News for SC Beekeepers: February 2013

Local News

South Carolina Beekeepers Spring Meeting  - The South Carolina Beekeepers Association will host a joint meeting with the North Carolina State Beekeepers Association on 1-2 March 2013 at the Baxter Hood Convention Center, York Technical College, Rock Hill, South Carolina. You will find included in this newsletter a meeting program. The Baxter Hood Convention Center is conveniently located near I-77 (see enclosed map). Take exit 79 off I-77 onto Dave Lyle Blvd.-West toward the city of Rock Hill. Go approximately 1 mile and take a left on South Anderson Road. The Baxter Hood Convention will be on your left just after turning on S. Anderson Road.

This will be a very informative meeting and we hope to have a good turnout of South Carolina beekeepers to welcome our beekeeping friends from the Tarhill State. You will note on the tentative program that we have some outstanding speakers scheduled for the meeting including  Jerry Hayes, Monsanto, St. Louis, Missouri; David Tarpy, N.C. State University; Sue Cobey, Washington State University; Bart Smith, USDA/ARS Beltsville, Maryland Bee Lab; Stanley Schneider, UNC-Charlotte; Jamie Ellis, Univ. of Florida, Gainesville; and Mike Hood, Clemson University, Clemson, SC.

You will need to preregister for this meeting. Go to our South Carolina Beekeepers website <scstatebeekeepers.org> to register by PayPal by 20 February 2013 or you may use the mail-in pre-registration form included in this newsletter.

The meeting program on Friday evening will include a delicious meal which will be catered by Jackson’s Restaurant, Clover, SC. A band will perform during the meal and the dinner will be followed by our keynote speaker, Mike Hood.  We must have an accurate headcount for the meal so you will need to pay in advance with your registration fee.  There will be a $10 extra registration fee for beekeepers who show up at the meeting and have not preregistered.

You must make your own hotel reservations by contacting the hotel of your choice. The conference center is located about two miles from several hotels including: Baymont Inn & Suites, rate: $79, breakfast included (803-329-1330), Wingate by Wyndham Inn, rate: $89, breakfast included (ph. 803-324-9000), and the Hampton Inn, rate: $104, breakfast included (803-325-1100). Highly recommend you make your hotel reservations soon because there are other events going on in the Rock Hill area that weekend. Other hotels in the area include: Holiday Inn, rate $99, breakfast not included (ph. 803-323-1900), Microtel Inn & Suites, rate $98, breakfast not included (ph.803-817-7700) and Towns Place Suites by Marriott, rate $109, breakfast included (ph. 803-327-0700).

Don’t delay; make plans today to attend this exciting meeting.

Two New Varroa Mite Control Products. South Carolina beekeepers should be able to purchase two new varroa mite control products by spring 2013.  Applications have been submitted to EPA for emergency use Section 18 labels which will allow SC beekeepers to purchase and use HopGuard (potassium salt of hop beta acids) and Apivar (amitraz).

Editor’s Note.  As you may know, I will be retiring from Clemson University on March 31, 2013, so this will be my last “News for South Carolina Beekeepers” newsletter. It has been my pleasure over the past 24 years to provide you beekeeping news on the local and national levels. Thanks for your support over the years.
 

AGRICULTURAL SPRAY ADDITIVES CAUSE LEARNING IMPAIRMENT IN HONEY BEES

Pennsylvania State University researchers used NIFA funds to investigate the impact of three classes of additives on the learning ability of honey bees, which is a characteristic symptom of Colony Collapse Disorder (CCD). This research was funded by Agricultural and Food Research Initiative’s Plant Health and Production and Plant Products: Insects and Nematodes Program. The additives were both orally ingested by the bees and applied to their antennae. Only oral ingested compounds impacted the bees. Only one non-ionic agent reduced the bee’s learning ability. Researchers also learned that the insecticide imidacloprid drastically reduced learning. This research suggests oral ingestion of certain additives and pesticides may impact honey bee behavior and should be further investigated for a role in CCD.

 SOURCE: http://www.nifa.usda.gov/newsroom/newsletters/update12/ 110712.html#nifa


MEXICO- FINE-SCALE LINKAGE MAPPING REVEALS A SMALL SET OF CANDIDATE GENES INFLUENCING HONEY BEE GROOMING BEHAVIOR IN RESPONSE TO VARROA MITES

Abstract

Populations of honey bees in North America have been experiencing high annual colony mortality for 15–20 years. Many apicultural researchers believe that introduced parasites called Varroa mites (V. destructor) are the most important factor in colony deaths. One important resistance mechanism that limits mite population growth in colonies is the ability of some lines of honey bees to groom mites from their bodies. To search for genes influencing this trait, we used an Illumina Bead Station genotyping array to determine the genotypes of several hundred worker bees at over a thousand single-nucleotide polymorphisms in a family that was apparently segregating for alleles influencing this behavior. Linkage analyses provided a genetic map with 1,313 markers anchored to genome sequence. Genotypes were analyzed for association with grooming behavior, measured as the time that individual bees took to initiate grooming after mites were placed on their thoraces. Quantitative-trait-locus interval mapping identified a single chromosomal region that was significant at the chromosome-wide level (p<0.05) on chromosome 5 with a LOD score of 2.72. The 95% confidence interval for quantitative trait locus location contained only 27 genes (honey bee official gene annotation set 2) including Atlastin, Ataxin and Neurexin-1 (AmNrx1), which have potential neurodevelopmental and behavioral effects. Atlastin and Ataxin homologs are associated with neurological diseases in humans. AmNrx1 codes for a presynaptic protein with many alternatively spliced isoforms. Neurexin-1 influences the growth, maintenance and maturation of synapses in the brain, as well as the type of receptors most prominent within synapses. Neurexin-1 has also been associated with autism spectrum disorder and schizophrenia in humans, and self-grooming behavior in mice.

