Stepping up the fight against Tuta absoluta in Kenya with safer and sustainable biocontrol products

By Harrison Rware, Ivan Rwomushana, Monica Kansiime

Tomato is one of the key vegetables grown by farmers in Kenya for income. However, production is constrained by numerous factors with insect pests as the most important. Farmers tend to manage tomato pests with pesticide sprays but these have associated risks to the environment, food safety and the health of sprayers.

CABI and Koppert Biologicals Systems in Kenya, with funding from the Netherlands Ministry of Agriculture, Nature and Food Quality (MinLNV), implemented a project to demonstrate the use of biological control options and Integrated Pest Management (IPM) for the management of tomato leaf miner (Tuta absoluta) in Kenya. The IPM regimen employed the use of a predatory mirid Macrolophus pygmaeus (Mirical), the pheromone trap system (Tutasan + Pherodis) and good agricultural practices.

Field demonstrations and associated training formed a major part of creating awareness of these practices of which both farmers and extension workers were trained. The trained extension workers in turn trained additional farmers in their areas of operation. They also raised awareness of the available biological methods for controlling and managing the tomato leaf miner.  

Koppert staff explaining the use and placement of Tutasan for trapping tomato leaf miner at Ngoriba Ward (Credit: CABI).

 
An end-line survey, carried out via telephone interviews with trained farmers, showed that all interviewed farmers displayed knowledge of the various biological control practices for the tomato leaf miner. Notably, 100% of farmers mentioned the use of pheromone traps (Tutasan and delta traps), 98% the sticky traps and 92% use of Trianum for management of soil borne pathogens.

They also mentioned other aspects that are critical to the sustainable management of Tuta absoluta. This including knowing about the good use of chemicals in the control of pests and scouting for pests (60%) and spraying only when the pest population has reached economic injury levels (50%).  

Farmers also pointed out the various benefits that biological controls deliver to them – including reduced pesticide sprays (50%) and reduced expenditure, better yields and less labour input (48%).

Farmers’ reported average expenditure on pesticides and labour was KES39,000 and KES35,957 per acre respectively before the project, compared to KES 23,220 and KES31,087 after the demonstrations and training – a reduction of KES 20,650 (USD 188). Labour for spraying reduced from KES11,649 to KES 6,780 per acre.

A tomato farmer from Juja farm in Kiambu county, gave a testimony after a field demonstration of the Tutasan was conducted at his farm.

The farmer said, “I have been hearing about these products from my farmer friend but I have not made a visit to this farm. I am excited my farm was chosen for farmers to come and practically learn and see how Tutasan is placed and works. I am excited to see that within minutes many of the Tuta pests have been trapped. This is a product that will help me reduce the production costs I incur.

“I usually spray with very expensive chemicals (Tian Radiant which costs ksh4500/= per spray where I spend a total of Kshs 11,000/= for chemical and labour. Normally I spray two times a week for a period of three months).

“But after the training on use of biological control methods, I was given one complete Tutasan package and I added two more at a cost of Kshs 695 each. I mounted this in my one-acre farm and I have seen immediate changes.

“With only three Tutasan traps in my one acre, I have reduced spray frequency to once in two weeks or only when I see presence of pests. This has also greatly reduced the tomato losses and the costs I previously incurred on pesticides and spraying labour.”

Although the use of biological control methods was rated as being very effective (95%) in controlling tomato leaf miner, the adoption of the promoted technologies was challenging for farmers due to limited availability in the local agro-shop stores (50%).

This was in line with the thoughts of an extension officer in charge of Ngoriba ward in Kiambu county, who said, “One of the challenges we have been having as extension agents is accessibility as we promote technologies that are beneficial to farmers.

“As a result, farmers go to alternatives which are mainly synthetic pesticides. Price has been an issue but we are working with the suppliers to supply farmer groups at reduced prices.”

Moreover, Kiambu County Horticultural Crops Officer, noted that farmers’ knowledge and capacity to use the technologies is a critical step in order for them to introduce the technology correctly. He further said that, “IPM does not begin at the middle crop life cycle but rather it should start from the beginning at the nursery level before transplanting.”

He added that a rigorous campaign will enable the wider adoption of safer methods for controlling common pests in agriculture that are also environmentally friendly. He saw farmers in Kalimoni Ward of Kiambu, after training, had coined a slogan of “Starting right and ending right for sustainable tomato farming” to always remind them of pest and disease-free tomato farming

Therefore, wider adoption of IPM practices will require joint efforts by the private sector (manufacturers) of the biological products, agro-dealers located close to farmers to stock these products and extension workers who are the link between the technology proponents and the farmers.