Species identification of Achatina and investigation of its infection with Angiostrongylus cantonensis in Hainan province
Objective To investigate the species diversity of Achatina and the infections of Angiostrongylus cantonensis in Hainan province by field investigation and laboratory analysis.Methods A total of 1 060 samples were collected from 53 sampling sites in 18 cities and counties in Hainan province from 2022-2023,and the samples were preliminarily identified according to their morphological characteristics.DNA extraction and COI gene amplification were performed in some samples with different morphological characteristics,and the species was identified by sequence alignment in GenBank database.The phylogenetic tree was constructed using Mega 11 software.At the same time,lung examination and digestion methods were used to investigate the infection of A.cantonensis,and the influencing factors were analyzed.Results Among the 1 060 samples,two species of Achatina were identified in Hainan province by morphological and molecular identification,with Achatina fulica accounting for 70.57％(748/1 060)and A.panthera accounting for 29.43％(312/1 060).Morphological differentiation was mainly based on the color of callosal region.The sequence identity of COI gene was 99.84％-100.00％in the samples belonging to the same clade as A.fulica.The COI gene identity was 90.75％-95.97％between the unidentified species samples and A.panthera.The average genetic distances between the two species and the closest related species were 0-0.003 and 0.043-0.102,respectively.The overall A.cantonensis infection rate was 5.85％in Achatina sp.in Hainan province.The prevalence of A.cantonensis infection was 5.08％(38/748)in A.fulica and 7.69％(24/312)in A.panthera,and the difference was not statistically significant(x2=2.728,P＞0.05).The median infection intensity of the two groups were 107.70 bars/g and 37.32 bars/g,respectively,and the difference was statistically significant(Z=2.067,P＜0.05).The highest infection rates of all snails were found in Chengmai(20.63％,13/63),Ledong(16.67％,12/72)and Haikou(11.11％,4/36).The highest infection rates of A.fulica were found in Chengmai(25.00％,9/36),Ledong(16.36％,9/55)and Lingshui(16.00％,4/25).The A.panthera were found in Ledong(17.65％,3/17),Haikou city(16.67％,3/18)and Wanning city(14.81％,4/27).There were significant differences in the prevalence of Achatina sp.and A.fulica(x2=68.33,37.16;all P＜0.05),but no significant differences in A.panthera among cities and counties(x2=3.578,P＞0.05).Conclusions The existence of unknown species was highly suspected to be Achatina panthera,which provided relevant research basis for the biodiversity of invasive species in the island.The infection rate of A.cantonensis in the sample did not decrease,but the infection rate varied greatly among regions,and the control measures should be tailored to local conditions.
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