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

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.

An investigation of hibernating members from the Culex pipiens complex (Diptera, Culicidae) in subterranean habitats of central Germany

“…Our calculation revealed a significant effect of sampling months on the number of mosquitos found inside the underground structure, i.e. the later the sampling in the winter, the fewer mosquitos were found inside the cave, which is corroborated by the study of Zittra et al 54 .…”

“…torrentium and 10 as Cx. p. pipiens, a finding which is supported by another study 54 . In light of the very low numbers of males and the lack of Cx.…”

“…p. molestus is not an underground biotype of Cx. p. pipiens or that subterranean objects are particularly suitable for hybridization 54 .…”

Monitoring of alien mosquitoes in Western Austria (Tyrol, Austria, 2018)

“…Fifty culicid species (Diptera: Culicidae; genera: Aedes , Anopheles , Culex , Coquillettidia , Culiseta , Ochlerotatus , Orthopodomyia , and Uranotaenia ) have been detected in Austria so far [ 53 ]. With the finding of Ae .…”

Mosquitoes (Diptera: Culicidae) in the Dark—Highlighting the Importance of Genetically Identifying Mosquito Populations in Subterranean Environments of Central Europe

“…Generalizations and expected distribution patterns extrapolated from these records were, however, not confirmed as members of the Cx. pipiens complex were found in sympatry in subterranean habitats of both urban and rural areas in Austria, Germany, and Hungary [18,29,33] At present, mosquito community composition, including members of the Cx. pipiens complex, in the subterranean realm, has been rarely studied using molecular tools, and baseline data [18,29,33] are slowly emerging in Europe.…”