STRATEGY ▶▶▶
Combatting the fall armyworm in Africa with wasps
In Africa, the invasive fall armyworm (FAW) is becoming a serious concern and has devastating consequences for maize crops, which the region relies on for food and animal feed. A natural enemy may assist in managing this crop-destroying pest.
F
AW targets maize, primarily, and in Africa, the cultivation of maize represents one of the most important sources of food security, income gener- ation and employment for over 300 million people.
The recent invasion of fall armyworm has led to losses of 8-20 million tonnes of maize across the continent. This has significant and far-reaching consequences for both human food and animal feed. Although broad-spectrum chemical insecticides are used to try to manage the invasion of the FAW, in Ethiopia and Kenya more than 50% of maize grow- ers reported that they only provide marginal control or are ineffective.
Maize-legume intercropping, biopesticides and wasps Since the first detection of the FAW in East Africa, the Inter- national Centre of Insect Physiology and Ecology (ICIPE) joined forces with national and international partners to re- search and better understand the ecology of the pest in Af- rica, and to work toward the development of sustainable management strategies. Maize-legume intercropping and biopesticides have proven to be key, but another initiative was born – the release of thousands of indigenous natural enemies (also known as farmers’ friends), namely wasps, in Kenya. “Though fall armyworm is an alien invasive pest, our re- search has unravelled significant information on widely dis- tributed native parasitoid species in Africa – namely Teleno- mus remus, Trichogramma chilonis and Cotesia icipe – and
their ability to successfully parasitise and kill the invasive pest,” says Dr Samira Mohamed, senior scientist at ICIPE. The approach taken by the team focused on evaluating the im- pact of these native parasitoids on various life stages of the fall armyworm to identify the most effective one. Toward the end of 2020, ICIPE, together with partners in Kenya, embarked on mass production and release of these parasitoids in fall armyworm hotspots along with other eco-friendly management technologies. So far, over 140,000 wasps each of Telenomus remus and Trichogramma chilonis that parasitise fall armyworm eggs; and 5,000 wasps of Cotesia icipe that parasitise the early larval stages of the fall armyworm, have been released in five counties in Kenya with very encouraging results. “Beyond Kenya, our future plans are to expand the parasitoid release to other Eastern African countries,” says Dr Sevgan Subramanian, principal scientist at ICIPE.
Reducing the FAW population The initial post-release field assessments revealed that the parasitism rates of the fall armyworm in the field increased by 55%, 50% and 38%, for Trichogramma chilonis, Telenomus remus and Cotesia icipe, respectively. “The released parasi- toids work synergistically to bring down the population of the fall armyworm by attacking different developmental stages of the pest (eggs and larvae). However, for these par- asitoids to be able to effectively contribute to suppressing the pest, they need to be conserved by minimising the ap- plication of broad-spectrum chemical insecticides,” added Dr Mohamed. “Effective conservation and augmentation of these natural enemies is critical for the success of biological control of the FAW in Africa. However, the current widely practised FAW control methods based on the use of synthet- ic pesticides, are detrimental to the conservation of indigenous natural enemies,” says Subramanian, adding, “Hence, conservation of natural enemies requires both maize farmers and agricultural policy makers to be aware of, promote and adopt sustainable FAW management strategies.”
▶ ALL ABOUT FEED | Volume 29, No. 4, 2021 11
Fall armyworm larva feeding on maize tassel ears.
PHOTO: SUBRAMANIAN SEVGAN
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36
