From bees to hummingbirds, pollinators are an essential strand in the web of life. Many are in trouble today, due in part to human activity. Jon McGinty looks at the way they impact our lives and offers tips on helping them to survive.
You don’t have to be a scientist to realize we all depend on plants to provide us with food, fiber, drink and many medications. But in order for flowering plants to thrive and reproduce, they need to be pollinated – the pollen from one flower must be carried to another, either on the same plant (self-pollination) or to another plant (cross-pollination). About 10 percent of these flowering plants, such as corn, grasses, and most trees, achieve this transfer by the action of wind or water.
The rest, which includes more than one-third of all human food crops, depend on about 200,000 species of pollinators to move the pollen from the male flower part to the female flower part. These pollinators include some bats, birds (especially hummingbirds) and other animals, but consist mostly of insects – beetles, butterflies, moths, flies, and particularly bees.
According to estimates by the U.S. Department of Agriculture, all pollinators contribute $217 billion (with a B) to the global economy each year. In the U.S., honeybees, native bees and other insects produce $40 billion worth of products annually.
“In general, bees are the best pollinators,” says Phil Pellitteri, an entomologist at the University of Wisconsin extension in Madison. “That’s what they are about, collecting nectar and pollen, dedicated full-time to working flowers. Other pollinators have other things going on, and pollination is incidental to their tasks.”
There are more than 3,000 species of native bees in North America, most of which are pollinators. Honeybees are not native to the continent (European honeybees probably arrived with the Jamestown colonists in 1621), but they account for a large percentage of the pollination of food crops in the U.S., for everything from asparagus to raspberries.
In our area of the Midwest, most farmland is cultivated for corn or soybeans, both of which are self-pollinated, although insects can insure a more abundant crop for soybeans. Other local cash crops which require insects to pollinate include apples, cucumbers, melons, pumpkins, tomatoes and cranberries.
“If you have an abundance of wild bees near your crops, you don’t need honeybees,” says Pellitteri. “Lots of pollination occurred here before they came along. But without enough native bees, growers need to ‘import’ honeybees, in order to guarantee an abundant harvest.
“The biggest shift in honeybee management in the past 40 years has been away from honey production to providing pollination services. It’s much more profitable to rent out your honeybees as pollinators. Because they form colonies, honeybees can be manipulated easily. Beekeepers can put their hives on trucks and take them to the nectar sources,” he says.
As a result, each spring hundreds of migratory beekeepers in the U.S. do just that. In the night, when bees are less active, they load their hives onto flatbed trucks and transport them across the country, following the crop bloom.
“For example, about half of all commercial honeybees in the U.S. end up in the almond groves of California at some point,” says Phil Nixon, University of Illinois extension entomologist in Urbana, Ill. “That’s one crop which is almost totally dependent on imported pollinators.”
According to many scientists, the numbers of both native bees and domesticated honeybees has been declining in recent years, due primarily to loss of habitat, diseases, invasive plant and animal species, and increased use or misuse of pesticides. During the winter and spring of 2006-2007, managed honeybee colonies in North America lost about a third of their population. The foraging bees simply disappeared from the hives. This sudden decline has been called Colony Collapse Disorder (CCD), and has continued to affect commercially managed bees. The U.S. lost almost 50 percent of its managed honeybees in the past 10 years.
The destruction of “wild” habitat has affected native pollinators as well as honeybees. Urban sprawl, which consumes farmland; the push to remove hedgerows; and mowing or removing roadside vegetation, all reduce the number of native plants available for food and nesting sites for bees and other insects. Roadside vegetation is especially important to migratory insects like monarch butterflies, whose numbers have decreased dramatically in recent years.
“When we widen a road or mow the roadside in rural areas too often, we lose a lot of food sources for pollinators,” says Nixon. “As we become a more ‘neatsy’ society, that’s rough on insects. A manicured lawn, for example, with only grass and no weeds, is essentially an ecological desert for pollinators. In California, the native bumblebee population has been dropping drastically, generating concern that some species may even go extinct. They’re linked very closely to native plants. When the plants go, so do the bumblebees.”
