Saturday, August 21, 2021

Insecticides Kill Bees


Honey bee foragers bring flower nectar and pollen into the hive as food. The nectar is carbohydrate that the bees convert into honey. Pollen is primarily protein; it also contains fats, vitamins, and minerals. When honey and pollen are combined in the hive, the food is called “bee bread.” Yeast and bacteria from the bees’ gut microflora cause fermentation of bee bread, breaking down the hard shell around pollen grains and exposing the proteins. Fermentation also preserves bee bread. Young worker bees consume bee bread, and glands in the workers’ head produce brood food that nurse bees feed to developing bee larvae. Bee bread is also used to produce royal jelly, a high-energy food fed to all brood in its first day and fed to the queen bee throughout her life.

When honey bee foragers visit flowers, pollen grains adhere to the bees’ hairy bodies. The bees groom the dusty pollen into pellets that they carry on “pollen baskets” on their hind legs. Honey bees at times pick up environmental dusts that adhere to their bodies similarly to pollen. Grain dust from poultry feed is commonly collected by honey bees. Chemical pesticides in dust form are also accidentally collected by bees and brought back to the hives. Carbaryl, an insecticide sold under the name “Sevin,” is particularly deadly to honey bees when applied to flowers in dust form. Insecticides may kill honey bees rapidly on contact or ingestion. However, they may kill bees more slowly if the poison is stored as pollen and later converted into bee bread. When the bees feed their brood secretions from poisoned bee bread, they kill the developing bees. Likewise, they can kill the queen by feeding her poisoned royal jelly. Beekeepers look for larger numbers of dead bees on the ground near the hive entrances, seen in today’s photo. I, and other area beekeepers, lost brood and queens in a number of hives. Those using insecticides should use caution and be prudent applying chemicals.