Johannesburg - A new species of armyworm could be disastrous for South Africa’s crops, especially maize, if not urgently contained.
For many South Africans maize is a staple food, accounting for 30 percent to 50 percent of low-income households in Eastern and Southern Africa.
Although an exact identification has not been made, the Department of Agriculture, Forestry and Fisheries said the species was similar in appearance to the fall armyworm.
Extensive damage reported in the country has been mainly to sweetcorn and white maize planted for seed production.
Spokesperson Bomikazi Molapo said once the department completed a full count survey, it would be in a position to determine exactly how many of the sweetcorn and white maize crops have been harmed.
“Damage was reported from all the districts of Limpopo, and in the North West Province between Swartruggens and Mahikeng as well as Lichtenburg,” she said.
Molapo said scientists from the Agricultural Research Council (ARC), together with North West University, had collected samples for identification.
“The insect must complete its life cycle before a positive identification will be made by the ARC Biosystematics Division.
Read also: Pests in SA maize "strongly suspected" to be armyworms
“The life cycle of fall armyworm from egg to adult (moth) is 24 to 40 days, depending on weather and available food. The identification process will commence once the moths have emerged from pupae.”
She said the identification would be verified by a recognised specialist in the taxonomy of the relevant insect group.
Dr Marinda Visser, the manager of the Grain Research and Policy Centre at Grain SA, said that if identified as the fall armyworm, it would be the first time the country has seen it.
“We are working on a worst-case scenario pest management protocol. Any new pest or disease is a concern and if it is identified as the fall armyworm, it’s potentially damaging and not just
to maize.
“Their host range is so wide and it could prove to be a problem to a great deal of crops, vegetables and flowers,” Visser said.
She added that there were also reports of the worm in the Free State in addition to North West and Limpopo.
Asked about the worm’s origin and how it came to South Africa, Visser said they were originally native to South and Central America and also occurred in the southern states of the US.
“What was explained to us is that the fall armyworm, which is a good flier, is carried along with wind currents for big distances. The adults move and when they land, the females lay eggs onto crops,” she said.
Since the pest is so new to Africa, little is known about its long-term effects. It may become a migratory pest similar to the African armyworm and may migrate in large numbers from one area to another, causing extensive damage.
To contain it, the department said that once the identity had been confirmed, an emergency-control strategy would be implemented.
“We want to ensure accurate information is provided to producers regarding the type of pest, pesticide control and on-farm management of the pest.
“The biggest danger is incorrect farm management of the pest which can lead to pesticide resistance and further production losses,” Molapo said.
What the department does know is that the armyworm is resistant to some pyrethroids and emergency registration of agricultural chemicals might be essential to control it.
“This pest becomes more difficult to control as maize plants mature because the caterpillars feed inside the leaf whorl, outside the reach of pesticides,” Molapo said.
The department has called on farmers to be on the lookout for new caterpillars on their maize especially in the leaves and to report them to the department.
The fall armyworm has ravaged crops across Zambia, Zimbabwe and Malawi. It was first detected on the continent a year ago in Nigeria and has since migrated to Central, Western and Southern parts of Africa.
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