Final report for FNE16-840
Project Information
The results of this study support the conclusion that the use of treatment-free hive management techniques can control mite levels in colonies just as well as using the formic acid based commercial miticide treatment: Mite Away Quick Strip.
Honey production was severely reduced in both the TF and the TFQ groups (less than 2 supers on average compared to between 3-4 supers for the control and Quick Strip groups, in each of the three years of the trial) most likely due to the interruption of the brood cycle and from the removal of bees and brood during the creation of nucleus colonies in the spring.
Survival between the treatment groups was similar (not statistically significant and therefore may be a product of chance) however, the time of year and the reason colonies in each group died is strikingly different.
Colony strength of the QS treated group in the spring of 2017 showed a significant improvement over those of the colonies managed for varroa utilizing treatment-free techniques.
I will continue to promote the use of beekeeper hive management to control mites as long as the total number of colonies in the beekeeper's apiaries in less than 50-60. Beekeepers looking to avoid the use of chemical mite treatments are likely to benefit most from knowledge of theses results. While all beekeepers keeping bees in northern climates could benefit from knowing that mite populations are naturally low at the end of winter and that treating for mites in spring is probably a waste of time and resources.
Outreach by way of workshops and classes were offered in multiple settings in the Northeast in 2018 and 2019. Two articles were submitted to Bee Culture and the American Bee Journal.
There are four physical management techniques that have the potential to impact Varroa mite population levels and their impact on colonies.
1. Bottom Boards outfitted with a screened surface, rather than a solid wooden surface, have the potential to remove mites that lose their grip while either crawling around the hive, and fall to the bottom of the hive. [T. Webster, et. al. (2000) Journal of Economic Entomology, Pettis and Shimanuki, (1999) American Bee Journal] One result of this is that screened bottom boards have become a way of monitoring natural mite fall in an effort to determine when treatments are necessary (by estimating varroa populations), and testing efficacy following treatments. While it is established that screened bottom boards have the capacity to remove a relatively small percent of the phoretic mites (mites on bodies of bees) in a hive, it has not proven to be a viable control for Varroa on its own.
2. The reproductive biology of the Varroa mite is closely tied to the reproductive biology of the honey bee as young mites feed on the fat bodies of the honey bee pupae and larvae during its development. On average, a female Varroa mite can raise about two additional mites during a single honey bee brood cycle of 21-24 days. [A.I . Root Co., ABC & XYZ of Bee Culture, (2006) 41st Edition, pg. 553] This leads to exponential population growth of the mites in infested hives. By interrupting the honey bee brood cycle, the reproductive cycle of the mite can be similarly interrupted resulting in a decrease in the speed with which the Varroa population can increase within a colony. Field observations indicate that hives experiencing an interruption in the brood cycle have an increased capacity to survive through winter when untreated, compared to untreated hives that do not experience a similar break in the brood cycle.
3. Beeswax is composed primarily of fatty acids and oils which act as a sponge absorbing petroleum based pesticides that the comb is exposed to. These pesticide residues can build up and concentrate in the wax over time. Beeswax comb has also been shown to accumulate honey bee disease organisms as it ages in a hive. Research has shown that old combs with chemical and pathogen residues have sub-lethal impacts on the health and vitality of honey bee colonies. [Wu, Anelli, and Sheppard, (2011) PLoS ONE] Since it has been established that honey bees exposed to outside stress, are unable to handle the additional stress of Varroa infestation as easily as unstressed colonies, it is theorized that by removing additional stress factors (such as old contaminated comb), colonies of bees will be able to survive the stress induced by Varroa mite infestation more successfully.
4. Due to the longer gestation period of honey bee drone brood, Varroa mites prefer to lay their eggs and raise their young in occupied honey bee drone brood cells. As much as two-thirds of all the mites infesting a hive at any time can be found reproducing in honey bee brood cells. By removing and destroying frames of capped drone brood before the mature drones emerge, large numbers of mites that are reproducing within the drone brood cells can be removed from the hive. [Calderone (2005) Journal of Economic Entomology, Wantuch and Tarpy (2009) Journal of Economic Entomology]
On their own, none of these approaches (Screened bottom boards, interruptions of the brood cycle, removing of old contaminated comb, and culling drone brood) have proven to keep honey bee colonies alive over an extended period of time while colonies are under stress from Varroa mites. However, when these approaches are combined, anecdotal reports are that they can keep Varroa infested hives alive without the need for other mite treatments of any kind. To date unfortunately, no scientific trials have tested this hypothesis.
