Embu — The most important post-harvest pest in Kenya's dryland areas is the larger grain borer, locally known as 'Osama' in testament to its aggressive destructiveness.
Farmers say it flourishes in high temperatures - a particular problem as climate change brings warming conditions in many parts of the country.
But smallholder farmers in Eastern Kenya and other parts of the country have found a way to combat the pest: metal storage silos that help protect grain from both insects and fungal infections.
At Kiritiri market in Embu County, in semi-arid Eastern Kenya, Benjamin Njue Ngari, a local tinsmith, and his assistants are now busy moulding galvanized metal sheets into airtight cylinders to meet surging demand.
"It has two openings, one on top for filling, and the other one at the bottom for emptying," explains Ngari. "We make them in different sizes to store between one and 20, 90kg bags of grain."
A small silo that can accommodate one bag of grain costs about Sh3000 ($35), while a huge one that can store 1.8 tonnes of grains costs Sh17,000 ($200). The silos can be used for more than one year.
Once filled with grain, a small space is left at the top where a burning candle is placed just before it is finally closed. The candle helps eliminate all the oxygen in the container to suffocate any pests trapped inside, Ngari said.
The storage system eliminates use of chemicals, which have been the most popular method for pest control in many parts of the country.
"I remember a few years ago, when our school lost over two and a half tonnes of maize after Osama's infestation," said Edith Nyaga, the storekeeper at Kamuthatha primary boarding school in Embu. But since the school bought six big metal silos for grain storage two years ago, "we've not had a problem even with the common weevils," she said.
According to Paddy Likhayo, a grain storage expert from the Kenya Agricultural Research Institute (KARI), post-harvest grain pests destroy up to 30 percent of all maize harvested in Kenya, or the equivalent of 162 million tonnes.
That is a problem that needs to be solved, with the United Nations predicting world population will hit 9.1 billion by 2050 and demand for grain surging.
It's also a particular concern for Kenya, where warmer temperatures are causing a spread of some types of pests.
"Osama is a real menace. With the changing climatic conditions we are worried that its infestation may spread to other parts of the country affected by the climate change, since it flourishes in high temperatures," said Likhayo. So far, the pest has already been spotted in Kitale, Kenya's grain basket in Western Kenya.
Heavy infestations of the grain borer can result in complete harvest losses, said Likhayo, who also heads the Effective Grain Storage for Better Livelihoods of African Farmers Project, implemented by the Maize and Wheat Improvement Centre (CIMMYT). The project introduced the metal silo technology in Kenya.
Until the year 2011, when the metal silos were introduced in Kenya, nearly all smallholder farmers stored their grain in sacks or in granaries, where they were susceptible to all kinds of pests including rats and rodents.
In Eastern Kenya, farmers who cannot afford to buy the metal silos have resorted to working in groups to purchase them.
"Through our self help group, we have purchased three metal silos, each with a capacity to store 1.8 tonnes of grain. We usually keep records of the amount of grain stored by each member of the group," said Gibson Wachira, chairman of Gikinyukia Producer Marketing Group in Nyanduro village in Embu.
The group stores maize, sorghum and beans, and tests the moisture content of the grain before sealing it inside the silos, to avoid contamination with aflatoxins, naturally occurring toxins that can grow on grain that has not fully dried.
The aflatoxins contamination affects the liver once in human body, and in many cases the victim dies. In Kenya, such contaminations have been witnessed mainly in the dryland eastern part of the country. The most notable one was in 2004, when 123 residents of Mutomo village in Kitui, Eastern Kenya died after consuming aflatoxins contaminated maize.
"To avoid aflatoxins contamination, we use simple techniques to test the moisture content before storing the grains in the metal silos," said Nephy Kathongo, the head teacher at Kamuthatha primary boarding school.
"We collect samples of the grains to be stored, and put them in a dry transparent bottle containing some common salt. We then shake the mixture. If salt particles stick on the grains or on the bottle wall, then it means that the grains are not fully dry - hence, susceptible to aflatoxin contamination. Such grains must be dried up further before storing," explained the head teacher.
So far, the metal silo grain storage technique has been introduced in Eastern and Western part of Kenya among small scale farmers. Likhayo said his organization now hopes to scale up the project, with experts from Malawi, Zambia and Zimbabwe visiting to learn from Kenya's sites.
"Use of metal silos in Kenya has worked as a good pilot," Likyao said. Now, "we are targeting to introduce the technology in the three countries come the next harvesting season."