DNA-aided identification of Culex mosquitoes (Diptera: Culicidae) reveals unexpected diversity in underground cavities in Austria

Otto Moog,Hans-Peter Fuehrer,Carina Zittra,Erhard Christian

doi:10.1007/s00436-019-06277-y

Abstract

Subterranean cavities serve as resting places and hibernation shelters for mosquitoes. In Europe, members of the genus Culex are often the most abundant insects on cave walls. Culex pipiens L., the common house mosquito, exists in two physically very similar, yet genetically and ecologically distinct biotypes (or forms, ‘f.’), namely Cx. pipiens f. pipiens and Cx. pipiens f. molestus. Autogeny and stenogamy of the latter form have been interpreted as adaptations to underground habitats. The epigean occurrence of the two biotypes and their hybrids was recently examined in Eastern Austria, but the hypogean distribution of the Cx. pipiens complex and morphologically similar non-members such as Cx. torrentium is unknown. Considering the key role of Culex mosquitoes in the epidemiology of certain zoonotic pathogens, the general paucity of data on species composition and relative abundance in subterranean shelters appears unfortunate.For a first pertinent investigation in Austria, we collected mosquitoes in four eastern federal states. Based on analyses of the ACE2 gene and the CQ11 microsatellite locus, 150 female and three male mosquitoes of the genus Culex, two females of the genus Culiseta and a single female of the genus Anopheles were determined to species level or below. In our catches, Cx. pipiens f. pipiens exceeded the apparent abundance of the purportedly cave-adapted Cx. pipiens f. molestus many times over. Records of Cx. hortensis and Cx. territans, two species rarely collected in Austria, lead us to infer that underground habitats host a higher diversity of culicine mosquitoes than previously thought.

Highlights

Members of the Culex pipiens complex are critical for the epidemiology of certain viruses that menace public and veterinary health (Brugman et al 2018)
We examined whether the presence of Cx. pipiens is much higher than the presence of any other culicid species, as the catalogue of Austrian cave animals (Strouhal and Vornatscher 1975) suggests, and whether alleged underground-adapted Cx. pipiens f. molestus are more abundant than Cx. pipiens f. pipiens or hybrids of the two biotypes
Four species, namely Cx. hortensis, Cx. territans, Cx. torrentium and a single female of Anopheles maculipennis s.l. were recorded for the first time in subterranean habitats in Austria (Table 2)

Summary

Introduction

Mosquitoes (Culicidae) include vectors of human and veterinary pathogens such as arboviruses, haemosporidians and filarioid nematodes (Norris 2004; Schoener et al 2017; Übleis et al 2018). About 10% of the 3500 known mosquito species play a major role in pathogen transmission (Becker et al 2010; Diniz et al 2017). Molestus is mammalophilic (preferring mammals), autogenous (can lay a first batch of eggs without a blood meal) and stenogamous (mates in restricted space without nuptial flight). Immature stages of both forms are found at epigean sites, whereas in hypogean sites only f. With reference to Austria, mainly focused on epigean urban and wetland habitats, completely neglecting less accessible sites such as natural caves (Lebl et al 2014; Zittra et al 2016)

Methods

Results

Conclusion