Rice farmers in Mwea could lose up to 60 per cent of their crop if the ongoing infestation by apple snails is not controlled, researchers have warned.
A new assessment shows the snails have infected 11 per cent of the rice paddies in Mwea, but eight in every ten farmers confirm they have spotted them.
Researchers said in other parts of the world, the invasive snails did not initially cause significant damage, but the situation worsened within three years.
“It is therefore essential that effective strategies are implemented to contain the spread of apple snail, especially since, in a relatively short period of time, damage can become significant,” they said in a paper published by the Pest Management Science journal.
“For example, in the Ayeyarwaddy Delta in Myanmar average rice yield losses after two to three years reached 20-44 per cent, despite the fact that initially apple snail did not cause significant damage or yield losses.”
The study was led by research group Cabi, the Ministry of Agriculture, Kirinyaga county government, the National Irrigation Authority Mwea Irrigation Agricultural Development, the Kenya Plant Health Inspectorate Service, Pest Control Products Board, Agrochemicals Association of Kenya, International Centre of Insect Physiology and Ecology (ICIPE), local agro-dealers and millers.
They noted in Mwea paddies where snails have infested more than 20 per cent of the cultivated area, farmers experienced 14 per cent and 60 per cent reductions in rice yield and net rice income, respectively, compared to farmers not yet experiencing apple snail invasion.
“This implies that the negative economic effect of apple snail is substantial when more than 20 per cent of the area cultivated to rice by a household is affected by the pest,” the study says.
Extension agents stated apple snail is one of farmers top five complaints and agro-dealers reported that 70% of complaints on a daily basis were due to apple snail, researchers said.
The invasive freshwater snail was listed in 2000 by the World Conservation Union (IUCN), as among “100 of the World’s Worst Invasive Alien Species”.
In Kenya, around 300,000 small-scale farmers are involved in rice cultivation, with the Mwea Irrigation Scheme in Kirinyaga County accounting for 80-88 per cent of the country’s rice production.
Ministry of Agriculture predicts that rice consumption will reach 1,292,000 tons by 2030. As a result, rice has been identified as a priority value chain in the National Agriculture Investment Plan (NAIP 2018-2028) and National Rice Development Strategy-2 (2019-2030), which aims to transform Kenya's agriculture towards sustainable food and nutrition security and socio-economic development.
Lead author Cate Constantine of Cabi said, “Rice farmers in Mwea face various challenges, including water shortages, rice blast attacks, high input costs, low land productivity, machinery shortages, bird damage, poor infrastructure, and a lack of resilient and acceptable rice varieties.
She added: “The recent introduction of apple snail has added to these challenges, posing a serious threat to rice production in the region and potentially across Africa.”
Fernadis Makale, co-author, added that, in response to the apple snail threat, a Multi-Institutional Technical Team (MITT) drawn from various national and international institutions has been established to lead management efforts and provide consolidated advice to farmers on how to effectively manage the pest.
Makale said, “There is a rapidly narrowing window of opportunity for potential containment, or possibly even eradication, before apple snail becomes widespread in Kenya, and the only feasible option will become management, with its associated high economic, livelihood and environmental costs.”
The scientists argue that in the absence of action to mitigate spread, the consequences could be disastrous, not only for farmers in Mwea but further afield. For example, if the snail spreads into the irrigated rice-production area of Ahero, at the edge of Lake Victoria, rice production in Tanzania and Uganda would be threatened, and from here inevitable further spread would occur.