Species inventory, ecology and seasonal distribution patterns of Culicidae (Insecta: Diptera) in the National Park Donau-Auen

Stechmücken haben aufgrund ihrer human- und veterinärmedizinischen Bedeutung als Krankheitserreger sowie als Vektor einer Vielzahl von Parasiten und Pathogenen eine große Bedeutung und werden daher hauptsächlich als Gesundheitsrisiko und Plage wahrgenommen. Die Ökologie der Stechmücken und in Folge auch ihre wichtige und bisher spärlich untersuchte Rolle in aquatischen und terrestrischen Nahrungsketten wurde bisher stark vernachlässigt. Um die ökologische Funktion der Stechmücken innerhalb eines Ökosystems nachvollziehen zu können, ist es unerlässlich, den derzeitigen Wissensstand über die Artverteilung und die jeweiligen Einflussfaktoren zu erheben und zu aktualisieren. Abiotische Parameter wie Wasserstand, Wasserführung, Sauerstoffkonzentration und Leitfähigkeit sowie biotische Parameter (Stechmücken und deren Predatoren) wurden an 20 Untersuchungsstellen im National Park Donau-Auen regelmäßig erhoben. Insgesamt wurden 34 Eischiffe, 1927 Larven, 80 Puppen und 200 adulte Culicidae während der Untersuchung gesammelt. Es wurden 15 Stechmückenarten aus 6 Gattungen (Anopheles, Culex, Culiseta, Coquillettidia, Aedes und Ochlerotatus) bestimmt, wobei die häufigsten Arten Ochlerotatus geniculatus (68%) und Culex territans (13%), gefolgt von Culex pipiens und Aedes vexans mit 5% und 4% der Gesamtabundanz darstellten. Biometrische Daten wurden verwendet, um die Lebenszyklen der abundantesten Arten zu rekonstruieren. Culex pipiens und Culex territans zeigten mit 2 Generationen einen bivoltinen und Ochlerotatus geniculatus mit 3 Generationen einen multivoltinen Entwicklungszyklus. Basierend auf den erhobenen abiotischen und biotischen Parametern wurden die Untersuchungsgebiete in vier Habitatgruppen zusammengefasst. Die Resultate ergaben, dass Wasserstand, Wasserführung, pH, elektrische Leitfähigkeit und Phosphatkonzentration einen signifikanten Einfluss auf die Artverteilung ausüben und somit die Auendynamik einen Schlüsselfaktor für die saisonale und räumliche Verteilung von Stechmückenpopulationen im National Park Donau-Auen darstellt.Mosquitoes are known as hosts for a variety of parasites and pathogens and are therefore considered as nuisance and as vectors of human diseases. Until recently not much attention had been paid to their ecology although they play an important but poorly understood role in food chains (Poulin 2010). In order to understand the ecological function of Culicidae in an ecosystem it is imperative to update information on culicid species distribution and to investigate the factors controlling it. We monitored abiotic parameters such as water level, nutrients, oxygen concentration and conductivity as well as biotic parameters (Culicidae and potential predators) from March to October 2011 at 20 sampling sites in the National Park Donau-Auen. A total of 34 eggrafts, 1927 larval, 80 pupal and 200 adult Culicidae were collected. We detected 15 mosquito species belonging to 6 genera (Anopheles, Culex, Culiseta, Coquillettidia, Aedes and Ochlerotatus), whereas Ochlerotatus geniculatus (68 %) and Culex territans (13 %) were most abundant, followed by Culex pipiens and Aedes vexans with approximately 5% and 4 % of total abundance. Biometrical data were used to reconstruct life cycles; at the study area Cx. pipiens and Cx. territans were bivoltine and Oc. geniculatus multivoltine. Based on abiotic and biotic parameters, sampling sites were grouped into 4 clusters. The results show that water level and persistence, pH, electric conductivity and phosphate concentrations had a significant influence on species distribution and that flood plain dynamics are a key factor for the seasonal and spatial distribution of mosquito larvae in the National Park Donau-Auen

Fifth European Dirofilaria and Angiostrongylus Days (FiEDAD) 2016

Peer reviewe

Hydraulic engineering of Drusinae larvae: head morphologies and their impact on surrounding flow fields

