山东省烟台市2019-2020学年高二下学期期中考试英语试题试题详情
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The outbreak of locusts, an insect that mainly lives in Africa and Asia, is the worst experienced by Kenya in 70 years. The crowds are some three times the size of New York City, eating their way through thousands of acres of crops and animal grassland and destroying livelihoods in the process.
"These hungry things are alarming," says Keith Cressman, the UN Food and Agriculture Organization's senior locust forecasting officer. "A crowd the size of Manhattan can, in a single day, eat the same amount of food as everyone in New York and California combined."
Desert locusts are infamous for their ability to breed(繁育)rapidly in large numbers every three months. And with some help from the wind, they can travel as much as 80 miles a day. Most years, the insects stay in African deserts. However, under the right environmental conditions, they can multiply quickly, spread as much as 400 times every six months and cause extensive destruction if left unchecked.
"The insect has the ability to take advantage of good conditions." Cressman says.
The "good conditions" the scientist is referring to began in mid-2018 when a rainstorm from the Indian Ocean struck a remote area of the Arabian Peninsula known as the "Empty Quarter". Normally, it would dry out within a short period, killing most of the locust population, which depends on green plants for food. However, in late 2018, a second rainstorm struck the same region. The huge sandy area got wet, which is exactly what desert locusts need to lay their eggs and breed. The extra food supply caused the population to explode for the second time in six months.
Luckily, the locusts, experts say, are easy to control with chemicals. Kenya badly needs equipment and a steady supply of chemicals to effectively wipe out the massive insects. Hopefully, leaders worldwide will recognize the tough situation and contribute generously to control the locust outbreak.
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