Improving Native Bee Pollination Part 2: Alternative Nest Boxes Building on the Lessons from the Field in 2008

View the project final report

• 2009 annual report

Commodities

• Fruits: melons, apples, apricots, berries (blueberries), berries (brambles), berries (strawberries)
• Vegetables: beans, cucurbits, eggplant, peas (culinary), peppers, tomatoes
• Additional Plants: native plants

Practices

• Crop Production: crop rotation, fertigation, foliar feeding
• Education and Training: demonstration, farmer to farmer, on-farm/ranch research, participatory research
• Farm Business Management: community-supported agriculture
• Natural Resources/Environment: biodiversity, habitat enhancement
• Pest Management: biological control, chemical control, cultural control, integrated pest management
• Production Systems: holistic management, transitioning to organic

The recent national and international economic crisis emphasizes more than ever the need to start making changes in our pollination management for creating a healthy agricultural industry. The current pollination management that relies on renting migratory honeybees for pollination is neither sustainable nor environmentally minded. The honeybee is not native to North America, has a flight range that covers more than 32,000 acres , and is the Hummer of the bee world in the way it consumes fuel (nectar). Moreover, the keeper can box her up and ship her, sometimes accidentally along with pests and diseases, wherever the mono-crop cultures need pollination. Additionally, the following facts support the need for a pollination strategy change. Honeybee colonies are rapidly decreasing--more than 26% in the past 15 years , which means that in the future we will have to rely on more honeybee imports; After two years of intense research, Colony Collapse Disorder is still unresolved and proves to be a chronic problem; Because of the honeybee shortage, honeybee hive rentals are reaching record high fees for some early crops; As they are shifted around the country and in between continents, honeybees are exposed to a wide range of diseases, pests and pesticides; Contaminated honeybees vector diseases to native bees, and non-migratory and feral honeybee populations, thus threatening the local honey production and, ultimately, the environment; Wide flight ranges plus being extensively moved around can make honeybees a significant vector of plant pathogens such as Fire Blight, Mummy Berry Disease or Botrytis Gray Mold; Migratory beekeepers’ vehicles and equipment can spread soil born diseases, pests and weeds; It has been shown that honeybees prefer some exotic weeds and can increase their seed production; For some native plants, honeybees act as floral parasites – harvesting the rewards without causing pollination; Without regard to the availability of native bees for pollination on each field, agricultural fields are flooded with between three times to two thousand times more honeybees per acre than are found in their natural habitat; Over-pollination can be just as detrimental as too little pollination and, by collecting nectar for days after ensuring pollination, honeybees can weaken the plant and crop that is being set. After commercial pollination, beekeepers move tens of thousands of honeybee colonies in wild fields for recovery and honey making, which very likely negatively influences the ecosystem balance; Honeybees are suspected to be out-competing native bees through resource competition; Nonetheless, the migratory beekeeping industry artificially sustains environmental-harmful monocrop cultures at the expense of a more sustainable, diverse and local agriculture. Native bees can provide superior pollination services over honeybees since they have a diverse range of behaviors that allows them to forage in colder and wetter conditions for nectar and pollen and to be specialized in certain crops, hence ensuring cross-pollination. For example, only 250 female orchard bees are required to pollinate an acre of apples, a task that would need 1.5 to 2 honeybee hives - approximately 15,000 to 20,000 honeybees. Unlike honeybees, some native bees can perform buzz pollination, which is beneficial for cross-pollination, setting larger and more abundant fruit in tomatoes, peppers, cranberries, blueberries, etc. Moreover, the native bee population is very diverse, about 4,000 species in North America, and if one bee species declines because of parasites or diseases, other bee species can fill the gap. Native bees cannot be managed and shifted around, and have much shorter flight ranges in comparison with honeybees--meaning less exposure to a wide range of pests and diseases, and thus making them reliable pollinators. Long-term agricultural goals should include the conservation and restoration of the native bee habitat. This way the farmer will have, besides free pollination services, a healthy and diverse population of pest predators, reduced farm soil erosion, irrigation water loss and fertilizer runoff, as well as more windbreaks, weed suppression, etc. Encouraging native bees on farms by protecting and enhancing their habitat will result in free, sustainable pollination with superior yields. Studies in Canada have shown that in the absence of honeybees, canola growers can increase their income if 30% of their farmland is left as natural habitat.