Cooperators
- - Technical Advisor
- (Educator)
- (Educator)
Research
As planned, 45 nucleus colonies were purchased, divided into three groups of 15 colonies each, and established in two apiary locations. One location (Bassett Knoll) is the home of 15 hives that are acting as the Control (C) group. The other location (Elgin Springs) is about 3/4 miles from Bassett Knoll and is the location of a total of 30 hives: the 15 Treatment-Free (TF) hives in which the Queen, brood and bees are removed each spring to break up the brood cycle, as well as the 15 hives that are to receive Mite Away Quick Strip (QS) treatment for mites.
An addition was made to the original design of this project by creating a fourth apiary composed of the bees and queens removed from the treatment-free (TF) yard during year one. This fourth apiary location is about 15 miles from the other yards and makes up the Treatment-Free with Queen (TFQ) Group. These bees were treated the same as the treatment-free apiary (TF) except, rather than removing bees, brood and the queen as is was donee with the TF group at Elgin Springs, the queen stayed with the colony when bees and brood were removed to interrupt brood rearing.
The following performance targets outlined in the project description are summarized below based upon all available data to date. (See attached data file For specifics).
Mite Monitoring - Varroa mite loads were typically monitored in late June/early July (2016) or late May 2017-2019 after the TF group had undergone a brood break and had successfully raised a new queen naturally, and again in late August/early September 2016-2018 after the QS group had received its commercial mite treatment. Average mite loads were as follows:
June 2016 Mite Counts
Control (C) Group: Initial mite levels June 29 - July 3, 2016 ranged from a low of 4 mites per 300 bees to a high of 53 mites per 300 bees. The average number of mites per 300 bees was 20 for C group.
Mite Away Quick Strip (QS) Group: Initial mite levels in June 29, 2016 ranged from a low of 1 mite per 300 bees to a high of 19 mites per 300 bees. The average number of mites per 300 bees was 8.5 for QS group.
Treatment-Free (TF) Group: Initial mite levels in June 29, 2016 ranged from a low of 1 mite per 300 bees to a high of 10 mites per 300 bees. The average number of mite per 300 bees was 4.7 for TF group.
Treatment-Free with Queen (TFQ) Group: Initial mite levels in June 25, 2016 ranged from a low of 0 mites per 300 bees to a high of 11 mites per 300 bees. The average number of mite per 300 bees was 3.7 for TFQ group.
2016 Late August/early September Mite Counts
Group C: Mite levels in September 2016 ranged from a low of 15 mites per 300 bees to a high of 50 mites per 300 bees. The average number of mite per 300 bees was 28.8 for C group.
Group QS: Mite levels in September 2016 (Prior to treatment) ranged from a low of 11 mites per 300 bees to a high of 45 mites per 300 bees. The average number of mites per 300 bees was 24.7 for QS group prior to treatment.
Group TF: Mite levels in September 2016 ranged from a low of 1 mite per 300 bees to a high of 29 mites per 300 bees. The average number of mite per 300 bees was 8.2 for TF group.
Group TFQ: Mite levels in September 2016 ranged from a low of 2 mites per 300 bees to a high of 25 mites per 300 bees. The average number of mite per 300 bees was 10.6 for TFQ group.
2016 Mid-September Mite Count
A final mite count was taken from Group QS following their treatment with the Mite Away Quick Strips: Mite levels on September 19, 2016 (Following treatment) ranged from a low of 3 mites per 300 bees to a high of 17 mites per 300 bees. The final average number of mites per 300 bees was 13 for QS group.
2016 Survival - Colony survival in the first year of the trial:
Control (C) Group: Of the 15 colonies initially established May 2016, 14 colonies (93.3%) were alive and healthy heading into the winter of 2016-2017, 5 colonies were alive in April of 2017 (33.3%).
