Impact of Supplemental Feed Type on Winter Survival of Honey Bee Colonies

Final Report for FS11-252

Project Type: Farmer/Rancher
Funds awarded in 2011: $9,957.00
Projected End Date: 12/31/2012
Region: Southern
State: North Carolina
Principal Investigator:
Barry Harris, Jr.
Silver Spoon Apiaries, Inc
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Project Information


Bees fed High Fructose Corn Syrup (HFCS) in preparation for winter did not have higher winter mortality or higher incidence of Nosema ceranae. There was no difference in winter outcomes or incidence of Nosema ceranae based on the composition of winter feed stores. However, a predicate experiment conducted by myself and Dr. Tarpy showed that the buildup of package bees could be significantly accelerated by making HFCS Type 55 the primary sugar source rather than feeding only liquid sucrose. There are significant advantages to feeding bees a 40/60 blend of liquid sucrose/HFCS Type 55 rather than only liquid sucrose or only HFCS Type 55 including avoidance of feed fermentation, avoidance of feed crystallization, and faster colony buildup over a broad spectrum of environmental conditions. Obtaining blended feed in appropriate amounts is a particular problem for emerging commercial beekeepers in the 300 to 600 colony size range as they typically lack the resources to obtain and store the feed. Obtaining good winter outcomes is most likely the result of the cummulative effect of multiple colony management best practices such as keeping diseases and pests under control, maintaining young queens in the colonies, timely provision of adequate supplemental carbohydrates, proteins, and amino acids, optimizing hive configuration, and consistently employing good hive manipulation practices.


Beekeepers are experiencing increasing winter losses of colonies due to the increased presence and variety of honey bee diseases and pests. Consequently, commercial beekeepers are looking for methods to help reduce winter losses and to more efficiently replace winter losses so that replacement colonies are at production strength in time for pollination work and honey production. This is of particular concern in the Southern, USA where there is a very short time between the availability of package bees and queens and the pollination and production seasons. The principal method of colony replacement for most commercial beekeepers is package bees. Rapid buildup of replacement colonies requires substantial supplemental feeding of liquid bee feed. Some within the beekeeping community have asserted that High Fructose Corn Syrup (HFCS) is a major factor in losses of honey bee colonies. However, HFCS, either by itself or as a primary component of a blended feed is the only viable feed for commercial beekeepers. At the end of the day, it is the commercial beekeepers that get the crops pollinated and produce virtually all of the U.S honey. It is therefore of fundamental importance as to how different types of liquid bee feed effect winter survival and the buildup of package bees. In this SARE funded experiment we studied the effect of liquid bee feed type on winter survival, generally, and the incidence of Nosema ceranae, specifically, Immediately prior to this experiment we conducted a large scale experiment on the effect of liquid bee feed on spring package bee buildup. The results of the SARE experiment are reported herein. Where appropriate, we have included references to the predicate experiment to provide context for the SARE funded experiment. We are in the process of finishing a manuscript covering both experiments which will be submitted to "The Science of Bee Culture" for peer review and publication.

Project Objectives:

We designed this SARE experiment prior to designing our predicate bee feed experiment on the effect of liquid bee feed on the buildup of package bees. Initially, we had three objectives in the SARE experiment:

  1. Determine if the feeding of HFCS led to higher winter losses or incidence of Nosema ceranae.
    If the answer to the first question was yes determine if this negative effect could be countered by the inclusion of a moderate amount of liquid sucrose in the feed.
    If the inclusion of liquid sucrose was beneficial determine if it is practical for emerging commercial beekeepers to employ this strategy.

