The Bumblebees' Nest

Suitable nesting places are in great demand for small creatures. A birdhouse, built by a friend using old bee hive lumber, hangs on the porch railing of our home. Each year there is considerable competition between finches, wrens, bluebirds, and sparrows for the use of this nesting box. This spring, sparrows won the battle and reared a clutch of baby birds. After the fledgling birds left the nest, bumblebees moved in. Typically, bumblebees live underground in abandoned mouse nests. Unlike honey bees, which have colonies containing thousands of members, bumblebees establish small colonies of several dozen bees. Bumblebees collect nectar and pollen from flowers, and inside the bumblebees’ nest they build small honey pots to hold their food stores. Bumblebees, like honey bees, are gentle insects; however, they both defend their nests from intruders by stinging. When gray squirrels started gnawing at the entrance to the bumblebee colony’s birdhouse home, the bees came out in force. Bumblebees attacked and chased all squirrels and songbirds in the vicinity. They also chased humans from the area. Protected by my beekeeper’s protective veil and gloves, I removed the bumblebee nest from the birdhouse. The disturbed bumblebees persisted in continuing their attempt to drive me away. While bumblebees ignore the touch of a bare hand while they are foraging on flowers, one would surely not want to handle their nest without protective gear!

A trap-door arrangement on the birdhouse allowed me to remove the sparrows’ nest intact. The bumblebee nest filled a vacancy in the center of the soft bird nest material. Today’s photo shows the neat wax honey pots and pollen stores. Bumblebees have longer tongues than honey bees; thus they are able to forage on flowers with deeper, bell-shaped coronas. They carry pollen in pollen baskets on their hind legs. They have a stinger without barbs. Bumblebees are important pollinators of crops and wildflowers, but they don’t produce a surplus of harvestable honey. They are used to pollinate tomatoes grown in greenhouses.

--Richard

Global Warming and Bumblebees

When Colony Collapse Disorder was detected in 2007, researchers immediately started searching for causes of the massive honey bee die-offs. They also looked at other species of bees to see if they were being affected as well, and they found that several species of bumblebees are also declining. We now know that honey bee and native bee populations are declining as a result of a combination of factors including habitat loss, nutritional problems, pesticides in the environment, and increasingly virulent pathogens. A large-scale study of bumblebees in Europe and North America concludes the effects of global warming as also being significant contributors to bee losses. The study described in The New York Times, http://www.nytimes.com/2015/07/10/science/bumblebees-global-warming-shrinking-habitats.html, traces 420,000 observations of 67 species of bumblebees over 110 years. The researchers analyzed bumblebee observations for every year from 1900 through 2010, recording the geographic range of each species. They found that bumblebee ranges declined at “continental scales” in the years following 1974 when human-caused climate change increased at a significant rate. With temperatures rising by two degrees Celsius since 1974, the southern limits of bumblebee ranges retreated toward the north at a rate of about three miles per year. One species of bumblebee once found in North Carolina and the Mid-Atlantic is now found in Maine, New Hampshire, Ontario, and Quebec. Another bumblebee once found in Georgia is now found in small numbers in Illinois, Maine, and Wisconsin. The researchers were surprised to find that bumblebee ranges didn’t merely move northward; the areas shrunk. The northern borders of the bumblebees’ ranges didn’t move into new territories.

As climate changes occur in temperate regions, like Europe and North America, species relationships are changed. Timings of flower blooming may result in a dearth of food for bees at critical times. Some species can’t tolerate changes in climate heat. In today’s photo, we see bumblebees foraging pickerelweed flowers along an Arkansas waterway. The native pickerelweed is an efficient biological filter of polluted water.

