Monthly Archives: April 2011

New Paper: a role by cell size in honey bee caste differentiation

Diet and Cell Size Both Affect Queen-Worker Differentiation through DNA Methylation in Honey Bees (Apis mellifera, Apidae)


Young larvae of the honey bee (Apis mellifera) are totipotent; they can become either queens (reproductives) or workers (largely sterile helpers). DNA methylation has been shown to play an important role in this differentiation. In this study, we examine the contributions of diet and cell size to caste differentiation.

We measured the activity and gene expression of one key enzyme involved in methylation, Dnmt3; the rates of methylation in the gene dynactin p62; as well as morphological characteristics of adult bees developed either from larvae fed with worker jelly or royal jelly; and larvae raised in either queen or worker cells. We show that both diet type and cell size contributed to the queen-worker differentiation, and that the two factors affected different methylation sites inside the same gene dynactin p62.

We confirm previous findings that Dnmt3 plays a critical role in honey bee caste differentiation. Further, we show for the first time that cell size also plays a role in influencing larval development when diet is kept the same.

Yuan Yuan Shi1, Zachary Y. Huang2,3*, Zhi Jiang Zeng1*, Zi Long Wang1, Xiao Bo Wu1, Wei Yu Yan1

1 Honeybee Research Institute, Jiangxi Agricultural University, Nanchang, Jiangxi, China, 2 Department of Entomology, Michigan State University, East Lansing, Michigan, United States of America, 3 Ecology, Evolutionary Biology and Behavior Program, Michigan State University, East Lansing, Michigan, United States of America

MSU Package Bee Installation (Day 2 and 3)

Day 2, Friday, April 22.
Dr. Samina Qamer and I went to the “George Yard”, about 25 miles away and near the Sleepy Hollow State Park. Here we used 12 buckets (2 gallon ones) as feeders and 2 ziplock bags for the rest (A total of 14 colonies). A medium super is not quite tall enough to house the bucket (probably 1″/2.54 cm short), but it is better than nothing.

All the shots below were by an infrared modified camera, but unprocessed (which involves channel swapping using Photoshop, do not have time right now :(

The hives before installation.

Shaken bees

Dr. Qamer smiling, infrared can “see” through the veil much better than a regular camera.

Bucket as a feeder, probably better than any other type (hive top feeder/in hive frame feeder: to many bees drowned; ziplock: difficult to control flow rate; entrance feeder: too cold to be used now), if the screen is not broken (which could lead to a leak).

Almost all done. I was still learning (even after 10 years of installing packages), here I put an empty super on top, thinking that it would be easier to shake the bees into it (instead of shaking into the deep with 3 frames removed, which one would have a hard time putting the frames back because of the pile of bees on the bottom). I put the inner cover on….30 min later, the bees mostly clustered around the queen cage, metal can, and hanging on to the inner cover! Bees always want to move UP (if it is dark). They will move down if exposed to light. So in the end we doubled our time because we had to brush all the bees back before putting the inner cover on top of the deep and putting the bucket feeder on.

You need a plugin called Quicktime Player to see the following videos automatically. It was recorded by the old Nikon coolpix 990 camera. 40 seconds max, no audio.

Here Dr. Qamer shows the steps before shaking the bees:

Here Dr. Qamer shows the actual shaking. Please click the link below to watch the video — my code to prevent auto start does not work :(


Day 3, Saturday, April 23.
Shot by D70, a 6 year old camera (bought March 2004).

I wanted to see how the ziplock bags were doing since I had no prior experience with them. I found 2 bags almost totally empty (probably a leak near the zipper) and most did not leak enough. I had to put another 4-10 holes for each bag to make the bees happy.

I saw three deers on the road there, right in front of another house! Beekeeping really puts you in close contact with nature!

This one must be a baby. They are always so curious and would look straight into your eyes (or camera!).

Look at the wonderful beeswax already! Only 2 days, not yet 48 hours after installation.

I found one queen out of 3 colonies…She is a beauty! A blondie. She has 2 copies of a mutated gene called Cordovan, which makes her a reddish leather color and all pink legs.

End of Part 2.

2011 MSU Package Bee Installation (Day 1)

This is definitely the worst year for the MSU apiary – 100% bee loss. I could have saved about 5-6 colonies if we had sugar boards in Jan/Feb, since some colonies died with brood and with bees that were emerging. Instead I had to purchase 40 three-pound packages, at $70 each. I ordered 20 Italian queens and 20 Carniolans.

The packages arrived and were picked up Monday (April 18th), but the weather was too cold to install them. We tried on Tuesday but it was raining and cold (about 4C), and we gave up after almost getting totally wet. But we did setup 10 hives to house the new packages. These 10 could be installed at any time (although still preferably above 11C/51F during installation, so that bees can cluster, because bees can become immobilized below that) since they have some honey (2-3 frames of old honey) and do not rely on feeders.