For successful native bee population conservation and enhancement, their habitat has to contain both foraging and nesting areas. While most of the native bees nest in undisturbed locations, these locations are increasingly less available due to continuous habitat destruction. Moreover, because of liability issues not all farmers are willing to accept large numbers of mice or snags (standing dead trees) on their farms for encouraging the native bees. Therefore, a well-designed bee nest that is attractive for a diverse native bee species would be a key element for having a sustainable native bee population available for commercial pollination. Secondary benefits from using this type of nests will be that they would provide a better understanding on the native bee populations’ health, diversity, availability, and life cycle.

Through the ‘Improving Pollination through bumblebee habitation; Evaluation of nest box types in bumblebee colonization’ grant awarded in 2008 by Northeast SARE, we have had the chance to advance the knowledge on bumblebee nesting requirements in Pennsylvania. While the results are still being analyzed and the trial has to be repeated in the following years for having an empirical result, some of the early conclusions are:

The most numerous and widespread bumblebees in Pennsylvania are Bombus impatiens. This bumblebee species nests almost exclusively in the ground, in disused mice nests; About 15% of bumblebee domiciles trialed have been occupied by solitary bees, which indicates that the native wood-nesting solitary bees could use more nesting habitat. Even though wood is a relatively cheap and easy material to work, it proved that when used for constructing bumblebee nests, even after it is properly dried and painted, it warps, splits and rots and is prone to varmint damage;

In response to these conclusions, we will modify the bumblebee domicile used in 2008 in a nest that will accommodate a wide and diverse range of bee species, including wood- and ground-nesting solitary bees and ground-nesting bumblebees. This design will include a version of the bumblebee domicile used in 2008, which will have attached to the lid a container opened on both sides for accommodating bamboo shoots of different diameters. For emulating a mice nest, the bee domicile will be provided with a two-foot long 5/8 inch diameter corrugated pipe, which will have one end attached to the bee nest and the other end attached to a plumbing PVC ‘T’. The bee nest will be set just above the ground, and will have the corrugated pipe buried with the ‘T’ end up in a manmade one-foot high mound of sandy soil. (See the appended pages # 2 and # 3 with the bumblebee domiciles used in 2008, and page # 4 with the bee nest for 2009.)

For building bumblebees nest boxes, the literature suggests untreated wood. While the untreated wood is a relatively cheap and easy to work, it showed that even after it is properly dried and painted, it is still highly sensitive to humidity and it warps, splits and rots. Moreover, a series of varmints damage it by chewing it. Therefore, in the following year we have decided to build the bee nest out of wood plastic composite. This material is made of recycled plastic and wood wastes, is resistant to cracking, splitting, warping, rotting and it requires far less in intensive labor in cleaning and sterilizing. In addition, because of its high density, is far less attractive to varmints.

For nesting, the solitary wood-nesting bees require above ground tunnels of different diameters and lengths found in snags, and they can readily nest in paper straws, bamboo sections or drilled wooden blocks, if provided by the farmer. The drilled wooden blocks can last several seasons but need to be cleaned by being re-drilled and sterilized each spring after the bees have left their chambers. For avoiding the laborious cleaning of tunnels, the paper straws represent a good solution because they can be discarded and replaced but they have to be protected from moisture. For the bee nest we will be using bamboo shoots because they can be discarded and replaced each year without an environmental concern, are not as sensitive to humidity, don’t need to be drill, and are readily available.

The solitary ground-nesting bees will be provided with nesting habitat through the one-foot high mound of sandy soil used to cover the bumblebee domicile pipe used as an entrance. For a better colonization success, the sandy soil mound will be kept undisturbed and free of excessive vegetation.

Having developed a set of plans for building a bee nest and instructions for how to install and maintain it will provide the farmers with a useful and simplified tool for controlling their crop pollination. In addition, providing manmade nesting habitat for a diverse bee population will increase the awareness of the native bee diversity and will be a useful tool in monitoring them.