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Warmer Climate Will Bake Tropical Bugs
Global warming could cook tropical insects, with unpredictable knock-on effects, say researchers who warn that rising temperatures also
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tropical frogs and lizards (蜥蜴).
Temperatures are
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to increase much faster in temperate (温和的)and polar (极地 的) regions than in the tropics. But no one had looked at how warming would affect insects and other cold-blooded animals
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had evolved in tropical regions with little temperature variation.
Curtis Deutsch at the University of California at Los Angeles and colleagues analysed data
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insect survival and reproduction for 38 species in different ecosystems (生态系统), and then estimated how these values would
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with predictions of climate change for the 21st century.
The team found that the reproductive
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of tropical insects tends to peak very close to the temperatures where they normally live, but
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sharply at higher temperatures. This means that cranking up (提高) the heat only a small amount can exert a heavy toll, leaving insects unable to reproduce
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enough to keep up their numbers.
Temperate insects reproduce well over a broader range, and do not live as
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to their thermal (热的) limit, so they can reproduce successfully when their climate warms more than in the tropics.
"Tropical insects do very well in a narrow band of temperatures, but move them above that
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and they die," says team member Josh Tewksbury of the University of Washington in Seattle.
The heart of the
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is temperature tolerance. Temperate-zone insects have evolved to survive the much broader temperature range of seasonal climates than have their tropical relatives.
The
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appears worse for animals that live in hot stable climate of the lower levels of tropical forests. Lizards in clear areas can find shade to cool down, but those living in the forest are already in the
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, and there"s not much they can do to get cooler, Deutsch says.
Too few tropical insects have been studied so far to
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if any particular group will be particularly hard-hit, says Tewksbury. Insects play important
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in forest ecology (生态学).
The team are now starting to evaluate how temperature affects ecological interactions of insects with other species, including crops such as African corn.