It is easy to cut a path between the maize plants in Barthelemy Allah’s maize field. But, at this time of the growing season, tall stalks and large leaves usually block your view. But this season, the young shoots—just 40 centimetres high—are full of holes, and some are torn.
Mr. Allah lives in Bonou, a community in the department of Ouémé in southwestern Benin. His field of maize has been attacked by fall armyworms.
He says, “They ate all the maize. The invasion occurred just 15 days after planting. Without these caterpillars, you would have seen very pretty plants.”
He worries that a poor harvest will decrease his income, impacting his life and that of his family.
Many farmers in this area are suffering from an invasion of fall armyworms, which first appeared in Benin in 2016. Some have turned to using pesticides to ward off the invaders, but with little effect.
Albert Gnansounou lives down the road from Mr. Allah. The destruction on his farm is less visible. When the caterpillars appeared, Mr. Gnansounou used pesticides extensively to try to fend off the invading insects.
In this area, farmers don’t typically use pesticides on their maize. Mr. Gnansounou says he turned to pesticides because it was the only way to save his crop. He explains: “We started spraying the field [and] we are at ten treatments, but the results are inconclusive. Elsewhere, in the face of the abundance of caterpillars, we simply had to abandon the fields.”
Farmers in Zimbabwe are facing similar devastation. Vavariro Mashamba is a farmer in Karoi district, in northern Zimbabwe. When fall armyworms appeared in his field, he sprayed his plants. But with little effect. He says, “There was no change. Instead, the worms continued to multiply in my field.”
Researchers note that some pesticides are only effective when armyworm larvae are small and before they have caused visible damage to crops. After this stage, there is no quick solution for fighting the pest.
In February, the UN Food and Agriculture Organization, known as FAO, organized an emergency meeting about fall armyworm in Harare, the capital of Zimbabwe. Many southern African countries are searching for ways to limit the damage caused by the pest. FAO says that 130,000 hectares of maize may already be infested in Zimbabwe, as well as 90,000 hectares in Zambia, and 50,000 in Namibia.
Fall armyworm can cause crop losses of more than 70%. This poses a threat to food security in many areas.
In Benin, about 41,000 hectares of land have been infested since fall armyworm first appeared in 2016. April is the height of the growing season for maize in Benin, and farmers are worried about their crops. They are counting on authorities to take measures to avoid a disaster. But for now, no effective solutions have been proposed.
Noël Kpoahoun is the head of plant protection for the government of Benin. He says chemicals are the best tool to fight the fall armyworm, even if success is not guaranteed. The government provided pesticides for some farmers who had been trained to handle and use the products.
In Zimbabwe, farmers have also been given pesticides to combat fall armyworm. They are being advised to spray with high pressure, either early or late in the day, at a high rate of application.
Since the pest is resistant to many methods of control, FAO warns it could be here to stay.
David Phiri is FAO’s sub-regional coordinator for southern Africa. He suggests that early planting of quick-maturing varieties may lessen infestation and damage. Other methods proposed at the Zimbabwe meeting include releasing insects which feed on armyworm eggs, including parasitic wasps, flies, lacewings, and ladybirds.
But the situation may get worse in the short term. In early February, a study by the Centre for Agriculture and Bioscience International, known as CABI, found that fall armyworms were spreading rapidly and feeding primarily on maize. The study noted that the armyworm can eat “more than 100 different plant species,” including rice, beetroot, cabbage, soya bean, cotton, tomatoes, and potatoes.
This article is based on reporting from two stories, produced by BBC Afrique and IRIN. To read the full story from IRIN (in English), “After drought, Zimbabwe contends with fall armyworm invasion,” go to: http://www.irinnews.org/feature/2017/03/29/after-drought-zimbabwe-contends-fall-armyworm-invasion 
For more information on the CABI report (in English), from BBC Africa, go to: http://www.bbc.com/news/science-environment-38859851 
To learn more from BBC Afrique (in French), listen to this interview with agronomy professor Many Madika from Kinshasa: http://www.bbc.com/afrique/media-39111820 
Photo: Armyworm // Credit: Phil Sloderbeck/Kansas State University/Bugwood.org