Monoculture, the practice of growing of only one or two crops over wide areas, demands a high population of pollinators at bloom, but such fields becomes a barren wasteland for hungry bees during other times of the year. Also, since many native bees are ground nesters, undisturbed soil is important to them.
“A barren landscape is not a natural one,” says Pellitteri. “With it, you can expect more problems for pollinators. The more diverse the habitat, the more diverse the pollinators.”
Honeybees often suffer from viral, bacterial and fungal infections, as well as parasitic mites and pesticides, all of which may partly explain CCD. Systemic pesticides, such as neonicotinoids, which get into the tissues of plants (including the pollen that some bees collect), are especially problematic. Since beekeeping is regarded as an agricultural commodity, it is regulated by the U.S. Department of Agriculture. Hives are registered, and beekeepers must keep records of diseases and other problems.
“Because of this, we have a fairly decent handle on the condition of local honeybees,” says Nixon. “We haven’t seen a lot of CCD in resident hives in our area. But we really don’t know if our native pollinators are in trouble. I have noticed an increase in feral [wild] honeybee colonies since the mid-1990s, however.”
To increase public awareness about pollinators and assist scientists in gathering data about them, the University of Illinois has created a website called BeeSpotter, at beespotter.mste.illinois.edu. At this site, citizen-scientists can post their photos of bee sightings throughout the state for entomologists to identify. The information collected is then used to gain a better idea of bee demographics in Illinois.
The following organizations are dedicated to helping reverse the decline in pollinators.
The Pollinator Partnership, on the Web at pollinator.org, promotes conservation, education and research to improve the health of pollinators critical to our food supply. Its North American Pollinator Protection Campaign, for example, disseminates eco-regional planting guides to support pollinators, and information on the proper use of pesticides.
The Xerces Society, on the Web at xerces.org, is an international non-profit agency that protects wildlife through the conservation of invertebrates and their habitat. Members work with leading native pollinator ecologists to translate the latest research findings into on-the-ground conservation.
Bob Arevalo has been an amateur beekeeper for about eight years, ever since attending a workshop on the hobby at Jarrett Prairie Center in Byron, Ill. Workshops are held on the 2nd Sunday of each month, from 2-4 p.m. For more information, contact Jeff Ludwig at (815) 703-7436. A retired clinical lab scientist from OSF St. Anthony hospital, Arevalo has four beehives behind the barn at his rural Boone County home.
“We have five acres full of prairie plants, most of the acreage being a designated nature preserve, so it’s a nice place to keep honeybees,” says Arevalo. “With my background in science, I’ve always been interested in nature and creatures. And honeybees are fascinating!”
Although a beekeeper’s tasks are greatest during the summer, there are many things to be done year round. During winter months, Arevalo occasionally inspects each hive to make sure the bees have enough to eat. If not enough honey is left, he supplements their diet with sugar water and a pollen substitute.
As the bees become active in the spring, Arevalo makes sure the queen in each hive is laying eggs for the brood. When the honey flow starts, he adds one-story extensions called “supers” to the top of each brood box, so the bees will store the honey in these detachable boxes.
“If you don’t add the next story soon enough, the hive becomes overcrowded and the colony will swarm,” says Arevalo. “When a super is full, I remove it and take it to a ‘honey house’ to extract the honey. The bees will continue to make honey to replace what I’ve harvested.”
Each frame of stored honeycomb is capped with a layer of beeswax, which Arevalo removes with an electric knife. The comb is then placed in an extractor, a big centrifuge which draws out the honey as it spins. The honey flows through a filter into a five-gallon bucket, which Arevalo uses to fill his plastic containers.
“My honey is raw – unpasteurized – so it retains its full flavor and nutrients, unlike most honey you buy in stores,” says Arevalo. “I don’t sell it. I enjoy giving a jar to friends.”
During the fall, Arevalo periodically inspects his hives to make sure enough honey has remained to overwinter the colony. “I use a hive tool to pry up the combs and estimate the weight of the remaining honey,” he says. “Each hive needs around 75 pounds of honey to survive the winter months.”
Arevalo recommends a beginning beekeeper start with two hives, to assure that at least one will survive the first year. He says that, for less than $1,000, a beginner can purchase the necessary equipment to start the hobby, including a starter package of several thousand bees and a mated queen (which sometimes arrives by mail), brood boxes and supers with removable frames, protective clothing, and a smoker to distract them when disturbing the hives.
