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Science Notes / Entomology, biology

Parasitic wasps unleashed to fight emerald ash borer

Tiny parasitic wasps, Wisconsin's newest weapon in the war against the emerald ash borer, took flight this month in a forest that is under siege from the invasive tree killer. Two species of stingless Asian wasps that feast on the larvae of the emerald ash borer were released by scientists from the University of Wisconsin-Madison. A third species that feeds on the egg stage of the bug will be introduced later this summer.

It was the first time that the wasps, which are invasive species in their own right, have been used in Wisconsin to battle the destructive beetle.

UW-Madison entomologist Ken Raffa and research assistant Todd Johnson released about 800 wasps in a mosquito-ridden forest infested with the emerald ash borer. The wasps parasitize the larvae and eggs of the insects.

The metallic green bug -- whose larvae kill ash trees by interrupting the flow of nutrients beneath the bark -- is responsible for the death of tens of millions of ash trees nationwide since 2002.

-- Milwaukee Journal Sentinel


Genes play a role in altruistic behavior

If natural selection means that only the fittest individuals survive to pass their genes on to the next generation, then selfless behavior should not exist. Yet dolphins are known to support their injured brethren, and some species of monkeys will scream to warn others of danger, even though doing so makes them an easier target.

Biologists have a theory to explain such altruistic behavior: Animals will help each other if they have strong genetic ties, since such aid preserves genes they have in common. Known as Hamilton's rule of kin selection, the theory predicts that animals are prepared to make bigger sacrifices for close relatives -- who share more genes -- than for distant cousins.

But testing this theory in the real world would require careful observation of whole populations of animals over hundreds of generations. So Swiss researchers built a population of 1,600 simulated robots and hundreds of thousands of their offspring that evolved over 500 generations.

The result: Groups of robots that were closely related acted more altruistically than groups that were made up of strangers. The stronger the genetic ties within the group, the more sacrifices the robots made.

Hamilton's rule "really seems to be a fundamental principle of a natural system," said Markus Waibel, a roboticist at the Ecole Polytechnique Federale de Lausanne in Switzerland, who worked on the study published by the journal PLoS Biology.

-- Los Angeles Times