--Richard

Clothianidin Studies

The neonicotinoids are insecticides developed with the hope of being less harmful to wildlife and beneficial insects than the available insect killers, the pyrethroids and organophosphates. The neonicotinoids came into widespread use with the understanding that they would not kill beneficial insects like the honey bee and bumblebee. The use of neonicotinoids coincides with the die-off of honey bees and significant reductions in bumblebees. Two studies linking honey bees’ having difficulty in navigating from flowers to the hive confirm that neonicotinoids impair bees’ senses. The studies are reported by The Washington Post at http://www.washingtonpost.com/national/health-science/new-bee-research-details-harm-from-insecticide/2012/03/29/gIQAZrnGjS_story.html. The studies find that bee hives exposed to low levels of neonicotinoid insecticides have fewer bees and bumble bees produce markedly fewer queens. Bayer CropScience, a manufacturer of neonicotinoids, calls the studies inconsistent with their findings. Beekeepers and the Center for Food Safety petitioned the Environmental Protection Agency to ban the use of clothianidin that the EPA approved using Bayer’s tests.

Neonicotinoids are generally applied as a seed coating. The systemic action of the insecticide causes the poison to be distributed throughout the plant including the nectar and pollen, highly attractive bee foods. Traces of neonicotinoids are taken back to the bee hive by foraging bees. While beekeepers in the United States are taking annual honey bee colony losses of one third each year, the effects are often more subtle than total colony failures. Colonies are often described as simply not thriving. Bee populations may be low; bees may have shortened life expectancies; or hives may lack sufficient bees of appropriate foraging age. Each of these situations leads to colonies that are susceptible to diseases and parasites. With small populations, colonies don’t produce surpluses of honey. Bee hives used for pollination service fail when graded according to bee population. With the ever increasing use of neonicotinoid insecticides that have been shown to have a detrimental effect on pollinators, the crops, lawns, and golf courses flourish while honey bee colonies, native bees, and beneficial insects quietly disappear.

--Richard

A New Bee Parasite Found

A phorid fly known to be a parasite of bumblebees and paper wasps has been found to also parasitize honey bees. This fly, recently identified in California and South Dakota, is in the same genus as the “decapitating flies” that parasitize fire ants. The phorid flies, widely found across the US, multiply inside the bee hive and can infect the queen; female phorids deposit eggs into the abdomen of honey bees. Honey bees that are attacked by the phorid fly leave the hive at night and die. Then, the phorid fly larvae emerge from the dead bee and pupate elsewhere. The abandonment of the hive by worker bees is demonstrated in Colony Collapse Disorder, now thought to be caused by the interactions of multiple pathogens and parasites. Both phorid adults and larvae are found to carry honey bee deformed wing virus and Nosema ceranae, two pathogens associated with CCD. The researchers that detected the phorid flies parasitizing honey bees also found the infected bees flying from the hive at night, not a normal honey bee behavior. Honey bees infected with phorid flies were also found flying around lights at night in a manner similar to moths, also not a normal honey bee behavior. A potential threat exists if the phorid fly has moved from bumblebees’ small, seasonal colonies to infect the much larger, year-around colonies of honey bees. The entire report by Core et al. may be viewed at http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0029639.

One of the great mysteries of CCD is that not all colonies affected by the multiple suspected stressors--viruses, Nosema ceranae, and pesticides--collapse. Some of the beekeepers who have taken losses from CCD have questioned whether there is a triggering mechanism that brings about the collapse of colonies. The finding of phorid flies parasitizing honey bees may be an important clue to solving the CCD mystery. Today’s photo shows a paper wasp attacking a honey bee hive. A guard bee quickly responds to challenge and repel the intruder.

--Richard

Ground Nesting Bees

Bees need the same basic things that humans need: a place to live, food, and an environment free of poisons. Many of the important native pollinators nest underground. Among these are bumblebees and numerous solitary bees. These bees prefer to enter the soil in bare areas not covered by grass, foliage, or mulch. One reason many native pollinators are declining is that favorable habitat is becoming increasingly scarce. Modern large-scale agricultural fields are plowed leaving little undisturbed margin for ground nesting bees. Golf courses and home lawns likewise afford little bare ground when they are covered by a turf of grass. To improve the habitat for ground nesting bees which add much to the effectiveness of pollination of many crops some farms are incorporating strips of ground between crop plantings to accommodate the bees. Homeowners may provide habitat by clearing a portion of a garden or landscape planting of mulch and then leaving the ground bare and undisturbed. Bumblebees, like the one in today’s picture flying from her underground nest, often build dwellings in abandoned mouse holes. With a long tongue, bumblebees are effective pollinators of many crops, especially tomatoes and eggplants.

