Pest Invasion of African Agriculture
Nov 17, 2017
Back in early October, reporting on the deaths of four U.S. soldiers in Niger allowed the American public to learn more about the scope of U.S. military engagement in the continent. The chairman of the Joint Chiefs of Staff, General Joseph Dunford, disclosed that there are more than 6,000 troops stationed in about 20 different countries as part of the U.S. African Command (AFRICOM), mainly to help combat the spread of ISIS and allied terrorist groups in the region.
There is another threat spreading across Africa that the United States government also needs to help with--the invasion of a pest known as fall armyworm, that has devastated crops in at least 28 countries just this year. The fall armyworm (Spodoptera frugiperda) is the caterpillar (larval) stage of a moth that is actually native to North America. Its presence was first detected and reported on the island nation of Sao Tome and Principe off the coast of West Africa in early 2016. The precise source of that first infestation is not known, although speculation centers on the possibility that one or more live caterpillars burrowed into or live eggs were deposited in a shipment of grain arriving in the region that was not subject to fumigation.
The main crop being affected is maize (corn), which is by far the top grain crop grown across Sub-Saharan Africa. Maize accounted for 43 percent of total grain produced in Africa in 2012. However, this species of fall armyworm is particularly voracious, much more so than the armyworm species native to Africa, and they have also been feeding on sorghum, rice, and sugarcane crops across the affected region. It has been estimated by the Centre for Agriculture and Biosciences International (CABI) that the losses from the maize crop alone could range between $2 billion and $5.5 billion per year.
Once the fall armyworms arrive in a field, they typically devour between 60 and 75 percent of the crop being grown. They damage not just the grain portion but also often degrade the stalk portion of the plant, which reduces the amount of crop residue left to the farmer after harvest. That loss could reduce soil carbon content and thus affect the field’s innate productivity even after the pest moves on.
The life cycle of this pest is fairly rapid--the eggs hatch a few days after being laid, then the larval form persists for 2 to 4 weeks, then the larva pupates underground for 1-4 weeks. The adult moth lives for 1-3 weeks, with the females laying eggs for most of that time. The moths are known to be able to fly up up to 100 kilometers over a single day, making their spread even more difficult to contain. As the affected region is expected to expand north on the African continent over the next few years unless the spread can be checked, parts of southern Europe could be in range of the fall armyworm moth at some point. The emerging effects of climate change in Africa could make the situation even worse, as these pests prosper in wet and hot climates.
Farmers in Africa are attempting to combat this spread through use of pesticides, but it is often not effective beyond the first few days of the larval stage. Scientists have expressed the fear that overuse of pesticides could hasten the development of pesticide resistance within the species and also harm the environment and the farmers using the chemicals.
Efforts are underway to develop alternative strategies to slow down the devastating spread of fall armyworms--these including developing biopesticide and seeking to breed maize varieties that are resistant to these pests. Unfortunately, these are both long-term approaches, likely taking several years for solutions to emerge. In the short term, one approach would be to identify and bolster the presence of natural predators of the fall armyworm.
In the United States, this pest has not flourished because it does not survive winters in the Midwest and other northern states, where most of the corn is grown. In addition, corn producers no longer fear the worst impacts of fall armyworms due to past work done to incorporate resistance to this pest through use of genetic engineering of corn varieties suited for cultivation in this country. Such GMO crops have not been widely adopted in Africa in the past, but this technology may need to be part of the response to fall armyworm infestation in the years to come.
This ongoing disaster was the subject of much discussion at the recent Borlaug Dialogue event held in conjunction with the awarding of the World Food Prize last month in Des Moines, IA. In his remarks at the Borlaug Dialogue, USAID Administrator Mark Green issued a call to action to potential partners to mobilize the resources necessary to tackle this massive problem. On October 19, he announced that “the Feed the Future initiative has already begun assembling like-minded international and African organizations, companies, and research institutes to mobilize their solutions to the Fall Armyworm epidemic.”