Fascioliasis in Llama, Lama glama, in Andean Endemic Areas: Experimental Transmission Capacity by the High Altitude Snail Vector Galba truncatula and Epidemiological Analysis of Its Reservoir Role

South American camelids are definitive hosts of Fasciola hepatica. However, their capacity to participate in the transmission and epidemiology of fascioliasis has never been appropriately studied. Therefore, an F. hepatica isolate from Argentine llama is for the first time analyzed using Galba truncatula lymnaeids from Bolivia. Experimental follow-up studies included egg embryogenesis, miracidial infection of lymnaeid snails, intramolluscan larval development, cercarial production, chronobiology of cercarial shedding, vector survival to infection, and metacercarial infectivity of mammal host. Shorter prepatent and patent periods were leading to markedly lower cercarial production, shorter cercarial shedding, and a higher negative impact on snail survival. The usually low liver fluke prevalences and intensities and low daily fecal outputs indicate that llamas do not substantially contribute to fascioliasis transmission. The defecating behavior in dung piles far from freshwater collections prevents lymnaeid infection by eggs shed by this camelid. All results suggest the reservoir role of the llama to be negligible and, therefore, no priority within control measures in endemic areas. However, llamas may play a disease-spreading role if used as pack animals in rural areas. In the Northern Bolivian Altiplano human hyperendemic area, neither llamas nor alpacas should be considered for control measures within a One Health action.

Crenobiont, stygophile and stygobiont molluscs in the hydrographic area of the Trebišnjica River Basin

In the paper the crenobiont, stygophile and stygobiont malacofauna of the karst area of Popovo Polje around Trebinje (Eastern Herzegovina, BiH) is presented. The materials were collected from springs, caves and interstitial habitats (with a Bou-Rouch pump) at 23 localities. The following species were found: Pisidium cf. personatum A.W. Malm, 1855, Theodoxus callosus (Deshayes, 1833), Sadleriana fluminensis (Küster, 1852), Radomaniola curta (Küster, 1852), Radomaniola cf. bosniaca (Radoman, 1973), Kerkia briani Rysiewska & Osikowski, 2020, Montenegrospeum bogici (Pešić & Glöer, 2012), Litthabitella chilodia (Westerlund, 1886), Travunijana vruljakensis Grego & Glöer, 2019, a new genus and species of the Sadlerianinae, Emmericia ventricosa Brusina, 1870, Iglica cf. absoloni (A.J. Wagner, 1914), Plagigeyeria tribunicae Schütt, 1963, Paladilhiopsis arion Rysiewska & Osikowski, 2021, Valvata montenegrina Glöer & Pešić, 2008, Radix labiata (Rossmässler, 1835), Galba truncatula (O. F. Müller, 1774), Ancylus recurvus Martens, 1783, Ancylus sp. and the amphibiotic Succinea cf. putris (Linnaeus, 1758). The redescription of the genus Travunijana Grego & Glöer, 2019, applying the characteristics of shell, female reproductive organs and penis, is also presented. The new genus and species are described, based on the shell, penis, radula and fragmentary data on the female reproductive organs. For all species, the mitochondrial cytochrome oxidase subunit I (COI) is applied to confirm the determination; in the case of Travunijana and the new genus, the nuclear histone H3 locus is also used, in order to infer both their distinctiveness and phylogenetic relationships.

CICLO BIOLÓGICO Y POTENCIAL BIÓTICO DE FASCIOLA HEPATICA EN GALBA TRUNCATULA

Fasciola hepatica tiene un ciclo biológico complejo, que incluye un caracol limneido como intermediario, donde acontece su multiplicación larval partenogenética. Se realizó por ello un estudio experimental del ciclo de F. hepatica y se estimó su potencial biótico (r) en Galba truncatula. Habiendo seleccionado 215 de estos caracoles para su infección con miracidios obtenidos a 26°C, en presencia de luz; se procedió a la disección de cinco caracoles cada tres días, realizando el seguimiento de la cuantía de estadíos de F. hepatica mediante microscopía de campo claro, observando características externas y tiempo de desarrollo de miracidios, esporocisto, redias y cercarias. Resultando que el modelo de crecimiento exponencial es el que mejor se ajusta a la dinámica de F. hepatica, con un potencial biótico de 6,69%, una media de 203 cercarias por miracidio y 270 cercarias por caracol.

Galba truncatula (O.F. Müller, 1774) (Gastropoda, Lymnaeidae): the colonization of new stations on acid soil by low numbers of snails

Samples of 5, 10 or 20 adult Galba truncatula each were introduced into 25 slope rush beds and 24 road ditches on acid soil to study the colonization of these new sites by the snail. Surveys were conducted over the following eight years to determine the area where these G. truncatula colonized in these new stations and to count the number of overwintering snails in April or May. Snail populations were present in about 50% of the sites where samples of 5 snails each were introduced and in all sites when each sample included 10 or 20 snails. The average area of these habitats showed a peak before decreasing in the following years and this peak was all the more late as the sample introduced into the station increased in size. In contrast, snail abundance in all cases peaked in the second or third year after introduction and gradually decreased thereafter. In all cases, a concentration of snails was noted in the most upstream zone, whereas the number of individuals decreased gradually towards the downstream zone. These results demonstrate that a small number of snails (10 or 20 adults per sample) allow the development of a new population of G. truncatula in new acid soil stations.