We wanted to establish most colonies Nosema-free for our studies. These would have all the wooden parts (bottom board, hive body, wooden frames, inner cover, outcover) autoclaved and start with new foundations. They thus need to be provided with lots of sugar syrup (especially at this weather!). We have three types of feeders:
1. We only had 12 bucket feeders (2 gallon buckets with a screened hole in the center) which are not much affected by weather (i.e. bees can probably drink from it around near-freezing temperature).
2. Hive top feeders, which require bees to climb up and drink from a tray located on either side. These feeders will not work during cold weather — bees will not be able to go up and take food, if it is below 11C/51F.
3. We have tons of hive-top feeders, but cannot use them due to cool weather. So I decided to try ziplock bags. Have not really used them before, so first time for me.

The following is a photo journey for what we did on Thursday.

These packages have been sitting in the garage for 4 days.

Matt preparing Fumidil for feeding the bees. This antibiotic will only disrupt Nosema spore reproduction after the spores are germinated inside the midgut of bees.

This is the home site…packages will be housed in old equipment – it will provide us sources of Nosema ceranae through natural infection (hopefully! Usually packages bees came with a high dose of Nosema).

The first step is to separate the packages from the wooden support.

Now the packages are ready. Samina, a postdoctor fellow from Pakistan was helping. She probably did more packages since I was trying to take photos and installing at the same time. I used an old point and shoot camera for the photos.

This frame has signs of AFB (American foulbrood) and I had to throw frames like these out. Last time in the rain we did not inspect carefully enough.

I did not use a veil, got 5 stings in my head at this yard. At Simons I got about 25 more! So use a veil! I did the next day (and also today).

Take the queen cage out by sliding the metal out.

The queen would be inside this cage. The cage has no food, but all 40 queens were alive.

Removing the cork so that queen can escape – I am not sure if I made the right decision to release alt the queens the same day. It is possible that bees might turn against their queens when too stressed. I was thinking to let the queens out right away since the packages have been sitting in the garage for 4 days and they had enough time to “know” their queens. It would have been safer to come back the 2nd day and release the queens. This type of cage did not have the option of “self-release” — some cages have sugar filled holes and once you remove a cork, bees can eat through the sugar and release the queen. One can also use a nail to punch a hole in the sugar to make that process faster.

Shaking the bees to the hive.

Bees shaken out to the hive.

20 min later, bees are spread onto all the frames.

Bees flying around after done. It was about 54 that day. I had to right the packages (with the hole upward) later since at these orientations the bees could not get out.

At Simon yard. These packages are orientated correctly so bees can escape easier (they tend to go up!).

Our ziplock bag “feeder” (1 gallon size).

Using a pin to punctuate 1-2 holes per bag. I was afraid the syrup would run too fast when I saw it was sprouting out quite quickly. But when I checked today (Saturday, April 23rd, most bags were too full, and I had to add 6-10 holes per bag). But 2 bags were nearly empty, perhaps due to a leak from zipped area, unintentionally.

With a medium super to give room for the feeder.

Matt had a bad reaction to bee sting and had to visit an urgent care. So Samina and I did not finish all 40 packages the first day. We checked each can for enough syrup. If empty, we punched a hole in the center and added some syrup (about 20% of the can), which we estimated it would be enough for one more day. The hole on the side can let the air out and making adding syrup easier. Sorry I have not used a point and shoot camera for a while and this one was not focused. SLR would not do this but I did not want to have my $3000 camera gunked up with propolis and beeswax.

Then ducktaped the holes. Next day I found on some, the tape was chewed by bees and all sugar leaked out.

Honey bee update and fruit pollination

An update on Colony Collapse Disorder and how to get the best pollination this season.

Published April 14, 2011, Digg Email Facebook Google Reddit Spurl StumbleUpon Technorati TwitThis

Zachary Huang and Walt Pett, Michigan State University Extension, Department of Entomology

Importance of honey bees to Michigan agriculture

The Western honey bee Apis mellifera plays a crucial role for U.S. agriculture because it provides pollination for a large number of crops. The value of agricultural crops dependent on honey bee pollination was estimated to be $14.6 billion per year in the United States. According to the most recent production data published in October 9, 2009, Michigan’s fruit and vegetable industry produces over $2 billion per year and nearly 50 percent of that value is due entirely to honey bee pollination, or $978 million. This is more than 100 times the value of honey alone, which was $7.4 million in 2008.

