contrary to popular belief that global warming will lead to population explosion in insects, a recent study claims otherwise. It says the phenomenon will lead to extinction of insects in the tropical zone by the end of the century. Survival options are two: either they learn to adapt to the rising temperatures or migrate to higher latitudes, the authors said in the paper published in the May issue of Proceedings of the National Academy of Sciences. Insects in the temperate zones and the poles could in fact experience a dramatic increase in numbers, the study says.

The reason for extinction, the authors say, as temperatures increase insects will not be able to perform physiological functions such as reproduction and locomotion. Since they are cold blooded, they cannot regulate their body temperature. Classed as ectotherms, they operate in a specific temperature range called critical thermal limit. As the temperature increases in this range, physiological activity increases. It reaches an optimum level and then declines sharply, said the researchers of University of Washington, usa, who carried out the study. Tropical insects are already at the higher end of the critical thermal limit and hence the threat is imminent. Insects in colder regions may survive and proliferate because they are still at the lower end of the temperature range.

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