Sum of fears among intraguild predators drives the survival of green sea turtle ( Chelonia mydas ) eggs

Ecologists have long theorized that apex predators stabilize trophic systems by exerting a net protective effect on the basal resource of a food web. Although experimental and observational studies have borne this out, it is not always clear what behavioural mechanisms among the trophically connected species are responsible for this stability. Fear of intraguild predation is commonly identified as one such mechanism in models and mesocosm studies, but empirical evidence in natural systems remains limited, as the complexity of many trophic systems renders detailed behavioural studies of species interactions challenging. Here, we combine long-term field observations of a trophic system in nature with experimental behavioural studies of how all the species in this system interact, in both pairs and groups. The results demonstrate how an abundant, sessile and palatable prey item (sea turtle eggs, Chelonia mydas ) survives when faced by three potential predators that all readily eat eggs: an apex predator (the stink ratsnake, Elaphe carinata ) and two mesopredators (the brown rat, Rattus norvegicus , and kukri snake, Oligodon formosanus ). Our results detail how fear of intraguild predation, conspecific cannibalism, habitat structure and territorial behaviour among these species interact in a complex fashion that results in high egg survival.

Prevalence and molecular characterization of Spirometra erinaceieuropaei spargana in snakes in Hunan Province, China

Sparganosis is an important foodborne parasitic zoonosis; however, few reports on the prevalence of snake-infecting plerocercoids from Hunan province in China are available. Therefore, we investigated the prevalence of spargana infection in wild snakes from this region in 2018, and identified an astonishing prevalence rate of 91.7% (344/375). Spargana parasites were found in 99.1% of Zaocys dhumnades, 94.1% of Elaphe carinata and 86.7% of Elaphe taeniura. Parasites exhibited various distributions: 50% were located in muscular tissue, 32.1% in subcutaneous tissue and 17.9% in the coelomic cavity. To identify the specific status of spargana collected from wild snakes, partial mitochondrial cytochrome c oxidase subunit 1 (cox1) gene sequences were amplified, sequenced and analysed. Sequence variations for cox1 among all the examined plerocercoids ranged between 0.0 and 2.9%, with 21 variable sites identified (4.71%, 21/446). Phylogenetic analyses identified that all plerocercoids isolated from Hunan province were Spirometra erinaceieuropaei. This is the first report of S. erinaceieuropaei infection in snakes in Hunan province. The risks and harms of sparganosis should be publicized, and illegal wildlife trade should be controlled.

Genetic Analysis of Avian Gyrovirus 2 Variant-Related Gyrovirus Detected in Farmed King Ratsnake (Elaphe carinata): The First Report from China

Avian gyrovirus 2 (AGV2), which is similar to chicken infectious anemia virus, is a new member of the genus Gyrovirus. AGV2 has been detected not only in chicken but also in human tissues and feces. This study analyzed 91 samples (8 from liver tissue and 83 from fecal samples) collected from king ratsnakes (Elaphe carinata) from 7 separate farms in Hubei and Henan, China, for AGV2 DNA using PCR. The results demonstrated a low positive rate of AGV2 (6.59%, 6/91) in the snakes, and all the positive samples were collected from the same farm. The AGV2 strain HB2018S1 was sequenced, and its 2376 nt genome comprised three partially overlapping open reading frames: VP1, VP2, and VP3. Phylogenetic analysis revealed that the HB2018S1 and NX1506-1 strains from chickens in China belong to the same clade and that they have a nucleotide identity as high as 99.5%. Additionally, recombination analysis showed that HB2018S1 might originate from the recombination of viruses similar to those detected in chickens and a ferret. A total of 10 amino acid mutation sites (44(R/K), 74(T/A), 256 (C/R), 279(L/Q), and 373(V/A) in AGV2 VP1; 60(I/T), 125(T/I), 213(D/N), and 215(L/S) in AGV2 VP2; and 83(H/Y) in AGV2 VP3) different from those observed in most reference strains were found in the genome of HB2018S1, indicating that the differences may be related to a transboundary movement among hosts, which needs further elucidation. To the best of our knowledge, this study is the first report on an AGV2-infected poikilotherm, suggesting that cross-host transmission of viruses with circular single-stranded DNA genomes would be a public health concern.

