Monday, March 27, 2017  

Plight of the Bumblebee


I was knee deep in oregano when I heard the familiar rumble of the UPS truck coming up the drive. The driver hopped out, smiling, a large carton tucked under his arm. “New plants for your garden?” he asked, noting the air holes around the carton’s perimeter. It was late spring, and our driver often found me amid the herbs in my kitchen garden. “No, actually it’s bees,” I said, as the sounds of extremely agitated bees became apparent the further he got from his truck. His smile froze as he quickly handed me the carton and beat a hasty retreat.
I had been anticipating this delivery and the new hive’s home was ready: a two foot high stack of cinderblocks tucked under our gazebo. Nearby, the winterberries were in full bloom, so it wouldn’t take long before the bees enjoyed their first meal in the wild.
In the herb garden, catmint and valerian beckoned, while the betony had put on fat blossoms. I had been busy planning for the bees’ arrival as one would a new baby. Soon, I hoped, dozens of Bombus impatiens, or Common eastern bumblebee, would be buzzing about my garden.
Each spring, these furry native pollinators are one of the first insects to emerge as the ground slowly warms and the first wildflowers appear. But this year was different. As I had worked in the garden in early April, I was suddenly struck by the fact that, although there were several azaleas in full bloom, and the temperature a balmy 68º, there wasn’t a single bumblebee in sight. How odd.
By late April I was mystified, so I drove a mile up the road to Brent and Becky’s Bulb Shoppe and walked through their expansive teaching gardens. Not a bumblebee in sight. I spoke with one of the Heaths’ gardeners and we went looking, but none were to be found. 
Now he was puzzled. Where were all the bumblebees?
An online search turned up alarming reports of bumblebees gone missing across the country. It wasn’t as if bumblebees were simply in hiding somewhere, waiting for the right conditions to venture out. While many folks are familiar with the plight of the domesticated honey bee, few have noticed that our native bees—bumblebees, wild honey bees, and other pollinators like butterflies and moths—have been disappearing for some time now. In the case of wild bees, this has been gradual over the years, but we’re witnessing steeper declines now and, more recently, the extinction of some species.
Scientific theories abound: habitat loss, disease, pesticides, herbicides, climate change, the importation of non-native bees, and competition from the growing number of commercially managed bees. The trade in bees used for honey or to pollinate crops has begun taking a toll on wild bees and other insects, scientists in the US, Canada, and the UK have noted. In late 2014 environmentalists in the US filed a lawsuit against the federal government to have a once common bumblebee species placed on the endangered species list.
Bumblebees are extremely important foragers. Unlike honey bees, they are adept at foraging under cold, rainy, and cloudy conditions. In fact, when the weather gets too warm, they will retreat into the shade until the heat of day passes. They are one of the first pollinators to emerge in spring, and so are dependent on the few early flowering plants and trees to sustain them. Native flowering plants are some of the first to flower to spring. By eliminating wildflowers and native plants, often considered weeds, bumblebees can starve.
They are excellent pollinators of a variety of crops to which honey bees are not attracted—tomatoes, peppers, squash, cucumbers, eggplants, beans, and a variety of fruits, such as strawberries, cranberries, cherries, and apples. Bumblebees are even used commercially to pollinate tomatoes in greenhouses.
Bumblebees feed exclusively on pollen and nectar, and, with exceptionally high metabolic rates, must eat continually to keep warm. Noted bee expert Dave Goulson of Oxford University has noted “a bumblebee with a full stomach is just forty minutes from starvation. If a bumblebee runs out of energy, she cannot fly, and if she cannot fly, she cannot reach flowers to get more food, so she is doomed.”
Bumblebees are eusocial, meaning the mother (in this case the queen) cares exclusively for her brood until there are enough worker bees to take over care of the nest so the queen can concentrate on laying more eggs. Worker bees are sterile females. Towards the end of the colony’s life cycle, the queen produces male bees for the exclusive purpose of mating. The newly-mated queens go into hibernation at summer’s end, while the old queen, workers, and males perish. If something happens to affect the hibernating queens, the next generation of bumblebees is doomed.
There are nearly fifty species of bumblebees in North America and, for many, their numbers are in steep decline. Scientists have documented that where the number of pollinators has declined, so have the plants that are dependent on them for pollination. Bumblebees not only help produce fruits and vegetables for human and animal consumption, they help maintain bio and genetic diversity within their surrounding ecosystems. Conversion of grasslands and diversified crops to one of monoculture has eliminated vital food sources on which bumblebees and other pollinators are dependent.
The liberal use of chemical herbicides and pesticides negatively affects developing larva inside the nest, and studies have shown that bumblebees are particularly sensitive to systemic insecticides like neonicotinoids. While herbicides do not directly target pollinators, they do target their flowering food sources.
Pressure has also been brought to bear from honey bees. Honey bees were brought to North America by settlers in the early 17thc. Recent research has shown that competition from honey bees reduces bumblebee foraging efficiency, worker size, and reproductive success. A single honey bee hive can contain more than 50,000 bees, who collectively remove hundreds of pounds of nectar and pollen from an area in a single year. The presence of large numbers of honey bees force bumblebees off flowers, and pollen has been shown to be a vector for disease transmission between species of bees.
Bumblebees require a rich supply of flowers during the colony’s life. They have co-evolved with native wildflowers and clovers, preferring pink, purple, and yellow flowers that bloom from early spring to fall. They also show a strong preference for perennial rather than annual flowers. My gardens were well suited for bumblebees; so I decided to buy a hive.
Online I contacted a biological systems company who specialized in bumblebee hives. My hive would include a number of worker bees, a laying queen, a developing brood that would continue to provide new workers during the life of the colony, and enough food to feed them until they began foraging in the wild.
When the hive arrived, we were advised to place it on a stand or bench away from bright sunlight, with good air circulation, preferably with shade on all sides. The hive exit hole was covered with fiber tape and covered with a plastic sliding door. Once the hive was in place, we slid the door open, leaving the tape in place. The instructions stated that the bees would need some time to settle down, and then they would chew their way through the fiber tape in one to 
two hours.
It wasn’t long before we could hear the sounds of chewing inside the box. The fiber tape was gradually eaten away and the first, tentative Bombus impatiens stuck her head out of the doorway. She made a tentative, short flight into the winterberry nearby and then returned to the hive, presumably to tell her hive mates what she’d seen. Before long, a steady stream of workers left the nest and began foraging in my herb garden and among the tiny wildflowers blooming in my yard.
For the remainder of late spring and into early fall, our bumblebees were constant companions as we harvested strawberries, green beans, peppers, and tomatoes and cut bunches of chives, tansy, rosemary, and horehound. They swarmed over the catmint and became intoxicated on betony blooms. They emerged from inside foxgloves covered in pollen, and dangled from the ends of bleeding hearts. Their heavy drone was a welcomed sound.
The winter of 2014 brought wave after wave of polar vortexes to the upper south. The hive box was now empty, and I worried about the young queens and how they were surviving the brutal cold. Spring was late to arrive, and many of the wildflowers that carpeted our yard were late to bloom. Had my experiment been in vain?
Then, as the first wild ajuga, wood poppies, and azaleas burst forth in bloom, the bumblebees arrived. Whether they were offspring of my hive is unknown, but I was certainly delighted to see them. Our neighbor’s honey bees had not fared as well, succumbing to starvation.
We have barely begun to understand the complexity of species interactions and dependencies, or fully comprehend the consequences of our altering or destroying vital ecosystems. For many species, it may already be too late.