Dispersal and evolution of the invasive snail Pomacea canaliculata, an intermediate host of Angiostrongylus cantonensis: A field study around its initial introduction site in South China

¹ Pearl River Fisheries Research Institute, Chinese Academy of Fishery Sciences, 510380 Guangzhou, China
² College of Fisheries and Life Science, Shanghai Ocean University, 201306 Shanghai, China

^* Corresponding author: ld@prfri.ac.cn

Abstract

Eosinophilic meningitis caused by Angiostrongylus cantonensis is an emerging infectious disease in mainland China due to the invasive apple snail species serving as the primary source of infection. However, knowledge regarding the snail’s natural distribution, population structure and phenotypic characteristics is limited. To better understand the parasite vector Pomacea canaliculata, a large-scale field survey was conducted around its initial introduction site in South China. We assessed 564 sampling sites and measured 10,145 snails with shell heights exceeding 1.5 cm. The average population density was 20.31 ± 11.55 snails/m². Morphological analysis indicated an average body mass of 8.93 ± 3.95 g, a shell height of 3.38 ± 0.66 cm, a sex ratio of 2.39 ± 1.01 females to males, and a shell color ratio of 9.34 ± 7.52 brown to yellow. Notably, body mass was significantly correlated with shell height (r = 0.88, p < 0.01) and shell color (r = 0.55, p < 0.05). Spatial correlation analysis revealed that shell height was the only factor significantly spatially autocorrelated (MI = 0.27, z = 2.20, p = 0.03), with weak autocorrelations observed in body mass and shell color. The geographic variations in phenotypic traits suggest a human-mediated evolutionary process in snail populations and highlight the complexity of the parasite transmission system. These findings may enhance the assessment of the epidemiological health risks associated with angiostrongyliasis and inform strategies for controlling infectious snails.