Paper prepared by Miguel E. Arechavaleta-Velasco, Karla Alcala-Escamilla, Carlos Robles-Rios, Jennifer M. Tsuruda and  Greg J. Hunt

GERMANY BAYER IS WORKING ON A NEW SPRAYING TECHNIQUE TO REDUCE THE IMPACT OF PESTICIDES IN HONEYBEES

 

Written by Analia Manriquez

According to Dr. Maus, the company has started a global survey project in cooperation with a university that will be ongoing for the next two years that will look at all existing crops to determine the pollinator of each crop, any relevance to beekeeping, any managed pollination, etc.” In the area of application technology, he said research is being conducted to find bee friendly application techniques. An ongoing project with other stakeholders involves looking at ways to apply pesticides that will minimize the exposure to bees, he explained. One of those techniques involves spray technology. Together with Syngenta, Hohenheim University in Germany, and manufacturers of application components, the use of Dropleg application technology is being evaluated. Maus explained how the Dropleg technology works. “On the sprayer equipment, normally the spray bar is above the crop, and it sprays the canopies from above,” he said. “With the Dropleg equipment, its hook extensions reach down into the crop and spray it laterally or from below.” The end result, he said, should reduce any impact on honeybees.

SOURCE: Growing Produce, December 2012

SECRETS OF THE HONEYBEE BITE REVEALED

A previously unknown honeybee defense weapon against varroa and a potential new natural anesthetic for humans.

Researchers have discovered that honeybees can bite as well as sting and that the bite contains a natural anesthetic.  The anesthetic may not only help honeybees fend off pests such as wax moth and the parasitic varroa mite, but it also has great potential for use in human medicine. 

The surprise findings discovered by a team of researchers from Greek and French organizations in collaboration with Vita (Europe) Ltd, the UK-based honeybee health specialist, will cause a complete re-thinking of honeybee defense mechanisms and could lead to the production of a natural, low toxicity local anesthetic for humans and animals.

The natural anesthetic has been discovered in the bite of the honeybee and measured at the University of Athens is 2-heptanone (2-H), a natural compound found in many foods and also secreted by certain insects, but never before understood to have anesthetic properties.  Independent tests have verified Vita’s findings and the potential of 2-heptanone as a local anesthetic.

As a naturally-occurring substance with a lower toxicity than conventional anesthetics, 2-heptanone shows great potential.  Vita has already patented the compound for use as a local anesthetic and is seeking pharmaceutical partners to develop it further.

Until recently, research seemed to indicate that 2-heptanone was either a honeybee alarm pheromone that triggers defensive responses, or a chemical marker signaling to other foraging bees that a flower had already been visited.  Vita’s results contradicted these notions.

The new research clearly shows that 2-heptanone paralyses small insects and mites bitten by bees for up to nine minutes.  Somewhat like a snake, the honeybee uses its mandibles to bite its enemy and then secretes 2-heptanone into the wound to anaesthetize it.  This enables the honeybee to eject the enemy from the hive and is a particularly effective defense against pests, such as wax moth larvae and varroa mites, which are too small to sting.

SOURCE: News from Vita Europe Ltd., October 17, 2012

BEE WHAT YOU WILL

Honeybees make for a versatile workforce.  They start as nurses, tending the larvae and the queen; after several weeks, however, many become foragers, searching for pollen, nectar, and water.  All workers in a beehive are sisters that are genetically very similar, yet they perform one of two types of jobs that require very distinct skills—and they can switch roles if the hive needs more of the other.  How is that possible?  Gro V. Amdam of Arizona State University and a team of geneticists suspected that the answer involved DNA methylation, small epigenetic changes—chemical tags on the DNA—that can profoundly affect gene expression while leaving the genetic sequence unchanged.

The researchers compared DNA extracted from the brain cells of nurses and foragers and found differences in the methylation levels in 155 genetic regions, at least some of which presumably account for the differences in behavior between the two types of workers.  They then removed all the nurse bees from the hive, leaving the queen and larvae bereft of care.  When foragers were confronted with the hive under those conditions, some continued foraging but others reverted to their former nursing roles.  Those reverted nurse bees showed DNA methylation changes in more than a third of the same gene regions.