Mite Away Quick Strip (QS) group: Of the 15 colonies initially established in May 2016, 13 colonies (86.6%) were alive and healthy heading into the winter of 2016-2017, 10 colonies were alive in April 2017 (66.6%).
Treatment-Free (TF) group: Of the 15 colonies initially established in May 2016, 5 colonies died out within the first 2 months of the trial (4 went queenless when they failed to successfully raise a new queen following nuc making, and 1 colony went queenless after suffering a severe case of chaulk brood). A total of 9 colonies (60%) were alive and healthy heading into the winter of 2016-2017, 8 Colonies were alive in April 2017 (53.33).
Treatment-Free with Queen (TFQ) group: Of the 15 colonies initially established in May 2016, 15 colonies (100%) were alive and healthy heading into the winter of 2016-2017, 7 were alive in April 2017(46.66%), and 6 were alive in September 2017 (40%).
May 2017 Mite Counts
Control (C) Group: Initial mite levels May ranged from a low of 2 mites per 300 bees to a high of 9 mites per 300 bees. The average number of mites per 300 bees was 4.6 for C group.
Mite Away Quick Strip (QS) Group: Initial mite levels in May 2017 ranged from a low of 3 mites per 300 bees to a high of 9 mites per 300 bees. The average number of mite per 300 bees was 5.0 for QS group.
Treatment-Free (TF) Group: Initial mite levels in May 2017 ranged from a low of 0 mites per 300 bees to a high of 13 mites per 300 bees. The average number of mite per 300 bees was 3.89 for TF group.
Treatment-Free with Queen (TFQ) Group: Initial mite levels in May 2017 ranged from a low of 0 mites per 300 bees to a high of 6 mites per 300 bees. The average number of mite per 300 bees was 2.83 for TFQ group.
2017 Late August/early September Mite Counts
Group C: Mite levels in September 2017 ranged from a low of 16 mites per 300 bees to a high of 48 mites per 300 bees. The average number of mite per 300 bees was 26 for C group.
Group QS: Mite levels in September 2017 (Prior to treatment) ranged from a low of 6 mites per 300 bees to a high of 29 mites per 300 bees. The average number of mites per 300 bees was 17.14 for QS group prior to treatment.
Group TF: Mite levels in September 2017 ranged from a low of 0 mites per 300 bees to a high of 18 mites per 300 bees. The average number of mite per 300 bees was 5 for TF group.
Group TFQ: Mite levels in September 2017 ranged from a low of 2 mites per 300 bees to a high of 70 mites per 300 bees. The average number of mite per 300 bees was 22.67 for TFQ group.
2017 Mid-September Mite Count
A final mite count was taken from Group QS following their treatment with the Mite Away Quick Strips: Mite levels in September 2017 (Following treatment) ranged from a low of 0 mites per 300 bees to a high of 6 mites per 300 bees. The final average number of mites per 300 bees was 2.86 for QS group (following treatment).
2017 Survival - Colony survival approximately half-way through the trial (18 months) is as follows:
Control (C) Group: Of the 5 colonies that were alive in April of 2017 (33.3%), 5 were alive heading into the winter of 2017 (33.3%) and none survived until April 2018.
Mite Away Quick Strip (QS) group: Of the 10 colonies (66.6%) were alive in April 2017, 7 were alive heading into the winter of 2017 (46.6%) and all 7 were alive in April 2018.
Treatment-Free (TF) group: Of the 8 Colonies were alive in April 2017 (53.33), all 8 were alive heading into the winter in September 2017 (53.33) and all 8 were alive in April 2018.
Treatment-Free with Queen (TFQ) group: Of the 7 were alive in April 2017 (46.66%), 6 were alive heading into the winter of 2017 (40%) and 4 survived and were alive in April 2018.
May 2018 Mite Counts
Control (C) Group: Colonies did not survive to the spring of 2018.
Mite Away Quick Strip (QS) Group: Initial mite levels in May 2018 ranged from a low of 0 mites per 300 bees to a high of 7 mites per 300 bees. The average number of mite per 300 bees was 2.857 for QS group.
