New plague of caterpillars deals blow to farmers

JOHANNESBURG / DPA

One of the most damaging pests in North and South America has reached Africa and is threatening the maize crop in many countries there.
Experts are also warning that the fall armyworm (Spodoptera frugiperda), the larva of the fall armyworm moth, could soon spread from Africa across the Mediterranean to southern Europe.
“Whether this year, next year, or in five years – I think it’s likely to happen,” says Matthew Cock, director of the Britain-based Centre for Agriculture and Biosciences International (CABI).
“I don’t think we’ll be able to stop it. It’s not possible to eradicate,” he continues.
Africa is not prepared for the invasion of the caterpillars, which grow up to four centimetres long and get their name from the way in which thousands will descend on a field of crops, typically maize, eat everything there and then march on to the next field.
“It’s like a huge army. They go in columns,” says David Phiri, UN Food and Agriculture Organization (FAO) coordinator for southern Africa.
In Zambia 130,000 hectares are already affected, while in Zimbabwe the pests have been found in nine out of ten provinces.
“I am hoping that the government brings in pesticide because I cannot afford to spray the whole field. I never anticipated this outbreak,” says Joseph Gomo, a farmer in Chegutu district, around 100 kilometres south-west of Harare. “If the situation remains like this, hunger is certain.”
South Africa, by far the region’s biggest maize producer, has also been affected.
The arrival of the fall armyworm is a huge problem for Africa, where maize is the most important foodstuff, with 70 per cent of arable land dedicated to it.
The extent of the damage to crops is not yet clear, but the FAO, which recently called an emergency meeting in Harare to discuss the problem, warns that the pest can destroy up to 70 per cent of a harvest.
The caterpillars keep eating for three weeks before they turn into owlet moths (Noctuidae), which, with the aid of a strong wind, can quickly spread out over hundreds of kilometres and lay up to 1,000 eggs each.
The fall armyworm was discovered in Nigeria at the beginning of 2016 and a year later it has also established itself 5,000 kilometres further south.
Because of the mild weather, there are no frosts to kill the pests and so each year as many as 12 generations can be produced.
It represents a threat of a whole new magnitude to Africa.
“The problem is that it’s a new pest,” says Cock. “Nobody in Africa knows how to deal with it.”
Researchers in the United States have been working on strategies to fight the caterpillar for decades. “It is described as one of the worst pests in the Americas,” Cock adds.
He believes the fall armymoth was accidentally introduced to Africa via airfreight.
While the pest prefers maize it will eat other grains and vegetables too. And just a few can cause “heavy damage,” says Cock.
Their arrival also comes just as southern Africa is recovering from a drought which affected 40 million people in 2016, according to UN estimates. Farmers had been hoping to finally get a good crop this year.
The best way to fight the fall armyworm is to target the young caterpillars with pesticides. Once the pest has started eating maize it can no longer be stopped.
“That’s why early detection is so important for fighting it,” says Phiri.
Birds are also the caterpillars natural enemy. They’re most likely to eat them when the pests move from one field to the next en masse, in plain view.
In North and South America ants also eat the moths’ eggs, according to Cock. There are also more traditional ways to fight the pests. Farmers can for example dig a trench around an affected field, making it easier to kill the caterpillars when they try to reach a neighbouring field, Phiri says.
African farmers have already had some success using this method in containing a native pest, the African armyworm (Spodoptera exempta), a less dangerous cousin of the fall armyworm.
The African armyworm is easier to combat because it can only produce up to the three generations in a year and its moths can’t travel as far.
It also tends to eat maize leaves rather than the stalks or cobs, unlike its more aggressive American cousin.
In countries like Zambia, Malawi and Zimbabwe, the majority of the population lives off agriculture and the arrival of this new pest could be especially devastating as many are subsistence farmers.
Without a harvest they cannot feed their families and in many of the affected countries there is no insurance against crop failure, either as a commercial product or provided by the state.
The only safety net most people have are their relations – whose fields might also be affected.
Cock says that farmers in America are using genetically modified maize in a bid to combat the pest, but that’s not a solution available in Africa, where the fight against them is just beginning.
“Our worry is that this is going to be a problem for the future,” says Phiri. “This is not just a problem for one season.”