Signs of Spring 4: Updates on Bats and Bees

USFWS, Wikimedia Commons

USFWS, Wikimedia Commons

My bat house came down this past December along with the wind broken spruce tree to which it was attached. I had put the bat house up back in 2010 in hopes of sheltering some little brown bats (Myotis lucifugus) and to try to help make a contribution in their recovery from the decimating impacts of white nose syndrome. No bats ever came to live in my bat house, though, and the house is now in my garage waiting to be repainted and, hopefully, reattached to some tree that will be noticed by some homeless little brown bats!

In summers past I would sit out on my deck in the early evening and watch a busy swarm of bats (mostly little browns) flying circles and crossing patterns in the fading light of the early night sky. Last summer, though, I would see, at most, one or two bats a night (each of whom was flying around my bat house tree with no recognition of its wonderful aspect (facing the rising morning sun) or its very high quality of construction!).

There was a report on the Penn State News website this past winter (December 4, 2015) that updated the bat population census from the Shaver Creek Environmental Center over near State College. In 2007 (the year coincidentally that the white nose fungus infection was first reported in hibernating North American bat colonies) 1400 little brown bats were in residence at Shaver Creek. Every night in the summer a crowd of observers gathered at dusk to watch clouds of bats emerge out into darkening night sky. This past year there were only 2 little brown bats at Shaver Creek. White nose syndrome and the immense winter die-off that it triggers was the cause of this staggering decline in these important animals.

Photo by A. Valentine, Flickr

Photo by A. Valentine, Flickr

A single bat will eat between three hundred to three thousand insects a night. A million bats, according to the Wisconsin Bat Monitoring Program, eat six hundred and ninety-four tons of insects a year! That’s a lot of mosquitoes and potential crop pests! It has been estimated that a farmer in our bat-deprived world will have to spend between four and five thousand dollars a year on pesticides just to achieve the insect pest control that the bats had provided for free.

Bats reproduce very slowly. A female can have only one pup per year, so the time frame for the recovery of the little brown bat population is going to be incredibly long, and this recovery will only occur if the winter die offs from the white nose fungus infections stops; a very big (and very uncertain) “if.”

There is a very recent piece of good news about bats and their response to the fungus that causes white nose syndrome. A paper published on March 9 in the Proceedings of the Royal Society B clearly demonstrated that Chinese bat species are resistant to these fungal infections, and the authors’ speculate that this resistance is genetic! If white nose syndrome’s spread can be slowed down, then, the hope is that Natural Selection for these similar genes in North American bat populations might result in fungal resistant bat populations here.

Last winter (January 23, 2015 “Signs of Winter 8”) I wrote about the winter survival strategies of a number of species of North American bees. For the sake of time and space several additional bee species missed the cut, so to speak, and their descriptions had to be edited out of the final essay. In order to start my bee discussion here on a positive note, I wanted to include a short description of a little known bee species that many keen bee observers find quite interesting: the mason bee.

Photo by B. Moisset, Wikimedia Commons

Photo by B. Moisset, Wikimedia Commons

Mason bees (Osmia spp.) are very short-lived (only six weeks or so), solitary bees. These bees nest in tubes or holes and have earned the name “mason” because of their tendency to build wall-like partitions made of mud inside of their tubular nests. A mason bee will gather pollen and nectar from the flowers that are blooming during its short life and primarily use its gatherings to pack food around the eggs that it lays in those mud-wall partitions of its nest. A mason bee may fill up more than one nest with its eggs and its accumulated nectar and pollen. The eggs then hatch into larvae, feed on the stored food and steadily grow and develop. The walls are extremely important here because they keep each larvae isolated with their own food supply! The mature larvae then spin a cocoon and develop into pupae which will, still inside the cocoon, then molt into adults. It is inside of this protective and insulating cocoon that the mason bee overwinters. In the spring, the male mason bees emerge first and wait outside of the nest for the later emerging females so that they can mate. After they mate, the males die, and the females then find suitable tubular structures for their nests and begin to lay eggs, gather nectar and pollen, and, as a great ecological tie-in to this activity, pollinate many different species of flowering plants.

So what else have we heard lately about bees?

In a report late this past summer (N. Y. Times, July 23, 2015) 70% of the honey and pollen samples collected from honeybees in Massachusetts contain neonicotinoid insecticide residues. As I reported in the “Signs of Fall 6” (October 1, 2015), a paper published in the April 25, 2015 issue of Nature showed that both honeybees and bumblebees were strongly attracted to flower nectars that contained neonicotinoid pesticides. These pesticides are commonly used for insect control on crops but have been linked to significant bee damage in many studies (The European Union has banned these pesticides because of their links to high levels of bee mortality. Bills have been proposed in the US Congress to restrict the use several of these pesticides, but these bills were sent to committee and no definitive action was taken). This unexpected affinity of bees to these chemicals may explain why they are so toxic to these important pollinators.

Argentine ant (Photo by Penarc, Wikimedia Commons

Argentine ant (Photo by Penarc, Wikimedia Commons

In a February 8, 2016 article in the N. Y. Times, it was reported that the Asian virus that causes wing deformities in infected honeybees was being spread not only from honeybee colony to honeybee colony but from continent to continent (Asia to Europe! Europe to North America! Europe to Australia!) primarily by the commercial trading and transporting of honeybee colonies! This virus has raced around the world in a very short time period and can, especially if combined with Varroa mite infestations cause colony collapse disorder. The Times also reported (in a September 11, 2015 article) that Argentine ants (Linepithema humile)(an invasive species ranked among the one hundred worst animal invaders in the world!) can spread these bee wing deforming viruses from honeybee colony to honeybee colony within their considerable invasive ranges (15 countries and 6 continents)! The introduction of a virus infected honeybee colony into an area also infested with Argentine ants seems to guarantee that the virus will be quickly spread to all honeybees in the area.

So, we have short-sighted pest control policies coupled with careless dispersion of infected and invasive species! It’s amazing we have any honeybees left at all!

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