Amdam’s team is currently trying to identify which areas in the bee brain, which as been extensively mapped, are associated with those epigenetic changes.  They hope that their research will help clarify complex behavioral issues in humans and perhaps one day lead to ways to reverse the brain-changing effects of psychological trauma. (Nature Neuroscience)

SOURCE: Natural History, November 2012

USA- VARROA MITE REPRODUCTIVE BIOLOGY

Article written by Zachary Huang, Department of Entomology, Michigan State University

The varroa mite (Varroa destructor Anderson and Trueman) is an ecto-parasite of the Western honey bee (Apis mellifera) and is distributed worldwide. Because A. mellifera colonies almost always die within two to three years after mite infestation, if not treated, feral bee colonies (unmanaged colonies in the wild) in U.S. were almost totally wiped out by this mite around 1995, less than a decade after it was introduced to the USA (around 1987). There is anecdotal evidence that honey bees might be becoming feral again in recent years (resistant genetics possibly leaking out due to swarming), but there is no systematic study proving this. Unless otherwise noted, throughout this paper I will use “varroa”, “varroa mite” or the generic “mite” interchangeably to refer to V. destructor. The varroa mite is currently the most severe pest of managed honey bees worldwide. Understanding the varroa mite’s reproductive biology will therefore allow us to better manage this important pest.

The Life Cycle of Varroa

Varroa mite life cycle has two stages (Fig. 1). During the phoretic stage, mites ride on adult workers or drones, at the same time feeding on blood (hemolymph) from bees, usually from the inter-segmental membrane on the abdomen. The phoretic stage lasts about 5-11 days when there is brood in the colony. Of course, mites are forced to remain phoretic if there is no brood, and this can last 5-6 months in cold climates. Mites change hosts (hop from one bee to another) often and this contributes to transmission of various viruses, by picking them up from one bee and inject to another during feeding. Mites experience higher mortality during the phoretic stage, because they make mistakes, and fall to the screen bottom board, if a hive has one, get bitten by workers during grooming, or die due to old age. The “natural drop” on a screened bottom board reflects a combination of all of these factors. However, the total of these fallen mites are less than 20% of the population. Therefore, using a bottom-screen-board alone will reduce, but not eliminate, chemical use for varroa management. The phoretic stage is important for mites to transfer horizontally to other colonies, by being accidentally dropped onto flowers and then picked up by other foragers (this probably does happen, but we do not know the actual probability), by mite-carrying bees drifting to another colony, or finally by bees robbing a colony dying from mite infestation. In the last situation, we are actually selecting for mites with high virulence, because while in a natural forest, mites that kill a colony will also die with their host (due to the low likelihood of being found by a neighboring colony), while in an apiary this robbing behavior is guaranteed, insuring the successful transfer of mites from the dying colony to another, where it will repeat the cycle again.

The other stage is the reproductive stage, and only during this time when it is possible for mites to increase their population. This occurs only under the capped brood cell. Mature female mites are already mated when they emerge, as bees emerge from the cell. The varroa mite invades a host (worker or drone larvae) cell just prior the cell being capped. Once inside, she will hide in the brood food in an upside-down position (viewed from the top of the cell). Mites have special appendages called “peretrimes” (essentially as snorkeling tubes) that help them breathe. Shortly after a cell is capped, the larva inside will spin a cocoon, and then becoming a prepupa. The mite will not feed until about five hours after the cell is capped (after spinning is done) and the first egg is laid 70 hours after cell capping. The first egg is not fertilized, and becomes a male. This is the same as in honey bees, as both organisms have what is called the “haplodiploidy” sex-determination mechanism, whereby males are haploid (having no father) and females are diploid (having both parents). After this, approximately every thirty hours, the mite lays a female egg. If the mother mite was not mated properly, then all of her offspring will be males. A total of five (on worker pupae) or six eggs (on drone pupae) can be laid in a capped cell. However, because worker bees will emerge about eleven days after capping, and drones fourteen days, but a daughter mite takes six days to mature, most of these eggs do not have time to develop into adults, (6 + 70 hrs delay in egg laying + 1 day for first egg as male=10 days, leaving only 1 daughter to mature). The males and the unsclerotized (white) females, who are not fully developed, all die shortly due to dehydration after a cell is opened (after bee emergence, or uncapping by hygienic bees). Therefore only the mature, tanned female mites,, but not most nymph stages and males, are seen by most beekeepers (Fig. 2). Males will mate with a female repeatedly to result in a total of about 35 spermatozoa inside the female spermatheca.

Varroa mites have “fecal sites” on the cell, where they deposit their feces, which are white due to a high concentration (~95%) of guanine. For some unknown reason, any mite that defecates on the pupa directly are also sterile (Fig. 3).

Methods for Studying Mite Reproduction

There are two methods for studying mite reproduction. One method is simply to survey, uncapping worker or drone cells in colonies and determining the percentage of mites that reproduced (fertility), or the number of offspring (fecundity) of mites. This method gives information about what is happening under natural conditions, but the information one gets is limited because nothing is controlled or manipulated. Another method is to perform manipulations, either on the mites or on the host, then artificially introduce mites into the cells and wait 9-10 days to determine fertility and fecundity. The frames can be reintroduced into a colony (which risks removal by bees due to hygienic behavior), or incubated in a laboratory. The basic steps for this process are as follows. 1). Harvest mites either from brood cells or from phoretic hosts in a colony with a high number of mites. We now routinely harvest mites using the sugar dusting method,, and then clean the sugar off them using a moistened brush. 2). Obtain brood cells that are recently capped (within 6 hours). This should be from a colony with no mites, so that you do not have natural invasion into the cells that you are trying to introduce mites to– if you have two mites in one cell, you do not know which one is the introduced one. Mites will not reproduce if introduced into cells that have been capped for more than 14 hours. Ideally, the cells should be capped within the last six hours. Scientists often use a piece of transparency to map the brood; marking those that are being capped (with holes on the cap), waiting for six hours, coming back and marking again. Those cells that had a hole the first time, but were totally capped after, are the cells that you need. Make sure to mark the two holes (from fixing the transparency on the frame) on the wooden frame with Sharpies also, because bees may seal the small holes with wax, and you lose the reference. 3). Open the cell slightly using a fine scalpel, an insect pin, or a pair of fine forceps, and introduce a mite carefully into the small slit using a horse hair or a fine brush. 4). Push the wax capping back, and seal it with melted beeswax with a brush. 5). Keep the frame upright at all times, and the relative humidity at 50%, and at a temperature of 32-35 °C. 6). Check the frame daily for signs of wax moth larvae, because they can destroy the data; do not put the frame flat on a surface, but keep it upright during this process. 7). Finally, on day nine (mite transfer day designated as day one), one can uncap the cells and count and record how many males, daughter mites (mature, deutonymphs and protonymphs) are there.

