Why Do Bees Buzz?: Fascinating Answers to Questions about Bees

10. Dangers to Bees

TEN Dangers to Bees Question 1: What dangers threaten bees in the environment? Answer: Poor nutrition, disease, parasitic mites (see this chapter , question 3: What parasites and insects prey on bees?), pesticides , and pollution are some of the threats that stress colonies and cause them to fail. Honey bees are totally dependent on the weather for creating their food supply, and malnutrition is common when a lack of rain or extreme temperatures interfere with the normal bloom cycle of plants that are their nectar and pollen sources. A rainy period keeps the bees inside the colony, forcing them to use up food that had been stored for the winter, and if the weather has been poor, plants may not be robust and the pollen may not contain the usual proteins, vitamins, and other substances required by the bees. If bees are in poor health, they are more susceptible to disease, including about twenty known viruses to which bees are vulnerable (see this chapter, question 2: How do bees survive harsh weather?). Insecticides are used as a seed treatment and in spray applications on plants. They become distributed throughout the tissues of the plants and can cause a toxic reaction when bees consume the nectar and pollen. Pollution also threatens habitat, as do housing developments and other large ground-clearing projects like airports, golf courses, and intensive agricultural projects that completely remove habitat. R5192.indb 154 R5192.indb 154 11/30/09 3:02:57 PM 11/30/09 3:02:57 PM DANGERS TO BEES 155 Question 2: How do bees survive harsh weather? Answer: Rain provides a hazard for bees, including the danger of being knocked out of the sky by a big raindrop. When it rains, the bees stay in the colony and survive on stored food. An extended rainy period can deplete supplies stored for the winter, endangering the survival of the colony. If foragers are caught away from their colony by a sudden rainstorm or cold snap, they sometimes take shelter under flowers or vegetation until the weather conditions improve enough for them to head homeward. Fig. 30. The black arrows point to small perforations in the wax cappings over brood; these are signs of stress in an otherwise healthy colony. Some beekeepers believe that these imperfections signal future trouble within the colony, despite the absence of any current disease. (Photo by Debra Cook-Balducci.) R5192.indb 155 R5192.indb 155 11/30/09 3:02:57 PM 11/30/09 3:02:57 PM 156 WHY DO BEES BUZZ? In the warm weather, bees are very active, but in winter they become sluggish and their metabolism slows. So-called warmblooded animals regulate their metabolism and maintain a relatively constant body temperature regardless of the temperature in the environment, and although cold-blooded creatures like bees and other insects are hot when their environment is hot and cold when their environment is cold, they do have some control over their body temperature through a process called thermoregulation. Thermoregulation enables bees to adjust their body temperature by generating some heat when their environment is cool by, for example, shivering and crowding together. On cold winter days, bees keep warm by clumping together in large groups and beating their wings in order to produce heat, alternating positions on the colder perimeter of the cluster with their sisters who have warmer spots in the middle. The temperature in the center of the cluster averages 21 degrees Celsius (almost 70 degrees Fahrenheit), with a manageable range of approximately 12 to 34 degrees Celsius (54 to 94 degrees Fahrenheit). L. Fahrenholz and colleagues at the University of Berlin found that if the central temperature falls below about 15 degrees Celsius (59 degrees Fahrenheit) and the peripheral temperature is even lower, the bees are in danger. The colony is more stable in the winter because the queen stops laying eggs and there are no fragile larvae requiring constant care and feeding. Honey bees can survive a normal winter sheltered in the hive, in a hollow tree, or in some other cavity, as long as they have enough stored honey to provide a source of energy. Most beekeepers only harvest the honey made during the spring and early summer for themselves, leaving the honey made from late summer and early fall flowering plants for the hive to consume during the cold weather. After the bees have eaten the honey in one...