While the decline in honey bee populations since the mid-1980s has been carefully tracked, the status of native bees and other pollinators has not been documented as closely. One large-scale effort to identify the location and population of native bees enlists thousands of citizens to become data-collecting scientists. The program, The Great Sunflower Project, involves observing bees that are attracted to a single variety of sunflower. People, young and old, plant Lemon Queen seeds; and when the plants grow and flower, they identify and count the bees that come to forage. To sign up to participate in the project or view this year’s results, go to http://www.greatsunflower.org/. The participating citizen scientists found a bee every 2.6 minutes, but 20 percent of gardens had no bees at all. The count is important for identifying areas having shortages of native pollinators.

--Richard

Bumblebees are Active

Bumblebees are foraging on early fall flowering plants. They can be found in abundance on the open flowers of vitex trees and goldenrod. Other bumblebees are pollinating late-blooming tomato plants, like the one in today’s photo. Click on the photo to see the bumblebee’s pollen baskets filled with light-colored pollen. Bumblebees carry pollen on their hind legs similar to honey bees. The bumblebee vibrates the flower using its flight muscles to dislodge pollen in action similar to the honey bee’s use of flight muscles to generate heat to warm the cluster of bees in the wintertime. The bumblebee’s long tongue and buzz pollination capability make it an effective pollinator of many vegetables.

The warm, sunny early fall days reveal numerous species of bees, wasps, and other insects. Honey bees are dragging drones from the hives. Worker bees returning to the hive with hind leg baskets full of pollen are passing workers stinging and dragging drones. The workers’ stings, though barbed, penetrate the soft exoskeleton of other bees without tearing from the bees’ abdomen as when they sting a human. Red wasps seek shelter and warmth on cool nights under the edge of bee hive covers. Large numbers of red wasps gather around vegetable plants looking for caterpillars. While red wasps are quite defensive of their nest, they ignore my bare hands around the tomato plants as they hunt for caterpillars. I watch a solitary wasp drag a tomato hornworm much larger than its body a great distance through the grass. Some wasps are parasites of caterpillars, laying eggs inside the caterpillar’s body. Mud dauber wasps collect orb spiders to use to nourish their offspring. These paralyzing insects place sting-immobilized spiders inside their mud nests to feed the developing mud dauber wasps. Carnivorous throughout most of the year, yellow jackets seek carbohydrate in the fall and try to enter bee hives for the honey. Numerous species of butterflies visit sunflowers, and single monarch butterflies pass overhead in their fall migration.

--Richard

Protection by Behavior

The honey bee genome project told us that honey bees have fragile immune systems with fewer genes associated with their immune system than many other insects. With the individual bees slightly protected, it seems that the honey bee evolved a number of behaviors to protect the health of the colony as a whole. On a warm winter day, with temperatures rising slightly above 50 degrees Fahrenheit, the bees leave the hive to make cleansing flights. Honey bees keep a clean nest, and they never defecate inside the hive. Today’s picture shows honey bees returning to the hive’s entrance, reduced to a small opening for the winter. Occasional warm days allow the bees to leave the hive briefly and reduce the effect of Nosema disease. Other colony health behaviors include the protection of the hive by guard bees, and workers’ removing dead bees from the hive. An important behavior for the protection of the colony involves sick or diseased bees leaving the hive to die, thus not spreading pathogens to healthy bees of the colony. The absence of sick or dead bees has made the study of Colony Collapse Disorder even more difficult.

