[Pollinator] Bugs signal the effects of warmth

[Laurie Adams]

Bugs signal the effects of warmth

      ARTHUR EVANS
      WHAT'S BUGGING YOU Jan 11, 2007 


On the east side of our house is an exotic species of honeysuckle. Each spring it is covered in blooms and becomes a magnet for early-season insect pollinators.

This year, little more than one week into the new year, it is already clothed in flowers, but only a few honey bees are in evidence. The native, solitary ground-nesting bees that are usually clambering over its blooms are nowhere to be found.

Apparently, the spate of warm winter weather has crossed the honeysuckle's temperature threshold for producing blooms, but not that of the indigenous pollinators.

Will there be any flowers left by the time the bees emerge from their underground burrows? Probably not. It appears that the link between our honeysuckle and this pollinator has been broken, at least temporarily.

The lesson here is that even small, temporary shifts in temperature can have unpredictable effects that ripple through the environment.

Long-term impact
Given the apparent short-term impact of this warm winter on species in my yard, I began to wonder what might be the long-term effects.

Higher temperatures would undoubtedly improve the reproductive capabilities of some species but would drive others toward the poles or to higher elevations as they seek cooler temperatures.

 This shift would force some species into smaller or less desirable habitats, where they would either adapt or die. Those species successful in colonizing new habitats would be destined to alter entire ecosystems just by their presence and numbers.

As climates shift, the synchronicity of some flowering plants and their pollinators would be disrupted, resulting in reduced seed set as well as pollen and nectar production.

Plants grown in atmospheres with higher-than-normal concentrations of carbon dioxide produce nutritionally inferior tissues. Some leaf-feeding insects might be forced to eat more leaves to obtain enough nourishment to complete their development. Others might shift their attention to other species of plants, if they are genetically predisposed to do so.

Increasing populations
Increased levels of greenhouse gases also might affect the production and reception of insect pheromones. Many insects employ pheromones -- airborne chemical substances -- as their primary means of communication. Pheromones exert enormous control over such diverse insect behaviors as sending out alarm signals, or locating food and mates.

Higher temperatures would no doubt increase the populations of some insect species by shortening their development time and increasing the length of their reproductive season.

By applying this math to populations of mosquitoes, you can begin to appreciate the potential risk of increased exposure to mosquito-borne diseases.

The study of insects has much to offer in terms of understanding the effects of global warming. Although not as interesting to some people as polar bears, insects are much better as "canaries in the coal mine" because they are ubiquitous and react more quickly to subtle changes in the environment than other organisms.

In light of what we do know, one thing is clear: As with all other organisms, there would be winners and losers. I wonder in which column we will find ourselves.



Dr. Arthur V. Evans is a research associate at the Smithsonian Institution and the Virginia Museum of Natural History. Look for his column on the second Thursday of each month. Contact him at arthurevans at verizon.net.
FROM TIMES DISPATCH.COM Richmond, Virginia

Laurie Davies Adams
Executive Director
Coevolution Institute
423 Washington St. 5th
San Francisco, CA 94111
415 362 1137
www.coevolution.org
www.nappc.org
www.pollinator.org

Visit the above sites to register for the October 18
Pollinator Symposium at the USDA Jefferson Auditorium

Our future flies on the wings of pollinators.
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