Spatiotemporal Monitoring of Floodwater Mosquito Dispersal in Osijek, Croatia

Abstract

This paper demonstrates the possibility of using geostatistics to monitor the dispersal of mosquitoes for mosquito control programs at the municipal level. The case study objective was to quantify the dispersal of floodwater mosquitoes from the natural marshland Kopacki rit into the city of Osijek, Croatia, and to analyze the main factors controlling it. Fifty thousand adult Aedes vexans, Ochlerotatus sticticus, and Ochlerotatus caspius mosquitoes were marked with a powdered fluorescent pigment and released from the southern part of Kopacki rit on April 28, 2004. Forty CO2-baited Centers for Disease Control and Prevention traps were set in the area of the municipality of Osijek (171 km2) and were monitored for 10 days. A total of 582,471 mosquitoes were captured and examined in the laboratory. The mosquito counts from different sites were then interpolated using ordinary kriging and visualized dynamically to detect the dominant migrational directions. Mosquito dispersal and frequency were greatly influenced by wind speed (r = 0.82). The marked mosquitoes were found at 12 sites located from 1 km to 11.7 km away from the release point. The recapture rate was 0.044% (54% Oc. sticticus, 32% Ae. vexans, and 14% Oc. caspius). Based on the Lincoln index, the estimated total population size for floodwater mosquitoes in the study area ranged from 875 million to 2.0 billion mosquitoes. Limitations of the approach, recommendations for the improvement of the monitoring network, and spatial predictions are further discussed.

Seasonal dynamics of mosquitoes (Diptera: Culicidae) in Osijek (Croatia) for the period 1995–2004

“…vexans can move to a distance up to 32 km from the breeding site (Brust 1980;Carpenter & LaCasse 1955;Headlee 1945;Sparks et al 1986). In a research on mosquito migration in the Osijek area, the species has been observed 7.7 km from the breeding site (Sudarić Bogojević et al 2007). This indicates that host-seeking females of Ae.…”

“…The same seasonal dynamics of the species was reported in Slavonski Brod in 2001 (Merdić et al 2003). Ochlerotatus sticticus is widespread and a nuisance mosquito that can fly up to 11.7 km from the breeding site (Sudarić Bogojević et al 2007). …”

“…In the Osijek area, the programme of mosquito control deals with invasions of primary floodwater mosquito species (Aedes vexans and Ochlerotatus sticticus), the abundance of which typically reflects floods in the wetlands of the Nature Park Kopački rit and inundations close to Osijek, and constitutes a major nuisance to local public (Merdić & Lovaković 2001;Sudarić Bogojević et al 2007). There are also some other species hatching in stagnant waters and channels (the most numerous Anopheles maculipennis complex) and species having their breeding sites in barrels, cans, drains, septic tanks etc.…”

The flight distances of floodwater mosquitoes (Aedes vexans, Ochlerotatus sticticus and Ochlerotatus caspius) in Osijek, Eastern Croatia

“…The floodplain area of Kopački rit is situated north-east of the city of Osijek in the Baranja region, in a triangle formed by the rivers Drava and Danube, and it is described in detail in a previous paper (Sudarić Bogojević et al 2007). The sampling was conducted in five different environments: flooded (5 stations), urban (8 stations), urban near water -Drava River (4), agricultural -crops or orchards (17 stations), and combinations of urban and agricultural habitats (6 stations).…”

“…The objective of the work was to study movement of floodwater mosquitoes from Kopački rit to Osijek, however, traps could not be set north of the marking site because of mine fields as a result of recent war activities. So it is unknown how many mosquitoes dispersed in these directions (Sudarić Bogojević et al 2007). Information about the dispersal of mosquitoes from their breeding sites is useful when defining boundaries of area to be treated with insecticides to prevent the annoyance caused by mosquitoes in neighbouring communities.…”