A plague of armyworms is marching across Africa, devastating crops, and claiming new territory at an alarming rate
May 18, 2017 — Speaking Darwinistically, the planet should have no truck with the spodoptera genus, commonly known as armyworms. Fat, slow over the ground and unspeakably terrible looking, they should never have evolved into anything more than an entomological pilot project.
In some variants, their heads resemble human brains that have been caramelized with a blowtorch. Mandibles, jammed into the bottom of the face part, glisten with alien goo. In their most gregarious morphological variation, black and dun stripes run down their bodies, mimicking something an avid golfer would wear to a funeral. They are speckled with sparse little hairs, like the budding moustache of a teenage Lothario, while their stubby legs appear to have been distributed randomly, and without consideration for balance and mobility.
Unfortunately, as it happens, armyworms do not appear fat and ugly to each other – or not, following one of nature’s great acts of mercy, when they’ve hatched into the world’s most boring looking moth. They reproduce at a staggering rate, with each female laying about 1000 eggs in a 10-day lifetime. And though they may be slow crawlers, they are strong fliers. Every year spodoptera frugiperda, or the fall armyworm, travels from Mexico to Canada, a distance of at least 3000km.
But if they have a dominant evolutionary superpower, it is rapacious communalism: in their larval stage, they advance in squadrons, platoons, battalions, armies – tens of millions storming the countryside, eating every crop or garden they can get their mandibles on. Most pests will consume only the good bits, but armyworms will strip even a fully-grown maize plant down to the last leaf.
Spodoptera have proved to be a blight in North America, South America, the Middle East, the South Pacific islands, Australia – pretty much everywhere. There are five species of armyworms, but we’re concerned here with the aforementioned frugiperda which is headquartered in North and South America; and the exempta, usually based in Africa.
Spodoptera exempta – the African armyworm – specialises in cereals, and has been causing havoc on the continent for decades now, spreading out slowly from the east and in 2009 sparking a state of emergency in Liberia.
The new arrival, however, is spodoptera frugiperda, more commonly and chillingly known as ‘the fall’. This variant, which eats pretty much anything, has enjoyed a long, awful history in South America – managing it costs the Brazilian economy a staggering $600 million a year. In January 2016 it was detected for the very first time in Africa, in Nigeria. (As for how it it got there from the Americas, it either flew in on prevailing winds, or caught a plane. No one is yet sure).
By April 2016, the pest had travelled to several other West African countries and to Central Africa. By December, it was detected in Zambia, Zimbabwe and Malawi, and was storming South Africa’s borders. Last week, Ghana’s parliament was asked by the minister of agriculture to declare a ‘state of emergency’, and take urgent action as the fall arrived en masse.
But why this particular plague, and why now? Is it the newish mash-up between local and invasive species that has produced such unstoppable consumption machines? Or has modern farming – in particular, modern African farming, which depends increasingly on planting vast tracts of a single staple – made it easier for them to advance? In regions stricken by climate change, and which in some parts have recently suffered (or, in some cases, is still suffering through) a once-in-a-generation drought, are armyworms not just another manifestation, albeit the most revolting, of the colossal challenges facing Africans as the world warms? At this stage, no one is really sure certain how best to answer these questions. But there is one last, and far more pressing, problem: can the armyworms be stopped before they eat Africa bare?
If there is a three-star general currently conducting the war against genus spodoptera, it must be a Lancaster University professor named Kenneth Wilson. According to his university profile, Wilson “ is fascinated by the interactions between parasites and their hosts, be they insects, birds, mammals or humans.”
He first became interested in African armyworms after studying their migration through Kenya 25 years ago. The sweetener, as far as his particular discipline was concerned, was the armyworm’s achilles’ heel: when he tried to transport live specimens back to a lab in Nairobi, he found that they would succumb to a virus, and none of them would survive the journey. There was a devastating natural loop at work here: a voracious parasite was felled, and easily so, by a voracious infectious agent. His work began to echo almost exactly the plot of HG Wells’ War of the Worlds, in which invading Martians are eventually killed off by microbial infection to which they had no immunity – “slain, after all man’s devices had failed, by the humblest things that God, in his wisdom, has put upon this earth.”
Wilson, who is currently in the field in Tanzania, remains in equal measures enthralled and terrified by these critters. “I got to wondering how armyworms could be such a devastating pest when they seemed so susceptible to this virus,” he explained over email, “and I have been studying the interaction between armyworms and their viruses ever since.”
His research suggested that the obvious solution to any armyworm infestation was to replicate the virus, and employ it as a biological agent in order to eradicate the blight. But this was easier said than done, and his research was anyway focused exclusively on the African armyworm. The recent introduction of the fall into the African theatre served, according to Wilson, “as the latest twist.”
And not a good twist. Given that the fall has only been in Africa since January 2016, no one is quite sure how severe the impact will be. “People are rightly scared about what’s going to happen,” Wilson told me.
Making matters worse, armyworms tend to love maize, the local staple. The practice of monoculture farming – lots and lots of maize, as far as the eye can see – is a key component to any form of industrial agriculture. But it has provided the African armyworm, which specialises in cereals, with a continent-wide all-you-can-eat buffet. “For the many farmers who also grow small amounts of other crops such as beans, peas and other vegetables, their livelihoods were safeguarded to an extent by these other crops,” Wilson explained. “But the fall armyworm has a much broader host range”– translation: it’ll eat anything – “so potentially can also eat these other crops if maize is not available.”
