Biologia 66/4: 678—683, 2011 Section Zoology DOI: 10.2478/s11756-011-0073-7 The flight distances of floodwater mosquitoes (Aedes vexans, Ochlerotatus sticticus and Ochlerotatus caspius) in Osijek, Eastern Croatia Mirta Sudari´ c Bogojevi´ c, Enrih Merdi´ c & Tomislav Bogdanovi´ c Department of Biology, Josip Juraj Strossmayer University of Osijek, Trg Ljudevita Gaja 6, 31000 Osijek, Croatia; e-mail: mirta.sudaric@biologija.unios.hr Abstract: In spring 2004, the mark–release–recapture study was conducted in the Osijek area, covering the total of 171 km 2 , to describe dispersal pattern of three floodwater mosquito species (Aedes vexans, Ochlerotatus sticticus and Oc. caspius). Forty CO2 baited Center for Disease Control and Prevention (CDC) traps were set at distances varying from 0.95 to 16.7 km from release site. Fifty thousand mosquitoes were released, and a total of 22 marked mosquitoes were recaptured in 12 traps, 82% of which were collected in the first six days after release. The maximum distance of recaptured mosquito (Oc. sticticus) was found at 11.68 km from the release site. During the study, the average dispersal rate per day for mosquitoes ranged from 0.96 km to 3.6 km in regard to different species. Key words: floodwater mosquitoes; flight distances; mark-release-recapture method; Croatia Introduction The research on the dispersion of floodwater mosquitoes, which have very strong flying abilities, in general was conducted by a few authors (Smith et al. 1956; Brust 1980; Horsfall et al. 1973, 1975; Briegel et al. 2001). The dispersion of specific species of floodwater mosquitoes, Ochlerotatus sticticus (Meigen, 1838) and Aedes vexans (Meigen, 1830) was investigated by Stage et al. (1937), Gjullin et al. (1950), and Brust (1980), while the pas- sive migration of Ae. vexans was investigated by Hors- fall (1954). Previous research has identified that those species can cover significant distances from their breed- ing site, ranging from 620 m to more than 48 km, but at least 10 km (Ba et al. 2005; Becker et al. 2003; Brust 1980; Carpenter & LaCasse 1955; Gjullin et al. 1950; Headlee 1945; Mohrig 1969; Sparks et al. 1986). In this study we focus on flight distance of three floodwater mosquito species of Aedes and Ochlerotatus in the area of Osijek (population approximately 130,000) and the adjacent Nature Park Kopački rit. The fauna and the species abundance of the studied area is published by Merdi´ c (1993), Merdi´ c & Lovakovi´ c (2001), Merdi´ c& Sudari´ c (2003) and Sudari´ c Bogojevi´ c et al. (2009). Ge- ographical, hydrological and climatic characteristics of Kopački rit create ideal conditions for the development of large mosquito populations of the important pest species: Ae. vexans, Oc. sticticus and Oc. caspius (Pal- las, 1771) which occur from April to October. Due to the high density of mosquito populations in this area, females in search of blood meal randomly move to the direction of forests, but also to urban areas close to their breeding site (Horsfall et al. 1973). In our research the nearest residential area is the city of Osijek, the edge of which is just over 1 km southwest of the breeding sites in Kopački rit. 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 (Sudari´ c Bogojevi´ c et al. 2007). Information about the dispersal of mosquitoes from their breeding sites is useful when defining bound- aries of area to be treated with insecticides to prevent the annoyance caused by mosquitoes in neighbouring communities. Knowledge of the flight behaviours of dif- ferent mosquito species is also necessary for the moni- toring and prevention of the spread of mosquito-borne diseases. All species in our study have been shown to be potential vectors of West Nile virus (Zeller & Schuf- fenecker 2004; Medlock et al. 2005) and Tahyna virus in Europe (Becker et al. 2003). Despite the importance of floodwater mosquitoes as pests and potential vec- tors of arboviruses, limited research has been addressed to the dispersal of these mosquitoes. The purpose of the present paper was to determine how far floodwater mosquitoes fly and in what direction from their breed- ing sites, in order to improve current surveillance and control practices in the Osijek area. Study area The location of the study was the city of Osijek, including c 2011 Institute of Zoology, Slovak Academy of Sciences Unauthenticated Download Date | 7/27/18 10:41 PM