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

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.

First records of Aedes pulcritarsis (Rondani, 1872) (Diptera: Culicidae) in Austria.

Aedes pulcritarsis is a tree-hole breeding species with its main distribution in the Mediterranean area. Within the scope of two independent monitoring programmes, this mosquito species was detected for the first time in Austria, in the province of Lower Austria (2018, districts Mistelbach and Gaenserndorf; 2020, district Bruck an der Leitha). As the climatic and habitat situation in Central Europe seems to be generally suitable for this species, the most likely explanation for the species not being recorded previously is that it might have been overlooked in the past due to its specialized breeding habitat. However, further research on the distribution of Ae. pulcritarsis in Austria would be needed to support this hypothesis. The results from this study will contribute to the investigation of the northern distribution limit of Ae. pulcritarsis in Europe and possible changes thereof.

A multi-year study following BACI design reveals no short-term impact of Bti on chironomids (Diptera) in a floodplain in Eastern Austria.

Short-term impacts of aerial application of Bacillus thuringiensis israelensis (Bti) on Culicidae and Chironomidae were investigated over several years in temporary waters of the Dyje and Morava floodplains in Eastern Austria. The sampling followed a Before-After-Control-Impact (BACI) approach with sampling dates immediately before and shortly after the application and was repeated for 3 years. To test for effects of the Bti treatment on the two Diptera families, linear mixed-effects models were used. Data analysis included the factors Before-After and Control-Impact as fixed effects, while general temporal and spatial variables were random effects. One hundred sixteen taxa of chironomids were identified. Abundance varied between 2 and 1125 larvae per m2, while culicid densities reached values of several 100 ind. per liter. Total culicid abundance significantly decreased after the Bti treatment, whereas no significant effects were found on the abundance of total chironomids and dominant chironomid subfamilies, tribes, and genera, on relative proportions of chironomid feeding guilds, diversity, and species composition. Further studies from this area are needed to extend the investigation over a period of several weeks in order to reveal possible delayed effects of the larvicide application.