Emergence and Genetic Analysis of Avian Gyrovirus 2 Variants-RelatedGyrovirusin Farmed King-ratsnakes (Elaphe carinata): the First Report in China

ABSTRACTAvian gyrovirus 2 (AGV2), which is similar to chicken infectious anemia virus, is a new member of theCircovirusgenus. AGV2 has been detected not only in chicken but also in human tissues and feces. In this study, a total of 91 samples (8 liver tissues and 83 faecal samples) collected from king-ratsnakes (Elaphe carinata) at 7 separate farms in Hubei and Henan, China, were analyzed to detect AGV2 DNA via specific PCR. The results indicated a low positive rate of AGV2 (6.59%, 6/91) in the studied animals, and all of the positive samples were from the same farm. The AGV2 strain HB2018S1 was sequenced, and the genome with a total length of 2376 nt contained three partially overlapping open reading frames: VP1, VP2, and VP3. Phylogenetic tree analysis revealed that the HB2018S1, NX1506-1 strain from chickens in China belong to the same clade, with nucleotide homology as high as 99.5%. In total, 10 amino acid mutation sites, including 44R/K, 74T/A, 256 C/R, 279L/Q, and 373V/A in AGV2 VP1; 60I/T, 125T/I, 213D/N, and 215L/S in AGV2 VP2; and 83H/Y in AGV2 VP3, were found in the genome of HB2018S1 that were different from those observed in most reference strains, suggesting that the differences are related to an transboundary movement among hosts which needs to be further elucidated.IMPORTANCERecently, AGV2 has been detected in live poultry markets and human blood in mainland China. Previous findings indicated future studies should investigate the large geographic distribution of AGV2 and monitor the variants, the host range, and the associated diseases. To the best of our knowledge, this study is the first report on AGV2 infected poikilotherm, suggested that cross-host transmission of viruses with circular single-stranded DNA genomes would be a public health concern.

Comparative analysis and characterization of the gut microbiota of four farmed snakes from southern China

Background The gut microbiota plays an important role in host immunity and metabolic homeostasis. Although analyses of gut microbiotas have been used to assess host health and foster disease prevention and treatment, no comparative comprehensive study, assessing gut microbiotas among several species of farmed snake, is yet available. In this study, we characterized and compared the gut microbiotas of four species of farmed snakes (Naja atra, Ptyas mucosa, Elaphe carinata, and Deinagkistrodon acutus) using high-throughput sequencing of the 16S rDNA gene in southern China and tested whether there was a relationship between gut microbiotal composition and host species. Results A total of 629 operational taxonomic units across 22 samples were detected. The five most abundant phyla were Bacteroidetes, Proteobacteria, Firmicutes, Fusobacteria, and Actinobacteria, while the five most abundant genera were Bacteroides, Cetobacterium, Clostridium, Plesiomonas, and Paeniclostridium. This was the first report of the dominance of Fusobacteria and Cetobacterium in the snake gut. Our phylogenetic analysis recovered a relatively close relationship between Fusobacteria and Bacteroidetes. Alpha diversity analysis indicated that species richness and diversity were highest in the gut microbiota of D. acutus and lowest in that of E. carinata. Significant differences in alpha diversity were detected among the four farmed snake species. The gut microbiotas of conspecifics were more similar to each other than to those of heterospecifics. Conclusion This study provides the first comparative study of gut microbiotas among several species of farmed snakes, and provides valuable data for the management of farmed snakes. In farmed snakes, host species affected the species composition and diversity of the gut microbiota.

