Battling Fall Armyworm with nature for food security
Ghana’s agriculture has over the years experienced attacks from new invasive pests.
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The coming in of Fall Armyworm has changed the narrative about invasive pests, primarily due to the “Rambo style” by which the pest invaded and impacted the country’s economy.
It caused nationwide destruction of Ghana’s number one food security crop, maize, thereby creating panic among the populace. Fall Armyworm was officially reported in Ghana in 2016 and during the early years of the invasion, there was uncertainty as to the effective management strategy to adopt.
With the projection of high food security risk associated with the attack, mass application of synthetic insecticides was the surest bet at the time. The government generously supplied free insecticides, mostly synthetic, to all maize farmers to help combat the ravaging pest. Subsequent suppliers gradually increased quantities of biorational insecticides.
Research on armyworm control
Researchers, since the invasion, have been working behind the scenes to develop appropriate integrated management strategies that are user and environmentally friendly. These include push-pull, intercropping, use of natural enemies and microbial agents such as nematodes, fungi etc.
The Fall Armyworm did not come to Ghana alongside its natural enemies that will subdue them, leading to the population explosion witnessed in 2016 to 2018. However, nature always has mechanisms to balance biological skewness. Several insects and other organisms present in our natural landscape have been found killing and destroying the eggs and caterpillars of the fall armyworm.
In exploiting nature to tame nature, researchers have identified some ladybird beetles, ear wigs, ants, flies and wasps that are Fall Armyworm destroyers and are therefore, leveraging on them to suppress the population of the pest.
Among these is a tiny wasp called Telenomus remus, which is very efficient in suppressing fall armyworm population. Telenomus is an egg parasitoid, which means they lay their eggs into the eggs of the fall armyworm.
The Fall Armyworm eggs consequently fail to hatch into the usual destructive fall armyworm caterpillar. The Telenomus rather develops and emerges out of the fall armyworm egg.
Having good numbers of Telenomus in maize field can drastically reduce the Fall Armyworm caterpillar numbers, hence damage to maize. This Telenomus can now be reared for release onto the field as and when needed.
To complement the activity of the parasitoid, native fungi and nematodes that can kill the Fall Armyworm have been isolated. These nematodes and fungi naturally occur in the soil and upon diligent assessment of a number of them has led to the identification of some that are very efficient.
Both laboratory and field trials have proved to be efficacious against the pest. The effectiveness of these bioproducts against the Fall Armyworm is comparable to common synthetic insecticides used countrywide.
New cropping season
A new cropping season is at hand, and Fall Armyworm is lurking around for the new maize. It is therefore, recommended that farmers reduce the application of synthetic insecticides and rather apply biopesticides such as those from fungi, nematodes, bacteria, plants (e.g. neem) etc.
This will boost the proliferation of Telenomus and other natural enemies in the wild, as our researchers try to rear and release more of these parasitoids. Other natural enemies are expected to be identified in the near future.
Our breeders together with donors such as Alliance for a Green Revolution in Africa (AGRA), and Korea-Africa Food and Agriculture Cooperation Initiative (KAFACI) in conjunction with the Plant Protection and Regulatory Directorate (PPRSD) of MoFA are also working around the clock in developing Fall Armyworm tolerant maize varieties.
This is expected to boost the Crops Research Institute’s “using nature to tame nature” agenda against the Fall Armyworm.
The writer is a Senior Research Scientist, Entomologist – CSIR-Crops Research Institute
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