Novel 3D in situ visualization of seal heartworm (Acanthocheilonema spirocauda) larvae in the seal louse (Echinophthirius horridus) by X-ray microCT

Ebmer, David; Handschuh, Stephan; Schwaha, Thomas; Rubio-García, Ana; Gärtner, Ulrich; Glösmann, Martin; Taubert, Anja; Hermosilla, Carlos

doi:10.1038/s41598-022-18418-y

Cited by 5 publications

(3 citation statements)

References 39 publications

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“…This allows the isolation and visualization of external and internal features and facilitates the quantification and categorization of complex 3D structures. Recent advances in the availability of 3D imaging have enabled quantitative measurements and analyses of even small parasites [ 22 , 23 ].…”

Section: Introductionmentioning

confidence: 99%

Parasite escape mechanisms drive morphological diversification in avian lice

Kolencik,

Stanley,

Punnath

et al. 2024

Proc. R. Soc. B.

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Organisms that have repeatedly evolved similar morphologies owing to the same selective pressures provide excellent cases in which to examine specific morphological changes and their relevance to the ecology and evolution of taxa. Hosts of permanent parasites act as an independent evolutionary experiment, as parasites on these hosts are thought to be undergoing similar selective pressures. Parasitic feather lice have repeatedly diversified into convergent ecomorphs in different microhabitats on their avian hosts. We quantified specific morphological characters to determine (i) which traits are associated with each ecomorph, (ii) the quantitative differences between these ecomorphs, and (iii) if there is evidence of displacement among co-occurring lice as might be expected under louse–louse competition on the host. We used nano-computed tomography scan data of 89 specimens, belonging to four repeatedly evolved ecomorphs, to examine their mandibular muscle volume, limb length and three-dimensional head shape data. Here, we find evidence that lice repeatedly evolve similar morphologies as a mechanism to escape host defences, but also diverge into different ecomorphs related to the way they escape these defences. Lice that co-occur with other genera on a host exhibit greater morphological divergence, indicating a potential role of competition in evolutionary divergence.

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Section: Introductionmentioning

confidence: 99%

Parasite escape mechanisms drive morphological diversification in avian lice

Kolencik,

Stanley,

Punnath

et al. 2024

Proc. R. Soc. B.

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“…Recently, A. spirocauda was recorded from monk seal ( Monachus monachus ) in the Mediterranean (Papadopoulos et al ., 2010 ). The seal louse Echinophthirius ( E. ) horridus (Anoplura; Insecta) has been hypothesized to be the intermediate host for heartworm filariae that are transmitted via the blood meal and undergo several moults in the insect vector (Geraci et al ., 1981 ; Lehnert et al ., 2015 ; Ebmer et al ., 2022 ) before becoming infective and being directly transmitted to a potential new host via infected louse vectors – transferred e.g. during haul-out on sandbanks between seal individuals.…”

Section: Introductionmentioning

confidence: 99%

Heartworms in Halichoerus grypus: first records of Acanthocheilonema spirocauda (Onchocercidae; Filarioidea) in 2 grey seals from the North Sea

Lehnert,

Herzog,

Boyi

et al. 2023

Parasitology

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The assumed definitive host of the heartworm Acanthocheilonema spirocauda (Onchocerdidae; Filarioidea) is the harbour seal (Phoca vitulina). This filaroid nematode parasitizing in cardiac ventricles and blood vessel lumina of harbour seals (P. vitulina) has a low prevalence and seldom causes severe health impacts. The seal louse (Echinophthirius horridus) is the assumed intermediate host for transmission of A. spirocauda filariae between seals, comprising a unique parasite assembly conveyed from the terrestrial ancestors of pinnipeds. Although grey seals (Halichoerus grypus) are infected by seal lice, heartworm infection was not verified. Analysing a longterm dataset compiled over decades (1996–2021) of health monitoring seals along the German coasts comprising post mortem investigations and archived parasites, 2 cases of A. spirocauda infected male grey seals were detected. Tentative morphological identification was confirmed with molecular tools by sequencing a section of mtDNA COI and comparing nucleotide data with available heartworm sequence. This is the first record of heartworm individuals collected from the heart of grey seals at necropsy. It remains puzzling why heartworm infection occur much less frequently in grey than in harbour seals, although both species use the same habitat, share mixed haul-outs and consume similar prey species. If transmission occurs directly via seal louse vectors on haul-outs, increasing seal populations in the North- and Baltic Sea could have density dependent effects on prevalence of heartworm and seal louse infections. It remains to be shown how species-specificity of filarial nematodes as well as immune system traits of grey seals influence infection patterns of A. spirocauda.

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“…It infects at least eight species of pinnipeds (Siebert et al 2007; Leidenberger and Bostrom 2008; Lehnert et al 2016). The intermediate host and vector for this parasite is the seal louse, Echinophthirius horridus , although its entire life cycle has not been determined (Lehnert et al 2016; Ebmer et al 2022). The seal louse is one of the few insects adapted to a marine environment, although it is not common and generally affects young animals (Lehnert et al 2016).…”

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confidence: 99%