In their dormant form almost all honeybee diseases can exist in any hive or are just waiting outside. Vigorous and strong colonies are far less under threat than weak colonies.
By following proven strategies you can reduce the health threat to your bee colonies:
1. Avoid colony stress which can be caused by excessive opening of the hive, manipulation of combs, feeding and relocating colonies.
2. Maintain colonies with queens with good egg-laying potential - colonies prepared for winter should have a good population of young bees.
3. Minimise the number of squashed bees during hive inspection - any infection will be spread when their remains are cleared away by hive cleaning bees.
4. Avoid stagnant water sources which may become contaminated by dead bees and bee excreta.
5. Keep your bee colonies strong - high bee density per hive volume. If the number of bees fit in one box, don't stack on another box. When you open your hive and not every frame is covered with bees, try to compact the volume of your hive by reducing the number of boxes from two to one, squeezing all bees into one box. If in summer your hive consisted of two or three boxes packed with bees, in autumn try to squeeze all bees into one or two boxes for winter. Bees need to keep the hive warm inside - this is impossible for a hand full of bees in a hive consisting of three or more boxes stacked on top of each other. Don't hesitate to compact the colony of bees into a nucleus when the bees don't fill an 8-frame box. When compacting, always make sure that they have sufficient food stores, not only honey but also some pollen.
6. Place your hive in a dry and well ventilated area - humidity is a major contributor to fungus diseases.
7. Place hives in a sunny position in the cooler months of the year - choose apiary sites that have good air drainage and protection from cold winds. Avoid cool shady and damp sites. Place the hive in a sun trap where it obtains maximum sun and maximum shelter from cold winds.
8. Provide good ground clearance to keep the dampness out - always elevate your hives from the ground; on a hive stand, on pallets, on bricks - the higher, the better - it will keep the moisture from the ground out of the hive.
9. Ensure hives prepared for winter have good supplies of honey - colonies with more honey had lower spore counts compared to colonies wintered with less honey.
10. Ensure colonies have adequate supplies of high protein pollen in autumn - this will help to ensure good population of young bees.