Scientists discover invasive snail that’s damaging Mwea rice farms

Scientists have discovered the presence of a highly invasive apple snail that is wreaking havoc in rice production and the livelihoods of farmers in Mwea.

Widely considered to be one of the most invasive invertebrates of waterways and irrigation systems, the apple snail was discovered in the expansive Mwea irrigation scheme where 70 per cent of Kenya’s rice is grown, raising a new threat to agriculture and the environment.

The research, which was published in the Centre for Agriculture and Biosciences International (CABI) journal, CABI Agriculture and Bioscience on March 25, confirmed that apple snail, scientifically known as Pomacea canaliculata, is now in Kenya.

The scientists, including lead author and senior molecular microbiologist at CABI, Dr Alan Buddie, published their findings under the title, First report of the invasive apple snail, Pomacea canaliculata in Kenya.

The discovery was made in collaboration with the Kenya Plant Health Inspectorate Service (KEPHIS) scientists.

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The findings came following numerous reports of an invasive snail causing crop damage in Mwea rice farms where samples of snails and associated egg masses were collected and forwarded to CABI laboratories in the UK for molecular identification.

DNA barcoding analyses confirmed the identity of the snails as Pomacea canaliculata, a pest that is indigenous to the Americas.

“Molecular tools provide an invaluable aid to species-level identifications within groups of organisms that look almost identical to non-specialists. In the present case, taxonomic experts in this group of invertebrates are rare. We demonstrated that, as long as we can obtain a small amount of DNA from a snail (or even a single egg), we can obtain the same level of identification if such experts have deposited authenticated sequences in public access sequence databases,” said Dr Buddie.

Apple snailis listed among ‘100 of the world’s worst invasive species.’

Its introduction and spread in South East Asia was thought to be largely due to intentional but it has turned into a serious agricultural and ecological pest, causing significant economic losses in wetland rice cultivation and threatening biodiversity.

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Dr Ivan Rwomushana, senior scientist, invasive species management, CABI, said: “We collected samples of the snail for barcoding. Following confirmation of the new species, we completed a delimiting survey to establish the extent of snails’ spread. Our findings show that other schemes are still unaffected, although seed and machinery brought from Mwea poses a risk for invasion. We will work with the relevant national agencies to develop a rapid response and containment strategy for this new invasive species.”

Given the impact of this species in Asia, there is need for an assessment of the risk to Africa, and the roll out of an appropriate response in Kenya and elsewhere to manage this new threat to agriculture and the environment.

Prof. Theophilus Mutui, Managing Director of Kephis, said, “since its first point of detection in Mwea, apple snail has spread gradually to other areas. Strict quarantine measures should be instituted and implemented to curb not just the spread of the snail but entry into other rice producing risk areas in the country. To achieve this, area wide management should be exercised such as training and awareness creation, installation of physical barriers, mechanical control, and community-based snail management.”

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