Comparative analysis and characterization of the gut microbiota of four farmed snakes from southern China

Background. The gut microbiota plays an important role in host immunity and metabolichomeostasis. Although analyses of gut microbiotas have been used to assess host health,as well as for disease prevention and treatment, no comparative study of gut microbiotasamong several species of farmed snake is yet available. In this study we characterized andcompared the gut microbiotas of four species of farmed snakes (Naja atra, Ptyas mucosus,Elaphe carinata, and Deinagkistrodon acutus) using high-throughput sequencing of the16S rDNA gene in southern China and tested whether there was a relationship betweengut microbiotal composition and host species. Results. A total of 629 operationaltaxonomic units (OTUs) across 22 samples were detected. The dominant bacterial phylawere Bacteroidetes, Proteobacteria, Firmicutes, and Fusobacteria; the dominant bacterialgenera were Bacteroides and Cetobacterium. This was the first report of the dominance ofFusobacteria and Cetobacterium in the snake gut. Our phylogenetic analysis recovered arelatively close relationship between Fusobacteria and Bacteroidetes. Alpha diversityanalysis indicated that species richness and diversity were highest in the gut microbiota ofD. acutus and lowest in that of E. carinata. Significant differences in alpha diversity weredetected among the four farmed snake species. The gut microbiotas of conspecifics weremore similar to each other than to those of heterospecifics. Conclusion. This studyprovides the first comparative study of gut microbiotas among several species of farmedsnakes, and provides valuable data for the management of farmed snakes. In farmedsnakes, host species affected the species composition and diversity of the gut microbiota.

Comparative analysis and characterization of the gut microbiota of four farmed snakes from southern China

Background. The gut microbiota plays an important role in host immunity and metabolichomeostasis. Although analyses of gut microbiotas have been used to assess host health,as well as for disease prevention and treatment, no comparative study of gut microbiotasamong several species of farmed snake is yet available. In this study we characterized andcompared the gut microbiotas of four species of farmed snakes (Naja atra, Ptyas mucosus,Elaphe carinata, and Deinagkistrodon acutus) using high-throughput sequencing of the16S rDNA gene in southern China and tested whether there was a relationship betweengut microbiotal composition and host species. Results. A total of 629 operationaltaxonomic units (OTUs) across 22 samples were detected. The dominant bacterial phylawere Bacteroidetes, Proteobacteria, Firmicutes, and Fusobacteria; the dominant bacterialgenera were Bacteroides and Cetobacterium. This was the first report of the dominance ofFusobacteria and Cetobacterium in the snake gut. Our phylogenetic analysis recovered arelatively close relationship between Fusobacteria and Bacteroidetes. Alpha diversityanalysis indicated that species richness and diversity were highest in the gut microbiota ofD. acutus and lowest in that of E. carinata. Significant differences in alpha diversity weredetected among the four farmed snake species. The gut microbiotas of conspecifics weremore similar to each other than to those of heterospecifics. Conclusion. This studyprovides the first comparative study of gut microbiotas among several species of farmedsnakes, and provides valuable data for the management of farmed snakes. In farmedsnakes, host species affected the species composition and diversity of the gut microbiota.

The occurrence of the strongylid nematodes Kalicephalus brachycephalus, K. bungari and K. indicus in snake species from Hunan Province, China

Kalicephalus is a genus of strongylid nematodes infecting snakes and causing serious diseases and even death when it is complicated with secondary bacterial infections. The infection of snakes with Kalicephalus has been reported in many countries in the world. However, little information is available on the prevalence of Kalicephalus in snakes in China. In the present study, the prevalence of Kalicephalus in snakes was investigated. The worms were examined, counted and identified to species according to existing keys and descriptions. Three species of Kalicephalus, namely K. indicus, K. bungari and K. brachycephalus, were found in six species of snakes (Elaphe carinata, Zaocys dhumnade, Naja najaatra, Elaphe taeniura, Bungarus multicinctus and Dinodon rufozonatum). The total prevalence of Kalicephalus in snakes in Hunan Province was 39.7%. The most common species was K. indicus, with the highest prevalence 72.8%, followed by K. bungari (24.0%). The prevalence of K. brachycephalus was 0.9%. This is the first report on the prevalence of Kalicephalus species in snakes in China, and the findings have important implications for the control of Kalicephalus infections in snakes in China.