Posts about beetle

Darwin’s Beetles Still Producing Surprises

As part of National Science Foundation-funded research on the evolution of male dimorphism in insects, biology professors J. Mark Rowland, UNM, and Douglas J. Emlen, UM, were surprised to find that many species of beetles are capable of producing not only two, but three different types of males.

The sex lives of animals is known to be complicated business. Where competition in mating is particularly intense, many kinds of animals produce enlarged weapons that function in male combat and utilize alternative tactics in deploying them. Such exaggerated structures include horns in dinosaurs and deer, and tusks in elephants and walrus.

Elaborate male weapons are also known to occur in many types of insects. Now it appears, as the research of Rowland and Emlen illustrates, that male weaponry and alternative mating tactics can be much more complex in the lives of beetles than previously imagined.

“We discovered a novel mating system in which the individual males of various species of beetles have the capacity to express one of three alternative morphologies,” said Rowland. “In many dung beetles , smaller males are unlikely to prevail in direct contests with alpha males. These beta males develop disproportionally smaller horns and employ alternative, less aggressive, reproductive tactics.

“The trimorphic species reported here have alpha, beta and gamma (completely hornless) male – three qualitatively distinct forms. A mating strategy with three such tactics implies considerable complexity, but may actually involve operational rules reminiscent of the old rock, paper, scissors game.”
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Appetite for Destruction

photo of Mountain Pine Beetle

Appetite for Destruction (link broken, so I removed it) by Eric R. Olson:

“Once the beetles are at the level they’re at in British Columbia, there’s nothing you can do – it’s like a rapidly spreading fire,” says Barbara Bentz, research entomologist with the U.S. Department of Agriculture Forest Service. If the beetle continues to devour trees at the current rate, 80 percent of British Columbia’s mature pines will be killed off by 2013, according to Natural Resources Canada, an arm of the Canadian government.

Global climate change, which is pushing temperatures higher, has altered the beetle’s natural life cycle. Now the insect threatens one of the world’s largest forest systems: Canada’s boreal forest, a 600-mile-wide band of pine woodlands that stretches from the Yukon in Alaska all the way to Newfoundland on the East Coast.

The source of all this destruction is an insect not much bigger than a grain of rice. A native of North America, the pine beetle does its damage by burrowing beneath the bark and feeding on the living tissue of the tree called the phloem. This tissue is composed of long tubes that transport nutrients from root to limb, and once it is destroyed, the tree can no longer survive.

In the past, cold snaps — quick drops in temperature in the spring and fall — have kept beetle populations in check. Although the insects can survive temperatures as low as minus 35 degrees Fahrenheit in the winter, it takes time for their bodies to accumulate enough glycol, the same ingredient found in antifreeze, to survive such frigid temperatures.

Photo: Mountain Pine Beetle (Dendroctonus Ponderosae) under a scanning electron microscope. [Credit: Leslie Manning/Canadian Forest Service]

Related: Rain ForestsDeforestation and Global WarmingBed Bugs, Science and the Media

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