Host Preference During Phoretic Stage

Whether or not varroa mites can choose phoretic hosts was studied previously, using caged bees and petri dishes. Varroa mites preferred nurses when they were presented with a choice between foragers and nurses in a petri dish. Mites also transferred more often to young bees than to old bees, when they were confronted with freshly frozen young and old bees. This discrimination by varroa was later shown to be related to the repellent effect of geraniol, a component of the Nasonov pheromone, which is high in foragers. However, it was not clear whether mites show the same preference under a more realistic colony condition. One study showed nurses had a higher percentage of mites than newly emerged bees, but no difference was found between nurses and foragers. Another study found nurses were the most preferred but the experiment was conducted in one colony (i.e. not replicated). My laboratory studied mite distribution among one-day-olds,nurses (5-11 day old marked bees recovered from a colony) and foragers (unknown age but the average age of foraging bees should be higher than 21 days in a typical colony), and found a clear preference of nurses > day-old-bees > foragers (X. Xie, Z.Y. Huang and Z. Zeng, in preparation). Thus, mites do show the same preference for nurses, even in a colony setting.

Why Phoretic Stage?

Scientists were puzzled as to why mites bother to go through a phoretic stage, because they experience a high mortality rate during this period. Under laboratory conditions, varroa can reproduce successfully without a phoretic stage. That is, mites that were transferred immediately upon bee emergence to another newlycapped brood cell still reproduced, for up to seven cycles. The average number of total offspring (including males) was four during the first four to five cycles. This seemed higher than in our experiment (Fig. 4). However, upon closer inspection, the author said there were mites that did not have offspring (21.7%), and that this was most likely not included in the calculation. So the actual fecundity was 4*(1-0.217) = 3.17, which also included the males. After subtracting the males (which were about two per mother, instead of one, strangely, in their study, Fig. 4 of De Ruijter, 1987), we have 1.17 female offspring per mother. This would be slightly lower than the 1.6 female offspring per mother that we observed in mites fed on newly emerged bees. Therefore, mites that do not experience the phoretic stage have a lower fertility, especially compared to those hosted by younger nurses (see below).

Our recent study showed that mites preferred nurses, perhaps not only because of their proximity to larvae (nurses inspect/feed larvae frequently), but also because nurses provide phoretic mites extra nutrition for reproduction. Our study found that mites artificially fed on nurses had the highest number of offspring, followed by those on foragers, and those fed on the newly-emerged bees having the lowest number of offspring. In addition, when we compared the fecundity of mites hosted by bees with different ages, we found a significant negative relationship between mite fertility and the age of nurses (Fig. 4).

Differences in Mite Reproduction is Important for Resistance Against Mites

Varroa mites can reproduce on both worker and drone brood in Apis mellifera, but reproduce exclusively on drone brood in A. cerana, its original host. Many factors, such as grooming behavior (removing mites during phoretic stage from adults), hygienic behavior (removing mites from pupae during reproductive stage), duration of brood state, and attractiveness of brood, contribute to varroa tolerance (reviewed by Büchler, 1994). However, I think that reduced reproduction (including both reduced fertility and fecundity) on worker brood is the most significant factor for honey bee resistance against the Varroa mite. This is because the infertility of Varroaon worker brood correlates well with the degree of tolerance of that bee to the mite. For example,A. cerana is highly tolerant to the mite and causes 100% mite infertility in worker brood; the Africanized bee (A. mellifera scutellata) is intermediately tolerant with a 40% infertility; while A. mellifera in U.S. is the least tolerant with the lowest infertility rate (10-20%) in worker brood. In a strain of European bee that was artificially selected to be tolerant of mites, infertility of mites plays the most significant role in depressing the mite population, while other factors (such as grooming behavior, hygienic behavior, and the duration of the postcapping period) are not as important (Harbo and Hoopingarner, 1997). Although we currently know that the original “SMR” (suppressing mite reproduction) trait is actually due to “VSH” (varroa sensitive hygiene), VSH can be considered a special trait causing lower reproduction, due to the interruption of the reproductive cycle of the mites, especially since the bees do not open cells containing non-reproducing mites, but rather target those having mite daughters.

