both considered acceptable methods for providing protein to honey bees! If the colony does not require additional protein, it typically will not consume the patties or collect from the feeding stations. Overfeeding protein is therefore not usually a big concern.
If you have any questions, please feel free to contact me!
Salut!
Rhéal Lafrenière
Production Specialist – Provincial Apiarist
Manitoba Agriculture and Resource Development
204-545 University Crescent
Winnipeg, Manitoba, Canada
R3T 5S6
Rheal.Lafreniere@gov.mb.ca