Pollinators At Work

Pam Haze
Adams County Master Gardener

(9/15) In July Penn State held the second Pollinator In-Service meeting in State College. I was able to attend this meeting along with two other master gardeners from Adams County. Margarita López-Uribe, Assistant Professor of Entomology in Penn State's College of Agricultural Sciences, organized and hosted the two-day meeting that brought over 100 extension staff and master gardeners from across the State of Pennsylvania up to speed on the status of bees, our most important pollinators.

The news was not good. Beekeepers are reporting that over 50 percent of their honey bee colonies are dying each year. bee populations are disappearing and in decline, perhaps by as much as 30-60 percent worldwide. About one-quarter of the 46 bumble bee species found in North America are facing extinction risks. Much less is known about the status of other native bees that represent the majority of the over 400 species in Pennsylvania. Key challenges confronting all bees include loss of habitat, use of chemicals, climate change, invasive species, parasites, and disease.

These issues are of concern because bees provide pollination services for about 70 percent of flowering plants including fruits and vegetables that supply one-third of our food. Bees also pollinate important feed crops, like alfalfa, used for raising cattle. Bee pollination services have a value to us because of their contribution to our food supply and economy.

The intensively managed honey bee is highly valued for its contribution to agriculture in the United States. On an annual basis, honey bees add about $15 billion in crop value, assisting in the pollination of more than 90 different crops. Honey bees are also the source of nutritional and medicinal products namely honey, pollen, royal jelly, beeswax, propolis, and venom. The annual production of honey is valued at about $340 million.

Increasingly, native bees are being used in commercial agriculture in lieu of or in addition to honey bees. Native bees, including bumble bees and solitary bees, are more effective pollinators than honey bees on a per visit basis. Native bees are a valuable asset in all settings, including our home gardens because they bring specialized pollination services needed by flowering plants.

Take for example, tomatoes. Bumble bees are almost exclusively used to pollinate greenhouse tomatoes because they can buzz pollinate. The bumble bee uses its chest muscles to buzz or vibrate the flower’s anther (the male flower part) and loosen pollen granules. Once loosened, the granules adhere to the bee and are transferred to the stigma (the female flower part), which begins the fertilization process leading to development of the tomato seed and fruit. Approximately $25 million in revenue is generated each year from tomato production in Pennsylvania.

Bee pollination services improve both the quality and yield of seeds, fruits, vegetables, and nuts. A large, fully formed apple requires the development of all ten apple seeds, requiring that large amounts of pollen be moved from apple flower anther to stigma. Bees do this. Without bee pollination, apples are small and misshapen and yields are greatly diminished. Why is this important? Because, Pennsylvania orchards produce nearly 500 million pounds of apples each year, making Pennsylvania the fourth largest producer of apples in the U.S. with an estimated economic value of $124 million a year.

In addition to the contribution that bees make to our food supplies and economy, bees add to the health and diversity of plant communities. Bees are cross-pollinators, moving pollen from plant to plant, thereby helping to maintain a diverse gene pool and healthy plant populations.

How does an appreciation of the importance of bees translate into actions that individuals can take to help sustain bee populations? Fortunately, Pennsylvania is one of a limited number of states that has developed and issued a Pollinator Protection Plan. The plan identifies best practices for agricultural, natural, and residential areas; recommendations for pesticide use; and guidance for beekeepers. The plan includes helpful links to detailed and comprehensive information to guide landscape planning, plant selection, site preparation, and maintenance for bees and other pollinators; strategies to combat pests while protecting pollinators; and information to address cultural, disease, and pest issues impacting managed bee populations.

You’ve no doubt heard the expression "the bees knees" referring to something wonderful or of high quality. Have you wondered what is so wonderful about the knees of bees? Do bees have knees? Perhaps the expression originated because bees have highly specialized physical characteristics uniquely suited to their lifestyle and earning them a reputation as efficient and effective pollinators. For example, bees’ bodies are covered in fine hairs that are branched and electrostatically charged to hold onto pollen granules. The legs of a bee have comb-like structures they use to remove the pollen that adheres to their bodies as they move around inside flowers looking for nectar, and stiff, bristle-like hairs that store the pollen that they use to feed their young.

Bees possess mouthparts that are suited to the flowers on which they feed, long-tongued bees feed on tubular flowers like penstemon, while short tongued bees feed on flowers with an open structure, like daisies. Leaf-cutting bees have mandibles that are capable of cutting leaves that they use to line their nests, while carpenter bees have grinding mandibles to allow them to tunnel into wood for their nests. These and other adaptations developed over millions of years as bees and the flowering plants they pollinate evolved together in a mutually beneficial relationship. In this relationship, plants offer attractive flowers with scent, color and nectar to attract bees and secure their pollination services while the bees, seeking nectar and pollen move pollen from male to female flower part and fertilize the seeds, leading to seed set and the production of fruits, vegetables, and nuts.

In addition to physical attributes, bees also have specialized capabilities that enhance their pollination abilities. An excellent example is the southeastern blueberry bee (Habropoda laboriosa). Prized by blueberry farmers, these bees help to maximize blueberry production by moving large amounts of pollen, thereby ensuring the fertilization of blueberry seeds and formation of fruit. Blueberry bees deploy buzz pollination, by grabbing onto the anther (the male flower part) and use their chest muscles to vibrate and loosen pollen granules, which flow onto the bee like salt from a shaker. As the pollen covered bee moves around the flower it transfers pollen onto the receptive stigma (the female flower part). Although these little, half-inch sized bees are active for only a few weeks, in its lifetime each bee can visit up to 50,000 flowers leading to the production of nearly 6,000 blueberries.

The blueberry bee is one of about 400 native bee species that occur in Pennsylvania. There is incredible diversity among these native bees in every possible aspect including shape, size, and color; timing of emergence and period of activity; floral diet; nesting habitat; and socialization. Most native bees live solitary lives. Female and male bees emerge from their nests in the spring and mate. The female establishes a nest in which she lays eggs along with a supply of pollen for the young to feed on. When these young emerge, they begin the cycle again.

The Pennsylvania native bee population includes about 13-17 bumble bees species. These are social bees that live in colonies that are established each spring when the already-mated female bees emerge from hibernation and find a nest site and lay eggs that mature into worker bees. The colony population builds over the season to a possible maximum size of 200 individuals and in the fall the colony dies-off when the young queens go into hibernation.

Like the blueberry bee, bumble bees are capable of buzz pollination. This ability combined with a long period of activity and their willingness to pollinate in weather that may be unsuitable to other bees, makes these bees effective and efficient pollinators. Bumble bees can regulate their temperature and warm themselves by vibrating their chest muscles, allowing them to be active early in the spring and in the fall; during overcast, cloudy, and rainy weather; and from early in the morning until late in the day.

These and other native bees are increasingly being recognized for their importance to the pollination and ongoing reproduction of flowering plants. In our home gardens and in small-scale agricultural operations, native bees can perform all of the pollination services that are needed. In larger agricultural operations native bees can augment the services of managed honey bees. Our gardens can serve as reservoirs for native bees that are experiencing population declines. To encourage these wonderful insects to stay in your garden, plant a diverse mix of plants to provide for a succession of blooms from spring through fall including as many native plants as possible.

Consider the importance of bees and check out the plan.

Read other articles by Pam Haze