Restricted genetic variation in populations of Achatina (Lissachatina) fulica outside of East Africa and the Indian Ocean Islands points to the Indian Ocean Islands as the earliest known common source.

Christopher M. Wade,Fred Naggs,Donald James Colgan,James Rainier M. Garcia,Ian Kendrich C. Fontanilla,Hemant Ghate,Inna Mikaella P. Sta. Maria

doi:10.1371/journal.pone.0105151

Abstract

The Giant African Land Snail, Achatina ( = Lissachatina) fulica Bowdich, 1822, is a tropical crop pest species with a widespread distribution across East Africa, the Indian subcontinent, Southeast Asia, the Pacific, the Caribbean, and North and South America. Its current distribution is attributed primarily to the introduction of the snail to new areas by Man within the last 200 years. This study determined the extent of genetic diversity in global A. fulica populations using the mitochondrial 16S ribosomal RNA gene. A total of 560 individuals were evaluated from 39 global populations obtained from 26 territories. Results reveal 18 distinct A. fulica haplotypes; 14 are found in East Africa and the Indian Ocean islands, but only two haplotypes from the Indian Ocean islands emerged from this region, the C haplotype, now distributed across the tropics, and the D haplotype in Ecuador and Bolivia. Haplotype E from the Philippines, F from New Caledonia and Barbados, O from India and Q from Ecuador are variants of the emergent C haplotype. For the non-native populations, the lack of genetic variation points to founder effects due to the lack of multiple introductions from the native range. Our current data could only point with certainty to the Indian Ocean islands as the earliest known common source of A. fulica across the globe, which necessitates further sampling in East Africa to determine the source populations of the emergent haplotypes.

Highlights

Within the last 200 years, the Giant African Land Snail Achatina ( = Lissachatina) fulica Bowdich, 1822 has spread rapidly across the tropics from its native range in East Africa
Achatina fulica is a serious crop pest causing significant damage to vegetables and other food crops [1,2] and serves as the intermediate host of the rat lungworm Angiostrongylus cantonensis that causes eosinophilic meningitis in humans [3]; the spread of the parasite is affected by the dispersal of its snail host, as seen in the case of A. fulica in the Pacific [4]
Eight haplotypes were found in the two East African countries: Uganda with one haplotype (O) and Tanzania with seven haplotypes (I, J, K, L, M, N, and R, with K being the most numerous at 30%); mean haplotype diversity for the East African populations based on these two countries was 0.797 with a mean nucleotide diversity of 0.012

Summary

Introduction

Within the last 200 years, the Giant African Land Snail Achatina ( = Lissachatina) fulica Bowdich, 1822 has spread rapidly across the tropics from its native range in East Africa. It is found across Africa, the Indian subcontinent, Southeast Asia, the Pacific, the Caribbean, and North and South America. Achatina fulica is a serious crop pest causing significant damage to vegetables and other food crops [1,2] and serves as the intermediate host of the rat lungworm Angiostrongylus cantonensis that causes eosinophilic meningitis in humans [3]; the spread of the parasite is affected by the dispersal of its snail host, as seen in the case of A. fulica in the Pacific [4]. The tendency of people to transport the snails and release them into the wild either intentionally or inadvertently provides available pathways of dispersal that helps to spread them further [6,7]

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