Apple snails

New research published today by scientists at CABI and the Kenya Plant Health Inspectorate Service (KEPHIS) confirms that the apple snail (Pomacea canaliculata) has been discovered in Kenya for the first time. Widely considered to be one of the most invasive invertebrates of waterways and irrigation systems, the apple snail threatens Kenya’s rice production and raises the question, how much damage will it cause in Kenya and will it spread further?

The scientists, including lead author and Microbiology Research Leader at CABI, Dr Alan Buddie, published their findings under the title, First report of the invasive apple snail, Pomacea canaliculata in Kenya in the CABI journal, CABI Agriculture and Bioscience. The paper was also posted as a preprint to agriRxiv in December 2020.

The discovery came following reports of an invasive snail causing crop damage in the expansive Mwea irrigation scheme in Kenya, where samples of snails and associated egg masses were collected and sent to CABI laboratories in the UK for molecular identification. DNA barcoding analyses using the cytochrome oxidase subunit I gene, supplemented by elongation factor 1-alpha sequencing, confirmed the identity of the snails as Pomacea canaliculata, a pest indigenous to the Americas.

This timely identification shows the benefit of molecular identification when combined with a reliable database such as that provided by the Barcoding of Life Data system. CABI found that the egg masses tested gave an identical barcode sequence to the adult snails, allowing identifications to be made more rapidly.

Apple snail egg masses

Apple snail egg masses (Credit: CABI).

Pomacea canaliculata is 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 introduction and it has become a serious agricultural and ecological pest, causing significant economic losses in wetland rice cultivation and threatening biodiversity.

Quickly assessing and addressing the potential invasive species threat is essential. Farmers in Kenya are already talking about the damage caused to rice in Mwea, where over 70% of the country’s rice is grown.

Given the impact of this species in Asia, there is need for an assessment of the risk to Africa, and the implementation 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, areawide management should be exercised such as training and awareness creation, installation of physical barriers, mechanical control, and community-based snail management.”

Dr Alan Buddie, lead author and Senior Molecular Microbiologist at CABI, said, “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.”

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.”


Additional information

Main image: Apple snail (Credit: CABI).

Funding acknowledgement

Funding acknowledgement

The research was financially supported by the Foreign, Commonwealth and Development Office (FCDO), UK, and the Directorate‐General for International Cooperation (DGIS), Netherlands, through CABI’s Action on Invasives programme. CABI is an international intergovernmental organisation and we gratefully acknowledge the core financial support from our member countries and lead agencies, including the United Kingdom (Department for International Development), China (Chinese Ministry of Agriculture), Australia (Australian Centre for International Agricultural Research), Canada (Agriculture and Agri-Food Canada), the Netherlands (Directorate-General for International Cooperation), and Switzerland (Swiss Agency for Development and Cooperation). For details see: who-we-work-with/key-donors/

Full paper reference

Buddie, A.G., Rwomushana. I., Offord, L.C., Kibet, S., Makale, F., Djeddour, D., Cafa, G., Vincent, K.K., Muvea, A.M., Chacha, D. and Day, R.K. (2021). First report of the invasive snail Pomacea canaliculata in Kenya. CABI Agriculture and Bioscience. DOI: 10.1186/s43170-021-00032-z

This paper is available to view open access here:

Find more information about the apple snail on the Apple Snail Portal in the Invasive Species Compendium

Find more information about CABI’s work on invasive species at Action on Invasives