Treatment-Free (TF) Group: Initial mite levels in May 2018 ranged from a low of 1 mite per 300 bees to a high of 7 mites per 300 bees. The average number of mite per 300 bees was 3.625 for TF group.
Treatment-Free with Queen (TFQ) Group: Initial mite levels in May 2018 1 mite in each of 3 colonies per 300 bees. One colony was queenless at the time of mite counts and I did not take mite samples since there was no brood in the hive. Turned out that I had inadvertently removed the queen when I had make a spring nucleus colony from that hive. Upon discovery of my mistake, I returned the queen to its hive so that the queen had only been removed from the colony for a period of 5 days. The average number of mite per 300 bees was 1.0 for TFQ group.
2018 Survival - Colony survival approximately half-way through the trial (18 months) is as follows:
Control (C) Group: Of the 15 colonies initially established May 2016, 14 colonies (93.3%) were alive and healthy heading into the winter of 2016-2017, 5 colonies were alive in April of 2017 (33.3%), 5 were alive in September 2017 (33.3%), all 5 died over the winter of 2017-2018 and none survived into the spring of 2018. (0.0%)
Mite Away Quick Strip (QS) group: Of the 15 colonies initially established in May 2016, 13 colonies (86.6%) were alive and healthy heading into the winter of 2016-2017, 10 colonies (66.6%) were alive in April 2017, 7 were alive in September 2017 (46.6%), all 7 survived the winter and were alive in April 2018, and 6 survived the summer and were headed into winter in November 2018. (40.0%)
Treatment-Free (TF) group: Of the 15 colonies initially established in May 2016, 9 colonies (60%) were alive and healthy heading into the winter of 2016-2017, 8 Colonies were alive in April 2017 (53.33), 8 were alive heading into winter in September 2017 (53.33), all 8 survived the winter and 7 survived the summer and were headed into winter in November 2018. (46.6%)
Treatment-Free with Queen (TFQ) group: Of the 15 colonies initially established in May 2016, 15 colonies (100%) were alive and healthy heading into the winter of 2016-2017, 7 were alive in April 2017(46.66%), 6 were alive in September 2017 (40%), 4 colonies were alive in April 2018 (26.67%) and all 4 were heading into the winter in November 2018. (26.67%)
2018 Early September Mite Counts
Group C: N/A
Group QS: Mite levels in September 2018 (Prior to treatment) ranged from a low of 11 mites per 300 bees to a high of 160 mites per 300 bees. The average number of mites per 300 bees was 84.333 for QS group prior to treatment.
Group TF: Mite levels in September 2018 ranged from a low of 0 mites per 300 bees to a high of 40 mites per 300 bees. The average number of mite per 300 bees was 15.286 for TF group.
Group TFQ: Mite levels in September 2018 ranged from a low of 5 mites per 300 bees to a high of 45 mites per 300 bees. The average number of mite per 300 bees was 16.75 for TFQ group.
2018 Late-September Mite Count
A final mite count was taken from Group QS following their treatment with the Mite Away Quick Strips: Mite levels in September 2018 (Following treatment) ranged from a low of 5 mites per 300 bees to a high of 46 mites per 300 bees. The final average number of mites per 300 bees was 18.0 for QS group.
2019 Colony Survival
Control (C) Group: Of the 15 colonies initially established May 2016, none survived into the spring of 2019 . (0.0%)
Mite Away Quick Strip (QS) group: Of the 15 colonies initially established in May 2016, 1 colony was alive in the spring of 2019 (6.6%).
Treatment-Free (TF) group: Of the 15 colonies initially established in May 2016, 7 were headed into winter in November 2018 and 1 colony was alive in the spring of 2019 (6.6%).
Treatment-Free with Queen (TFQ) group: Of the 15 colonies initially established in May 2016, 2 survived the winter and were alive in the spring of 2019 (13.3%).
Productivity - Honey supers harvested from all hives were recorded. (see attached data table) In establishing the figures below, it is assumed that a full shallow super harvested typically contains 20 pounds of honey.
