How to prevent and control nosema disease in bees? Eight measures to help you deal with it

Nosema disease is a disease of adult bees that causes crawling bee disease. It is a common disease of Western honey bees (Apis mellifera). Most apiaries suffer from this disease to varying degrees, and it is very difficult to cure completely. However, because of differences among apiaries in four-season management, preventive treatment and other measures, the incidence varies from mild to severe, and severe cases weaken colony strength and affect production.

Based on years of observation and experience in amateur beekeeping, the predisposing causes of nosema disease outbreaks include: a site with little sunlight all year round, low-lying and damp terrain, dirty surrounding environment, unclean water sources, lack of proper cleaning and disinfection of hive equipment and combs, weak colony strength, lack of pollen after autumn, excessive humidity inside the hive, and neglect of prevention and control. In particular, long periods of low temperature and rainy weather, when bee colonies cannot fly freely to defecate, also easily trigger nosema disease. Seasonally, it occurs more often in early spring, late autumn and early winter. In affected colonies, adult bees continuously crawl out of the hive; a few have slightly black heads and tails, while most show no difference in hair color; most are empty-bodied, while a few have swollen abdomens; they quiver their wings, are unable to fly though they try, and crawl everywhere. Dead bees lie all over the ground, a shocking sight, and colony strength declines rapidly, sometimes becoming too weak to remain a colony. For prevention and control, prevention should be more important than treatment. I have the following eight measures for preventing and controlling nosema disease: First, the site should face south with its back to the north, be sheltered from wind and exposed to sunlight, and the terrain should be high rather than low. Hives should be placed 20—30 cm above the ground, with bricks, benches or wooden stakes used to prop up the hive legs as appropriate. The waterproof asphalt felt on the hive outer cover should extend 2—3 cm beyond the edges on all sides, and the hive bottom legs should be recessed by 2—3 cm to prevent rainwater from soaking into the hive from above and below. It is also necessary to ensure sufficient sunlight in front of the hive entrance, using the ultraviolet rays of sunlight to kill various pathogens in the bee colony. Second, the environment around the apiary should be clean and hygienic, and there should be a clean water source nearby for the bees to use. Dead branches, fallen leaves, weeds, and chicken, goose, pig and sheep manure and garbage around the apiary should be cleaned frequently; dead bees and diseased bees should be swept up and buried far away to prevent repeated infection. In spring, summer and autumn, some lime should be spread regularly around the apiary for disinfection and sterilization. It is best to have green trees shading the hives, but not dense shade covering them. Third, hives, combs, bee equipment, honey extractors and honey containers should be cleaned and disinfected regularly. Every spring and autumn, after scraping off propolis, burr comb and wax flakes from the hive, disinfect with a blowtorch flame; the hive can also be turned upside down and smoked with a straw bundle or waste newspaper for one to two minutes for sterilization and disinfection (be careful not to scorch the hive body). After scraping off propolis, cutting off the drone cells at the lower corners and removing burr comb, soak the combs in a 3% alkaline water solution for 6—8 hours for sterilization and disinfection, then rinse clean with water, dry and use. Other bee equipment can be cleaned and disinfected with hot 3% alkaline water. Fourth, for apiaries with a history of nosema disease in previous years, in early spring, late autumn and before overwintering, recurrence of nosema disease should be prevented by feeding medicated syrup (white granulated sugar mixed with water at 1/2). For each kilogram of syrup, add 0.5—1 g citric acid, 50,000—100,000 units of chloramphenicol, or 2 g benzalkonium bromide (benzalkonium bromide should be mixed and used immediately). Feed 30—50 g per frame of bees each time, once every two days, for 3 consecutive feedings, which can prevent recurrence of nosema disease. Fifth, strong colonies should be maintained year-round, keeping honey and pollen sufficient. Near late autumn and early winter, weak colonies of fewer than 5 frames should all be merged. Sixth, breeding disease-resistant bee stock is another effective way to prevent and control nosema disease. When nosema disease occurs in an apiary, the severity always varies among colonies, and some colonies may even have not a single crawling bee. This provides conditions for breeding resistant stock. Records should be kept promptly, and when replacing queens in spring, summer and autumn, choose disease-free colonies for queen rearing and eliminate all queens from diseased colonies. After several generations of selection and breeding, nosema disease can be controlled. Seventh, frequently turn and air the insulation materials of the bee colony, keep the inside of the hive properly dry, reduce cold and dampness inside the hive, and encourage the colony to fly and defecate. Eighth, when a few crawling bees appear in a colony, never take it lightly and think that a few crawling bees in such a large colony do not matter, thereby delaying treatment. You should know that once crawling bees break out everywhere, it becomes difficult to manage. This is especially true in late autumn and early winter, when you must not be negligent, and you should not mistakenly assume it is honeydew poisoning (honeydew poisoning mostly presents as crawling bees with swollen abdomens). Treatment should be started immediately: for each kilogram of syrup or diluted honey, add 1--2 g citric acid and 100,000—200,000 units of chloramphenicol, feed 50—100 g per frame of bees each time, once every 2 days, for 5 consecutive feedings, which can basically cure the disease.