Molecular and Morphological Characterizations of the Fish Parasitic Isopod Mothocya parvostis (Crustacea: Cymothoidae) Parasitizing Optional Intermediate Hosts: Juveniles of the Cobaltcap Silverside Hypoatherina tsurugae and Yellowfin Seabream Acanthopagrus latus

Mothocya parvostis (Isopoda: Cymothoidae) is a parasitic crustacean that infests the opercular cavities of fishes. Its main final host is the Japanese halfbeak, Hyporhamphus sajori. However, M. parvostis also infests the black sea bream, Acanthopagrus schelgelii, as an optional intermediate host. Understanding the use of optional intermediate hosts is important for understanding the life history of Cymothoidae, and further information should be obtained. In this study, we aim to investigate the life cycle of M. parvostis. We collected and examined 20 mancae and 144 juveniles of M. parvostis from 129 cobaltcap silversides, Hypoatherina tsurugae, and 494 yellowfin seabreams, Acanthopagrus latus. Molecular analysis of the cytochrome c oxidase subunit I gene and 16S rRNA genes revealed that cymothoid mancae and juveniles from the two fish species were identified to be M. parvostis. All M. parvostis on H. tsurugae and A. latus might be mancae or juveniles, with no adult parasites; thus, H. tsurugae and A. latus juveniles were optional intermediate hosts of M. parvostis. In the results of morphological description, M. parvostis juveniles infesting the final host H. sajori lacked swimming setae, while juveniles parasitizing the two optional intermediate hosts had them. Mothocya parvostis mancae infested juveniles of both species just after metamorphosis, grew with the host. As the fish grows further, the parasite detached from the fish. The parasitic status of M. parvostis in the three optional intermediate hosts indicated that M. parvostis likely reproduced from June to December, and different optional intermediate hosts were used depending on the time of year in Hiroshima Bay. Therefore, a parasitic strategy involving optional intermediate hosts might increase the infestation success of M. parvostis to H. sajori.

Wheat as a new host for potato aphid Macrosiphum euphorbiae Thomas (Hemiptera: Aphididae) and construction of its age-stage two-sex life tables

Wheat (Triticum aestivum L.) is the major global staple food crop that meets the food security demands of various nations across the continents. The recent reduction in wheat production is attributed to several biotic and abiotic factors especially, temperature and rainfall patterns, and pest occurrence. Among insect pests, aphid species are emerging as new pests of economic importance in India and elsewhere. The present investigation identified a new association of Macrosiphum euphorbiae Thomas with the wheat crop. Life table parameters were studied for M. euphorbiae and Rhopalosiphum padi fed on wheat foliage. The total nymphal duration and life cycle duration, respectively, of R. padi (4.76 ± 0.54 and 9.71 ± 1.38 days) and M. euphorbiae (5.84 ± 0.69 and 9.96 ± 1.31 days) were significantly different for these species. The fecundity of the two aphid species was 23.95 ± 8.67 and 11.6 ± 4.10 progeny/female, respectively. Age-specific survival rate (lx), age-specific fecundity (fx), and population age-specific fecundity (mx) were higher in R. Padi compared to M. euphorbiae. Reproductive value (Vxj) was high in R. padi and the duration of reproduction was less, while these parameters showed an opposite trend in M. euphorbiae. The gross reproduction rate (GRR) was found higher in R. Padi (29.17 offspring/adult lifetime) compared to M. euphorbiae (19.58 offspring/adult lifetime). The M. euphorbiae being a pest of solanaceous crops seems to have shifted to a new host, i.e., wheat. This new adaptation strategy to survive for long periods on a wheat crop might pose a serious threat to wheat crop cultivation in near future.

First report on the diversity and distribution of parasitic monogenoids (Platyhelminthes) from catfishes (Siluriformes) in Arunachal Pradesh, India

