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

Sustainable Agriculture

The annual Farm to Table Conference held in Memphis at Rhodes College is designed to bring together farmers and those who buy and use their produce. I conducted an introduction to beekeeping session attended by a number of farmers considering adding bee hives for pollination. The farmers conducting other sessions spoke along common themes: sustainable agriculture, quality of produce, food security, and integrated pest management. Sustainable agricultural practices include irrigation water usage and conservation, soil erosion control, and soil moisture retention. Several farmers spoke of the effects of climate change on farming practices. Climate change especially affects water usage and plant variety selection. Certain plant varieties known to be reliable in the past must now be replaced by a diversity of varieties that thrive under new environmental conditions. Climate change also affects planting dates, growing seasons, and harvest dates. To grow high quality produce, the farmers stress testing for soil fertility, acidity, and nutrients. Integrated pest management involves disease and pest prevention and control. Specific crop pests must be identified, and broad-spectrum insecticides should be avoided. Non-chemical controls include selection of resistant plant varieties, crop rotation, removal of diseased plants, and mulching between crop rows.

Robert Hayes, a New Albany, Mississippi blackberry grower, who also manages bees to pollinate his berries, attracts hummingbirds to his farm. Adult hummingbirds feed crop-damaging thirps and aphids to their young birds, a biological pest control. Farmers recognize the need for beneficial insects, particularly honey bees, to pollinate their crops. As well as keeping honey bees, Hayes drills nesting holes in dead trees to make nesting sites for blue orchard bees, effective native pollinators. My presentation to the other farmers explored the reality of maintaining honey bees on today’s farms. It is unfortunate that with the high level of annual colony losses beekeeping can hardly be called sustainable agriculture. The farmers’ awareness of agricultural practices that help and harm bees is important. Cool weather today prevented honey bees from foraging elm trees in full bloom.

--Richard