C Group -
2016 - an average of 1.5 supers of honey was harvested from each hive in September 2016 representing approximately 30 pounds per hive.
2017 - An average of 2.4 supers of honey was harvested from each hive in September 2017 representing approximately 48 pounds per hive.
2018 - No honey was harvested in 2018 due to total colony loss in this apiary.
QS Group -
2016 - An average of 1.18 supers of honey was harvested from each hive in this group representing 23.5 pounds per hive.
2017 - An average of 3.625 supers of honey were harvested from each hive in September 2017 representing approximately 72.5 pounds per hive.
2018 - An average of 2.917 supers of honey were harvested from each hive in September 2018 representing approximately 58.34 pounds per hive.
TF Group -
2016 - No honey was harvested from any of the hives in the TF group in the first year.
2017 - One super of honey was harvested from the TF group in September 2017 representing an average of .125 supers per hive and approximately 2.5 pounds per hive.
2018 - 3.5 supers of honey were harvested from the TF group in September 2018 representing an average of .5 supers of honey per hive and approximately 10 pounds per hive.
TFQ Group -
2016 - An average of .1 super of honey was harvested from each hive in September 2016 representing 2 pounds of honey per hive.
2017 - An average of 1.67 supers of honey were harvested from each hive in September 2017 representing an average of 33.33 pounds of honey per hive.
2018 - An average of .625 supers of honey were harvested from each hive in September 2018 representing an average of 12.5 pounds of honey per hive.
Colony Strength in Spring
Eleven months after the study commenced, colony strength in each group was measured in late April 2017 by placing a piece of one-inch hardware cloth cut to the size of a frame of comb over each comb containing brood within each hive and counting the number of full one-inch squares of brood. This provided a total number of square inches of brood within each hive and gave a very accurate picture of the relative strengths of each colony.
In late April 2017 when surviving colonies were evaluated for strength (based on number of square inches of capped brood). The following averages were observed:
C Group - A high of 611 sq. inches and a low of 299 sq. inches of brood was found with an average of 456.6 sq. inches of brood within the group. (note: one square inch of brood represents 25 worker bees (or 16 drones).
QS Group - A high of 710 sq. inches and a low of 406 sq. inches of brood was found with an average of 555.4 sq. inches of brood within the whole group.
TF Group - A high of 713 sq. inches and a low of 69 sq. inches of brood was found with an average of 430.75 sq. inches of brood within this group.
TFQ Group - A high of 490 sq. inches and a low of 170 sq. inches of brood was found with and average of 379 sq. inches of brood within the group.
Due to time constraints, hive strength as indicated in terms of square inches of capped brood was not measured in 2018 or 2019.
During the three years that this study was conducted mite loads were monitored in each colony using a sugar shake once in spring and again in late summer, honey production tracked, winter survival noted, and after the first winter, colony strength measured as indicated by the number of square inches of capped brood in each hive.
Average mite loads observed throughout the study are represented in the following graph. (SARE Full Varroa Sampling Graph) The graph shows average mite populations measured within each of the four study groups: the control group represented by the line labeled C; the Mite Away Quick Strip treated group represented by the line labeled QS; the treatment-free group maintained using all four mite management techniques (screened bottom board, brood interruption via removing the queen to make a nucleus colony, culling drone brood and rotating out comb older than 5 years) is represented by the line labeled TF; and the apiary where all hives received the same management as the treatment-free group except the queen was not removed from the hive when a nucleus colony was made each spring is represented by the line labelled TFQ.
The graph depicts the seven sampling events that took place during the course of the study. Sampling event #1 in late June/early july of 2016, sampling event #2 in late August/early September 2016, Sampling event #3 in late May 2017, sampling event #4 in early-mid September 2017, sampling event #5 in mid-May 2018, sampling event #6 in mid-September 2018, and sampling event #7 in early May 2019. Mite counts were taken both before and after the late summer each Mite Away Quick Strip treatment in the QS study group.
Throughout the study, varroa mite levels tended to increase during the active season and tended to decrease over the winter in all four study groups. With the exception of the QS group during the second year of the study this pattern was consistent. The consistency appears whether colonies had high mite loads heading into winter or low mite loads heading into winter.
