Scientists mull using biological agents to fight fall armyworm

Thursday August 17 2017

Agriculture officials in Kenya’s Trans Nzoia County at the launch of the fall armyworm management campaign on May 9. PHOTO FILE | NMG


Scientists are looking into the possibility of using biological agents to fight the fall armyworm, which ravaged crops especially maize in many parts of East Africa last season.

The thinking is driven by conclusions that the worm and its rapid spread might have been as a result of climate change.

“The National Agricultural Research Organisation plans to explore and integrate the use of bio-control agents like parasitoids, predators and possibly viruses and bacteria both local and exotic to manage the fall armyworm,” said Charlotte B. Kemigyisha, the principal public relations officer of the Uganda-based research agency.

“This will be in addition to exploring the use of pheromone and light traps as part of an integrated approach.”

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In countries like Honduras, Brazil, Barbados and Venezuela in South America, both egg and larval parasitoids have been used to manage the fall armyworm in maize, sorghum and vegetables.


One particular egg parasitoid, Telenomus remus, has been credited with reducing the worms’ populations wherever it has been introduced.

Currently, Uganda’s Ministry of Agriculture is evaluating the extent of the damage caused by the worms’ invasion to the first season’s crop. The worms mainly attacked maize, sorghum, sugarcane and elephant grass, but could spread to other crops if not controlled.

Dr Michael Otim, the head of cereal research at the National Crop Resources Research Institute Namulonge advised farmers to continue using dudufenos, rocket and striga and any insecticide that contains the profenofos compound.

The fall armyworm causes serious leaf feeding damage.

While armyworms can damage plants in nearly all stages of development, it will concentrate on later plantings that have not yet silked according to experts.

It can be controlled effectively when the larvae are small. Early detection and proper timing of an insecticide application are therefore critical, they add.

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The fall armyworm however seems to have established base requiring a different approach as there are no known chemicals that have been developed specifically to kill them.

“NARO will be collaborating with countries that have a long history of managing the fall armyworm to introduce maize germplasm for breeding for resistance in addition to the pesticides that will continue to play a major role in the management of the worm,” said Ms Kemigisha.

The armyworms feed during the day and night, but are usually most active in the morning or late afternoon. If presents in damaging numbers in the field, they must be controlled while the larvae are still small experts said.

Scientists advise that control measures be considered when egg masses are present on five per cent of the plants or when 25 per cent of the plants show damage symptoms and larvae are still present. Controlling larger larvae is difficult because they are hidden under excrement.

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