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Background: The area of Oncomelania hupensis snail remains around 3.6 billion m 2 , with newly emerging and reemergent habitats continuing to appear in recent years. This study aimed to explore the long-term dynamics of snail density before and after the operation of Three Gorges Dam (TGD)., Methods: Data of snail survey between 1990 and 2019 were collected from electronic databases and national schistosomiasis surveillance. Meta-analysis was conducted to estimate the snail density. Joinpoint model was used to identify the changing trend and inflection point. Inverse distance weighted interpolation (IDW) was used to determine the spatial distribution of recent snail density., Results: A total of 3777 snail survey sites with a precise location of village or beach were identified. For the downstream area, snail density peaked in 1998 (1.635/0.11 m 2 , 95% CI: 1.220, 2.189) and fluctuated at a relatively high level before 2003, then declined steadily from 2003 to 2012. Snail density maintained lower than 0.150/0.11 m 2 between 2012 and 2019. Joinpoint model identified the inflection of 2003, and a significant decreasing trend from 2003 to 2012 with an annual percentage change (APC) being - 20.56% (95% CI: - 24.15, - 16.80). For the upstream area, snail density peaked in 2005 (0.760/0.11 m 2 , 95% CI: 0.479, 1.207) and was generally greater than 0.300/0.11 m 2 before 2005. Snail density was generally lower than 0.150/0.11 m 2 after 2011. Snail density showed a significant decreasing trend from 1990 to 2019 with an APC being - 6.05% (95% CI: - 7.97, - 7.09), and no inflection was identified. IDW showed the areas with a high snail density existed in Poyang Lake, Dongting Lake, Jianghan Plain, and the Anhui branch of the Yangtze River between 2015 and 2019., Conclusions: Snail density exhibited a fluctuating downward trend in the Yangtze River basin. In the downstream area, the operation of TGD accelerated the decline of snail density during the first decade period, then snail density fluctuated at a relatively low level. There still exists local areas with a high snail density. Long-term control and monitoring of snails need to be insisted on and strengthened., (© 2023. The Author(s).)

Oncomelania hupensis plays a significant role in the transmission of schistosomiasis japonica, which remains a major public health concern in China. Understanding the biological characteristics of O. hupensis is a prerequisite for its control; however, there are currently no studies investigating the intestinal microbiota of the O. hupensis snail. This study aimed to profile the intestinal microbiome of O. hupensis across different ecological landscapes in mainland China. DNA was extracted from the intestines of the collected snails and the bacterial communities were detected using 454 pyrosequencing. A total of 3,799 operational taxonomic units (OTUs) were obtained, and Proteobacteria, Firmicutes, and Actinobacteria were identified as the dominant bacterial taxa at the phylum level. Bacillus and Lactococcus were the most common genera in samples obtained from the four ecological landscapes. Snail specimens were clustered into three clades according to microbial community diversity, and thirty-seven genera that contributed to differential microbiota distributions were identified. Co-occurrence network analysis indicated a symbiotic relationship for the intestinal microbiota of O. hupensis, and PICRUSt analysis predicted forty-one metabolic functions in all snail samples, including membrane transport, amino acid metabolism, carbohydrate metabolism, replication and repair, energy metabolism, as well as xenobiotics biodegradation and metabolism. These findings improve our understanding of bacterial ecology in the O. hupensis intestine; further studies will focus on the relationship between O. hupensis intestinal microbiota and the microbiota in their specific ecological environments., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Background: Achatina fulica, the giant African snail, is the largest terrestrial mollusk species. Owing to its voracious appetite, wide environmental adaptability, high growth rate, and reproductive capacity, it has become an invasive species across the world, mainly in Southeast Asia, Japan, the western Pacific islands, and China. This pest can damage agricultural crops and is an intermediate host of many parasites that can threaten human health. However, genomic information of A. fulica remains limited, hindering genetic and genomic studies for invasion control and management of the species., Findings: Using a k-mer-based method, we estimated the A. fulica genome size to be 2.12 Gb, with a high repeat content up to 71%. Roughly 101.6 Gb genomic long-read data of A. fulica were generated from the Pacific Biosciences sequencing platform and assembled to produce a first A. fulica genome of 1.85 Gb with a contig N50 length of 726 kb. Using contact information from the Hi-C sequencing data, we successfully anchored 99.32% contig sequences into 31 chromosomes, leading to the final contig and scaffold N50 length of 721 kb and 59.6 Mb, respectively. The continuity, completeness, and accuracy were evaluated by genome comparison with other mollusk genomes, BUSCO assessment, and genomic read mapping. A total of 23,726 protein-coding genes were predicted from the assembled genome, among which 96.34% of the genes were functionally annotated. The phylogenetic analysis using whole-genome protein-coding genes revealed that A. fulica separated from a common ancestor with Biomphalaria glabrata ∼182 million years ago., Conclusion: To our knowledge, the A. fulica genome is the first terrestrial mollusk genome published to date. The chromosome sequence of A. fulica will provide the research community with a valuable resource for population genetics and environmental adaptation studies for the species, as well as investigations of the chromosome-level of evolution within mollusks., (© The Author(s) 2019. Published by Oxford University Press.)