Body morphologies are significantly different amongst the members of the Drusinae subfamily. Aligned with such differences is the selective niche location chosen by many species from the subfamily. Typically, they live on the sediments of cold, well-oxygenated mountain streams from the Eurasian Region. However, each of the three evolutionary lineages (shredders, grazers and carnivorous filter feeders) inhabit different hydraulic locations according to their foraging behaviour. To investigate the relationship between the body morphology and the flow field near the body, we use Large Eddy Simulations to compute the flow past five different species of the subfamily. We selected species representing the three evolutionary lineages of the subfamily, Drusus alpinus Meyer-Dür 1875 from the shredders clade, D. bosnicus Klapálek 1899 and D. monticola McLachlan 1876 from the grazers clade and Cryptothrix nebulicola McLachlan 1867 and D. discolor (Rambur 1842) from the filter feeders clade. For the simulations, three-dimensional body shapes were reconstructed from X-ray micro CT data and exposed to a turbulent flow corresponding to water-depth and velocity data measured in the field. The total forces acting on each morphotype were found to be comparable. The lift coefficients computed and ranging from 0.07 to 0.17 are smaller than the drag coefficients which were found to range from 0.32 to 0.55. The local distribution of the skin-friction indicates flow-separation zones near the edges of the bodies, in particular, between the head and the pronotum, which are differently located according to each species. Moreover, we observe higher streamwise normal stresses upstream of the head of the filter feeder species. It is hypothesised that the upstream horseshoe vortex can lift up drifting food particles and transport these to the larvae’s filtering legs, thereby enhancing the encounter rates of particles with the filtering devices

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

Mosquitoes are of major importance to human and animal health due to their ability to transmit various pathogens. In Europe the role of mosquitoes in public health has increased with the introduction of alien Aedes mosquitoes such as the Asian tiger mosquito, Aedes albopictus; the Asian bush mosquito, Ae. japonicus; and Ae. koreicus. In Austria, Ae. japonicus has established populations in various regions of the country. Aedes albopictus is not known to overwinter in Austria, although isolated findings of eggs and adult female mosquitoes have been previously reported, especially in Tyrol. Aedes koreicus had not so far been found in Austria. Within the framework of an alien mosquito surveillance program in the Austrian province of Tyrol, ovitraps were set up weekly from May to October, 2018, at 67 sites- 17 in East Tyrol and 50 in North Tyrol. Sampling was performed at highways and at urban and rural areas. DNA obtained from mosquito eggs was barcoded using molecular techniques and sequences were analysed to species level. Eggs of alien Aedes species were found at 18 out of 67 sites (27%). Both Ae. albopictus and Ae. japonicus were documented at highways and urban areas in both East and North Tyrol. Aedes koreicus was found in East Tyrol. During this mosquito surveillance program, eggs of Ae. albopictus, Ae. japonicus, and Ae. koreicus were documented in the Austrian province of Tyrol. These findings not only show highways to be points of entry, but also point to possible establishment processes of Ae. japonicus in Tyrol. Moreover, Ae. koreicus was documented in Austria for the first time

The larva of Drusus dudor Ol\ue1h, 2017, including an updated key to larval Drusinae Banks, 1916 (Insecta, Trichoptera, Limnephilidae)

Volume: 908Start Page: 137-15

Morphological and molecular identification of nasopharyngeal bot fly larvae infesting red deer (Cervus elaphus) in Austria

Nasopharyngeal myiases are caused by larvae of bot flies (Diptera: Oestridae), which have evolved a high specificity for their hosts. Bot flies (n = 916) were collected from 137 (57.6 %) out of 238 red deer (Cervus elaphus) hunted in Vorarlberg and Tyrol (Western Austria). After being stored in 75 % ethanol, larvae were identified to species level and developmental stage using morphological and morphometric keys. Larvae were also molecularly characterized by polymerase chain reaction (PCR) amplification and partial sequencing of the mitochondrial cytochrome oxidase subunit I gene. Morphological and molecular analysis allowed identification of larvae as Cephenemyia auribarbis and Pharyngomyia picta. Genetic variations were also examined within the specimens collected in both geographical locations

Landscape structure affects distribution of potential disease vectors (Diptera: Culicidae)

Abstract Background Vector-pathogen dynamics are controlled by fluctuations of potential vector communities, such as the Culicidae. Assessment of mosquito community diversity and, in particular, identification of environmental parameters shaping these communities is therefore of key importance for the design of adequate surveillance approaches. In this study, we assess effects of climatic parameters and habitat structure on mosquito communities in eastern Austria to deliver these highly relevant baseline data. Methods Female mosquitoes were sampled twice a month from April to October 2014 and 2015 at 35 permanent and 23 non-permanent trapping sites using carbon dioxide-baited traps. Differences in spatial and seasonal abundance patterns of Culicidae taxa were identified using likelihood ratio tests; possible effects of environmental parameters on seasonal and spatial mosquito distribution were analysed using multivariate statistical methods. We assessed community responses to environmental parameters based on 14-day-average values that affect ontogenesis. Results Altogether 29,734 female mosquitoes were collected, and 21 of 42 native as well as two of four non-native mosquito species were reconfirmed in eastern Austria. Statistical analyses revealed significant differences in mosquito abundance between sampling years and provinces. Incidence and abundance patterns were found to be linked to 14-day mean sunshine duration, humidity, water–level maxima and the amount of precipitation. However, land cover classes were found to be the most important factor, effectively assigning both indigenous and non-native mosquito species to various communities, which responded differentially to environmental variables. Conclusions These findings thus underline the significance of non-climatic variables for future mosquito prediction models and the necessity to consider these in mosquito surveillance programmes