“In nature, the honeybee’s greatest threat is a forest fire,” Arevalo explains. “If they smell smoke, they immediately go into survival mode by gulping a load of honey and preparing to escape the hive. They’re not interested in stinging.
Ken Hall, owner of Edwards Apple Orchard near Poplar Grove, Ill., is a local grower who imports honeybees to help pollinate his crops. Bob Edwards started the orchard in 1964 and Hall has worked there since 1984, taking over the operation in 1990.
“We have 52 acres of apple trees – about 23,000 – and every spring we bring in about 60 colonies of honeybees, each of which contains around 30,000 bees,” says Hall.
Although he has used bees from a variety of commercial beekeepers, Hall prefers to obtain them from a bee yard in Janesville, Wis.
“I prefer the local bees, ones that have overwintered here in the Midwest,” says Hall.
The bees usually arrive in early May, when the apple blossoms appear. After the hives are evenly distributed throughout his orchard – one or two hives per acre – Hall conducts two bee counts to insure that his trees are being pollinated. On a sunny afternoon, during peak activity, he randomly picks a tree far from a hive, and counts how many bees visit it.
“If I don’t see at least two bees per minute in that tree, I call for more colonies,” he says. “I also count how many bees exit a hive per minute.”
The honeybees stay at Edwards Orchard for about 10 days to two weeks, then are shipped north by flatbed truck to cranberry bogs in central Wisconsin. One year, when he couldn’t get local bees soon enough, Hall purchased bumblebees from Canada, which arrived in 20 self-contained cardboard “hives” via UPS.
“Bumblebees are fantastic pollinators,” says Hall. “Unlike honeybees, they fly in cooler temperatures, in rain, and can stay out all day. One bumblebee can do the work of many honeybees, but they’re more expensive.”
They’re also a “one-way trip,” since bumblebees don’t create a permanent colony. Only young, mated queens hibernate in the soil during the winter; all others die off in the fall.
Hall recognizes that his orchard is surrounded by a monoculture landscape of corn or soybean farms. Last year, in order to encourage the production of more native pollinators in his area, with the help of University of Illinois graduate students, he began a program of installing “diversity strips” of native perennial plants between rows of apple trees.
“The idea is to have native plants blooming all year, to provide habitat for native bees and other pollinators that were here before domestic honeybees were introduced,” says Hall. “I don’t intend to compete with managed beekeepers, but it’s not a good idea to put all things in one basket. The reason most growers don’t do more of this is the cost: $1,100 per acre for seed.”
Hall has also restored a wetland and several wooded areas on his property. While he still needs to use fungicides and insecticides to control diseases and insects harmful to his apple crop, he’s always searching for solutions with the least harmful impact on the environment.
“I’m not an organic grower, but I try to be a low-input grower,” he says.
Claudio Gratton is an associate professor of entomology at the University of Wisconsin in Madison. Two of his graduate students, Hannah Gaines and Rachel Mallinger, are studying the importance of wild native bees in Wisconsin agriculture.
“Managed honeybees are not doing that well,” says Gratton. “Colony Collapse Disorder (CCD) is affecting some, and the overall quality is not as high as it once was. So managed pollination is not something we can continue to take for granted. Honeybees are also not cheap, costing growers between $60 and $100 per hive. Our study is asking if honeybees can be augmented or replaced by wild bees, of which there are about 600 species in Wisconsin.”
Mallinger studies bee populations in about 35 apple orchards throughout southern Wisconsin, from Milwaukee to the Mississippi River, and a few in Door County. She compares the yield of orchards which use honeybees to orchards that don’t.
“About 25 percent of the orchards I’m studying don’t import honeybees and don’t manage them on their properties,” says Mallinger. “My preliminary conclusion is that wild bees are already doing a lot of the pollination, and in most cases produce the same number of apples as those orchards which use honeybees.”
Mallinger believes many growers decide to import honeybees as an insurance against lower wild bee populations. “Honeybees will also always be valued for their honey,” she says. “No wild bee can replace them for that.”
