Thursday, November 29, 2012

Cotton and Bees

Crops grown in today’s modern industrial agriculture employ improved seed, chemical pesticides and fertilizers, irrigation, and heavy machinery. Farmers are keenly aware of industrial agriculture’s impact on the natural world, and most producers are diligent stewards of the environment. They take great care in protecting their land and the wildlife that lives on it. Cathy Foust, Shelby County, Tennessee’s Extension Director, invited me to attend a presentation on protecting pollinators by Dr. Don Parker, Integrated Pest Management Manager with the National Cotton Council. Also attending were several other beekeeping friends, Richard Coy, president of Arkansas Beekeepers Association, Charles Force, president of Memphis Area Beekeepers Association, and Jon Zawislak, apiary instructor with University of Arkansas Extension Service. The audience of interested agricultural producers listened intently as Dr. Parker discussed the impact pesticides make on honey bees and native pollinators. Many of the producers were not aware that honey bees forage cotton fields. Some had not considered the effect of cotton insecticides on beneficial insects; they had only concentrated on killing pests. Cotton growers asked numerous questions of the beekeepers and seemed to be equally interested in protecting pollinators.

Dr. Parker spoke of some of the difficulties involved in protecting beneficial insects while trying to control pest insects with insecticides. One suggestion was to only apply insecticides at night while bees are not flying. Dr. Parker mentioned how dangerous it would be to fly a crop duster at night with cotton fields surrounded by trees and power lines. Such practices are completely unacceptable. Cotton growers and beekeepers were interested in discussions of the effect on beneficial insects when spraying insecticides on crop plants with “indeterminate growth” in which pollinators are continuously attracted by nectar. Here, bees can be poisoned even when the crop is not blooming. Other insecticide spraying challenges exist with plants, like cotton, which have “extrafloral” nectaries secreting nectar outside the flower. Today’s photo: a honey bee and a bumblebee, a native pollinator, share fall goldenrod near cotton fields.

Tuesday, November 13, 2012

Abandoned Bee Hives

When honey bees swarm they frequently move into cavities previously used by other colonies of bees. They are attracted to old bee nests by hive odors of beeswax, honey, propolis, pollen, bees, and their pheromones. It is common for a colony of honey bees to occupy a hollow tree for a couple of years and then die after being weakened by parasitic Varroa mites. Even if the combs are destroyed by hive scavengers, like wax moths and small hive beetles, the cavity is likely to attract another colony of bees. The same sequence of events commonly occurs when people attempt to drive honey bees from the walls of their houses. Old colonies are soon replaced by new colonies. Colonies of bees replace one another so frequently that it may appear a hive is occupied continuously when it actually held a series of different colonies. The attractiveness of hive odors makes old bee hives effective bait hives for capturing swarms in the spring and summer. Old abandoned bee hives are attractive to swarming honey bees as well.

I received a call asking me to remove bees from some abandoned hives. I found a very large feral colony occupying a stack of rotting hive bodies. While wood rot and termites had consumed most of the woodenware, combs were held together by propolis. One by one, I transferred the frames of brood into new hive boxes. After all intact frames were moved, a number of broken pieces of brood comb remained. I placed these in a nucleus hive. After several weeks I found the feral queen hiding among the broken combs in the nucleus hive. The bees in the larger hive produced a new queen. I now have two strong hives with good behavior and characteristics. I welcome these locally-adapted feral genes into my bee yards. Was the colony in the abandoned hive equipment truly feral? Possibly, or its queen may have been purchased from a breeding program by another beekeeper. Lucky find.

Wednesday, November 7, 2012

Parasitic Mite Syndrome

Beekeepers are detecting large populations of parasitic Varroa mites in their hives this fall. The Varroa mite is the most serious pest of honey bees in America. Though the mite weakens honey bees by sucking their blood, called hemolymph, they cause the most hive damage by spreading disease through the bee colony. Varroa mites reproduce inside the capped bee hive cells containing the pupa stage of developing bee brood. The parasitic mites pierce the exoskeleton of honey bees with their mouth parts to suck nutrients. The perforations caused by the mites allow entry of bacterial, fungal, and viral infections. At least 15 honey bee viruses are spread by Varroa mites. The combined effect of these honey bee diseases is known as Parasitic Mite Syndrome. Hives experiencing PMS often show reduced populations of bees as they decline and eventually collapse. One easily recognizable symptom of PMS is the existence of young bees in the hive with diminished, curled wings as the result of Deformed Wing Virus. Varroa mite populations increase steadily in bee hives anytime that bees are reproducing. Mite populations large enough to collapse colonies typically occur in the late summer and early fall. Beekeepers should measure mite populations and, if necessary, treat the hives with “soft” treatments of organic acids or essential oils.

Parasitic Mite Syndrome produces brood patterns with numerous empty cells as opposed to continuous patterns of capped cells. Some of the empty cells result from workers removing honey bee pupae that they detect having mites reproducing and developing with the bee pupae. This genetically heritable honey bee activity, known as “hygienic behavior,” is the basis for Varroa resistant honey bee stock. In today’s photo we see a brood frame from a hive showing signs of Parasitic Mite Syndrome. The brood pattern is “spotty;” a number of capped cells have been opened, and the bees are chewing out the pupae. Other hive conditions, such as American foulbrood and chilled brood, may have a similar appearance.

Monday, November 5, 2012

Fall Bee Hive Management

In the fall it is important to look inside the bee hives and set them up for winter. Fall bee hive management is designed to help the bees survive the winter. This week I checked bee hives with Corinth, Mississippi beekeeper, Heidi Hendrix, and my 12-year-old grandson, Ethan. There are two important issues for over-winter success: food and hive ventilation. We make sure that the brood nest is located low in the hive with frames of capped honey above. To get this arrangement, we may need to move frames or rearrange hive bodies. It is the tendency of honey bees to move upward in the hive over the winter. The heat of the bees’ winter cluster warms the stored honey above the cluster; the bees eat this honey; and then they move up to occupy the empty cells. If the bees begin the winter with their brood nest located high in the hive, they may not move down to feed on available honey stores. It is frustrating for beekeepers to find honey bee colonies that starved while there is plenty of available honey stored inches away from the bees’ winter cluster. If the hive is light in weight when one end is lifted, the bees need feeding. For fall feeding, “heavy” syrup of two parts sugar to one part water is readily converted to honey and stored.

The second important issue in bee hive set-up for winter is ventilation. Bee hives are warm and damp on the inside. Cold winter temperatures outside the hives cause condensation to form on the inside hive walls. The effect is opposite that of a glass of iced tea on a hot, damp Delta summer day where condensation forms on the glasses’ outside surface. Water dripping in the hive can kill bees. A small vent at the top of the bee hive is all that is needed to remove hive moisture. Today’s photo shows a full box of capped honey above the brood nest.