Sustainable Honeybee Strains for Western North Carolina
Season two of this two year project involved evaluating how three different strains of honeybees–New World Carniolan, Minnesota Hygienic, and Russian–performed in a commercial beekeeping setting. Colonies were used to pollinate apples, then blueberries, before being moved into Sourwoods for Western North Carolina’s most profitable honey flow. Colonies were evaluated on a two week cycle. These evaluations included documenting the quantity of brood, pollen, and honey in the colonies, as well as colony size, queen quality, and colony temperament. Disease and mite pressure were also noted, and formal mite counts were performed in August.
Each of the three strains of honeybees studied in this project have been “improved” via genetic selection in an effort to find a honeybee that is well-equipted for survival in these challenging times for the beekeeping industry. The objective of season two was to study the merits of each of these strains in an effort to determine which are adaptable to Western North Carolina. In doing so, the hope is that breeders will be better informed in their stock selection choices and consequently be in a position to provide beekeepers with improved stock options.
In accomplishing this objective, the goal was to conduct the study with as much objectivity as possible by quantifying as many observations as possible. The project consisted of four colonies of each of the three strains being studied (New World Carniolan, Minnesota Hygienic, and Russian) in addition to a control group of four colonies consisting of locally outcrossed queens. These colonies followed a schedule modeled after a typical regiment for a commercial beekeeper in Western North Carolina. The colonies were housed in identical equipment, and managed the same in an effort to reduce variables.
The first consideration of season two, was to determine how each of the strains over-wintered. The Russian Bees and Minnesota Hygienic Bees each lost one colony through the winter, resulting in a 25% mortality rate. The Carniolian Bees and the control group lost two colonies each for a 50% mortality rate. The USDA Bee Lab in Beltsville, MD found samples of dead-outs to be free from varroa and tracheal mites as well as a significant number of nosema spores.
These winter losses should be taken in the context that 30% is the national average mortality rate. These losses were anticipated and surplus colonies were substituted for the colonies that did not over-winter.
Secondly, eight colonies (two of each group) were taken to an apple orchard to pollinate in April. The number of frames containing pollen and colony size were recorded before and after the apple bloom. These two measurements were found to be directly related. Larger colonies not only have more foragers available to collect pollen, but they also have more brood rearing occurring, and consequently have a greater need for pollen compared to colonies that are slow to build in the spring. With this in mind, the Minnesota Hygienic (Italian) colonies were more than twice the size of the Russian and Carniolan colonies in April, and therefore foraged significantly more pollen by comparison.
Thirdly, the other eight colonies (two of each group) were taken to a blueberry farm to pollinate in April. Colony size was more or less the same during the blueberry bloom as it was during the apple bloom, therefore, the same trend witnessed in apples was largely repeated in blueberries.
Finally, the colonies were taken to a location traditionally used for Sourwood honey production. The Sourwood bloom occurred in the second week of June locally and continued through the end of the month. Albeit, it was a poor flow, nonetheless, colonies had equal opportunity to forage for what was available. The Russian Bees produced the most, averaging 21 lbs. per colony. The Minnesota Hygienic stock followed at 17 lbs. per colony, then the control group at 16 lbs. per colony, and the Carniolians at a mere 6 lbs. per colony.
Impacts and Contributions/Outcomes
Comparing the growth curves of each strain in relation to significant nectar flows reveals why some stocks were better suited than others for particular purposes. This is most evident early in the season when crops such as apples, blueberries, and blackberries require pollination in Western North Carolina. Efficiently pollinating these crops requires colonies that build up quickly in the spring. Based on my experiences with this project, it is easy to understand why the industry is dominated by Italian stock. The industry is driven by almond pollination in California in February. Stocks that require a nectar flow to begin brood rearing, such as Russians, are difficult to get up to full strength before such early flows.
Carniolian Bees, on the other hand, are known for their “explosive” spring build-up, which was quite different from the experiences of this project. The Carniolian bees used for this project were slow to build in the spring, much like the Russian stock. However, they hit their high point during the Tulip Poplar flow in May and then contracted during the dearth between the Poplars and Sourwoods in June. This growth curve made them both inefficient pollinators for apples and blueberries early in the season, and poor Sourwood foragers mid-season. As I said, this slow Spring build-up is uncharacteristic, and I think can be explained by the late acquisition of the stock in season one and the inability for these colonies to fully establish before winter. This hypothesis is supported by light colony weights going into winter, and the above average winter mortality rates experienced.
While spring build-up is a significant factor with many commercial pollination applications, it is not necessarily indicitive of mid-season colony strength as seen in the Sourwood honey portion of this project. While slow to start, the Russian colonies by mid-season were hitting their stride and produced on average a Sourwood crop that was 20% greater than their Italian (Minnesota Hygienic) counterparts. The bell curve tracking colony population in the Russian colonies corresponded ideally to the Sourwood bloom. By contrast, the Minnesota Hygienic colonies spiked during the Tulip Poplar flow, declined during the short dearth preceeding the Sourwood flow, and only showed a slight “bump” during the bloom period. Such data helps explain the popularity of Russian Bees in Southern Appalachia where the Sourwood bloom can be profitable for beekeepers.
Non-foraging related data such as mite resistance, colony temperament, and queen quality will be discussed as it relates to a broader discussion involving stock selection choices in the project’s final report.
North Carolina State University
1558A Gardner Hall Addition, North Carolina State University, Dept. of Entomology, Campus Box 7613
Raleigh, NC 2769-7613
Office Phone: 9195151660
120 Hospital Ave NE
Lenoir, NC 28645
Office Phone: 8287571291
1558A Gardner Hall Addition, NCSU Dept. of Entomology
Campus Box 7613
Raleigh, NC 2769-7613
Office Phone: 9195151660