Factors Affecting Mite Reproduction

A. Effect of Caste of Brood

It has been known for a long time that varroa mites preferred drone brood over worker brood, in a ratio of nine to one. That is, if there is an equal number of cells available, the drone brood would harbor nine times as many mites as the worker brood. Natural selection undoubtedly favored mites that preferred drones, because drone brood has a longer capped-period, enabling more daughter mites to mature. Indeed, Martin (1994, 1995) calculated the effective reproduction rate (i.e. the number of vial/mature daughters per invading mother) as 1.3–1.45 in a single infested worker brood, while for drone brood it was 2.2–2.6. In A. mellifera, transferring mites from drone to worker brood always deceased mites’ reproduction rate, while transferring mites from worker to drone brood increased reproduction rate. Queen larvae would be a dead end for invading mites, because queens emerge at 16 days, five days faster than a worker, thus leaving the daughter mites no time to mature. Varroa mites do avoid queen cells, apparently due to some chemical odor from royal jelly.

B. Effect of Host Species

The transferring of mites across different species suggests that host species also affects mite reproduction. When mites from A. cerana were introduced to A. mellifera worker brood, only 10% of the mites reproduced, while 80% reproduced when A. mellifera mites were transferred toA. cerana worker brood. In our study, Varroa destructor, Korea haplotype, from A. melliferareproduced equally well (all > 90% reproduced), regardless of whether it transferred to A. mellifera or to A. cerana, in both drone and worker castes (Ting Zhou, Shuangxiu Huang and Zachary Huang, unpublished data). In contrast, V. destructor, Vietnam haplotype, from A. ceranaonly reproduced on A. cerana drones (83% reproduced, N=62), and not on A. cerana workers (0% reproduced on workers, N=60). These results suggest that the mites on the two honey bee species are different: mites from A. cerana refrain from reproducing on worker brood of the same species, and mites from A. mellifera reproduce well on worker brood, regardless of the host species. It appears that only the Korea haplotype of V. destructor had a genetic change that enabled it to reproduce on either drone or worker brood in A. mellifera, therefore allowing it to build up to levels damaging to the bees. In China, my colleagues and I did not find damaging levels ofV. destructor in A. cerana colonies – in fact, in most locations, the mites could not be found. When we found it, it was the Vietnam haplotype which does not reproduce in the worker brood ofA. cerana. It is not clear why the Korea haplotype of V. destructor does not cause damage in A. cerana, since they can reproduce in both worker and drone brood in transfer experiments. However, it is possible that they do not reproduce on worker brood under natural conditions, when both the phoretic and reproductive hosts were A. cerana. Thus, transfer experiments should be supplemented with observation under natural conditions for the full picture.

C. Effect of Cell Size

Partly because mites reproduce better in drone brood than worker brood, people tend to think that smaller cells would decrease mite reproduction. However two recent studies show that there was either no difference in mite population between colonies (Ellis et al., 2009) using “small cells” (4.8 to 4.9 mm diameter) and regular foundations (5.2-5.4 mm), or small cells actually had a significantly higher mite population (Berry et al., 2010). Unfortunately, neither of these recent studies determined the fecundity or fertility of mites in the two types of cells.

Earlier studies were conflicting. Taylor et al. (2007) found that “foundation” cell size did not affect the reproductive success of V. destructor, but more mites invaded cells drawn from the 4.8mm foundation. However, Piccirillo and De Jong (2003) and Maggi et al. (2010) found that mite invasion rate increased positively, and linearly, with the width of worker and drone brood cells, probably because brood that develops in large cells receive more visits from nurses, increasing the invasion chance. Maggi et al. (2010) also found that the percentage of fertile mites was lower in smaller cells. An earlier study (Message and Goncalves, 1995) showed in Africanized bees, larger cells had a higher invasion rate, and also had higher effective fecundity in mites.

Our own study suggests that cells that are too large also reduce mite reproduction (Zhou et al., 2001). In a study trying to determine the mechanisms of why varroa mites do not reproduce on worker brood of A. cerana, we accidentally discovered that in both A. cerana and A. mellifera queens laid worker eggs in drone cells in the fall. We took advantage of this, and compared the reproductive output of mites on two hosts: workers reared in worker-cells (WW) or workers reared in drone-cells (WD). In 2001, both the fertility and fecundity of the two groups were significantly different (Fig. 4). It is not clear why mites would reproduce less on identical hosts that were housed in larger cells. One possibility is that workers reared in drone cells are fed a different diet by nurses (One study showed workers reared in drone cells were heavier and had moreovaries, suggesting a different diet or more nutrition). A second possibility is that workers spin larger cocoons in drone cells, and mites detect the extra space, and this affects their reproduction.

D. Effect of Humidity

Kraus and Velthuis (1997) wondered why varroa mites were not as big a problem in the tropics (besides that fact that most bees were African), and tested in the laboratory to see if high relative humidity would inhibit mite reproduction. They artificially transferred single mites into newly capped cells, and then kept the brood in an incubator. When relative humidity (RH) was set at 59–68%, on average, 53% of the mites produced offspring (N=174 mites); under 79–85% RH, only 2% (N = 127) of the mites reproduced. The difference in mite fertility was highly significant. My postdoctor recently incorrectly set the incubator at a RH of 75% (instead of 50%), and very few mites reproduced as a result. If there are ways to artificially increase the hive RH to about 80%, then the varroa mite population will never increase to a damaging level.