The data also shows that there was no significant differences in mite levels during throughout the study between the group treated with the commercial miticide and the group managed using the four management techniques described above. A significant difference in mite levels is indicated in the second year of the study within the group exposed to the four management techniques but that did not experience the brood break created by removal of the queen during nuc making.
The data also shows an unusually high mite population in mid-September of 2018 across all three remaining study groups compared to the late season populations during the two previous years.
With the exception of the control group, there was no significant difference in survival between the treated apiaries. Overall survival of each group of colonies by September 2017 (8 hives alive-TF, 7 hives-QS, 6 hives-TFQ, 5 hives-C) indicated no statistically significant differences between groups. The last of the colonies in the Control Group (C) died during the winter of 2017-2018. As of November 1, 2018 there were 6 colonies still alive in the Mite Away Quick Strip (QS) treatment group, 7 colonies still alive in the Treatment Free group (TF), and 4 colonies still alive in the Treatment Free group in which a break in the brood cycle is not induced by removal of the queen (TFQ). However, mite levels were high heading into the winter of 2018-2019 in all groups, including the MAQS treated group following treatment, and this was the likely reason most of the remaining colonies died during the final winter. In the spring of 2019 at the conclusion of the study, only one colony from both the QS and TF groups and two colonies in the TFQ group had survived. (see graph of survival here SARE Colony Survival Graph)
It is interesting to note that despite losing 25% of is colonies within the first two months of the trial, the group under treatment-free management (TF) had a survival rate, as measured by the number of colonies still alive each spring with a fertile laying queen, that was as good as, or better than all the other groups.
What is striking when is not so much survival data but the cause of colony death. With the exception of the final winter, the majority of the colonies in the C and TFQ groups died during the winter (inactive) months, with the apparent cause of death the added stress from elevated varroa mite loads.
Meanwhile the majority of the colonies lost in the QS and TF groups died during the summer (active) months. With QS colonies mostly collapsing due to queen loss. I suspect that this is caused by one of two situations: 1) the colony swarms and unsuccessfully raises a new queen leading to queenlessness. 2) Pesticide and Pathogen loads in the pollen and nectar brought into the hive combined with the chemical residues on the old combs lead to queen failure or supercedure and the colony is unsuccessful in raising a new queen leading to queenlessness.
During the summer of 2018 I observed one colony in the study (group QS) die out from symptoms that have been used to describe colony collapse disorder (CCD). This colony had a mite count of zero per 300 bee sample in June, had been building up very well and had two and half supers of honey stored in the hive, but by mid-July it dwindled down to a handful of bees on three frames of brood, and it died out by end of the month.
For some unknown reason, a four of the TF colonies died out due to failure to successfully raise a new queen following queen removal in the spring of 2016 in order to artificially produce an extended break in the brood cycle.
The data indicates a clear trend in honey production with the TF and TFQ (Treatment Free with Queen) colonies producing significantly less honey than the C and QS colonies. SARE Honey Production Graph
Due to time constraints, I was only able to monitor spring colony strength during the spring of 2017 by counting the square inches of capped brood in each hive. The data showed a clear honey production benefit to treating with the commercial MAQS treatment over the management modalities. (SARE Colony Strength Graph)
This study sought to compare the effectiveness of using treatment-free management techniques compared to a commercial mite treatment, for the management of varroa mites in honey bee colonies.
The results of this study support the conclusion that the use of treatment-free hive management techniques can control mite levels in colonies just as well as using the formic acid based commercial miticide treatment: Mite Away Quick Strip.
Honey production was severely reduced in both the TF and the TFQ groups most likely due to the interruption of the brood cycle by removing bees and brood during the creation of nucleus colonies in the spring.
Survival between the treatment groups was similar (not statistically significant and therefore may be a product of chance) however, the time of year and the reason colonies in each group died is strikingly different.
Colony strength of the MAQS treated group in the spring of 2017 showed a significant improvement over those of the colonies managed for varroa utilizing treatment-free techniques.
