Zambia is among other countries in the SADC region and the world at large that is vulnerable to a number of hazards both natural and man-made. The frequency and severity of extreme hazards such as pest invasions, droughts, environmental degradation and floods have posed serious implications for natural systems and farming systems as well as crop or plant growing season. Among other hazards, pest invasion has proved to have a profound effect on natural systems and economic sectors especially agriculture and livestock.
In the last 5-years, every year the country has been recording cases of armyworm invasions living many farmers in distress. Armyworms in Zambia are best known as pest that causes extensive damage in maize fields.
Literature indicates that armyworms get their name from their behavior of moving across fields in an army-like fashion. As larvae consume available food sources, they migrate as an army to new host plants. But then, there are a number of species of armyworm caterpillars, many with a distinct taste for a particular plant or vegetable. But some will eat anything green or red or yellow. And they’re most active at night and hide in plants and under garden debris during the day.
The armyworms that have invaded Zambia are velvety black back; greenish yellow underside and pale stripes down side. The armyworm moths normally grow approximately an inch long with a 1½ inch wingspan. Eggs, which resemble small white globules, are laid in rows or groups on leaves of host plants. After oviposition, the moth rolls the leaf blade of the plant around each egg mass.
Scientific reports indicate that during the day, moths remain hidden in grassy vegetation. Armyworm moths are active during the evening, feeding on nectar, mating, and searching for oviposition sites. Eggs are deposited in rows or clusters on the lower leaves of grasses or at the base of plants. Eggs hatch in 1 to 2 weeks. Newly hatched larvae move in a looping motion. Larvae are also active at night, feeding on host plants. During the day, they can be found under plant debris or in the top few inches of the soil.
Research suggests that since moths prefer dense vegetation for oviposition sites, armyworm infestations generally develop in areas such as grass pastures, roadsides, and along fence rows. Oviposition sites often include weeds and grassy in weedy or reduced tillage fields. Consequently, these fields’ armyworms are often a problem in these fields. If a herbicide is used to control the weeds, larvae move from the dead grasses to the corn. As larvae run out of available food sources, they move to other host plants such as small grains and corn.
Armyworms consume leaf tissue of corns. Feeding is usually confined to leaf margins, but in some instances, larvae may strip the plants entirely of leaf tissue. Corn generally recovers from damage caused by moderate infestations if the growing point has not been injured.
Ordinarily armyworms that attack young corn migrate from small grains or grass fields. Armyworm larvae chew the leaves of small grains and grasses. They may strip the leaf margins and move up the plant to feed on the panicles or flowers.
This year, among other places that have recently and so far been invaded with armyworms include Ndola, Kitwe, Mpongwe, and Chililabombwe districts on the Copperbelt province.
Copperbelt province Agriculture Coordinator Dr. Obvious Kabinda confirms that so far (December this year) four districts in the province have been attacked.
Dr. Kabinda explains that in Ndola, the estimated area that has so far been planted with maize is about 2000 and that the crop condition has been good owing to the favorable conditions for crop growth.
He, however, notes that the crop has been affected with suspected maize stalk borer in seven camps where 1, 920 farmers are affected with an estimated area of 965 hectares affected.
In Kitwe the pest has already caused 20 to 50 per cecnt damage in the fields attacked so far and that the affected camps include Mwekera, Mufuchani, Kamfinsa, and Luongo.
Dr. Kabinda further says in Mpongwe district, a farm located in Chowa camp in Lukanga block about 25km from Mpongwe has been invaded by suspected army worms.
He says the affected field is about 10 hectares and the area damaged is 0.5hectares where the pest attacked the maize crop from leaves ending with the stalk.
In 2014, Mumbwa district in Central province also recorded army worms which attacked maize fields in most parts of the district. The pest was put under control though most farmers had to replant the crop to cover up on the damaged areas.
Farmers have been more alert this season and hence they knew which pesticide to use to fight the destructive pests. A check in Kantupu, Kamisamba and Nachibwe areas which were badly affected showed a good crop stand.
In 2013, armyworms had invaded maize fields in Chipata District in Kalichelo and Munukwa agricultural camps of Chiparamba and Chitandika blocks respectively. In Munukwa camp 2 farmers had their maize fields affected, where a total of 2 hectares were under attack from the worm which caused damage of about 10 percent to the crop, while 9 farmers were affected in Kalichelo camp where about 20 hectares of maize was under attack.
