Abstract
Stylostome and skin inflammatory reaction during feeding of Neotrombicula talmiensis (Schluger, 1955) (Acariformes, Trombiculidae) larvae on the naturally infected host animals – voles Myodes rufocanus Sundevall, 1846 and Asian chipmunk Tamias sibiricus (Laxmann, 1769) were studied by histological methods. In addition, larvae were studied in scanning electron microscope (SEM). The apical hypostomal portions form a temporal sucker, which applies to the host skin during feeding. Larval feeding on both naturally infected voles and chipmunks causes an epidermal hyperkeratosis and a permanent delayed inflammation with predominance of neutrophil leukocytes, dilation of dermal capillaries and local hemorrhages. Larvae tend to feed in tight groups and may attach themselves to both ‘living’ epidermis and hypertrophic stratum corneum. The stylostome is organized nearly identically in the two host species, which points to the species-specific character of the feeding tube in trombiculid larvae. The stylostome does not penetrate the epidermis through, so it may be classified as belonging to the epidermal type. The stylostome is produced by a solidifying larval secretion and composed of the proximal eosinophil cone and the main stylostome tube, both pale-pink in azure-II-eosin with a greyish peripheral portion more pronounced in voles. No longitudinal and transverse stratification is found in the stylostome composition. In contrast with other trombiculid larvae studied so far, larvae of N. talmiensis also ingest, besides liquefied nutrients, a pure blood that reveals a possibility for trombiculid larvae to be natural bloodsuckers.
Highlights
Larvae of trombiculid mites are known as ectoparasites of the wide range of vertebrate animals, several species serve as vectors of tsutsugamushi disease agents – Orientia tsutsugamushi (Hayashi)
scanning electron microscope (SEM) of N. talmiensis larvae has revealed two eye lenses closely positioned on one plate on both sides of the scutum (Figure 1A-B) and long trifurcate palpal claws looking down and back nearby the sucker (Figure 1D)
Like in other trombiculid larvae (Shatrov 2000), the apical hypostomal lips form a temporal sucker during larval feeding (Figure 1D)
Summary
Larvae of trombiculid mites (chiggers) are known as ectoparasites of the wide range of vertebrate animals, several species serve as vectors of tsutsugamushi disease agents – Orientia tsutsugamushi (Hayashi). Larvae of all trombiculid species produce a special feeding tube – stylostome – in the skin of the affected animals for Distributed under Creative Commons CC-BY 4.0. How to cite this article Shatrov A. A. (2021), Stylostome of the trombiculid mite larvae Neotrombicula talmiensis (Schluger, 1955) (Acariformes, Trombiculidae) feeding on two host species in the Russian Far East. A pure blood was not recorded as typical food of trombiculid larvae
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