Is this the way foreward?

Beekeeping Forum

Help Support Beekeeping Forum:

Bcrazy 

Drone Bee
Joined
Nov 14, 2008
Messages
1,491
Reaction score
5
Location
Warboys, CAMBS
Hive Type
none
Number of Hives
nil bees given away all colonies
Article from USA _ARS Baton Rouge Bee Lab

Varroa Sensitive Hygiene and Mite Reproduction
Last Updated: November 18, 2010
View as web page

The USDA-ARS Baton Rouge Bee Lab has bred bees that hygienically remove mite-infested pupae from capped worker brood. This ability is called varroa sensitive hygiene, and bees expressing high levels of this behavior are called VSH bees. To select for the VSH trait in your bees, also see Selecting for Varroa Sensitive Hygiene

Figure 1. Hygienic removal of a mite infested worker pupa by adult worker honey bees is an important mechanism of resistance to varroa mites. The removal involves several bees, and results in death of the mite offspring. The mother mite usually survives.

Figure 2 shows uncapped and chewed pupae. Uncapped worker pupae may have a raised rim, resembling drone brood, as seen below the chewed pupa.

VSH is an important mechanism of resistance to varroa mites. The best resistance is found in pure VSH bees. However, hybrid VSH bees (e.g. VSH queens open mated to non-resistant drones) also have significant resistance to varroa mites.
VSH is very similar or the same as hygienic behavior that honey bees use to combat American foulbrood, chalkbrood, and the eggs and larvae of wax moths and small hive beetles. All colonies probably have individuals that perform VSH, and we do not yet understand how our selective breeding has resulted in colonies with greatly improved performance. Hygiene is performed by nest cleaning bees aged 15-18 days old. Removal of a mite-infested pupae begins when an uncapper smells the infested brood and chews a pinhole through the cell cap. Subsequently, removers enlarge the hole and either eat the infested pupa or pull it from the brood cell (Fig. 1).
VSH bees do not respond to all mite-infested pupae with equal intensity (Fig. 3). They are more likely to remove mite-infested pupae that are not pigmented or only lightly pigmented (stages 2–4) than prepupae (stage 1) or more darkly pigmented pupae (stages 5-8). Additionally, they are much less hygienic towards mite-infested drone brood than worker brood. Reasons for these trends are unclear.

Fig. 3. Some factors that influence the degree of varroa sensitive hygiene in colonies of bees include age and genetics of worker bees, age and type of brood, and infestation level of mites in capped brood. .


Removal of mite-infested brood is probably triggered by unusual odors that penetrate the cell cap to the outside where hygienic bees patrol the comb surface. We have observed that VSH bees respond vigorously to highly infested brood (e.g. 15–25 mites per 100 capped cells) that is transferred into the colony (Fig. 4). They uncap and remove many mite-infested pupae quickly. They respond with much less intensity to brood with low infestation rates (1–5 mites per 100 capped cells), probably because the chemical signals that trigger removal are less concentrated and harder to detect.

Figure 4. Comparison of mite-infested brood that had been exposed to VSH bees or controls for 24 hours. Uncapped pupae appear as white dots in this photo.


More characteristics of VSH bees

Figure 5. Often infertile mites from VSH colonies will defecate on the host pupa and not just on the cell wall, as seen here.

Figure 6. Sometimes mites from VSH colonies will die in this manner. They are found sandwiched between the cell wall and the cocoon which was spun by the current host bee as it prepared to pupate. We think this suggests that the mite was too weak to awake from the brood food as the last instar larvae finished eating prior to the molt. Perhaps the mite was already dead, or just too weak to escape the placement of the cocoon over it by the spinning larva.

Fig. 7. Pie charts showing the proportion of mites that are reproductive in VSH and control colonies.

Figure 8. Cell caps from normal (upper right) and recapped (lower two) brood cells. The three cell caps have been removed and flipped over.
Another characteristic of VSH bees is a reduced fertility of mites, when compared to non-VSH bees. In a colony, mite fertility is reduced several weeks after introduction of VSH queens into non-selected colonies. This led to the original name of the trait, Suppressed Mite Reproduction (SMR). This name describes the trait (or traits) selected in the experimental population of bees. The name of the trait was later replaced by Varroa Sensitive Hygiene (VSH). This is due to the finding that the primary mechanism of the trait is the removal of infested pupae from capped brood cells.
The VSH bees shown in Fig. 7 have about 30% reproductive mites (a normal family capable of producing a mature daughter). About 55% are infertile or non-laying mites (blue slice), and there are mites that die without producing offspring (red slice). There are also mites that produce a family, but their daughters do not mature before the bee emerges (yellow slice). These are fertile because they laid some eggs, but they are also considered non-reproductive because they will not produce even 1 mature daughter.
Sometimes, uncapped cells are recapped. VSH bees will exhibit this recapping more then non-hygienic bees , as seen in the following data (Villa et al 2010)
• Recapped cells (%)
o VSH: 38 ± 0.3 a
o Hybrid: 19 ± 0.8 ab
o Control: 17 ± 0.3 b
It is possible that uncapping and recapping interferes with mite reproduction. Caps from normal and recapped brood cells can look alike when viewed from outside (as when you look at a brood comb, see Fig. 8). However, when the caps are gently removed and flipped over the silk lining of the cap becomes visible. In normally capped cells (upper right Fig. 8) the silk lines the entire inner surface of the cap. The recapped cells on the bottom row (Fig. 8) show granular wax without a silk lining where holes that were used by hygienic bees to inspect cells are repaired by nest bees. The holes can vary in diameter from pinholes to the size of the entire cap.
________________________________________
________________________________________
• also see Selecting for Varroa Sensitive Hygiene
• Page authors: Jeffrey Harris, Robert Danka and José Villa, USDA-ARS
________________________________________
go to for images http://www.extension.org/pages/Varroa_Sensitive_Hygiene_and_Mite_Reproduction
 

rolande 

Field Bee
Joined
Oct 26, 2009
Messages
609
Reaction score
298
Hive Type
dadant
Is this the way forward?

