African countries mobilize to battle invasive caterpillar

Authorities and researchers have stepped up efforts to combat the invasive fall armyworm.

Fall armyworm caterpillars are crop destroyers in Africa.
Credit: Waldo Swiegers/Bloomberg via Getty Images

African nations are preparing to deal with an invasive crop pest known as fall armyworm, which has been rapidly spreading across the continent for just over a year. The caterpillar has wreaked havoc on staple crops including maize (maize), millet and sorghum. Experts have warned that Europe and Asia could be next.

Officials gathered for an emergency meeting – hosted by the United Nations’ Food and Agriculture Organization (FAO) regional office for Africa – in Harare, Zimbabwe, earlier this month to coordinate their response. Sixteen countries agreed on urgent plans to increase the region’s capacity to manage crop pests. “The main objective of the meeting in Harare was basically to strengthen countries’ preparedness,” says Joyce Mulila-Mitti, FAO’s Southern Africa Agriculture Officer. Affected countries are assessing their readiness for other new invasive pests.

Researchers are also launching studies to understand the pest’s behavior in new environments, as well as its susceptibility to insecticides.

Fall worm (Spodoptera frugiperda) It originates from Central and South America. First identified in West Africa in January 2016, it has since spread to 12 countries on the continent, reaching 7 of them in the last 2 months alone.

The pest is the larval form of the fall armyworm, and it has an indiscriminate voracious appetite, feeding on more than 100 different plants, including leafy crops. At least 290,000 hectares of agricultural land in 4 countries have already been destroyed, the meeting in Harare informed. They warn that this is an underestimate and the exact figure is probably much higher.

Fall armyworm is a serious problem in countries where it is endemic. The FAO estimates that Brazil alone spends $600 million annually to control infestations.

Africa has its own species of worm, Spodoptera exempta, which also eats the leaves of corn plants. But the invasive fall armyworm is of particular concern because it also eats the reproductive parts of a plant, eating the corn itself, causing even more crop loss.

African scientists are mobilizing their efforts to study the fall worm as it moves through different regions. “Although the basic biology of the insect remains similar, different environmental conditions and plant ranges confronting the pest can cause the pest to react differently,” says Johnnie van den Berg, from North-West University in Potchefstroom, South Africa. zoologists). .

Van den Berg and two colleagues will lead research into the ecology of the plague in South Africa. This will include studies on the effectiveness and management of fall armyworm on a so-called genetically modified (GM) maize. Bt corn. This transgenic crop is widely grown in the country, and the hope is that it may be more resistant to the pest than conventional corn, as Brazil’s experience has shown. The ecology study will examine the behavior of the fall armyworm in non-maize crops and investigate how it fares across the vastly different climate zones of South Africa.

The researchers will also examine the effectiveness of commercially available insecticides that have had to be introduced in emergencies through an ongoing emergency registration process to control fall armyworm.

“It is likely that the fall armyworm will spread quite rapidly from its current distribution in sub-Saharan Africa,” warns Ken Wilson, an ecologist at Lancaster University in the UK. “From there, it’s just a hop, skip and a jump to the south of Europe.”

As the caterpillar can live on a wide variety of plants, it is likely to persist throughout the year in southern Europe. So it’s “not unreasonable” to expect them to migrate to Eastern Europe and Asia or be transported there through agricultural exports, added Wilson, who will work with the University of Zambia in Lusaka to assess damage caused by the fall armyworm. .

Although no one knows how the insects made their way to Africa, increased trade and climate change are likely to blame, experts say.

The drought associated with the El Niño weather system of 2014-16, followed by the current heavy rainfall associated with the La Niña system, created “perfect conditions” for the worms to appear in Africa, Wilson says.

“With global climate change, we can probably expect more of that increase in temperature and precipitation,” he says. “Additionally, with increased global trade and travel, we can expect greater movement of pests within and between continents.” This could be exacerbated by food shortages that drive large movements of agricultural products.

Mulila-Mitti noted that the FAO has seen an increase in the spread of invasive species, especially in sub-Saharan Africa.

Last year, a team led by ecologist Dean Paini of Australia’s Commonwealth Scientific and Industrial Research Organization in Canberra studied 1,300 invasive species, along with countries’ main crops and international trade routes. studies1 He found that sub-Saharan African countries were the most vulnerable to invasive species.

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Savage, S. African countries mobilize to fight invasive caterpillars.
nature 543, 13–14 (2017). https://doi.org/10.1038/nature.2017.21527

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