In a similar development, moths believed to be for army worms which are feared to cause havoc to crop production were detected in Chibombo district. The moths were detected by the Ministry of Agriculture and Livestock (MAL) in Chiyuni Agriculture Camp in the district.
Confirming the development, Chibombo District Agricultural Coordinator Ms. Etambuyu Anamela confirmed that samples wre sent to Mount Makulu for determination. She urged farmers not to panic as the MAL was well prepared to handle army worm infestation if confirmed. She further appealed to farmers to report any suspicious worms in their fields.
And about 197,000 hectares of maize and 155,000 farming families had been affected in Southern province. Three farm blocks in Nyimba District, for example, were said to have lost 80 per cent of their crops due to army worms. “The situation was very serious. It affected most of the traditional maize-growing areas," explained Zambia National Farmers' Union's (ZNFU) Colliard Hamusimbi to Voice of America. "A majority of the farmers who were affected are small-scale farmers who produce more than 90 percent of the national maize crop."
Hamusimbi added that while army worm outbreaks were rare in Zambia, the unusually high temperatures in November may have created a conducive environment.
To detect army worms and other pest outbreaks that could lead to food shortages in the future, the ZNFU urged the Government to invest more in research, pest surveillance and extension services.
In 2012, the then Agriculture Minister Eustarkio Kazonga noted that armyworms in Zambia were threatening food security by reducing crop yields.
“Armyworms are attacking crops, causing major damage to maize, cassava, sorghum and rice. In Kabwe, the capital of the Central Province where the first cases were reported, armyworms have already been reported to have destroyed 6500 hectares of maize crop. Despite measures to prevent the spread, cases of armyworms have today been confirmed in 5 of the country’s 10 provinces,” according to plantwise blog.
The challenge that most farmers are faced with is detection of the armyworms in their fields. They often learn about the invasion when the damage has already been caused. A research conducted by Michigan State University indicates that several flies attack armyworm larvae therefore; they act as indicators of armyworms presence if they suddenly terrorize a particular field. Doug Johnson, Extension Entomologist of the University of Kentucky also suggests that in an event of the outbreak, treatment recommendations of armyworms could be based on scouting. Scouting is used to determine if armyworms are present (identify hot spots) and to evaluate the need for control before they cause economic damage. An easily detectable sign of armyworms is the presence of flocks of birds feeding on corn plants. As with other pests, timing is important. If invasions are detected too late, the damage may already have been done.
However, the risk of potential armyworms invasions can be minimized by control or elimination of grassy weeds from fields. Not only will moth egg laying activity be reduced, but so will the migration of larvae into the field. Watch for movement of armyworms from grass or weedy areas to field borders. If armyworms move into fields and infest crop areas, and insecticide treatment may be necessary.
In response to this hazard, Government through the Ministry of Agriculture on a yearly basis remind farmers to take precautions as the pest is unpredictable and could outbreak anytime when the environment is conducive but the reminder hasn’t been so effective that most of the farmers don’t understand how damaging this hazard can be.
Government also strives to help farmers to spray their fields in an effort to contain the armyworms. Insecticides are distributed, and Ministry of Agriculture technicians are sent out to help spray the crops.
There have been calls from the Zambia National Farmers Union (ZNFU) for more investment into the research and early warning systems in order to prevent severe outbreaks in the future. The ZNFU, alongside the National Agriculture and Information Services, have also been sensitizing farmers about the outbreak.
However, farmers and other concerned stakeholders with capacity to manage the armyworms outbreak at their fields at should consider buying the insecticides themselves while they wait for government intervention.
The armyworms can be controlled. As such, any farmer who spots armyworms in their field should immediately report to either the office of the District Agricultural Coordinator (DACO) at district level or direct to Ministry of Agriculture provincial offices.
Against the above background, armyworms often go unnoticed in fields until damage is severe. Larvae feed primarily at night and may cause damage before being detected. Therefore, strengthening control and preparedness capacities to manage armyworm outbreaks in Zambia is needed before a disaster is declared.
About the Author
Winston Muleba Junior is a Digital Journalist, Scientist, Researcher, Writer and Disaster Management Practitioner who uses media and ICT to promote environmental conservation; science, technology and innovation. He gravitates towards environment, water, aquaculture and agriculture as he is skilled at juxtaposing the latest research and expert opinion with the everyday lives and struggles of people on the ground.
Email: mwenyamuleba@gmail.com
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