Although our predicate experiment was designed after the SARE funded experiment it was performed first. Our perspective on our initial SARE experiment objectives was changed by our experience in the predicate experiment, itself, and by interaction with people in the bee feed industry sweeteners industry during the course of the experiment. Given the appropriate ambient temperature and length of day, bees are stimulated to raise brood, draw comb, and forage when they receive binomial carbohyrdates such as the sucrose in nectar or liquid sucrose. The bees must invert these complex disaccharide sugars into monomial or monosaccharide sugars such as fructose and dextrose. While the bees are stimulated by this process it is not energy efficient as they consume much of the feed in the inversion process itself. Our predicate experiment results led us to believe that bees have a stimulation threshold for binomial sugars and that once sufficient binomial sugars are available maximum colony buildup can be obtained by providing monomial sugars that the bees can use immediately without inversion such as the fructose and dextrose contained in HFCS. The energy saved by avoiding the inversion process can be utilized by the colony to raise brood, draw comb, and otherwise expand the colony and its nest. We also learned from interaction with the bee feed and sweeteners industries that liquid sucrose is extraordinarily prone to fermentation and cannot be stored for significant lengths of time. This is because, even at the maximum possible liquid sucrose solids content of 67.5%, the solids content is not high to establish a pH that is inhospitable to microbial growth. The threshold for this pH is 71% solids. HFCS Type 55 has a solids content of 77% and is therefore not in danger of fermentation. However, 41% of its solids are in the form of dextrose. Liquid feeds with dextrose contents greater than 25% are likely to crystallize at temperatures below 60 degrees Fahrenheit so crystallization is a risk with HFCS. By the time we actually began the SARE experiment we had come to the conclusion that a 40/60 blend of liquid sucrose/HFCS Type 55 would be optimal from the standpoint of storage and would increase the likelihood of rapid colony buildup over a broad spectrum of environmental conditions when compared to liquid sucrose or HFCS Type 55 alone. This caused us to see our SARE experiment objectives as even more potentially relevant than first thought.


Click linked name(s) to expand/collapse or show everyone's info
  • Barry Harris
  • Jill Harris
  • Dr. Merrill Holden


Materials and methods:

The surviving colonies from Experiment 1 were used for honey production in the same beeyard during the interim between Experiment 1 and Experiment 2 and were managed using standard commercial management practices.

In September of 2011 we began preparation of the colonies for Experiment 2. All colonies were treated for mites with Apiguard per manufacturer's instructions. The colonies were prophylactically treated for American Foulbrood with Tylan. The colonies were also treated for Noseama ceranae by feeding them one gallon of syrup which included 1-1/3 teaspoons of Fumagilin-B per gallon. each week for four consecutive weeks. The syrup used in this prepatory stage was a 1:2 mixture of 67.5% liquid sucrose and HFCS Type 55 and included Mann Lake Pro-Health.

60 colonies were utilized for Experiment 2. Fifty-nine of these colonies were selected from the remaining colonies from Experiment 1 and one colony from the same beeyard which had received identical treatment was also utilized.

Most of the colonies were in a “story and a half” (one deep and one medium) configuration with a few being in a “double deep” configuration.

The colonies were divided into six treatment groups of ten colonies each with the selection being made in manner that would optimize the similarity of the groups and the random distribution of the colonies throughout the beeyard. Colonies in "double deep" configuration were evenly distributed among the treatment groups. A thorough statistical analysis of the strength of each treatment group was performed to confirm similarity of the groups.

Nosema spore counts were taken for all colonies and ranged from zero to moderate except one colony which had a high count.

72 hour natural mite drops were taken on two average colonies from each treatment group. The counts were taken twice –once using Pam and once using Vaseline. 24 hour counts ranged from zero to two for all colonies tested (very low).

The specific liquid bee feeds for each treatment were:

  1. 67.5% liquid sucrose
    HFCS Type 55 diluted by 10% with water
    HFCS Type 42 undiluted
    80/20 blend of HFCS Type 55 diluted by 10% with water and 67.5% liquid sucrose
    80/20 blend of HFCS Type 42 and 67.5% liquid sucrose
    Mann Lake Pro-Sweet 77

Beginning in October of 2011 each colony was fed one gallon of their respective feed type per week until they consumed four gallons or stopped taking feed. All feed included 1-1/3 teaspoons per gallon of Fumagilin-B and Mann Lake Pro-Health at 3.2 oz per five gallons. Each colony was given up to one lb. of Mann Lake Ultra-Bee pollen substitute patties simultaneous to the liquid feeding. The patties were placed on top of the frames immediately above the brood nest. Hive covers were switched to metal covered migratory tops with a ¾ inch spacing rim permanently attached to the underside of the top. This spacing rim included a ¾” x 1-1/2” opening at one end for ventilation. This ventilation opening was positioned towards the front of the hive to allow condensation to drain forward and out of the hive. A four foot framing level and wooden construction shims were used to make sure that each colony was level side to side and tilted slightly forward to insure uniform drainage of all colonies. Commerical entrance reducers with a 4” by 3/8” opening were installed on each colony. On 1-1/2 story colonies with light medium supers we rotated the medium supers under the deep hive body so that the bees would not egress to an upper box with no stores during the winter.

