SCIENCE
Notebook
Monday, December 19, 2005; Page A12
New evidence suggests that insects make smart, instinctive dietary choices that strengthen their immune systems when they are battling infections.
Previous studies have shown that some leaf-eating insects alter their daily choices of leaf types to ensure they get a balance of nutrients. But what about when insects are sick? Do they make chicken soup? Although researchers have shown that some insects infected with parasites feed specifically on plants loaded with medicinal chemicals, it remained unknown if insects could do something more subtle: alter their protein and carbohydrate intake to maximize the general potency of their immune systems.
  A whooping crane, a species that a study identified as near extinction, with sandhill cranes near Hargill, Tex. (U.S. Fish & Wildlife Service -- Associated Press) |
Kwang Pum Lee of the University of Oxford and his colleagues tested that possibility in experiments with Spodoptera littoralis , a caterpillar known to dine on a variety of leaf types. The scientists infected scores of the caterpillars with a virus that is often fatal within a week and tallied the death rates in those fed diets with varying protein-to-carbohydrate ratios. Tests showed that the immune systems of the caterpillars that were fed lots of protein functioned better than those of the caterpillars that were fed lots of carbohydrates. The caterpillars with protein-rich diets also had significantly higher survival rates.
The team then offered a variety of foods to sick and healthy caterpillars. The healthy ones selected diets that were about evenly balanced with protein and carbohydrates. But the infected ones went for the high-protein, immune system-boosting meals.
"Our study provides the first experimental evidence that pathogen infection induces a compensatory shift in diet selection to supplement the specific nutrients required to fight infection," Lee and his colleagues reported last month in the Proceedings of the Royal Society B.
-- Rick Weiss
Alliance Lists Species, Sites In Need of Preservation Work
An alliance of conservation groups has identified nearly 600 sites that, if safeguarded properly, could stave off the extinction of hundreds of species.
The study, released last week by the Alliance for Zero Extinction, noted that a third of the sites it had located have legal protection, and most are surrounded by dense human populations. The United States ranked among the top 10 countries with the most critical habitat at stake, with sites ranging from a West Virginia cave to a Mississippi pond.
"Although saving sites and species is vitally important in itself, this is about much more," said Mike Parr, the alliance's secretary. "At stake are the future genetic diversity of Earth's ecosystems, the global ecotourism economy worth billions of dollars per year, and the incalculable benefit of clean water from hundreds of key watersheds. This is a one-shot deal for the human race."
Nearly 800 mammals, birds, amphibians, reptiles and conifers are in danger of extinction, according to the coalition of 52 conservation organizations, including the Bloody Bay poison frog, the volcano rabbit and the Sulu bleeding-heart dove.
-- Juliet Eilperin
Alliance Lists Species, Sites In Need of Preservation Work
An alliance of conservation groups has identified nearly 600 sites that, if safeguarded properly, could stave off the extinction of hundreds of species.
The study, released last week by the Alliance for Zero Extinction, noted that a third of the sites it had located have legal protection, and most are surrounded by dense human populations. The United States ranked among the top 10 countries with the most critical habitat at stake, with sites ranging from a West Virginia cave to a Mississippi pond.
"Although saving sites and species is vitally important in itself, this is about much more," said Mike Parr, the alliance's secretary. "At stake are the future genetic diversity of Earth's ecosystems, the global ecotourism economy worth billions of dollars per year, and the incalculable benefit of clean water from hundreds of key watersheds. This is a one-shot deal for the human race."
Nearly 800 mammals, birds, amphibians, reptiles and conifers are in danger of extinction, according to the coalition of 52 conservation organizations, including the Bloody Bay poison frog, the volcano rabbit and the Sulu bleeding-heart dove.
-- Juliet Eilperin