The decline of honey bees, a national trend

Despite the importance of honey bees, the beekeeping industry has been in decline since two parasitic mites, varroa (Varroa descructor) and tracheal mites (Acarapis woodi), invaded the United States in the 1980s. Varroa mites have nearly wiped out the feral, or unmanaged, honey bee population in the United States and managed honey bee colonies have been declining mainly due to more complicated management because of the mites. For example, in Michigan alone, the total number of honey producing colonies has decreased from the 95,000 in 1988 to 66,000 in 2009. This is almost a third reduction of managed bee colonies during the last 21 years. About 30,000 of these colonies are “migratory,” whereby beekeepers move their bees to southern states, such as Florida and Georgia, and California to overwinter their colonies, and come back in April for fruit tree pollination.

Varroa mites continue to be the major threat to our honey bees. For the first time since 1998 winter, MSU’s apiary lost 100 percent of its overwintering colonies. Many beekeepers reported losing 80 to 90 percent of their bees last winter. This was the first time at the ANR beekeeping program that all major package bee suppliers were sold out. Package bee prices went up to $70 to $85 per 3 pounds this year. It is likely that pollination prices will be $5 to $10 higher per colony this year, based on the increase of package bee prices.

Colony Collapse Disorder (CCD)

The most recent crisis in honey bee population is called colony collapse disorder (CCD), which has been reported in the national news during 2007. Colonies affected CCD show three symptoms. First, bees “disappeared” from their colonies with no dead bees inside or near the hive. A colony, seemingly healthy in September, will have no bees, or a handful of bees, with a queen, around October or November. The colony will have brood – eggs, larvae and pupae. This suggests adult bees left or died outside the colony quite rapidly. Usually, the colonies are not invaded right away by opportunistic pests such as small hive beetles, wax moths, and other honey bees (bees will take or “rob” honey from a nearby hive) for two to three weeks.

This disorder was reported in 33 different states and affected large beekeepers – 5,000 to 9,000 colonies – reporting losing up to 90 percent of their colonies. In Michigan, only about 6,000 colonies, out of a total of 65,000 colonies, were reported to be affected in 2006. But another Michigan beekeeper reported in February 2008 another loss of 2,300 colonies while pollinating almonds in California. The cause of this disorder is still unknown and honey bee scientists all over the country are studying the problem. A recent paper (Oct. 2010, PLOS One) concluded that a new virus, combined with Nosema ceranae could be the cause of CCD. This work remains to be verified.

Currently, most scientists think it might be a combination of several stresses: by pesticides applied inside for controlling mites and other pests, or outside for controlling pests on crops and brought back by bees; by migratory transportations across several time zones; by novel pathogens (a new nosema disease, Nosema ceranae was found to be present in this country for over 10 years, yet we only learned that it was here because of the CCD crisis); by the varroa mite, which suppresses the immune system of bees; and by the many types of viruses the mite transmits. IAPV is just one of the 20 viruses bees can be infected with. Other common viruses include acute bee paralysis virus (ABPV), black queen cell virus (BQCV), chronic bee paralysis virus (CBPV), Kashmir bee virus (KBV), and sacbrood bee virus (SBV). The cause(s) for CCD has not yet been identified as of today.

Importation of package bees from Australia was stopped this year due to the accidental introduction of the Asian honey bees (Apis cerana) into the Brisbane area from the Solomon Islands. This is yet another reason to secure bee colonies for pollination earlier this year.

In light of these problems of honey bees, the growers are urged to work even more closely with beekeepers to ensure good pollination results. We feel that the following steps can help growers to optimize their fruit and vegetable pollination.

Understand basic honey bee biology and behavior

Understanding some basic bee biology and beekeeping will facilitate your inspection of the hives, gauging of quality and strength of the hives, and help maximize the use of bees for your pollination.

Social structure. Honey bees are social insects and only the sterile female workers do all the in-hive work, such as cleaning, drying nectar into honey and feeding young, and outside work, such as foraging for water, pollen, nectar and propolis, and colony defense. The queen’s only job is to lay about 2,000 eggs per day and releases queen mandibular pheromone to let the workers know that she is present and healthy. The male’s, or drones, only job is to mate with queens and are produced only during May to August. A typical colony of bees has about 30,000 workers, one queen and a few to hundreds of drones. About a third of these workers are foragers. Foragers show flower constancy so that they tend to focus on flowers of a single species, resulting in more efficient pollination.

Internal factors affecting foraging behavior. To provide adequate pollination, honey bee colonies must be of sufficient strength, free of diseases, and have a laying queen with enough brood. A newly installed package bee colony, with 2 pounds of bees, would have about 9,000 to 11,000 workers and is considered on the weaker side. Such a colony would concentrate heavily on brood rearing and only have about 1,000 to 2,000 foragers. Only stronger colonies would send out about 30 percent of bees as foragers. A typical median strength overwintered colony would have about 30,000 workers and can send out 10,000 foragers. If you are comfortable checking bees and have the beekeepers permission, check for the presence of chalkbrood, American foulbrood and varroa mites. In general, three to five frames of solid brood suggest a fertile queen and a healthy colony.