Rapid detection of Galba truncatula in water sources on pasture-land using loop-mediated isothermal amplification for control of trematode infections

Background Fascioliasis caused by the trematodes Fasciola hepatica and F. gigantica, is a global neglected zoonotic disease estimated to cost the livestock industry over €2.5 billion annually. Farm management measures and sustainable use of anthelmintics can, in principle, effectively control trematode infection in livestock and reduce the rate of developing anthelmintic resistance. Previously, we designed an environmental DNA (eDNA) assay to identify a common trematode intermediate host, the freshwater snail Galba truncatula, in water sources to measure specific trematode infection risk areas on pasture-land. To improve this procedure, we now report a loop-mediated isothermal amplification (LAMP) assay to identify G. truncatula eDNA. Methods A LAMP assay was designed and optimised (e.g. temperature, time duration and primer concentration) to identify G. truncatula DNA. The ability of the LAMP assay to target G. truncatula DNA was identified, and LAMP assay limit of detection was investigated in comparison to conventional PCR. In the field, 48 water samples were collected from stream, ditch and water pool habitats in four locations at two Aberystwyth University farms over a seven week period to investigate the applicability of the LAMP assay for use on eDNA samples, in comparison to conventional PCR. Results The LAMP assay delivered detectable results in 30 min at 63 °C. The assay discriminated between G. truncatula DNA and non-target DNA, presenting a level of DNA detection comparable to conventional PCR. No significant difference was found between the ability of the LAMP and PCR assay to identify G. truncatula eDNA in water samples. Kappa coefficient analysis revealed a moderate level of agreement between LAMP and PCR assays. Conclusions This study demonstrated that the LAMP assay can detect G. truncatula eDNA in a simple and rapid manner. The LAMP assay may become a valuable tool to determine optimum pasture management for trematode parasite control.

Biology, immature stages, and systematics of snail-killing flies of the genus Colobaea (Diptera: Sciomyzidae), with overviews of aspects of the tribe Sciomyzini

All reared larvae of flies of the genus Colobaea Zetterstedt, 1837 (Diptera: Sciomyzidae), which comprises 15 valid species, kill and consume freshwater nonoperculate pulmonate snails. New data are presented on the geographic distribution, biology, morphology of immature stages, and classification of Colobaea. Life cycle information is provided from field data and laboratory rearings for four of the 11 Palearctic species—C. bifasciella (Fallén), C. deemingi Knutson & Bratt n.sp., C. pectoralis (Zetterstedt), and C. punctata (Lundbeck)—and for one of the three Nearctic species, C. americana Steyskal. Colobaea bifasciella is shown to be one of the most highly specialized parasitoid Sciomyzini, laying eggs on shells of Galba truncatula (O.F. Müller) and Stagnicola palustris (O.F. Müller) in temporary, intermittent, or vernal semiterrestrial situations. Each larva feeds in only one host snail, which is not killed until shortly before the larva completes development. Puparia are strongly modified to fit tightly within the shell of the host. The other reared species are shown to be less specialized than C. bifasciella, with eggs being laid upon vegetation, the larvae behaving as parasitoids-predators-saprophages of exposed aquatic snails, and the puparia of all four species being adapted to a lesser degree than C. bifasciella to fitting within the shell of the host snail. In nature, C. americana attacks Gyraulus parvus (Say) and Physa Draparnaud sp.; C. pectoralis attacks Anisus vortex (L.) and Bathyomphalus contortus (L.); and C. punctata attacks Gyraulus albus O.F. Müller, Lymnaea “peregra,” Planorbarius corneus (L.), and Planorbis planorbis (L.). In the laboratory, these species also attacked and consumed other freshwater nonoperculate snails; C. deemingi was reared on Gyraulus intermixtus (Mousson) and Radix gedrosiana (Say), and an adult fly of the Palearctic C. distincta (Meigen) emerged from a puparium found in the shell of Anisus spirorbis (L.) collected in nature. Described and figured are eggs, larvae of all three instars, and puparia of the five laboratory-reared species. To provide perspective on features of Colobaea, diagnostic features are summarized of the immature stages of the Sciomyzini and the suprageneric categories of Sciomyzidae. The biogeography of the tribe Sciomyzini is presented, along with details of known geographical distribution. The classification and phylogenetic position of Colobaea are discussed. Included are a checklist of all known taxa of Colobaea, maps of geographic distribution, and a key to adults of the 15 valid species.

Malacological survey in a bottle of water: A comparative study between manual sampling and environmental DNA metabarcoding approaches

To assess the effect of anthropogenic activities on ecosystems, it is of prime importance to develop new tools enabling a rapid characterisation of ecological communities. Freshwater ecosystems are particularly impacted and threatened by human activities and need thorough attention to preserve their biodiversity and the ecological services they provide. Studying such ecosystems is generally difficult because the associated organisms are hard to sample and to monitor. We present a ready to use environmental metabarcoding diagnostic tool to characterise and monitor the freshwater malacofauna from water samples. The efficiency of this new tool was compared to a classical malacological survey at 19 sampled sites from 10 distinct rivers distributed over Corsica Island (France). Our eDNA monitoring tool demonstrated a remarkable ability to reconstitute the local malacofauna compared to the malacological survey, with 97.1% of species detection confirmed by both methods. The present tool successfully detected the 11 freshwater snail species previously reported in Corsica by malacological survey but was limited at the genus level for some species. Moreover, our malacological survey allowed an update of the local distribution of a wide diversity of freshwater snails including invasive species (i.e. Potamopyrgus antipodarum and Physa acuta) as well as snail hosts of pathogens of medical and veterinary importance (i.e. Bulinus truncatus and Galba truncatula).