A species of armyworm has spread to over 20 African countries and threatens Africa's main food crop -- maize.
The warning comes from the United States Agency for International Development, or USAID.
Joseph Huesing works as an advisor to USAID. He suspects the fall armyworms were transported to Africa from the American state of Florida or islands in the Caribbean.
Huesing says the insects are attacking maize crops -- also known as corn -- in African countries south of the Sahara desert.
From Nigeria and Ghana, all the way to South Africa to Ethiopia, he told VOA. The most recent one is South Sudan, which reported fall armyworm infestation toward the end of June.
Huesing thinks fall armyworms are a big threat to African agriculture. When they invade a maize field, he said, the insects can eat 30 percent or more of the crop. They also eat other crops.
The fall armyworms got their name from fall, or autumn -- the time of year when they do the most damage in the northern United States. The first published report describing their presence in Africa appeared in early 2016. It suggested the insects had already been there for a year.
For several reasons, the fall armyworms may pose more problems for farmers than the African armyworm, which is native to Africa.
Fall armyworms can reproduce continuously under warm, moist conditions, says Yene Belayneh of USAID. He noted that they can feed off of more than 80 species in 27 plant families.
As adults, fall armyworms can fly up to 100 kilometers a day if pushed by winds. Some armyworms have found a ride on modern aircraft.
For this reason, Belayneh said, communication is especially important. If there is an outbreak, for example in Ethiopia, alerting Sudan or Eritrea would be a wise thing, he said.
In fact, the insects are in Ethiopia. The country's Plant Protection Directorate reported that as of July 10, fall armyworms have infested more than 440,000 hectares of crops. It said that about 305,000 hectares had been protected.
But chemical treatments may be less effective with the new invaders than with the African armyworms. The fall armyworm enters the plant and feeds from inside, says Belayneh. This makes the insect harder to recognize and harder to kill.
The species is defenseless in cold weather, but freezing conditions are rare in much of Africa.
Regina Eddy heads USAID's armyworm response team. She says her team's goal is to provide training and technical choices. She identified Brazil as a model for fighting armyworms. A recent USAID report noted that Brazil spends an estimated $600 million each year to control the insects.
One control measure experts are taking is to more carefully inspect food arriving at African airports. The fall armyworms may have arrived on the continent through a food shipment from overseas.
The fall armyworm is not causing a crisis yet. But Belayneh told VOA no one is taking the situation lightly.
I'm Mario Ritter.
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Her eyes were moist.
His immediate response was one of disbelief.
1.The warning comes from the United States Agency for International Development, or USAID.
come from... 来自于……
He's just come from the countryside.
The foreign students studying in Beijing come from all parts of the world.
2. ... which is native to Africa.
be native to... 产自于……
She said a major cause of the extinctions are plants and animals not native to Hawaii.
It is spread by the bite of an infected tsetse fly (Glossina Genus), a species native to the African continent.
约瑟夫(Joseph Huesing)是美国国际开发署的顾问。他怀疑这种秋行军虫是从美国佛罗里达州或者加勒比海盗传到非洲的 。
从尼日利亚到加纳，再一路抵达南非的埃塞俄比亚，他在接受VOA采访时如是说道。最近受灾严重的是南苏丹 。据报道，秋行军虫引起的灾荒持续到六月底 。
约瑟夫认为，行军虫是对非洲农业的巨大威胁。他表示，如果行军虫入侵了一片玉米地，那么至少30%的玉米将难以幸免 。除了玉米之外，它们也吃其他的庄稼 。
秋行军虫得名于秋天——因为秋天是它们对美国北部破坏力最大的时节。第一份有关秋行军虫记载的报告发布于2016年初 。报告指出，这种昆虫在美国已经出现了一年之久 。
美国国际开发署的恩毅(Yene Belayneh)表示，在温暖潮湿的环境下，秋行军虫可以持续繁殖。恩毅强调，这种昆虫能以27个植物科的80多个物种为食 。
实际上，秋行军虫已经抵达了埃塞俄比亚。埃塞俄比亚的植物保护部门报告称，到7月10日为止，秋行军虫已经入侵了44万多公顷的庄稼地 。该部门还表示，近30.5万公顷的庄稼地得到了保护 。
但化学处理的方法对秋行军虫这种新入侵者的效果可能不如对非洲行军虫的效果。恩毅表示，这种秋行军虫是进入到植物体内，从内部开始侵食 。这就给识别并杀灭这种昆虫加大了难度 。
里贾纳是美国国际开发署行军虫响应小组的负责人。她表示，自己小组的目标就是提供培训和技术选择 。她认为，巴西是抗击行军虫的典范 。美国国际开发署最近的一项报告显示，巴西每年花费近6亿美元来控制行军虫 。