News and knowhow for farmers

Scientist grows virus inside pest’s body taming its spread

A scientist has invented a biological pest control virus against the voracious African bollworm that attacks over 25 crop species, by growing the virus inside the body of the pest which assists the virus to multiply.

The virus loaded pests are then crushed and mixed with water to produce an end product biological pesticide dubbed HELITEC which is then packaged into various quantities ready for use.

“We had to develop a solution that is biological and at the same time lethal to the pest. By doing that we considered two factors; the resistance nature of the pest and the fact that many farmers have in many occasions been unable to access the international markets due to using hard pesticides thereby leaving their produce with high residue levels,” explained Joyce Njoroge a Technical consultant at Kenya Biologics limited.

The African bollworm is a pest of major importance in most areas where it occurs mainly due to its ability damage a wide variety of food, fibre, oilseed, fodder and horticultural crops. It is a major pest due to its high mobility, its ability to feed on many species of plants, its high reproductive rate, and its capacity to develop resistance to pesticides.

“This is a virus that is lethal to the pest and just like HIV virus to humans, the pest cannot resist it and as result it was the best bet to unleash to these voracious pests that have developed resistance to the other hard chemicals in the market. The virus is only specific to the bollworm alone and therefore cannot endanger any other animal species” explained Njoroge.

To produce the virus in plenty, Kenya Biologics team rear the bollworm and infect them with the inoculants containing the virus at a particular growth stage. When you infect the virus in the pest it multiplies into thousands in the host’s body. One litre of the solution retails at Sh5000 and is able to spray about two hectares. The ratio for mixing with water depends on crop in question and infestation rate although a litre can be mixed with 1000 litres of water. There is also a 25ml package retailing at Sh135 mainly designed for small holder farmers.

When HELITEC is sprayed on a crop, ABW caterpillars ingest virus particles and become infected. The virus replicates within the insect body causing death of the caterpillar. The flaccid caterpillar will spontaneously rupture, releasing millions of virus particles into the environment ready for ingestion by other caterpillars.

The solution is already making a kill for most commercial wheat, French beans, canolla and flower farmers in the country. Njoroge advised that a farmer keen on keeping the bollworms at bay should conduct regular scouting in his farm and introduce the solution immediately he/she notices any eggs or lavae of the pest in order to prevent any economic loss resulting from the pests. “Caterpillars of the African bollworm feed on leaves, buds, growing points, flowers and fruit. Leaf damage reduces leaf area, which can slow plant growth. Feeding on flowers and fruit causes the main damage. Flower feeding can prevent fruit formation,” noted Njoroge.

The severity of the damage varies between crops, regions and locations, and between seasons. The holes caused by the caterpillars serve as entry points for secondary infection by diseases causing fruit decay. One Carterpillar can damage several fruits/pods.

Crop losses at farm level in Kenya has been estimated at over 50percent on cotton and pigeon pea, over 20percent on sorghum and millet, and over 2 million stems on cut flowers. In addition, Njoroge noted that the African bollworm is a quarantine pest. “This is important for export crops. If a caterpillar of this pest is detected in a consignment of an export commodity like flowers, vegetables among other crops being shipped to Europe, the whole consignment is rejected which can amount to millions of shillings being lost.”

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