Schistosomiasis japonica caused by Schistosoma japonicum infection is recognized as a considerable economic and public health concern in Asia. Oncomelania hupensis is the sole intermediate host of S. japonicum. The only molluscicide recommended by World Health Organization (WHO) since 1960s is relative toxic to other aquatic species. In this article, we evaluated the novel molluscicide PPU07 in field trials on their efficiency against O. hupensis and toxicity for local fish. 25% PPU07 sulfate WP exhibited similar molluscicidal effect at 2.0 g/m 2 and 2.0 g/m 3 in the spraying and immersion trials with the WHO recommended molluscicide niclosamide (1 g/m 2 and 1 g/m 3 ). The mortality rates reached 95% and 96%, respectively. Moreover, little toxicity was observed for local fish and other aquatic organisms at the effective molluscicidal concentrations. In all, 25% PPU07 sulfate WP is a promising molluscicide for snail control, particularly in semi-commercial or commercial aquaculture ponds., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Oncomelania hupensis is the unique intermediate host of Schistosoma japonicum, which plays a key role during the transmission of schistosomiasis. It is mainly found in the Yangtze River valley and mountains or hills in southwest China. In this paper, we described 15 new microsatellite makers in O. hupensis. Polymorphism of each locus was assessed in 80 individuals from four wild populations (n = 20 per population). The number of alleles per locus ranged from 6 to 29, with an average of 15.8. The observed (H(O)) and expected (H(E)) heterozygosities varied from 0.397 to 0.851 and from 0.696 to 0.948, respectively. These microsatellite markers will be useful for population genetic studies and genome mapping in O. hupensis.

Background: Identifying and eliminating snail habitats is the key measure for schistosomiasis control, critical for the nationwide strategy of eliminating schistosomiasis in China. Here, our aim was to construct a new analytical framework to predict high-risk snail habitats based on a large sample field survey for Oncomelania hupensis, providing guidance for schistosomiasis control and prevention. Methodology/Principal findings: Ten ecological models were constructed based on the occurrence data of Oncomelania hupensis and a range of variables in the Poyang Lake region of China, including four presence-only models (Maximum Entropy Models, Genetic Algorithm for rule-set Production, Bioclim and Domain) and six presence-absence models (Generalized Linear Models, Multivariate Adaptive Regression Splines, Flexible Discriminant Analysis, as well as machine algorithmic models–Random Forest, Classification Tree Analysis, Generalized Boosted Model), to predict high-risk snail habitats. Based on overall predictive performance, we found Presence-absence models outperformed the presence-only models and the models based on machine learning algorithms of classification trees showed the highest accuracy. The highest risk was located in the watershed of the River Fu in Yugan County, as well as the watershed of the River Gan and the River Xiu in Xingzi County, covering an area of 52.3 km2. The other high-risk areas for both snail habitats and schistosomiasis were mainly concentrated at the confluence of Poyang Lake and its five main tributaries. Conclusions/Significance: This study developed a new distribution map of snail habitats in the Poyang Lake region, and demonstrated the critical role of ecological models in risk assessment to directing local field investigation of Oncomelania hupensis. Moreover, this study could also contribute to the development of effective strategies to prevent further spread of schistosomiasis from endemic areas to non-endemic areas. [ABSTRACT FROM AUTHOR]

[Display omitted] • Comparative proteomics explored the molluscicidial mechanism of PBQ against P. canaliculata. • A total of 245 DEPs were identified in snails following the exposure of PBQ. • DEPs were enriched in the ribosome, translation process and purine biosynthesis pathway. Angiostrongylus cantonensis is a zoonotic parasitic nematode that is the most common cause of human eosinophilic meningitis. The invasive apple snail Pomacea canaliculata is an important intermediate host of A. cantonensis and contributes to its spread. P. canaliculata control will help prevent its invasion and transmission of A. cantonensis. The new molluscicide PBQ (1-(4-chlorophenyl)-3-(pyridin-3-yl)urea) exhibits great potency against P. canaliculata and has low toxicity against mammals and non-target aquatic organisms. We studied the mode of action of PBQ using TMT-based comparative quantitative proteomics analysis between PBQ-treated and control P. canaliculata snails. A total of 3151 proteins were identified, and 245 of these proteins were significantly differentially expressed with 135 downregulated and 110 upregulated. GO and KEGG enrichment analyses identified GO terms and KEGG pathways involved in de novo purine biosynthesis, ribosome components and translation process were significantly enriched and downregulated. The results indicated that PBQ treatment had substantial effects on the synthesis of genetic material, translation process, and protein synthesis of P. canaliculata and were likely the main cause of snail mortality. [ABSTRACT FROM AUTHOR]