External factors affecting foraging behavior. Environmental factors also affect honey bee foraging. Bees do not work in the rain and work less on cloudy days. Foraging activity is positively related to temperature, with a linear relationship from 60°F to 90°F. Bees slow down when it gets too hot – over 90°F. High winds, above 20 mph, will also inhibit flying activity. Bees tend to fly lower, near the orchard floor when winds are high.

Finding a beekeeper nearest to you

Zachary Huang has established a database of beekeepers willing to provide pollination services, with over 420 beekeepers registered. The majority of them are from Michigan. Go to, click Beebase on the left, then click the number two option under Search Information From the Databases, “For beekeepers providing pollination services,” and you have a choice to search beekeepers by area code, county, zip code or a last name. Once you have a working relationship with a beekeeper, it is best to keep working with the same one year after year.

Pest management during pollination

Do not apply broad-spectrum insecticides when flowers are open. Bee hives should be removed immediately after pollination if post-bloom pesticide applications are planned. By monitoring for pest problems carefully during bloom, growers can help minimize the need for pest control. If an insecticide application is necessary during bloom, the compounds that are least toxic to bees should be used with careful observation of the pollinator-restrictions on the label. In general, dust form is more harmful to honey bees, and morning or day applications are not as safe for bees as evening applications. Inform the beekeeper before a spray so that colonies can be shut down for one to two days with wetted burlap blocking entrances, if highly toxic insecticides have to be sprayed. This pesticides database lists the toxicity of various pesticides to honey bees.

Different strategies for different crops

Use the “early” strategy for tree fruits. For tree fruit crops, it is advantageous to have bees working the flowers as soon as they open. This provides multiple benefits. It improves the odds that fertilization will occur before the ovules start to lose vigor, which can happen in only three days on some crops. Flowers are more likely to receive the multiple visits needed to deposit enough pollen. In many crops, it is important to pollinate the first flowers, like cherry, or “king blossoms,” like apple, because they set the best fruits.

Use the “late” strategy for small fruit crops

Generally, flowers of small fruit crops are less attractive to honeybees than other flowers due to flower shape and less nectar, so the opposite strategy is used. Let the crop start to bloom before bringing bees in so that bees tend to forage more on your crop. If brought in too early, bees will learn to forage elsewhere and when crops bloom, they are not attractive enough to get the bees “back” to where you want them. Blueberry flowers have about three days to be pollinated after the flowers open, but you want the bees to stay in the field, so move bees into blueberry fields after 5 percent bloom, but before 25 percent of full bloom. The “late” strategy is especially important for cranberries, which is not very attractive to bees. Luckily, cranberry flowers will stay open for a while if not pollinated, and the petals will turn to a rosy color if not pollinated in time. In cranberries, it is better to wait until 10 percent bloom in order to maximize the yield. If you see too many flowers turning rosy, this means you did not have enough pollinators, so make sure you increase the number of bee hives next year.

Hive density recommendations

Because Varroa mites had wiped most of our feral honey bee populations, recommended rates for pollination prior to 1987 have to be increased to compensate the lack of “free” honey bees. The table below lists recommended rates for hive density. From an economic point of view, it is best to start with the highest number of hives you can afford, then cautiously reducing it the following year to see if your yield is affected. An alternative method is to place different densities of honey bee colonies in separate orchards and determine if there is a difference in yield.

Table 1. Recommended density of honey bee colonies per acre for Michigan crops.

Table 1.

Internet resources

pdf fileHoney bees as pollinators

pdf fileBumble bees as pollinators

pdf filePollination and pesticides

Acknowledgements and references

CCD Working Group. 2007a. Map of CCD distribution.

CCD Working Group. 2007b. Map of CCD distribution. CCD Frequently Asked Questions (FAQ). pdf file

Kraus, B. & R.E. Page, Jr. 1995. Effect of Varroa jacobsoni (Mesostigmata: Varroidae) on feral Apismellifera(Hymenoptera: Apidae) in California. Environmental Entomology 24: 1473-1480

McGregor, S. E. 1976. Insect pollination of cultivated crop plants. USDA-ARS, Washington, D.C. available on line:

Morse, R. A., and N. W. Calderone. 2000. The value of honey bees as pollinators of U.S. crops in 2000. Bee Culture: 2-15. online: pdf file

NASS 2011. Guide_to_NASS_Surveys/ Bee_and_Honey/index.asp. Visited April 13, 2011.