E. Effect of Comb Movement

Aside from where they defecate, varroa mites are also very picky about where they feed. The mother herds her “children” to one particular feeding site on the pupa (between the pair of hind legs on the ventral side of the abdomen), and then leads them back to the defecation site. Therefore, any rotation of combs will cause the movement of the host pupa? and perhaps causes disorientation of the mites. The “Kônya beehive with rotating frame [sic] of brood nest” was invented (and patented) by Lajos Kônya, from Hungary. The hive body has round frames and they rotate ten degrees per hour, thus completing a circle in 36 hours. This is powered by a 12 volt battery. Varroa mites are not able to reproduce, due to the constant rotation of the cells. I was pretty confident that the claims were true based on mite reproductive biology. However, an abstract (Aumeier et al., 2006) said they studied the rotation of combs on mite reproduction for three years and found no evidence that it worked. Daily rotating or shaking of brood cells neither “affected fertility (93-100%) nor fecundity (2.6-3.0) of reproductive mites or mortality of mite offspring in the brood cells.” This is a bit surprising because I thought prior to filing for the patent, the inventor should have obtained data showing that the rotation affected mite reproduction? However the study did report that swarm cells were removed due to the rotation, so the Kônya hive does work for swarm prevention.

F. Effect of Host Age, a Kairomone, a Hormone, a Pheromone, and Genes

Varroa mites that have been artificially introduced into brood cells that have been capped for over 14 hours will never reproduce. Of mites that were introduced to cells 12 hours post-capping, about 10% reproduced. Garrido and Rosenkranz (2004) therefore hypothesized that an odor from fifth instar larvae are used as signals by mites to activate their ovaries. This chemical, since it benefits the receiver, should be called a kairomone. They then designed a special cage to confine mites over various testing objects, and found that mites activated oogenesis after perceiving larval volatilities, and those mites were deprived of food, since any bee blood could also contain signals. Pentane extracts of the larval cuticle also caused ovary activation, suggesting that the chemical signal is polar. The chemical remains unidentified.

Initially there was a hypothesis that the juvenile hormone (JH) in the honey bee larvae/pupae could be the factor that activated varroa ovaries, and therefore regulated their reproduction. JH is an important hormone and in most insects it regulates oogenesis and spermatogenesis. This theory was abandoned after observing no differences in JH titers in Africanized and European bee larvae, even though it has been proven that Africanized bees have much lower mite reproduction rates (mainly due to a much higher percentage of infertile mites).

When more than one mite invade a single brood cell, the per capita fecundity decreases, as the number of mother mites per cell increases. Mites invading brood cells in older combs also have fewer offspring. This led scientists to speculate that mites themselves might have a chemical to inhibit each other’s reproduction (a pheromone). A chemical, (Z)-8-heptadecene, was identified. In the laboratory, it caused a 30% reduction in mite fecundity. When tested in the colony, the average number of offspring was 3.48 in cells treated with (Z)-8-heptadecene, but 3.96 in control cells. This difference was small, but statistically, highly significant (P < 0.01). The effective fecundity (number of potentially mated daughters) was 0.94 in treated cells, and 1.31 in control cells; and this level of difference should have a rather large impact on population growth.

To initiate reproduction, many complicated physiological processes have to be in place. Finding genes critical to these processes can potentially lead to new ways of mite control. My lab recently started a project to hunt for genes important for survival and reproduction in mites, through the use of RNA interference (RNAi). RNAi is a method to inject a relatively large stretch of double stranded RNA (400-500 base pair long), which gets cut into 20-30 bases long, then binds to some complexes which eventually finds complementary stretches of RNA and degrade them, resulting in the reduction of a targeted gene’s messenger RNA, ultimately their protein product. Our basic principle is to search for the same genes regulating survival or reproduction in related organisms (e.g. ticks) in the mite genome, synthesize double stranded (ds) RNA, inject the dsRNA into mites, and then observe their survival. If the injected mites survive, then we proceed to observe their reproduction by introducing them into newly capped brood cells. Once a list of genes are found, we then need to ensure that the dsRNA are specific to mites, and will not affect bees, then find a way to introduce the dsRNA to mites (either directly or to the hemolymph of bees, which then get passed to mites due to their feeding).

Summary

In summary, many factors can affect mite reproduction. These range from type of reproductive host (drone, worker, or queen), cell size, age of the larvae, phoretic host type, relative humidity, or even movement of the combs. The more we understand about how reproduction is regulated in mites, the easier it will be for us to find a way that disrupts mite reproduction while not harming the bees. The trick is that the method has to be easy and economical to implement. Thus, “basic research” into the reproductive biology of mites will eventually become useful to beekeepers, as it may one day provide a new method for mite control.

Acknowledgement

I thank Melissa Huang, Meghan Milbrath, and Xianbing Xie for reviewing this manuscript. Research in the author’s laboratory on varroa reproduction was supported by a USDA SCP grant, the Chinese Natural Science Foundation, MSU GREEEN, and more recently (RNAi project) by grants from the Foundation for the Preservation of Honey Bees, National Honey Board, Almond Board of California, and MSU GREEEN. Research on Nosema was supported by a Managed Pollinator CAP USDA NIFA 20098511805718.

Main References

• Anonymous, KÔNYA' beehive with rotating frame of broodnest; visited July 20, 2012.