We are learning more about the mechanisms involved in the spread of Colony Collapse Disorder. Searching for the causes of CCD and its breadth, researchers are looking into the health of native pollinators as well as honey bees. Like the honey bees, a number of these native insect species are declining. Rajwinder Singh, et al reported in PLoS ONE, December 22, 2010, on their investigation into bumblebee health. The report can be read at http://www.plosone.org/article/info:doi/10.1371/journal.pone.0014357. Singh found that bumblebees can carry viruses normally found affecting honey bees. The investigators found that the viruses are transported between the different insect species in the pollen that they collect. Over time, we will learn much about the relationship between the honey bees, the other pollinators, and the environment. This mechanism of transmission of viruses is a key part of the unraveling story.

--Richard

Across the West

A drive across the American West gave me quite a view of breath-taking scenery. It also revealed much about the state of our agriculture, wildlife, honey bees, native pollinators, and the success of concerted conservation efforts by many. Travelling to Washington State University, Wes and I passed through eight western states: Arkansas, Oklahoma, Kansas, Colorado, Wyoming, Montana, Idaho, and Washington. My observations revealed an agriculture dominated by large-scale farms and ranches employing mono-cultural plantings of crops and largely supporting the production of beef. Considerable acreage is devoted to pasture grasses, corn, and wheat. Each of these is a grass, a plant propagated by wind and not requiring insect pollinators. Alfalfa, a legume, is a high-quality, high-protein crop grown for livestock food. Alfalfa is often grown in the arid West in irrigated fields. In several locations I observed that pallets of migratory bee hives had been brought in to pollinate the alfalfa. Having sufficient numbers of insect pollinators is especially important where the alfalfa is being grown to produce seed.

Wildlife seems to be thriving in the agricultural areas, forests, national parks, and even in the urban areas. I observed a number of mammals along the way: prairie dogs, ground squirrels, white tailed deer, mule deer, elk, pronghorn antelope, mountain goats, bison, and moose. A number of birds were observed: magpies, ravens, and shandhill cranes. Birds of prey I observed included red-tailed hawks, bald eagles, golden eagles, and osprey. Beekeepers always watch for bee hives as they travel. I spotted several bee yards along the way. Stationary bee yards were located on small farms with diverse crops and in residential areas. Migratory honey bee hives were located near fields of alfalfa. Wildlife thrives in the natural areas designated as national parks, and conservationists are connecting these to build corridors as migratory routes for animals such as elk, pronghorn antelope, and bison. Bumblebees, like this one pollinating flowers on the Frank Phillips ranch in Oklahoma, have hairy abdomens unlike carpenter bees.

--Richard

Clover in Bloom

In today’s photo we see a bumblebee foraging for nectar on white clover. White clover probably can be considered the most important honey plant. When the temperatures range between 80 and 90 degrees Fahrenheit, clover is a prolific nectar producer. Though the blossoms have been observed for quite a while, clover requires warm days to secrete large amounts of nectar. Clover is a member of the important family of bee plants, the legumes. Like a number of legumes, clover serves an important role in fixing nitrogen into a usable state in the soil. Even though the atmosphere is largely comprised of nitrogen, it is not available for plants to use. Bacteria growing on the roots of the clover plants are the active agent for converting the nitrogen. The result is increased soil fertility. Along with the clovers, the legume, or pea, family includes a number of important bee plants: peas, beans, peanuts, alfalfa, soybeans, lespedeza, vetch, kudzu, redbud, mimosa, locust, and Kentucky coffeetrees. Many of these plants provide food for wildlife and animal forage. Clover, alfalfa, and lespedeza are used as pasture crops for cattle; while soybeans are processed into feed for livestock and poultry.

Beekeepers plant clover around bee yards and in spare patches of land. The plant has a hearty root system and is easily propagated by seed. The seed is produced when honey bees forage the flowers. I often find the foot prints of deer in stands of clover around bee yards. As well as being an important forage plant for honey bees, it provides high-quality food for wildlife. Clover honey is light in color and mild in flavor, making it one of the favorites with the public. Bumblebees, like the one shown, are dwindling in many areas due to the loss of habitat. The Xerces Society for Invertebrate Conservation is attempting to make people aware of the potential for pollinator habitat restoral along the nation’s roadsides. You can read more at: http://www.xerces.org/pollinator-conservation-roadsides/.

--Richard