Taking on Fall Armyworm in Africa: The search for effective natural enemies

The Fall Armyworm (FAW), Spodoptera frugiperda has emerged as a serious threat to food security for millions of smallholder producers in Africa due to its rapid spread across the continent and extensive damage to staple cereals. At the last count, at least 28 countries were reported to be affected by the pest in Africa.

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Ghana and Zambia have not been spared by the insect’s invasion: recent research conducted by CABI (CABI evidence note 2017) shows that up to 112,000 hectares of farmlands are reported to have been invaded by FAW in Ghana, and could impact the country by as much as $163 million in 2017 as a result. Similarly in Zambia, FAW has ravaged more than 172 000 ha of maize. These are startling numbers that call for an immediate and concerted effort to thwart the impact FAW is causing to the farmer.

CABI’s Action on Invasives Programme with support from DFID (UK) and DGIS (Netherlands) aims to protect and improve the livelihoods of 50 million poor rural households that are impacted by the worst invasive species, including FAW. One of its key foci, amongst others, is to develop feasible and sustainable biological control strategies. CABI is working effectively with continental and regional partners to explore and integrate the use of biological control agents like parasitoids, predators and possibly viruses and fungi to manage FAW over the long term. At the onset, the programme is firstly seeking to understand which indigenous natural enemies of FAW are present in Ghana and Zambia, how effective they are at controlling the pest, and how affected they are by widespread chemical pesticide strategies utilised over the last year to control FAW.

In Zambia, the survey for natural enemies took CABI scientist Ivan Rwomushana to the Central and Southern Province covering Choma, Mazabuka, Pembe, Monze, Chibombo, Kafue and Chisamba. At this time, maize was in its mid growth stages (between V3 and V7), and largely infested with various life stages of FAW. The majority of farmers witnessed the damage on their maize, but were not aware it was FAW. “I first saw these caterpillars feeding on my maize last year, and they have returned this year. I used to harvest 20 bags of maize from my farm, but last year with the pest damage I harvested only 14 bags” says Jennifer Mubanga, an elderly farmer at Mazabuka. “What is the future of shima (a meal made from maize flour), the main staple for many Zambians” she laments? Several maize growers have chosen the pesticide option as the only way to deal with the voracious FAW. Agricultural officials at Pemba district have been distributing Chlorpyrifos to growers, which is not known as the most appropriate for this pest, to spray against the worm.

Indeed, following the invasion of FAW, the natural reaction in Ghana and Zambia was chemical control through national free mass spraying exercises. However, frequent re-infestation has been observed in affected crops suggesting that the pesticides used might be ineffective, the timing of their applications in the field may not be optimal, or that the pest may already be resistant to the chemicals.

Large commercial farmers are also being affected by FAW. During the natural enemy surveys in Ghana, I visited a commercial farm in Akuse district. At any one time, the farm has 40 acres of baby corn at different maturity stages, a good recipe for continuous multiplication and re-infestation by FAW. All stages of the pest, from egg masses, to mature caterpillars and moths were visible in different blocks on the same farm during the survey. The CABI approach of integrating biological control with other more eco-friendly control options was well received, although the sentiments are that the solution is needed immediately. The management of the farm decried the impact FAW has had on baby corn exports to Europe. “We as commercial producers and exporters of baby corn to Europe have experienced FAW first hand and truly appreciate the impact of the problem. We have increased the frequency of pesticide sprays to deal with the fall armyworm, but we also recognise we have to comply with Maximum Residue Levels. We are quite keen on the proposed CABI strategy and how best it can be integrated within our chemical strategy”.

The Fall Armyworm looks poised to cause significant yield losses in Ghana and Zambia if not well managed or in the absence of effective natural biological control during this cropping season. CABI is supporting a systems approach for an integrated pest management strategy that focuses on empowering cereal growers on early diagnosis of FAW for timely application of environmentally safe available options. Crucial among these will be the promotion of biological control with natural enemies.

Ivan Rwomushana is a Senior Scientist, Invasive Species Management at CABI Africa

2 thoughts on “Taking on Fall Armyworm in Africa: The search for effective natural enemies

  1. tuhirirwe tereza January 15, 2018 / 5:36 am

    thank you CABI

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