• Büchler, R., 1994. Varroa tolerance in honey bees – occurrence, characters and breeding. Bee World 49: 6–18.

• De Ruijter, A., 1987. Reproduction of Varroa jacobsoni during successive brood cycles. Apidologie 18: 321–326.

• Rosenkranz, P., P. Aumeier, B.Ziegelmann. 2010. Biology and Control of Varroa destructor. J. Invert. Pathol. 108: S96-S119.

• Zhou, T., J. Yao, S.X. Huang, Z.Y. Huang. 2001. Larger cell size reduces varroa mite reproduction. Proceedings of the American Bee Research Conference, American Bee Journal 141: 895-896.

2013 SCBA/NCSBA SPRING MEETING SCHEDULE
Friday,
March 1, 2013
12:00 Noon       Meeting Registration – Baxter Hood Convention Center Lobby 
                        Late Registration Fee - $10 Extra Individual and Family 
                        Exhibitor Setup - Baxter Hood Convention Center Lobby
2:00 p.m.          Invocation – Jimmy Powell, York County Beekeepers Assoc. Chaplain
                        “Welcome to Rock Hill and Legislative Update” – State Senator Wes Hayes, District 15 
2:20                 Announcements and Introductions - Mike Hood, Extension Apiculturist, Clemson University. 
2:30                 Presidents’ Comments – Eck Miller (SCBA) and Danny Jaynes (NCSBA)
2:45                 “Monsanto’s Commitment to Honey Bee Health” - Jerry Hayes, Monsanto, St. Louis, Missouri
3:15                 BREAK
3:40                 Door Prizes  
3:45                 “Enhancing Genetic Diversity in the US Honey Bee Gene Pool” - Sue Cobey, Washington State 
                             University
4:15                 “Honey Bee Research at the University of Florida” - Jamie Ellis, Univ. of Florida-Gainesville  
4:45                 Panel Discussion (questions from the audience) 
                        Panelists: David Tarpy, Sue Cobey, Jerry Hayes, Jamie Ellis 
6:00                 Adjourn                                 
7:00                 Banquet - Baxter Hood Convention Center - Advance Tickets Required ($18)
                        --Food
                        --Henry Nunnery and the “Old Fogies and Friends” country string band 
                        --Keynote Address-“Carolina Beekeeping on the South Side” – Mike Hood   
9:00                  Adjourn for Evening
 
Saturday,
March 2, 2013
 
8:30 a.m.          Announcements and Door Prizes
8:45                  “North Carolina State University Apiculture Research Update” - David Tarpy, Extension/Research
                              Apiculturist, NC State University
9:15                  “Worker – Drone Interactions & the Influence on Drone Quality On These Interactions” – Stanley
                              Schneider, Professor, Department of Biology, University of North Carolina, Charlotte, NC 
9:45                   Break - Visit Exhibitors    
10:10                 Door Prizes
10:15                  “The New World Carniolan Program, In Its 31st Generation” - Sue Cobey  
10:45                  “Impacts of Pesticides on Honey Bees” - Jamie Ellis
11:15                  “Stump the Professor” - Jerry Hayes (questions from the audience)  
11:45                   Announcements and Introduction to Workshops
12:00                   State Associations Meet Separately for Business  
12:45 p.m.           LUNCH on your own
2:00                    45 Minute Concurrent Workshops (All sessions will begin at 2:00, 3:00 and 4:00)  
                               1.  “How to Use the BEES Network in Your School” - David Tarpy 
                               2.  “Recognition and Treatment of Bee Diseases” - Bart Smith, Entomologist, USDA/ARS Bee
                                     Lab, Beltsville, MD
                               3.  “What You Need to Know about Africanized Honey Bees” - Jamie Ellis 
                               4.  “Rearing High Quality Queens” - Sue Cobey
                               5.  “Value of Pesticides and Their Proper Use in Beekeeping” - Jerry Hayes
                               6.  “Small Hive Beetle Management” - Mike Hood  
5:00                     End - Have a Safe Trip Home!

 

ADVANCED REGISTRATION FORM FOR JOINT SCBA & NCSBA

2013 SPRING MEETING, BAXTER HOOD CONVENTION CENTER,

YORK TECHNICAL COLLEGE, ROCK HILL, SC, MARCH 1-2, 2013

NAME(S) _______________________________ (CHILDREN) ____________________

ADDRESS: ______________________________ CITY: _________________________

STATE: _____________________ ZIP CODE:_____________ PH: (       ) _____________

REGISTRATION FEE (Note: These are ADVANCED mail-in fees, WALK-IN fees at the meeting will be $10 higher on individual and family registrations.)

                                                                                                                    Amount Paid

          Individual Registration (SCBA or NCSBA Member)          $20.00     ____________

          Family Registration (SCBA or NCSBA Member)               $30.00     ____________

          Non-Member (SCBA or NCSBA) Registration                   $25.00     ____________

          Non-Member (SCBA or NCSBA) Family Registration       $35.00     ____________

             (Note: North Carolina beekeepers are not required to join the SCBA to register for this meeting.)

