This work investigated the relationship of host size, seasons, and water quality parameters with the prevalence and intensity of Cornudiscoides agarwali on Mystus bleekeri collected from the Dikrong River in Arunachal Pradesh, India from February 2016 to January 2017. A total of 2760 specimens of C. agarwali were recovered from 114 individuals of M. bleekeri. The levels of mean intensity, but not the prevalence, of infection of C. agarwali were positively correlated with fish host size, peaking in the largest size class (45.20 ± 5.69 parasites/fish). The prevalence values had a statistically significant seasonal trend, reaching highest (100 %) during the pre-monsoon season, followed by 91.8% during the post-monsoon period and 87.5 % during the monsoon season. The levels of mean intensity of infection were also dependent on the seasons, reaching significantly higher levels during the pre-monsoon season (42.75 ± 4.18 parasites/fish). All water quality parameters measured were within the safety value recommended for freshwater aquaculture. Cornudiscoides agarwali maintained its prevalence above 87.5 % throughout the annual cycle, which means it was able to reproduce year-round in a non-polluted river. This could be an indication of monogenoidean community and population dynamics thriving best under optimum water quality parameters. Also, this article draws the attention of parasitologists and ichthyologists to a taxonomic problem of the misidentification of Mystus spp., and therefore, possibly of their parasitic monogenoids.
Climatic and ecological factors can influence the parasite load of a host. Variation in rainfall, body size, and sex of the hosts may be related to the abundance of parasites. This study investigated the helminth fauna associated with a population of Norops brasiliensis, together with the effect of host biology (sex, body size, and mass) and variation in rainfall regime on the abundance of helminths. Species of three groups of endoparasites were found (Nematoda, Cestoda, and Trematoda), with nematodes as the most representative taxa with eight species, prevalence of 63.2 %, mean intensity of 4.0 ± 0.58 (1 – 25), and mean abundance of 2.66 ± 0.44 (0 – 25). Nine helminth species are new host records for N. brasiliensis. The nematode Rhabdias sp. had the highest prevalence (53.3 %). There was no significant relationship between abundance of the trematode Mesocoelium monas and host sex or season, although the abundance of this parasite increased significantly with host body size and mass, while abundance of nematodes was related to season and host mass. This study increases the knowledge about the diversity of helminth fauna associated with N. brasiliensis, revealing infection levels of hosts from northeastern Brazil.
In this paper, seasonal samples of wild versus cultured groupers, Epinephelus spp., from Daya Bay, South China Sea were examined to survey the seasonality of two important species, Pseudorhabdosynochus coioidesis and P. serrani (Monogenea: Diplectanidae), and to analyze the interspecific relationships between these two parasites. Between April 2008 and January 2009, P. coioidesis and P. serrani were found to be parasitic only on E. coioides Hamilton during summer and winter in the natural waters of Daya Bay, exhibiting a high degree of host specificity, whereas they co-occurred and persisted on several species of hosts, such as E. coioides, E. bruneus Block and E. awoara Temminck & Schlegel, in an experimental polyculture pond during several seasons. E. coioides is the main host for both of these two monogenean species. The overall prevalences and mean intensities of these two parasites on polycultured Epinephelus spp. showed the same pattern of seasonal fluctuations, with the maximum values during autumn, except for the overall prevalence of P. serrani, which reached its maximum values during summer and winter and the minimum values during spring and autumn. Prevalence and mean intensity were found to be related to host size. In the wild, medium-sized fishes harboured higher infections, whereas under cultured conditions the small-sized and large-sized fishes were more heavily infected. Simultaneous infections of P. coioidesis and P. serrani were common, and there was a significant positive interspecific correlation between these two parasites.
& Duncan, 1997 ). Statistics for each season of Q. Kobinensis includes variance-mean ratio S 2 /X , parameter of negative binomial distribution K , average degree of congestion M *, and diffusivity index I∮ . T-test was used to detect the significance of different hostsize classes in the infecting effect of Q. kobinensis on the hosts. All statistical analyses were executed using SPSS 17.0 (SPSS Inc., Chicago, Illinois) at a significance level of 0.05.
Seasonal variations in populations of Q. Kobinensis
A total of 6041 specimens of Q
Shahid Mehmood, Kamran Sohail, Muhammad Qasim, Shupeng Xu, Haiyang Geng, Muhammad Usman and Zelle Huma
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