Following the feedout process 40% of the colonies in each test group were re-tested for Nosema spores with all colonies testing from zero to low.

Colonies with insufficient winter stores were fed quick fondant (queen candy) made with their respective feed type. Weak colonies were wrapped with a Bee Cozy and provided with upper insulation.

Otherwise standard commercial management practices were employed.

Final data was collected in March, 2012. Data collection for frames of brood and frames of bees was performed in a manner designed to avoid time of day impact on adult bee counts. We collected data from Treatment Group 1 - Colony 1, then Treatment Group 2 - Colony, etc. so that we were taking data from equal numbers of colonies in each treatment group throughout the day. No "round" through the treatment groups overlapped forarging commencement of cessation. Nosema spore counts were taken on all colonies.

Research results and discussion:

We could not find any difference in winter mortality or incidence of Nosema ceranae between treatment groups. 59 of the 60 colonies survived the winter. Nosema spore counts were zero to low for all colonies.

The issue of HMF (hydroxymethylfurfural) in HFCS has received a lot of recent attention (e.g., Leblanc et al., 2009; Ruiz-Matute et al., 2010). HMF occurs naturally in honey, but both HFCS and honey produce greater quantities of HMF when exposed to heat. Some in the beekeeping community have suggested that HFCS contributes to winter colony losses. We believe that the the issues related to high levels of HMF arise from post manufacturing handling of the syrup due to exposure to heat during efforts to liquify crystallized syrup. This can be avoided by blending enough 67.5% liquid sucrose with the HFCS Type 55 to lower the HFCS dextrose percentage to 25% or less (typically at least 40% liquid sucrose).

We accomplished our experiment objectives.

The experiment process and collaborating with Dr. Tarpy was very instructive for me. To the uninitiated, the budgets for many large scale experiments seem extravagant. However, once you start accounting for every mile, every hour, and every microscope slide, costs add up rapidily. I was also surprised to learn that it takes a substantial number of colonies in each treatment group for the results to have statistical relevance.

Participation Summary

Educational & Outreach Activities

Participation Summary:

Education/outreach description:

Our outreach efforts for both this SARE funded experiment and its predicate companion experiment were conducted simultaneously since the two experiments provide context for one another. It is much eaier to understand one when presented with the other. Dr. Tarpy and I are in the process of finishing a manuscript covering both experiments which will be submitted to "The Science of Bee Culture" for peer review and publication. I did an informal but significant outreach to commercial beekeepers. This effort is ongoing. I presented the results at a workshop at the 2012 North Carolina State Beekeepers Association Summer meeting. Our workshop was standing room only and many people had to be turned away for lack of space. I made presentations to eight separate county/regional beekeeping associations in North Carolina and one in South Carolina. Dr. Tarpy and I also fielded numerous e-mail and telephone requests for information.

Project Outcomes

Project outcomes:

My subjective analysis of the response to the experiment results during our outreach is that it varied noticeably based on beekeeper experience and philisophy. Commercial beekeepers were the most receptive to the information and readily understood the significance. Rural hobby beekeepers with significant beekeeping experience or parallel livestock feeding experience were also receptive to the information, understood it, and took immediate steps to implement it. Urban hobby beekeepers, most of whom embrace a "natural" beekeeping philosophy and typically do not have a agricultural background, were not generally receptive to the information. Novice hobby beekeepers generally did not have the experience to understand the information. The information provided by these experiments will help beekeepers adjust the sugar makeup of liquid bee feeds to optimize brood rearing, comb building, and the creation of winter stores. It will also help remove the spectre of doubt that has been cast on High Fructose Corn Syrup as a supplemental bee feed.


Potential Contributions

Taken collectively with its predicate companion experiment, these two experiments may well be the most significant bee feed experiments to date. Surpisingly, prior to these two experiments, there has been relatively little research done on liquid bee feed. This is noticeably different than the case with other livestock industries where optimization of feed expenditures has long been an area of intensive research. We believe that these experiments will make a notable contribution to beekeeeping both in and of themselves and also as starting points for future research.