BANQUET MENU: Fried Chicken & Roast Beef, Green Beans, Mashed Potatoes & Gravy, Sweet Potato

                        Souffle, Sour Dough Bread, Variety of Desserts and Tea/Coffee (Buffet Style) 

BANQUET TICKETS:  $18 ADULTS / $9 CHILDREN (6 yrs or younger) 

           Banquet Tickets (how many adults):     @ $18                                     _____________

           Banquet Tickets (how many children)   @ $9                                       _____________

ANNUAL SCBA DUES (Year 2013)              $10                                          _____________

                                                                 TOTAL CHECK  AMOUNT  =    _____________

PLEASE COMPLETE THIS FORM AND MAIL WITH CHECK NO LATER THAN 20 FEB 2013. MAKE CHECK PAYABLE TO SCBA & MAIL TO:

                                   Don Van Borsch, SCBA Secretary/Treasurer.

                                   407 Old Plantation Drive

                                   West Columbia, SC  29172

HOTEL RESERVATIONS: reservations are your responsibility. Three nearby hotels have special rates for beekeepers attending this meeting.

__________________________________________________________________________________________

FOR OFFICE USE ONLY:

Amount Paid: _________ Check No: _________    Date: _________


Calendar for 2013

February 8-9, 2013–Georgia Beekeepers Association will meet at Lake Blackshear, Cordele, GA.

March 1-2, 2013–South Carolina Beekeepers Association will meet jointly with the North Carolina State Beekeepers Association in Rock Hill, SC.

July 25-27, 2013–South Carolina Beekeepers Association will meet at Clemson University, Clemson, SC

August 5-9, 2013–Eastern Apicultural Society Annual Conference, West Chester, PA.

Recipes

 

HONEY ROASTED CHICKEN

Yield 4 servings

Ingredients 
  • 4 boneless skinless chicken breast halves (6 oz. each)
  • ½ cup honey
  • ¼ cup reduced-sodium teriyaki sauce
  • 2 Tbsp. orange juice
  • 1 ½ tsp. prepared mustard
  • ½ tsp. salt
  • ¼ tsp. pepper
Directions

Place chicken in a greased 13-in. x 9-in. baking dish.  Combine the remaining ingredients; pour over chicken.

Bake, uncovered, at 375° for 22-26 minutes or until a thermometer reads 170°, basting occasionally.

SOURCE: Taste of Home Simple & Delicious, October/November 2012 issue.  

HONEY-NUT CHRISTMAS COOKIES

Yields about 3 ½ dozen

Ingredients
  • 2 cups all-purpose flour
  • 1 cup cold butter, cubed
  • 1 pkg. (8 oz.) cream cheese, softened
  • ¼ cup sugar
  • 1 ½ cups chopped pecans, divided
  • ⅓ cup plus ¼ cup honey, divided
  • 1 tsp. butter, melted
  • ½ tsp. ground cinnamon
Directions

Place flour in a large bowl. Cut in cold butter and cream cheese until mixture resembles coarse crumbs. Shape into two disks; wrap in plastic wrap. Refrigerate for 2 hours or until easy to handle.

Place sugar and 1 cup pecans in a food processor; cover and process until pecans are finely chopped. Transfer to a small bowl, stir in 1/3 cup honey, melted butter and cinnamon.

Roll one portion of dough to 1/8-in. thickness on a floured surface. Cut with a floured 2-in. round cookie cutter. Place 1 teaspoon filling on center of half of circles; top with remaining circles.  Seal edges with a fork. Repeat with remaining dough.

Transfer to greased baking sheets. Brush with remaining honey and sprinkle with remaining pecans.  Bake at 325° for 18-22 minutes or until golden brown. Remove to wire racks to cool.

TO MAKE AHEAD: Freeze baked cookies for up to 1 month.

SOURCE: Taste of Home Simple & Delicious, October/November 2012 issue.  


PEACH-BLUEBERRY CRUMBLE TART

Yield 12 servings

Ingredients
  • 1 1/3 cups all-purpose flour
  • ¼ cup sugar
  • ½ cup butter, melted
  • ¼ tsp. ground cinnamon
  • 2 cups frozen unsweetened blueberries, thawed
  • 2 cups frozen unsweetened sliced peaches, thawed
  • 1 tbsp honey

 Crumb Topping

  • ¼ cup all-purpose flour
  • ¼ cup packed brown sugar
  • ¼ cup old-fashioned oats
  • ¼ cup chopped pecans
  • 1/8 tsp. ground cloves
  • 2 Tbsp. butter, melted
Directions

In a small bowl, mix the flour, sugar and cinnamon; stir in butter just until blended. Press onto the bottom and up the side of a 9-in. fluted tart pan with removable bottom. Bake at 350° for 15-20 minutes or until lightly browned. Cool on a wire rack. In a large bowl, combine the blueberries, peaches, and honey; toss to coat.  In a small bowl, combine the first five topping ingredients; stir in butter.  Spoon fruit mixture into crust; sprinkle with topping. Bake at 350° for 35-40 minutes or until topping is golden brown and filling is bubbly. Cool on a wire rack for at least 15 minutes before serving.

SOURCE: Taste of Home, October/November 2012 issue.  


 



Comments or Questions, Contact:

Mike Hood, Extension Apiculturist, 864-656-0346, mhood@clemson.edu

Clemson University, Dept. of Entomology, Soils, & Plant Sciences
Attn: "News for SC Beekeepers", Editor
Box 340110, 116 Long Hall, Clemson, SC 29634-0110
Phone: 864-656-3111, Fax: 864-656-0274

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