Gaines’ research focuses on about 45 cranberry growers in the marshes of central Wisconsin. In four years, she has collected about 200 native bee species in cranberry bogs.
“The majority of cranberry growers I’m studying currently rent European honeybees for pollination, as many as nine hives per acre,” says Gaines. “The larger farms with much surrounding agriculture tend to support fewer native bees. Their flight distance is usually shorter than honeybees, and most have specific nesting requirements, whereas honeybee hives can be placed exactly where the grower wants them.
“It’s still possible, however, for cranberry growers to put in native plantings and floral resources for native bees. By manipulating their property and encouraging such bees, they will derive free pollination services from them.”
“Both studies are showing us how extensive our native bee population is,” says Gratton. “We’re learning how to appreciate nature’s diversity, and how to manage our agricultural landscape to protect it.”
All About Honeybees
Like most insects, honeybees go through four stages of metamorphosis: egg, larva, pupa and adult. The adults differentiate into three types, or castes – workers, drones and queens – and emerge from their cells at different rates.
Drones are males, almost twice the size of workers, and their only function is to mate with the queen. All the workers in a colony, and the queen, of course, are female. As they mature, the workers’ job description changes from cleaning cells, keeping the brood warm and feeding larvae, to producing wax, building combs, transporting food within the hive or guarding the entrance.
By the time they’re about two weeks old, workers become foragers and leave the hive to visit flowers, collect pollen, nectar and propolis (a kind of tree resin used to bind things together in the hive). At the height of summer, most workers become bruised and battered from all this work, and die around 35 days from emergence. Worker bees that emerge in late autumn may live up to 16 weeks through the winter. As the colony prepares for winter, the drones are driven out of the hive to reduce the population, which must survive until spring on stored honey and pollen.
A queen is created from a worker larva that has been fed a large amount of a specific mixture of pollen and enzymes called “royal jelly.” If more than one queen emerges at the same time, they battle one another until only one survives. The remaining queen mates with several drones and retains their sperm in her body in a special sac called a spermatheca. The queen lays eggs all season to replace bees that have died off. An average queen might lay 1500 eggs a day, and may live for up to three years, laying half a million eggs in her lifetime.
Honeybees depend on flowers for their survival. Sugar in the nectar provides carbohydrates, while pollen is the primary source for proteins, fats, vitamins and minerals. An average colony of 40,000 to 50,000 bees can produce up to 180 pounds of honey per season, depending on weather and other factors, 2/3 of which can be harvested by a beekeeper.
The honeybee’s body and legs are covered with tiny hairs which collect the pollen as it forages from blossom to blossom. Periodically, the bee will brush pollen from its head, thorax and forelegs with the hairs on its mid-legs, then pack the pollen into a special chamber on the rear legs called a pollen basket. A colony of bees can collect as much as 100 pounds of pollen in one season.
Foraging bees must collect nectar from about two million plants to produce one pound of honey. Bees which discover sources of nectar communicate information about the distance, direction and quality of that source by means of a dance, and their orientation to the sun.
Nectar is cured into honey by the worker bees beating their wings to evaporate the moisture. The honey is stored in hexagon-shaped cells within the comb, and capped with beeswax when the cell is full. The cells slope slightly upward from the base, so the honey won’t run out before it’s capped. Honey combined with pollen produces “bee bread,” which is what the bees eat.
When a colony becomes overcrowded or an old queen needs replacing, the colony will swarm. The queen and about 60 percent of the population take a big gulp of honey, leave the hive and collect on a tree branch or other object nearby. Workers as “scouts” leave the swarm in search of a new location for the colony. When such a potential spot is found, the scouts bring others to inspect it, until a consensus arises within the swarm that this is going to be their new home. Then the cloud of bees moves to the new location to begin construction of the new hive.
When a worker bee stings, the barbed stinger stays in the flesh of the victim, but the venom sac and attached muscles are torn from the bee’s abdomen, so it dies. The muscles continue to contract, however, injecting more venom into the victim, as well as releasing pheromones to warn the hive of danger.
To safely remove a stinger, scrape the sac away with something stiff like a credit card or fingernail, then moisten the wound and coat it with baking soda to neutralize the venom.