Monogenoidea (Platyhelminthes), one of the largest groups of ectoparasitic metazoans worldwide, comprises over 7000 nominal species distributed globally, many of which may represent a serious threat to their fish hosts in aquaculture conditions. The fish fauna of Arunachal Pradesh, India-a global hotspot of biodiversity-is reasonably well-documented, with at least 213 known species (including 69 Siluriformes). These faunas are an essential resource for this tribal state's economy. In sharp contrast, information on parasitic monogenoids of fish from the region is extremely limited, with only nine species described to date. In this study, 21 species of catfishes were collected and examined with the aim of expanding the current knowledge of the diversity and distribution of monogenoid species from Arunachal Pradesh. 15 (62.5%) of the 21 catfish species studied were infected with a total of 25 monogenoid species (11 previously described and 14 newly discovered in this study). Ten species of catfish were the first host records for new parasite species, while two species of catfish were new host records for previously known monogenoids. Arunachal Pradesh represents new geographic locality records for all 11 previously described parasite species, thus significantly expanding their distribution area from North and South India to extreme Northeast India. The patterns of parasite species richness in relation to three ecological traits (fish habitat, body size, and elevation) as well as host specificity across the 21 examined species of catfishes, the unique problem of too many parasite species in Wallago attu, and the future of parasitology in Arunachal Pradesh, India are discussed.

Occurrence of Kudoa prunusi and K. lateolabracis (Myxozoa: Myxosporea: Multivalvulida) in Philippine-Sea Japanese parrotfish (Calotomus japonicus)

Multiple Kudoa spp. (Myxozoa: Myxosporea: Multivalvulida) have been recorded in Japanese parrotfish (Calotomus japonicus) from the Philippine Sea (Northwest Pacific Ocean), off southwestern Japan; Kudoa yasunagai in the brain, and K. igami, K. lateolabracis, and K. thalassomi in the muscles. This study examined eight Philippine Sea Japanese parrotfish samples collected in January and February 2019 and found K. prunusi in the brain (3-57 plasmodia/fish; average 17.9) and K. lateolabracis plasmodia in the trunk muscle of all fish individuals examined. The K. prunusi in this study was characterized by myxospores predominatetly with six shell valves (SVs) and a corresponding number of polar capsules (PCs), contrasting with the original description of the species from farmed Pacific bluefin tuna (Thunnus orientalis) brain that characterized the species as having predominately five SVs/PCs. Molecular-genetic characterization of 18S and 28S ribosomal RNA genes and mitochondrial DNA genes (cytochrome c oxidase subunit 1 and small and large ribosomal RNA subunits) clearly differentiated the K. prunusi isolate from K. yasunagai, commonly characterized by six or seven, but rarely five, SVs/PCs myxospores. The Japanese parrotfish is a new host record for K. prunusi and speculated to be an important reservoir host in its natural waters. Kudoa lateolabracis myxospores isolated from pseudocysts in the myofiber were morphologically and phylogenetically close to a clade of the Kudoa spp. that exhibit cruciform myxospores similar to K. thyrsites. This study is the first to sequence a mitochondrial DNA of small and large subunit ribosomal RNA of K. lateolabracis.

First record of Gongylonema nepalensis in domestic and wild ruminants in Europe

The gullet worm, Gongylonema pulchrum, is cosmopolitan in distribution, infecting a variety of mammals including domestic and wild ruminants. Gongylonema nepalensis recently collected from the esophageal epithelium of water buffaloes in Nepal was separated from G. pulchrum based on its distinctly shorter left spicule relative to body length and unique nucleotide sequences of the ribosomal RNA gene (rDNA) and the mitochondrial cytochrome c oxidase subunit 1 gene (cox-1). During meat inspections at four abattoirs on Sardinia Island, Italy, 25 Gongylonema worms were collected from one each individual of cattle (n=8), sheep (n=7), goats (n=4), and mouflon (Ovis aries musimon; n=6), and characterized morphologically and genetically. Intriguingly, all of the collected worms from these ruminants were G. nepalensis, exhibiting comparable body lengths to G. pulchrum in cattle from other regions but with significantly shorter left spicules like G. nepalensis (less than 20.9% of the entire body length in contrast to 21.8-65.6%, the reported proportion of G. pulchrum). Furthermore, the rDNA nucleotide sequences of these worms from different ruminant species on Sardinia Island were almost identical to each other and to Nepalese G. nepalensis isolates. With the exception of one worm from a sheep (displaying a single nucleotide substitution), the 369-bp cox-1 nucleotide sequences of all the Sardinian G. nepalensis isolates from the different host sources were absolutely identical, forming a clade with Nepalese G. nepalensis isolates and not G. pulchrum isolates. The present study reveals that G. nepalensis is not a local parasite in the Indian subcontinent (Nepal), but instead has a certain geographical distribution in Europe and takes several ruminant species as a definitive host.