Yes.

Best,
Roland
 

Bcrazy 

Drone Bee
Joined
Nov 14, 2008
Messages
1,491
Reaction score
5
Location
Warboys, CAMBS
Hive Type
none
Number of Hives
nil bees given away all colonies
Hi Roland,
Yes its my sentiments also which is why I am reducing my hives but possibly not my bees into 4 Langstroths to try some of the hygienic behaviour of the bees.

Mo.
 

rolande 

Field Bee
Joined
Oct 26, 2009
Messages
609
Reaction score
298
Hive Type
dadant
Hi Mo,

I've long been 'sold' on this approach, there are a few major concerns which have had success -Kefuss and Daniel Weaver spring to mind, literally running thousands of colonies without treatment; but they're far from alone. The articles by Larry Connor are also an ongoing source of information.

Good Luck -I for one will be interested to hear of any success you have (the silence of any failures will speak for itself!).

Best,
Roland
 

mbc 

Queen Bee
Beekeeping Sponsor
Joined
Feb 16, 2010
Messages
6,096
Reaction score
605
Location
bestest wales
Hive Type
national
Kefuss is the man, but I dont think he'd have got where hes got to starting with 4 hives
 

rolande 

Field Bee
Joined
Oct 26, 2009
Messages
609
Reaction score
298
Hive Type
dadant
Kefuss is the man, but I dont think he'd have got where hes got to starting with 4 hives
Hi,

In this instance I think that scale could be achieved by co-operation within local networks of beekeepers with the same goal. It's just a sad fact that many will probably dismiss the whole idea.

He does now suggest the so called 'Soft Bond Method' as an alternative for those who aren't prepared to follow his 'Live or Let Die' approach.

All the Best,
Roland
 

mbc 

Queen Bee
Beekeeping Sponsor
Joined
Feb 16, 2010
Messages
6,096
Reaction score
605
Location
bestest wales
Hive Type
national
Hi,

In this instance I think that scale could be achieved by co-operation within local networks of beekeepers with the same goal. It's just a sad fact that many will probably dismiss the whole idea.

He does now suggest the so called 'Soft Bond Method' as an alternative for those who aren't prepared to follow his 'Live or Let Die' approach.

All the Best,
Roland
I thought his system was always about selecting the most likely candidates as breeders from hundreds of colonies and only holding back from treating these to further whittle them down ie. the majority get treated at first

I agree that its sad that many will dismiss the possibility that co-operation could achieve great things but the realist in me recognises that the complexity of this task is beyond most hobyist beekeepers. When most beekeepers in my area dont often pry into the brood box how can you expect them to give a reasonably consistent evaluation of varroa load ?
 

rolande 

Field Bee
Joined
Oct 26, 2009
Messages
609
Reaction score
298
Hive Type
dadant
Hi mbc,


I thought his system was always about selecting the most likely candidates as breeders from hundreds of colonies and only holding back from treating these to further whittle them down ie. the majority get treated at first
I'm not sure but this actually sounds more like his recent suggestion for people who aren't too keen on his 'live or let die' approach. as I understand it he withdrew all treatment from all hives in 1999 or there abouts which resulted in the loss of two thirds of his colonies.

Regards,
Roland
 

Scutellator 

House Bee
Joined
Nov 2, 2010
Messages
114
Reaction score
0
Location
Bulgaria
Hive Type
langstroth
Number of Hives
40
There are great many anti-varroa mechanisms. Some of them are behavioral (like VSH, grooming behaviors..) or physiological ( shorther post-capping stage, unatractive worker brood to the mites, reduced mite fertility..), confining the selection just for one of them let to the scientists. Personally, I don't care how the resistance is caused as long as I don't need to use chemicals.

It seems that the young queens cope to resist better than the old ones, wich suggest that some of the mechanisms are conected with the queens' pheromones.
Also the use of chemicals suppress the imune system of the bee and may cause loosing the resistance, so when identifying the potential resistanst stocks be cautious. Powdered sugar dusting is an alternative.

Today the bees need les treatments than the most of the beeks suppose. If 30 years ago 2 treatments was necessary to keep the collony alive, today even a single treatment in the autumn is more than sufficient before the first indications (deformed wings) of varoa infestations become visible by the end of August. After 20 years varroa will be thing from the past.

To achieve resistance there is no need to follow the James' Bond aproach, in fact, it's not so difficult and expensive to the average beekeeper as it's taught. If a single treatment is sufficient for you, just wait 12 months, maybe not all of your collonies will need a treatment.

Infestation levels are different during the years, so take the environment into account as well.

Climate in your country is very different than mine.
Here, in Bulgaria the brood rearing stops for about a month or two during the winter.


Donnie
 
Top