This attack on regional food security has been compounded by an X factor: climate change. “Drought followed by lots of rain is perfect for armyworms,” said Wilson, describing exactly the kind of weather conditions that are becoming the sub-Saharan norm. And so, in dry years, African crops suffer for the obvious reasons. In non-drought years, there are still the armyworms to contend with. Southern Africa’s recent drought, vicious by any estimation, was broken by the tropical cyclone Dineo, which touched down on the coast of Mozambique mid-February. Much of the region was swamped with massive, in some cases unprecedented, amounts of rainfall. Undaunted – nay, encouraged – onward marched the armyworm.
Putting up the wanted posters
When the infestation was detected in South Africa in January, it did not come as a surprise to the Department of Agriculture, Forestry and Fisheries (Daff), who had effectively posted wanted posters throughout the agricultural community in preparation for a first sighting. The fall armyworm was already listed as a quarantine pest for South Africa in terms of the Agricultural Pests Act 1983. After the first suspected specimens were collected on a farm in the northern province of Limpopo, Daff requested a diagnostic report from the Agricultural Research Council, Plant Protection Research Institute (Arc PPRI), which on February 3 confirmed the armyworm’s identity.
Daff had already constructed a sort of historical narrative regarding the outbreak, which squared with Kenneth Wilson’s and other expert assessments. Relying on a worst case scenario, which had been realised in other countries as the worm made its way south, Daff thus informed commodity and research organisations of a possible threat, and encouraged farmers to report suspicious pest damage.
Serendipitously, Daff had recently introduced the South African Emergency Plant Pest Response Plan, which was designed to diagnose and detect new pest infestations. Wisely, the government treated the outbreak as a crisis, and detection was just the first in what was necessarily a tiered attack. According to Makenosi Maroo, Daff’s chief director, stakeholder relations and communications, the department set up an internal joint operations centre, along with a steering committee that included “research, industry and provincial government role players”. But if African armyworms were the known known, the fall was the known unknown – there was no protocol in South African on how best to halt its progress.
As ever, the fallback option was to nuke them with chemicals. But which chemicals? “As the fall armyworm is a new pest to South Africa, no pesticide was previously registered to be used against it,” said Daff minister Senzeni Zokwana, during a hastily called press conference on 6 February. “A process of emergency registration of agricultural chemicals is ongoing with two active ingredients already registered to be applied against this pest. As with all agricultural remedy applications the label instructions must be followed in accordance to the supplier’s recommendations.”
Which was sound advice. But given that the effectiveness of the pesticide regime was still largely speculative, South Africa was due a lucky break. And the country got one due to a quirk in the harvesting schedule: the bulk of the season’s maize crop was unaffected and already drying for harvest, which meant that the armyworms were late for dinner. And there was more good news, at least as far as South Africa was concerned: the country produces most of its maize crop in areas where frost occurs, and armyworms can’t handle the cold. But in the warmer northern provinces of Limpopo and Mpumalanga, to say nothing of the rest of the continent, this was hardly an upside worth mentioning.
Still, Hamlet Hlomendlini, a spokesperson at AgriSA, a local lobby group, seemed to feel that the crisis was not much of a crisis at all. “We don’t see it as a threat right now,” he told me. “We feel that the department of agriculture is on top of it, and it was restricted to a few isolated farms in Limpopo. It was a question of finding the right pesticides. It seems like things are under control.”
Ghana declares a state of emergency
This would likely sound like an excess of sanguinity to Wilson. When I asked him how seriously African policymakers should be taking the armyworm blight, he was unambiguous. “Very.”
Nothing is certain at this point, but it’s clear that the infestation is spreading rapidly, without respite. A state of emergency has just been declared in Ghana. But the real kicker is that fall and African armyworms, as Wilson puts it, “have teamed up to provide a deadly double act.” This entomological suicide squad will cost a lot of money to control, and if they aren’t kept in check, the stakes get higher. From Africa, said, Wilson, “it’s possible that they will spread to Southern Europe, with seasonal migrations into northern Europe and possibly also into Asia.”
There’s some hope of nailing down an effective pesticide regimen, but that comes with its own problems – poisoning the environment, pollinators, livestock and humans not minor among them. Besides, the fall is resistant to many of the chemicals currently being deployed across the continent. With this in mind, Wilson and his collaborators have been working on a biopesticide derived from the natural disease that was killing his specimens in Kenya all those years ago.
By his own admission, this is a time-consuming and expensive pursuit. At the moment, Wilson is in Tanzania battle-testing the new weapon. “We are currently at the stage where we are asking some fundamental questions,” he told me. “Will the armyworms develop resistance to the biopesticide in the same way as insects often do against chemicals? Will the virus evolve to be less effective if we produce lots of it under field conditions? And can we make the biopesticide more effective by formulating it in a different way?”
The armyworm is not waiting for Wilson and his team. And while the outbreak is apparently under control in South Africa, no other African country can match Daff’s sophistication. The Central African Republic is in the midst a long-simmering civil war; Zimbabwe is in perennial economic free-fall; and even boring Zambia is undergoing political instability. Next year, according to the experts, a drought beckons. The world’s ugliest worm thrives on exactly this kind of chaos.