Huge swathes of maize plantations in Africa are susceptible to destructive fall armyworm (FAW) pests, a new study reveals.

The new study by scientists from the Centre for Agriculture and Bioscience International (CABI), the University of Minnesota’s GEMS Informatics Centre, Global Advisor and Plant Health, highlighted how almost the entire African maize crop is grown in areas with climates that support seasonal infestations of the pest.

Published in the journal Frontiers in Insect Science, the scientists said they were wary that while Integrated Pest Management (IPM) practices constitute another, often complementary, strategy for controlling crop pests especially in tropical regions where natural enemies can have year-round survivability, IPM is not widely adopted in the developing world.

Geo spatial tagging

“Over 95 percent of the African maize area deemed climate suitable for FAW pests, can also support year-round survival of at least three or more pests. The spatial concurrence of climatically suitable locations for these pests raises the production risk for farmers well above the ones posed from FAW alone,” said Dr Senait Senay, lead author from the University of Minnesota.

Their multi-peril pest assessments showed that the maize grown in Africa is also especially vulnerable to infestations from a host of other crop pests.

“Starkly, over half (52.5 percent) of the African maize area deemed suitable for fall armyworm is also at risk from a further nine pests, while over a third (38.1 percent) of the area is susceptible to an additional 10 pests,” they added.

“This constitutes an exceptionally risky production environment for African maize producers, with substantive and complex implications for developing and implementing crop breeding, biological, chemical and other crop management strategies to help mitigate these multi-peril risks.” noted Professor Phil Pardey, co-lead author of the study.

The study assembled 3,175 geo-tagged occurrences of the fall armyworm worldwide and use that data in conjunction with information about the physiological requirements of the pest to spatially assess its global climate suitability.

Invasive Alien Species

First observed in Nigerian maize fields in January 2016, outbreaks of FAW spread to Benin, Togo and São Tome and Principe and have since spread to more than 40 African countries including Ethiopia, Kenya and Tanzania.

The paper highlights Africa’s climatic hospitability for both maize production and fall armyworm infestations. Half the world’s maize area, mostly in the moist and warm tropical locales, is also likely to sustain the development of the pest year-round, with the exception of South Africa, the leading producer of maize on the continent (and Lesotho). Africa is favourable climatically for FAW.

The study, which is part of a broader GEMS informatics effort concerning Global Pest Risk Analytics, concludes by suggesting that crop management may benefit more from genetic solutions and environmentally friendly biological control agents.

Pest risk assessments

Dr Day suggested that climates that favour maize production were also seasonably suitable for FAW infestations – not just in Africa. Indeed, around half of the world’s maize area, mostly in the moist and warm tropical locales, is also likely to sustain the development of fall armyworm year-round.

“Strategies to deal with FAW, or any other crop pest are best conceived and executed from a multi-peril pest perspective – especially as part of an Integrated Pest Management practice – rather than a piece-meal, pest-by-pest approach.”

These, they said, required less frequent and timely trips to markets to secure necessary insecticides as seasonal pest infestations unfolded. However, they also admitted that while Integrated Pest Management (IPM) practices constituted another, often complementary, strategy for controlling crop pests – especially in tropical regions where natural enemies can have year-round survivability, IPM was not widely adopted in the developing world.

“A multi-peril pest risk approach can be used to both benchmark future multi-peril pest risk assessments – under prospective changes in climate – while also informing current and nearer-term strategies to target market and government resources. This can be done in ways with the most beneficial effect in mitigating the complex of crop pests that pose the most risk for crops in particular locales,” Dr Senay added.