Education & Outreach Activities and Participation Summary
Participation Summary:
During 2018 I offered 3 presentations that shared the preliminary data and results produced by this study so far. The first was on August 5, 2018 for the Capital Area beekeepers in New Hampshire, the second was on October 24, 2018 for the Addison County Beekeepers Association, and the final presentation was on November 3, 2018 for the Pennsylvania State Beekeepers Association.
In 2019 preliminary data from this study was included as part of a beekeeping class I taught at the Metta Earth Institute in May. I also included my preliminary SARE study results during a workshop at the NOFA-VT winter conference in Burlington, VT, and am planning on sharing the results during workshops at the Common Ground Country Fair in Unity, Maine in September, and during the month of October, at the Northern Natural Beekeeping Conference in Benzonia, Michigan, for the beekeeping club, Detroit Hives, in Detroit, MI, the Chautaqua County Beekeepers Association of New York State, and at Paul Smith College.
Besides submitting an article describing this study to the two national beekeeping magazines, Bee Culture and the American Bee Journal, I am planning on submitting an article to be published in the Journal of Apicultural Research. Since papers submitted to the Jour. of Api. Res. are not permitted to have been published elsewhere, I plan on delaying the submittal of my articles to the national bee journals until my paper is accepted (or rejected) by the scientific journal.
Learning Outcomes
As a result of this study I learned several things.
Varroa mite counts in early spring have a tendency to be very low, no matter what level they are at in the beginning of winter. Whether Autumn mite counts were high (control group) or low, all colonies showed low mite counts by spring. It appears that in a northern climate such as in Vermont where there is a prolonged cold winter, the natural brood break that the bees utilize to conserve their food resources and survive the winter months greatly reduced the mite populations at the same time.
It can be difficult to get bees to draw out drone comb and fill it with drone brood when starting with drone foundation. Sometimes the bees would fill the drone comb with honey and pollen. In one case the bees built worker brood comb on the drone foundation.
Varroa levels can have little to do with the presence of Colony Collapse Symptoms. Once colony in the QS group displayed a zero mite count in June, but had totally collapsed and died out by mid-July after displaying the CCD symptoms of dramatic bee population loss over a relatively sort time, a lack of dead bees in or around the hive, and delayed invasion of scavengers into the collapsing hive.
The impacts of the Varroa bomb phenomenon appeared to be much more prevalent within an apiary than between apiaries. As long as mites were effectively controlled by mid-September, colonies had little trouble surviving the winter despite the presence of an apiary of untreated, mite infested hives located three-quarters of a mile away.
Varroa mite populations may fluctuate wildly from year to year. It was observed that for some unknown reason, mite populations were significantly higher in all colonies in year three, compared to the first two years of the study.
Mite Away Quick Strip treatments should be used within the first year that they are purchased. Left-over MAQS treatments from year two were used in year three with poor mite control results. This is despite the label stating that the strips can be stored for up to two years. It may be that the amount of time that the MAQS treatments are kept in storage and sit on the shelf prior to purchase must also be taken into account when calculating the two-year window for effective use.
Project Outcomes
One significant outcome of this project is that, at least for me, it appears that the number of colonies that can be successfully kept alive year-to-year using the combined management techniques described above to control varroa mites is limited. For about six years prior to the start of this study I managed 40-60 colonies using only management techniques to control mites and consistently experienced and average winter losses of less than 20 percent. Once I added the 60 colonies of the study to my work load, my winter losses jumped to between 38 and 51 percent in all three years.
During the course of this study, I was able to answer the questions I set out to answer with regard to mite populations, colony survival, and honey production between colonies exposed to different mite control approaches.
The unexplained dramatic increase in varroa populations throughout all hives in year three of this study suggests the need for more study into environmental, climate, and other factors that naturally effect varroa populations in honey bee colonies.
I will continue to promote the use of beekeeper hive management to control mites as long as the total number of colonies in the beekeeper's apiaries in less than 50-60.
Beekeepers looking to avoid the use of chemical mite treatments are likely to benefit most from knowledge of theses results. While all beekeepers keeping bees in northern climates could benefit from knowing that mite populations are naturally low at the end of winter and that treating for mites in spring is probably a waste of time and resources.