Global warming could reduce the locust population in China,
according to a study published by last week's Proceedings of
the National Academy of Sciences.
Researchers analyzed a 1,000-year record of locust plagues in
China between AD 957 and 1956 and found a correlation between
population size and decadal mean temperature. They found locust
population grew larger during cold periods than during warm
periods.
File photo: About 2,000
mu (133.4 hectares) of farmlands in the Jinyun Mountain,
southwest China's Chongqing Municipality, were plagued by
locusts in early August this year.
China's locust plagues have historically come from marshlands
among the tributaries of the lower reaches of the Yellow and
Yangtze river systems.
"The cold periods are generally accompanied by higher
frequencies of draughts or floods. In a draught or after a flood,
the size of habitats conducive to locusts' proliferation would
increase as the water receded," says Zhang Zhibin, co-uthor of the
research paper and director of Institute of Zoology of the Chinese
Academy.
However, previous research showed that a single warm year could
assist locust larvae's survival through cold winters and enable
larger swarms to form in the coming year. Zhang believes there's an
explanation for this paradox.
He points out that locusts' ecological response to temperature
changes could be completely different, depending on the length of
the cycles researchers analyze.
During a longer period - such that of a decade - the favorable
effects warm temperatures have on locust larvae growth could
compensate for its adverse effects on locusts' habitat
expansion.
"The research into the relationships between climate change and
locust plagues throughout history are very important for people to
understand the patterns of locust population growth and to help us
develop relevant strategies to curb its growth," says Zhang De'er,
chief scientist of National Climate Center of China Meteorological
Administration.
Since the 1950s, the government had adopted intensive management
measures to reduce the size of locusts' breeding habitats and has
monitored and recorded the incidence of locust plagues for several
decades. However, locusts have again become a serious problem in
North China in recent years.
According to Zhang De'er, locust plagues follow a cycle, which
is actually affected by such multiple factors as temperature,
changes in precipitation and geological shifting.
All About
Climate Change
Locusts
(
China Daily, China.org.cn.cn September 24, 2007)