New potential host for Ryukyua globosa (Crustacea, Isopoda, Cymothoidae) from Parangipettai, Southeast coast of India

In the present study Ryukyua globosa parasitic isopod on the marine fishes of the Parangipettai coast are reported. R. globosa was found attached in the gill chamber of Sardinella gibbosa. The attachment position of Ryukyua species differs from that of other member of this genus. Until now, R. globosa was only reported on Amblygaster sirm and A.leiogaster. S.gibbosa is a new host record for R.globosa. R. globosa, branchial parasites, already known from Japan and is now recorded from the Southeast coast of India.

Two Nerocila species parasitizing Pomadasys maculatus from Nagapattinam, Southeast coast of India

Two species of Cymothoidae (Nerocila loveni and Nerocila sundaica) were collected on the host fish Pomadasys maculatus from the Nagapattinam coast. Pomadasys maculatus is a new host for these parasitic isopods not previously recorded in the world. Nerocila loveni was mainly attached on the caudal peduncle of the fish and N. sundaica was collected from the pectoral fin and the body of the host. For N. loveni and N. sundaica, the prevalence reached 28.70 and 26.08 % respectively. One parasite was collected per host fish.

First report of Filaria martis Gmelin, 1790 in the European mink, Mustela lutreola (Linnaeus, 1761)

The riparian European mink (Mustela lutreola), currently surviving in only three unconnected sites in Europe, is now listed as a critically endangered species according to the IUCN. Habitat loss and degradation, anthropic mortality, interaction with the feral American mink (Neovison vison), and infectious diseases are among the principal causes of its decline. Surveys of helminth parasites of this host that also include focus on subcutaneous potentially pathogenic helminths such as those belonging to the genus Filaria are very scarce. We report here the presence of specimens of Filaria martis in the subcutaneous connective tissues of three M. lutreola individuals from Spain. This is the first finding of a subcutaneous nematode in a representative of the genus Mustela. The report also enlarges the known range of the definitive hosts of this nematode. These worms were mainly located in the dorsal region of mink and more rarely in the knees, elbows, and hips. Skin sloughing was only observed in one M. lutreola with both septicaemia and an associated high burden of F. martis. Therefore, more attention should be paid to potentially pathogenic helminths when designing conservation programs dedicated to M. lutreola.

Molecular identification of Taenia mustelae cysts in subterranean rodent plateau zokors (Eospalax baileyi)

Cestode larvae spend one phase of their two-phase life cycle in the viscera of rodents, but cases of cestodes infecting subterranean rodents have only been rarely observed. To experimentally gain some insight into this phenomenon, we captured approximately 300 plateau zokors (Eospalax baileyi), a typical subterranean rodent inhabiting the Qinghai-Tibet Plateau, and examined their livers for the presence of cysts. Totally, we collected five cysts, and using a mitochondrial gene (cox1) and two nuclear genes (pepck and pold) as genetic markers, we were able to analyze the taxonomy of the cysts. Both the maximum likelihood and Bayesian methods showed that the cysts share a monophyly with Taenia mustelae, while Kimura 2-parameter distances and number of different sites between our sequences and T. mustelae were far less than those found between the examined sequences and other Taeniidae species. These results, alongside supporting paraffin section histology, imply that the cysts found in plateau zokors can be regarded as larvae of T. mustelae, illustrating that zokors are a newly discovered intermediate host record of this parasite.

Molecular identification of Taenia mustelae cysts in subterranean rodent plateau zokors (Eospalax baileyi)

Cestode larvae spend one phase of their two-phase life cycle in the viscera of rodents, but cases of cestodes infecting subterranean rodents have only been rarely observed. To experimentally gain some insight into this phenomenon, we captured approximately 300 plateau zokors (Eospalax baileyi), a typical subterranean rodent inhabiting the Qinghai-Tibet Plateau, and examined their livers for the presence of cysts. Totally, we collected five cysts, and using a mitochondrial gene (cox1) and two nuclear genes (pepck and pold) as genetic markers, we were able to analyze the taxonomy of the cysts. Both the maximum likelihood and Bayesian methods showed that the cysts share a monophyly with Taenia mustelae, while Kimura 2-parameter distances and number of different sites between our sequences and T. mustelae were far less than those found between the examined sequences and other Taeniidae species. These results, alongside supporting paraffin section histology, imply that the cysts found in plateau zokors can be regarded as larvae of T. mustelae, illustrating that zokors are a newly discovered intermediate host record of this parasite.