First Nationwide Monitoring Program for the Detection of Potentially Invasive Mosquito Species in Austria

Abstract

In Austria, only fragmented information on the occurrence of alien and potentially invasive mosquito species exists. The aim of this study is a nationwide overview on the situation of those mosquitoes in Austria. Using a nationwide uniform protocol for the first time, mosquito eggs were sampled with ovitraps at 45 locations in Austria at weekly intervals from May to October 2020. The sampled eggs were counted and the species were identified by genetic analysis. The Asian tiger mosquito Aedes albopictus was found at two sites, once in Tyrol, where this species has been reported before, and for the first time in the province of Lower Austria, at a motorway rest stop. The Asian bush mosquito Aedes japonicus was widespread in Austria. It was found in all provinces and was the most abundant species in the ovitraps by far. Aedes japonicus was more abundant in the South than in the North and more eggs were found in habitats with artificial surfaces than in (semi-) natural areas. Further, the number of Ae. japonicus eggs increased with higher ambient temperature and decreased with higher wind speed. The results of this study will contribute to a better estimation of the risk of mosquito-borne disease in Austria and will be a useful baseline for a future documentation of changes in the distribution of those species.

Keywords: Aedes albopictus; Aedes geniculatus; Aedes japonicus; Asian bush mosquito; Asian tiger mosquito; invasive species; ovitraps; vectors.

Figure 1

Eggs of (a) Ae. albopictus: eggs with a shiny black surface, with symmetrically arranged large but narrow tubers in the center of the chorionic cells, (b) Ae. japonicus: black eggs with a matte surface, with uneven and irregularly arranged tubers and (c) Ae. geniculatus: eggs with a black surface, with symmetrically arranged flat but broad tubers in the center of the chorionic cells, larger than Ae. albopictus or Ae. japonicus eggs.

Figure 2

Mean number of eggs per day and site detected in the ovitraps. The number of eggs was categorized, the start and end values given in brackets for values > 0. Round brackets indicate endpoints which are excluded, endpoints with square brackets are included in a category. (a) Ae. albopictus, (b) Ae. japonicus, (c) Ae. geniculatus. Austrian provinces: W—Vienna, L—Lower Austria, B—Burgenland, U—Upper Austria, St—Styria, C—Carinthia, S—Salzburg, T—Tyrol, V—Vorarlberg. Map tiles by Stamen Design, under CC BY 3.0. Data by OpenStreetMap, under ODbL. Data source borders: NUTS units, Statistik Austria—data.statistik.gv.at, accessed on 18 January 2022.

Figure 3

Points and bold lines show the effects of the investigated parameters (a) habitat type, (b) latitude, (c) mean daily temperature, (d) daily sum of precipitation and (e) daily maximum wind speed on the number of Ae. japonicus eggs as predicted by the generalized linear mixed model for count data, error bars and thin lines represent 95% CI. Conditions for non-focus parameters are set to: habitat type—artificial surfaces, latitude—47.5° N, altitude—100–450 m a.s.l., temperature—20 °C, precipitation—0 mm, max. wind speed—8 km/h.