Barcoding of the Genus Culicoides (Diptera: Ceratopogonidae) in Austria—An Update of the Species Inventory Including the First Records of Three Species in Austria

Ceratopogonidae are small nematoceran Diptera with a worldwide distribution, consisting of more than 5400 described species, divided into 125 genera. The genus Culicoides is known to comprise hematophagous vectors of medical and veterinary importance. Diseases transmitted by Culicoides spp. Such as African horse sickness virus, Bluetongue virus, equine encephalitis virus (Reoviridae) and Schmallenberg virus (Bunyaviridae) affect large parts of Europe and are strongly linked to the spread and abundance of its vectors. However, Culicoides surveillance measures are not implemented regularly nor in the whole of Austria. In this study, 142 morphologically identified individuals were chosen for molecular analyses (barcoding) of the mitochondrial cytochrome c oxidase subunit I gene (mt COI). Molecular analyses mostly supported previous morphologic identification. Mismatches between results of molecular and morphologic analysis revealed three new Culicoides species in Austria, Culicoides gornostaevae Mirzaeva, 1984, which is a member of the Obsoletus group, C. griseidorsum Kieffer, 1918 and C. pallidicornis Kieffer, 1919 as well as possible cryptic species. We present here the first Austrian barcodes of the mt COI region of 26 Culicoides species and conclude that barcoding is a reliable tool with which to support morphologic analysis, especially with regard to the difficult to identify females of the medically and economically important genus Culicoides

Local Insect Availability Partly Explains Geographical Differences in Floral Visitor Assemblages of Arum maculatum L. (Araceae)

International audienceGeographical variation in abundance and composition of pollinator assemblages may result in variable selection pressures among plant populations and drive plant diversification. However, there is limited knowledge on whether differences in local visitor and pollinator assemblages are the result of site-specific strategies of plants to interact with their pollinators and/or merely reflect the pollinator availability at a given locality. To address this question, we compared locally available insect communities obtained by light-trapping with assemblages of floral visitors in populations of Arum maculatum (Araceae) from north vs. south of the Alps. We further investigated whether and how the abundance of different visitors affects plants’ female reproductive success and examined the pollen loads of abundant visitors. Local insect availability explained inter-regional differences in total visitor abundance, but only partly the composition of visitor assemblages. Northern populations predominantly attracted females of Psychoda phalaenoides (Psychodidae, Diptera), reflecting the high availability of this moth fly in this region. More generalized visitor assemblages, including other psychodid and non-psychodid groups, were observed in the south, where the availability of P. phalaenoides /Psychodidae was limited. Fruit set was higher in the north than in the south but correlated positively in both regions with the abundance of total visitors and psychodids; in the north, however, this relationship disappeared when visitor abundances were too high. High pollen loads were recorded on both psychodids and other Diptera. We demonstrate for the first time that the quantitative assessment of floral visitor assemblages in relation to locally available insect communities is helpful to understand patterns of geographical variation in plant–pollinator interactions. This combined approach revealed that geographical differences in floral visitors of A. maculatum are only partly shaped by the local insect availability. Potential other factors that may contribute to the geographical pattern of visitor assemblages include the region-specific attractiveness of this plant species to flower visitors and the population-specific behavior of pollinators

Screening blood-fed mosquitoes for the diagnosis of filarioid helminths and avian malaria

Abstract Background Both Dirofilaria repens and recently D. immitis are known to be endemic in Hungary. As one of several recent cases, the fatal case of a dog infested with D. immitis in Szeged, Southern Hungary, received attention from the media. Hence it was decided to catch mosquitoes in the garden where the dog lived to screen for filarioid helminths and Plasmodium spp. using molecular tools. Methods Mosquitoes were caught in Szeged, in the garden where the infected dog was kept, in July 2013 with M-360 electric mosquito traps and were stored in ethanol until further procedure. Female mosquitoes were classified to genus level by morphology. Each mosquito was homogenized and analyzed for filarioid helminths and avian malaria using standardized PCR techniques. Positive mosquito samples were further identified to species level by comparing a section of the mitochondrial COI gene to GenBank® entries. Results In this study, 267 blood-fed mosquitoes were caught in July 2013 in Szeged. Subsequent molecular screening revealed that not only D. immitis was present in the analyzed specimens but also DNA of D. repens, Setaria tundra and Plasmodium spp. was confirmed. Conclusions The analysis of blood-fed mosquitoes for the diagnosis of Dirofilaria spp. and other mosquito-borne pathogens seems to be an adequate technique to evaluate if filarioid helminths are present in a certain area. Usually only unfed female mosquitoes are analyzed for epidemiological studies. However, blood-fed mosquitoes can only be used for screening if a pathogen is present because the role of the mosquito as vector cannot be classified (blood of bitten host). Furthermore, Setaria tundra was confirmed for the first time in Hungary