Biting midges in the genus Culicoides (Diptera: Ceratopogonidae) transmit bluetongue virus (BTV) and epizootic hemorrhagic disease virus (EHDV) to ruminants, exerting a significant economic impact on animal agriculture worldwide. However, very little is known regarding the habitat requirements of Culicoides species, limiting the establishment of effective midge control strategies. Our research focused on examining the habitat associations/characteristics and the oviposition stimuli of Culicoides species associated with BTV/EHDV transmission in FL, USA. We found strong habitat associations for Culicoides haematopotus (Malloch) (stream edge) and Culicoides stellifer (Coquillett) (puddles), the most commonly emerging midge species from our samples. Suspected vector species of BTV/EHDV in the region, C. stellifer and Culicoides venustus (Hoffman), emerged mainly from habitats with moderate-high levels of pollution (edges of puddles and seepages) as indicated by the relatively higher concentrations/levels of organic matter, nutrients and other environmental variables in these samples. The gravid females of C. stellifer showed an overall oviposition preference for substrates with mud and vegetation from the larval habitat, depositing a significantly higher proportion of eggs on these substrates than on controls. Collectively, our findings suggest that C. haematopotus prefers habitats with low pollution levels while C. stellifer and C. venustus prefer habitats with moderate to heavy pollution levels. Mud and vegetation (Sphagnum spp. mosses) from the larval habitat likely provide strong oviposition cues to C. stellifer. Management strategies to discourage oviposition of C. stellifer and C. venustus midges should likely focus on altering the characteristics of mud and/or vegetation in/around commercial cervid facilities.
