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.

--Richard

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.

--Richard

Caution with Insecticides

Some insects are annoying pest that eat crops, contaminate food, and spread disease. Other insects are considered beneficial. These insects pollinate our crops, producing food and seed. Others help control pest insects. If insecticides are used to kill insect pests, they often kill beneficial insects as well. Insecticides described as “broad spectrum” kill all insects in the area regardless of whether they are considered pest or beneficial. This year’s late-summer spraying of insecticides killed honey bee colonies when other insect pests were the target. Annoying mosquitoes and flies were targeted in urban lawns, but honey bee colonies were killed as well. A Memphis beekeeper found thousands of bees dead on the ground around her hive with dozens of other bees crawling and twitching on the ground. They likely encountered a neighbor’s broad spectrum insecticide spraying arrangement.

An article in The New York Times describes efforts being made to develop methods of delivering poison to mosquitoes. Mosquitoes which spread malaria are a major killer of humans, especially young children, in parts of the world. Diseases, like malaria and dengue, are spread by mosquitoes when they bite humans to suck blood. Female mosquitoes, the only ones that bite humans, need the blood for its iron and protein to lay eggs. The insects can live, however, on nectar from flowers or from ripe or rotting fruit. The Times article,  http://www.nytimes.com/2011/09/27/health/27mosquito.html, describes how researchers are making nectar poisons known as Attractive Toxic Sugar Baits. While the initial trials are proving effective in killing large numbers of mosquitoes, the use of poisoned nectars is particularly troubling to beekeepers. We will be keenly watching the development of poisoned nectars. Many beekeepers feel that the systemic neonicotinoid insecticides now in widespread use affect honey bee immune systems and have a negative effect on honey bee health. Today’s photo shows tree frogs sharing the bee hive; bees seem to completely ignore the vulnerable frogs. Frogs and other amphibians are considered indicators of the health of the environment.

--Richard

Toxic Effects

The honey bee has been compared to the coal miner’s canary. Coal miners used the fragile birds as indicators of the condition of mines. As long as the canaries could breathe the mine’s air and continue singing, the atmosphere was considered safe enough for the miners to breathe. The death of the canary meant that the mine was in trouble. The death of honey bees may indicate that the environment is in trouble. Beekeepers experienced heavy losses of colonies throughout the Mississippi River Delta region this past summer. During a summer that set records as the hottest in recorded history, pest insect populations exploded in the Mississippi and Arkansas Deltas. Army worms and soybean loopers covered cotton and soybean plants, often stripping the plants of leaves. In response, growers sprayed broad-spectrum insecticides on these plants, which are highly attractive to honey bees and other pollinators. Broad-spectrum insecticides kill all insects, including beneficial pollinators, not just the targeted species. Some of the sprayed pesticides are considered persistent, meaning that they remain in the environment for a long time. For the honey bees, the summer-time insecticide sprayings were particularly damaging. Many of the crops sprayed with insecticides for the summer’s break-out of insect pests had previously been treated with systemic insecticides. Here, insecticide-coated seed poisoned the entire crop plant. Honey bees cannot detoxify multiple toxins in their bodies. With their immune systems severely damaged, the bees were attacked by multiple pathogens: bacteria, viruses, and funguses. Sick bees left the hives to die without contaminating the colony. Bees disoriented by neurotoxins were unable to navigate back to the hive and died.

The spraying of broad-spectrum insecticides in the summer resulted in heavy losses for the Delta beekeepers. Native pollinators were surely decimated as well. Continuous use of pesticides results in replacement of pest populations with new, chemical-resistant pest populations. My queen evaluation bee yard, shown dusted in light snow, lost more than one fourth of its colonies of workers, drones, and queens.

--Richard