By Jenny Bradley
Several YABeeP members managed to get along to the 2010 Combating Colony Loss day run by the Regional Bee Inspectors in Devon and this is Jenny's report:
Whilst the day was centred on conventional beekeeping practices it was suggested that the RBI are becoming more receptive to alternative hives and beekeeping husbandry.
In particular, they are recommending that chemicals for disease and pest treatment only be used where there is a problem, not as a prophylactic. All can leave residues in the hive. The day concentrated on nosema and varroa with workshops on both. Artificial swarming was suggested as one means of varroa control. The old queen is taken to a new hive and the older worker bees follow her. Varroa prefers younger bees and particularly the brood and so mostly remains in the original hive where it can then be killed. Swarming is therefore a 'natural' way of controlling varroa. They suggested monitoring varroa and treating above a certain threshold level. After treatment the mite can be back to full levels within 3 weeks.
Nosema is a parasite that lives in the gut of the bee. It does not cause dysentry but often appears with it. It affects a bee's ability to digest food and prematurely ages the bee thus shortening its life. It can be identified by mashing up about 30 dead bees with water into a 'soup' and putting it inder a microscope. Nosema looks like a grain of rice.
The final talk of the day was from Norman Carreck of Sussex University. Sussex does much work on bees and other swarming insects. His fascinating talk began with a historical account of incidences of bee diseases showing that colony collapse and disease is not new. He said that confining bees to a hive is the ideal place for disease. Colony loss is rarely from one single cause but it is often difficult to pin the cause down. Causes include late springs, lack of food, diseases, too many hives for the available forage. There are 30+ viruses in bees. The university is carrying out research on colony collapse and bee deaths. The amount of damage to a colony is not related to the number of varroa mites in a hive. However it seems to make bees more susceptible to deformed wing virus and to a lesser extent, slow paralysis virus. Research shows that if there are more than 2000 mites in a hive the colony will die within a year, but it is because they have deformed wing virus too. Another virus, Kashmir virus is virulent when varroa is present and harmless without. The spanish blame nosema for colony deaths, France insectidices and the USA viruses but they all have varroa. The USA has 30% colony losses, Europe up to 53% and Japan 25%. South America, Africa and Australia have no colony losses. Australia has no varroa, african bees are resistant to varroa and south american bees were brought from Africa and although they have varroa, it is a less virulent strain. Research is therefore clear that it is not the varroa in itself which is a threat to bees, but varroa in conjunction with another factor, a virus. Therefore varroa is our major problem. There is a serious lack of control measures and vaaroa has no natural pathogens. Research on a potential fungal control is waiting for further research money, funding having been withdrawn when varroa became so widespread that it was no longer notifiable. There are hygenic bees which are resistant to varroa. Britain has 10% hygenic bees. These are a hope for the future.
The day was extremely useful and it was also reassuring to see that there appeared to be a growing recognition that practice has to change.