Millennium Bugs

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Science  05 Oct 2007:
Vol. 318, Issue 5847, pp. 21
DOI: 10.1126/science.318.5847.21b

One thousand years ago, the Emperor of China ordered that locust abundance be recorded so as to predict swarms. Although wetland management techniques reduced locust outbreaks in the second half of the 20th century, they have recently become troublesome again in the Yangtze and Yellow River basins, perhaps as a consequence of global climate change. Locust numbers peak during drought years and in years after floods, reflecting differential effects of moisture and warmth on different life cycle stages. This discrepancy has made it difficult to predict how the warmer and wetter conditions that are projected to prevail in East Asia will affect locust numbers.

Stige et al. combined the millennial time-series data with recent temperature and precipitation reconstructions of historical weather and discovered that locust abundance is highest during periods with a high frequency of floods and droughts. The records reveal that these more variable climates actually tended to occur during the coldest and wettest decades. So, warmer conditions will not necessarily favor locust breeding. — CA

Proc. Natl. Acad. Sci. U.S.A. 104, 10.1073/pnas0706813104 (2007).

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