Lose the Sweet Tooth

May 27, 2013

One can safely assume that cockroaches are not among the typical urban resident’s favorite animals.  While they are not as dangerous as, say, a malaria-carrying mosquito, or a tse-tse fly, they can potentially transport infectious agents, and have been implicated in some human allergies.  Mostly, though, people just think that they’re gross.  They’re also quite hardy, and able to go for fairly long periods without food or water; getting rid of them can be a chore.

Back in 1976, the Black Flag company introduced a roach trap called the Roach Motel™; it is a small enclosure, which contains a slow-acting poison mixed with a bait.  (Other companies marketed similar products.) The idea is that roaches will be attracted to the bait, and then carry the accompanying poison back to their nests, thereby getting other roaches as well.  The product was quite successful, in part because of aggressive advertising, and its memorable slogan, “Roaches check in, but they don’t check out.”

More recently, though, users have noticed that the traps were becoming less effective. The New Scientist  has a recent article on some research that may explain why.   One of the ingredients in the bait used is the simple sugar, glucose.  It seems that the roaches have evolved a distaste for glucose.

In the race for world domination, cockroaches have scored another point against Homo sapiens. Their weapons? A distaste for sugar and a helping hand from evolution.

In a paper published in the journal Science, researchers at North Carolina State University in Raleigh discovered that some roaches of the species commonly known as “German cockroaches” [Blattella germanica] had a difference in their neurochemistry that caused glucose to “taste” bitter, a trait which they passed on to their offspring.  The use of glucose as a bait in poisoned traps creates selection pressure that favors roaches without a sweet tooth.  Hence, the authors suggest, evolution is at the heart of the traps’ decreased effectiveness.

This kind of evolutionary “arms race” is similar to what we have seen in the development of antibiotic-resistant bacteria, DEET-resistant mosquitoes, and herbicide-resistant weeds.  We humans are quite good, in many cases, at devising ways to modify our environment.  But we too often forget that our environment is not just a passive lump of matter — when we push, it frequently pushes back.

Alfred Russel Wallace’s Letters Online

January 26, 2013

Back in the summer of 2011, I posted a note here about the anniversary of the first presentation of the theory of evolution by natural selection, made to the Linnean Society of London on July 1, 1858.   That initial presentation was a composite of work by Charles Darwin, author of On the Origin  of Species by Means of Natural Selection, published in 1859,  and Alfred Russel Wallace, a young English naturalist, working in Malaysia, who wrote to Darwin in June, 1858, enclosing a short paper in which he outlined essentially the same theory as Darwin’s.  Darwin consulted the geologist Charles Lyell, and the botanist Joseph Hooker; they arranged for the composite paper to be presented, along their letter explaining the circumstances of the parallel development by Darwin and Wallace.

Although Wallace was well known during his lifetime, and received the Copley Medal from the Royal Society, in 1908 his work on developing the theory was to a considerable extent forgotten following his death in 1913.

Now, according to an article at Ars Technica, the Natural History Museum in London has put together a new Web site, Wallace Letters Online, that contains a digital archive of more than 4,000 of Wallace’s letters; his correspondents include many well-known names from 19th century science:

Wallace’s correspondents read like a “Who’s Who” of 19th century science and society, Charles Darwin, Thomas Henry Huxley, Joseph Dalton Hooker and Gertrude Jekyll, to name just a few.

The site is part of a larger project at the museum, Wallace 100, marking the centenary of Wallace’s death.  The project also includes a series of events throughout the year, sponsored by the museum and partner institutions.

As both Darwin and Wallace anticipated, the theory of evolution by natural selection was quite controversial when it was proposed.  Darwin ended up primarily being associated with the theory, probably because he was more directly connected with some of the controversy, and Wallace’s contribution was neglected.  It’s good to see that his work is being recognized.

Update Sunday,  27 January, 14:30 EST

The New Scientist has an imaginary “interview” with Wallace, with the answers taken from his letters.

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