Fall army worm in a maize cob. Integrated pest management may stop the rapidly spreading pest. Photo by BBC
Integrated pest management practice is one of the most effective ways of controlling the invasion of the fall army worm (FAW), which is threatening food security in Kenya and Africa.
The pest, which attacks more than 80 plants (food and non food) including maize, cotton, pear sorghum, rice, tomatoes, cucumber, pastures, onions, kales, spinaches, among others, can cause up to 100 per cent loses if uncontrolled.
“Attack on maize at vegetative stage can result in 100 per cent loss if no control is taken. Attack on young maize can totally reduce plant density, warranting re-planting,” reads a joint warning statement from the agricultural government agencies.
Chemical control has not tamed the pest, as it also mutates to counter the effects of this knock-down method. But the use of sexual lures, known as pheromones to separate males from females could help arrest the pest by preventing reproduction.
The deadly worm was first reported in the country in mid March, 2017 in Trans Nzoia, but is has spread to Bungoma, Kakamega, Busia, Nakuru, Baringo, Kericho, Nandi and Uasin Gishu counties within a month.
It spread from Uganda, in about three months after being reported in the coast of Western Africa in September 2016.
The worm has caused damage in Zimbabwe, Zambia, Togo, among other Sub Saharan Africa.
FAW is indigenous to the North and South America.
Although deep ploughing exposes the pests to the sun and predators, mechanical killing also may control multiplication given that one female lays tens of eggs, which hatch within two to seven days.
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Laying of many eggs, short hatching periods, mutations, among other characters, increase the chances of survival of the pest besides colonising new areas.
The worms are green, brown or black, depending on development stage.
Mature worms have distinct white lines between the eyes, forming an inverted ‘Y’ pattern in the face. There are also pronounced black spots aligned in a square near the back end of the caterpillar.
The larvae are the most destructive stages of the pest, drilling holes on leaves, ears of maize and whorls.
Given that the pest has moved from the western to the eastern world, the climatic conditions of the two extremes are diverse and therefore, chemicals may not effectively control it given that it is evolving fast to adopt to the new areas.
A UK firm, Russell IPM, recently reported remarkable success of its IPM products in trials against the pest in Zambia and South Africa, according to African Farming website.
It destroys the maize tassel and kernels.
The pest may soon colonise the Asian continent to become a global menace, and therefore, a threat to food security.