5.0 DISEASES, POISONING AND PESTS
The candidate will be:
5.3 able to detect the presence of Varroa (a mite) and describe its effect on the colony including awareness of the effect of associated viruses;
NOTES
The presence of varroa is most easily detected by having a mesh floor in the hive with an insert board below to catch debris including dead varroa mites. The insert board can be removed and inspected at leisure, ideally with a magnifying glass, to look for mites. Mites can also be seen in the hive attached to bees and larvae.
The mite is a reddish colour and has an squat oval (crab shaped) body with 8 forward pointing legs. http://en.wikipedia.org/wiki/Varroa_destructor
The mite punctures the body of the developing bee and feeds off the fat bodies. The fat bodies are food storage cells that also help with detoxification and the immune system. The larvae are weakened by this.
More seriously, the mite acts as a vector for transmission of viruses that may already be present in the colony. The action of varroa can therefore increase the spread of harmful pathogens. The symptoms of viruses can be any of these:-
- wing deformities
- trembling and paralysis,
- hair loss – leaving the bee with a shiny black appearance,
- reduced weight
- reduced disease resistance
- death
The effect on the colony largely depends on the level of infestation of mites. A strong colony where the mites are kept under control may show no ill effects but if infestation of varroa is allowed to increase then viruses can spread rapidly and cause a colony to collapse.
