Sometimes, the term VSH is used as meaning the same thing as varroa resistance. I think it’s helpful to clarify what VSH is. It is one of several resistance characteristics that affect the bees’ resistance to the Varroa mite.
VSH is not the same as uncapping capped brood cells with varroa inside and remove the pupae. It is one of a few different varieties of cleaning varroa invaded brood cells.
– VSH is opening (+ possible recapping, and / or + possible removing the pupae) of capped workerbee brood cells (not dronebrood cells) in which one or more varroa mites have entered AND the presence of offspring (children) to this (these) varroa mite(s) in these cells.
As we see from the description here there could be different varieties of this trait. It isn’t needed that the bees remove the pupa for this behavior to de called VSH. It is enough that they uncap pupae with invaded mites with offspring. The bees may well recap it again. Uncapping is enough to disturb the reproduction of the mite. Is this difference in behaviour (recapping the cell and not removing the pupa) due to genetic difference?
– Uncapping and cleaning of capped workersbrood cells with varroa which have no descendants is not VSH.
– Uncapping and cleaning of dronebrood with varroa is not VSH. (But this is though also a valuable feature.)
– Other properties like grooming (removal and biting of mites from the body of other bees or themselves is an important feature, especially if the colony is reinvaded by mites.
– Resistance to viruses, for example in the form of good production of suitable peptides (short amino acid strings) which “eat” viruses is important.
– Reduced inclination for robbery is not VSH, but is a good feature, as it means less risk for reinvading/reinvasion of mites from bee colonies with increased varroa level and as a consequence thereof a reduced defense against robbery.
– Good defense at the entrance not letting foreign bees enter the hive prevents bees with mites on them from other colonies to raise the varroa level..
– Bees that return to their own hive and not to the neighbor’s (drifting) is an important feature to prevent the spread of mites within the apiary.
– Forcing virus infected bees to leave the hive is one way for the hive to get rid of viruses, it’s not VSH, still very good. The house cleaning bees treat virus infects bees like trash, bees with damaged wings (DWV) or worker bees hatched too early (grey bees crawling around, APV-types).
– There are I’m sure more traits that are important for resistance.
VSH is a good feature!
VSH can sometimes be confused with less good development for a bee colony. This depends most often on a queen not laying eggs very well. But if a VSH colony is getting a lot of mites through reinvasion from colonies with high varroa levels in the neighborhood (within a distance of 2 km/1.5 miles) the result may be a lot of shotgun pattern brood combs due to a lot of uncapped and cleaned brood cells to get rid of mites. The consequence will be a slower development of the colony. But as mentioned above a true VSH trait give room for the variety that the pupae are not removed but they are recapped after uncapping. And this can happen more than once. In such a case the consequence needn’t be slow development of the colony even if the varroa level temporarily is a bit high.
This is a good example of VSHD. You see clearly that pupae in drone brood are removed as brown cocoon residues are left. This is the first round with brood. Also we see uncapped drone pupae with purple eyes, and some cells with uncapping having started with holes in the capping. Click on the pictures to make it bigger
Perhaps it’s good if more short names, such as acronyms as VSH, become common, names for different characteristics of resistance.
– With regard to the concept of Grooming, This term is well established. Bees have mites on their body and these are removed by other bees or themselves. We need no other term here.
– As far as VSH on drone is concerned, it is quite newly discovered and no special acronym is used as far as I know. VSHD = Varroa Sensitive Hygiene Drones.
That’s an important feature, maybe more important than VSH. The acronym VSHD could work well.
The mites are more attracted to dronebrood than to workerbrood. If a colony has 5-10% dronebrood in the brood area, as is often found in feral colonies (at least) and bees have a strong VSHD, the bee colony will not lose so many worker pupea (future valuable worker bees). Many mites will invade drone brood and will be cleaned out from this drone brood.
The Norwegian Hans-Otto Johnsen has shown (he is conducting such surveys and there is some notes about this in Norwegian bee magazine Birøkteren and on this blog) that bees more easily identifie mites in smaller dronebrood cells (6.2 mm) than in larger (7.2 mm), and clean out them from mites and pupae. Bees make smaller dronebrood cells naturally, the smaller the cell size is for workerbee cells. This is probably an important characteristic that small cell size provide. The drone cellsize is naturally 6.2-6.4 mm when the bees live on 4.9 mm worker bee cells.
These acronyms may work
– ED for entrance defense.
– LR for low robbery.
– LD low drifting.
– VP for virus peptides.
– VB for trashing virus infected bees
– If you have suggestions or comments don’t hesitate to share them, for example concerning more resistant traits. Maybe you have ideas how to measure resistance traits? Maybe the best selective tool is just measuring the varroa level a few times a year?