Future Recommendations

Collectively, both this SARE funded study and its predicate companion study on the impact of liquid bee feed on replacement colony buildup present several avenues of further inquiry.

First, we would like to repeat the colony buildup experiment during an extended nectar dearth. We suspect that we would find that the binomial/monomial blends, such as the Mann Lake Pro-Sweet 77 or medium invert sugar, would outperform liquid sucrose and HFCS Type 55 outside of a major nectar flow because they would both provide the stimulation via the binomial sugars and the immediately usable carbohydrates via the monomial sugars.

Second, we believe it would be valuable to do further experimentation aimed at establishing a “stimulation threshold” for sucrose as a percentage of total carbohydrate intake. In theory, once this threshold was known, beekeepers could adjust the sugar makeup of supplemental bee feed so that all carbohydrates fed above this threshold were in the form of monomial molecules that could be readily ussd by the bees for comb building and brood rearing.

Third, we would like to conduct further experimentation to establish “conversion ratios” for various feeds that would allow commercial beekeepers to maximize brood rearing, comb building, and setting aside of stores per dollar of feed expenditure. This subject is vigorously pursued in other agricultural pursuits involving livestock where optimizing weight gain is essential to profitability but has received no formal attention in honey bee research. It may be that commercial beekeepers could spend more per gallon on feed yet lower their aggregate feed costs through feed efficiency.

Fourth, the issue of the effect of liquid bee feed viscosity on comb building, brood rearing, and setting aside of winter stores remains an important issue. It is commonly recommended in various beekeeping “how to” books to feed 1:1 sugar syrup to stimulate brood and thicker 2:1 sugar syrup to provide the bees with winter stores. Some commercial beekeepers dramatically thin their HFCS Type 55 with water under the assumption that thinner syrup will simulate nectar (nectar is approximately 85% water ) and thereby stimulate comb building and brood rearing. We question this assertion, however, because bees being fed liquid bee feed that contains twice as much water will have to expend additional energy to dry that syrup out. The bees will perform more work to get half the nutrition. Additionally, in the case of liquid sucrose, they will also have to invert the syrup. Nonetheless, a study of the effect of syrup viscosity on comb building, brood rearing, and setting aside of winter store would be valuable, if for no other reason than to remove a stumbling block to embracing evolving reseach.

Fifth, one issue raised during our post experiment public outreach was that our use of Italian bees in the experiments may have influenced the experiment results. While different sub-species of bees do respond differently to carbohydrate and protein supplementation we do not think the use of Carniolan or Russian bees would have yielded different results. However, honey bee behavior is often counter-intuitive and it would be valuable to conduct further experimentation along this line if for no other reason than to make it easier for other reseach to be assimilated by beekeepers.

Bees are essential to sustaining agriculture due to their importance in pollinating almond, fruit, and cucurbit crops and the production of honey for resale. These tasks are accomplished almost entirely by colonies under the management of commercial beekeepers. Hobby beekeeping has been heavily promoted by most states in recent years and has experienced substantial growth. Commerical beekeeping is obviously important to the U.S. agricultural economy and to the process of establishing and maintaining national food self-sufficiency for purposes of national security. Despite this, commerical beekeeping has been steadily declining since the 1970's for a variety of reasons including a plethora of new diseases and pests, reduced profitability, lack of available capital, unattractiveness of the work to younger people, government import policy, and lack of government support. All levels of commercial beekeeping should receive more attention and support from the federal and state governments. Arguably, the most essential level of commercial beekeeping to foster is the small emerging commercial beekeeper. These operations typically manage 300 to 600 colonies. They have done enough of the "heavy lifting" in building an operation that they have a good chance of success but can still greatly benefit from "a little wind at their back". Supplemental feeding is particularly a problem for beekeeping endeavors of this size. Supplemental feed usually must be bought in 1/2 tanker or full tanker quantities. A half tanker of blended feed currently costs about $10,000.00 and the beekeeper must have facilities to store the syrup when delivered. These emerging commercial operations typically lack the resources to buy feed in this quantity but they require larger amounts at one time than can be practically handled with buckets, barrels, etc. Fostering of relatively local government run feed distribution facilities or government coordinated producer co-ops could be helpful.

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.