Posts Tagged ‘Bombus sp.’

Blueberry and Bumblebee

May 21, 2012

I have 4 cultivated blueberry bushes.  They usually flower in March, produce fruit in June, and offer lovely red foilage in  fall.  This year, winter ended 2 weeks earlier than normal, and Saturday (May 19th) I harvested my first blueberries.  They were plump from a recent drought-breaking rain.  I made my first batch of blueberry pancakes the following morning.  My bushes give me all the berries I need for pancakes, muffins, and desserts for about a month.

My blueberry bushes flower in February and March.  The bees swarm to them every year.  Without these pollinators there would be no fruit.

Note the bees.  The most common species pollinating the flowers are the southeastern blueberry bees and bumblebees.  The former looks similar to the latter but is smaller.

Two bushes.  Two varieties.  One of the four bushes (not pictured) is stunted and doesn’t produce much yet.

Good plump berries by May 18th.

Blueberry flowers attract several kinds of bees well adapted to late winter/early spring weather conditions.  Because these species of bees are covered with hair, they are able to withstand colder temperatures than most other insects and are among the first arthropods to emerge in early spring.  The black coloring also helps increase their body heat.  The southeastern blueberry bees, bumblebees, and honeybees pollinate over 96% of the blueberry crop in southeastern North America.  The southeastern blueberry bee (Hapropodia laboriosa) is by far the most common type pollinating my bushes.  They look like a small bumblebee and are a solitary species.  The female digs a long burrow in sandy soil and broods her nest in it.  Their lifespan matches the length of time blueberry bushes flower–about 3 weeks.  They are completely dependent upon blueberry bushes, unlike bumblebees (Bombus sp.) which pollinate a much greater variety of plants.  Bumblebees live in colonies of from 200-2000 individuals.  They also nest in burrows where the overwintering queen becomes the sole survivor when hard weather hits.  Both of these native bees are not aggressive.  I’ve never been stung by either one.  One would have to roughly handle one of these species or invade a nest to get stung.

Horticulturalists cultivated high bush blueberries, creating hundreds of varieties, but low bush blueberries only grow in the wild.  Nevertheless, there are such extensive stands of low bush blueberries in Maine that they’re gathered wild and can be found in the frozen food section of many supermarkets.  Low bush blueberries grow wild in my neighborhood, including my front yard.  These ripen in late July/early August but are of disappointing quality compared to my cultivated high bush blueberries.  Euell Gibbons claimed wild blueberries work better in muffins than cultivated ones, but the variety that grows in my neck of the woods is hard and bittersweet.  My wife and daughter love cultivated berries but declined to eat the wild ones after trying them.  Eight species of blueberries are native to the piedmont region of the southeast: sparkleberry (Vaccinium arboreum), black high bush blueberry (V. atroccum), high bush blueberry (V. corynborum), Elliott’s blueberry (V. elliotti), southern low blueberry (V. pallidum), deerberry (V. stamineum), slender blueberry (V. tenellum), and early low blueberry (V. vaccillum).

Blueberries generally grow in colonies and prefer sandy acidic soil.  They thrive in sunny open areas with little to no tree canopy.  They can tolerate a few pine trees which don’t shade them.  They’re another fire adapted plant–underground runners help them resprout following ground fires.  When Euell Gibbons went hunting for blueberries, he’d visit the office of a National Forest ranger and ask him to point out on a map where the most recent burns had taken place.  Native Americans set fire to the woods nearly every year to foster habitat for berries, though this was done for several other reasons as well such as improving habitat for game, eliminating insect and snake refuges, and increasing visibility to avoid being ambushed by other Indians.

Undoubtedly, blueberries were a common component of southern Pleistocene landscapes.  Dynamic factors–sudden climate changes, unchecked wild fires, and megafauna foraging–created highly diverse environments including the open spaces blueberries require.  Pleistocene-aged heath pollen in measurable amounts occurred in Nodoroc, a mud volcano near Winder, Georgia (the central part of the state).  The pollen dated to ~30,000 BP, a brief interstadial immediately preceding the Last Glacial Maximum.  The pollen record here suggests an environment dominated by pine, oak, and grass; though hickory, spruce, and fir were common, while maple, beech, chestnut, and birch were present in this diverse landscape. The presence of high amounts of ragweed, an early successional species, is evidence of an environment in constant flux.  Pine pollen and macrofossils at Nodoroc suggest a mixture of southern species (shortleaf) and northern species (jack, red, and white).  In Maine wild blueberries grow in large barrens and are associated with the northern species of pine mentioned above.  One caveat–the heath family also includes common non-blueberry species such as azalea, mountain laurel, and fetterbush, so it’s likely they contributed to the heath pollen.  Scientists can’t differentiate to the species level when examining heath family pollen.

Pleistocene environments in Georgia may have included vast blueberry barrens such as those occurring in Maine today, especially with large flocks of passenger pigeons spreading the seeds that eventually found ideal habitat.  William Bartram rode his horse through miles of what he referred to as “strawberry plains” in north Georgia and North Carolina.  This environment–common just 200 years ago–is now completely extinct. Strawberries require sunny conditions, just like blueberries.  In the extensive wilderness of the Pleistocene perhaps blueberry barrens and strawberry plains covered miles of territory.

Maine blueberry barren.  This photo must have been taken during fall when the leaves turn red.  The owners of this land burn it often to faciliate the growth of wild blueberries–an uncultivated cash crop. Did Pleistocene Georgia have extensive blueberry barrens such as this?  Or did they just grow in small colonies wherever a fire burned a small section of forest?