Medical and Veterinary Entomology (2011) 25, 17–24 doi: 10.1111/j.1365-2915.2010.00900.x Meteorological effects on the daily activity patterns of tabanid biting flies in northern Queensland, Australia K. VAN HENNEKELER 1 , R. E. J O N E S 2 , L. F. S K E R R A T T 1,3 , M. O. M U Z A R I 1 and L. A. F I T Z P A T R I C K 1 1 School of Veterinary and Biomedical Sciences, Faculty of Medicine, Health and Molecular Sciences, James Cook University, Townsville, Queensland, Australia, 2 School of Marine and Tropical Biology, Faculty of Science and Engineering, James Cook University, Townsville, Queensland, Australia and 3 School of Public Health, Tropical Medicine and Rehabilitation Sciences, Faculty of Medicine, Health and Molecular Sciences, James Cook University, Townsville, Queensland, Australia Abstract. Information on the daily activity patterns of tabanid flies is important in the development of strategies that decrease the risk of pathogens transmitted by them. In addition, this information is useful to maximize numbers of tabanids trapped during short-term studies and to target feeding behavior studies of certain tabanid species to their times of peak activity. The current study examined the effects of various meteorological factors on the daily activity patterns of common tropical species of tabanids in north Queensland. Each species studied responded differently to weather factors. Tabanus townsvilli Ricardo (Diptera: Tabanidae) was most active during late morning and early afternoon, whereas Pseudota- banus silvester (Bergroth) and Tabanus pallipennis Macquart were most active in the late afternoon. Tabanus dorsobimaculatus Macquart was most active in the morning and early afternoon. Data on daily activity patterns of tabanid flies indicates that in an area such as Townsville, North Queensland, where several species of tabanid are present concur- rently in high numbers, the overlapping periods of high activity for these species indicate a high risk of pathogen transmission for most of the day (10.00–19.00 hours). Similarly, because each species responds differently to weather variables, only extreme weather conditions are likely to inhibit activity of all species. These data also indicate that for maximal results, trapping and feeding behavior studies should be tailored to the preferred activity period of the species under investigation. Key words. Activity, insect vectors, meteorological, surra, surveillance, tabanid, trapping, weather, Australia. Introduction The present study focuses on the daily activity patterns of tabanid flies as part of a project investigating the potential risk to tropical Australia of an incursion of surra. Surra is a disease of livestock caused by the protozoan parasite Trypanosoma evansi, which is mechanically transmitted by tabanid flies. Surra is currently not present in Australia, but is considered a high quarantine risk (Anon, 2007). Tabanid flies are also Correspondence: Dr K. van Hennekeler, Department of Agriculture and Food, Western Australia, Locked Bag, 4 Bentley Delivery Centre, Western Australia 6983, Australia. Tel.: +61 8 9368 3333; Fax: +61 8 94742479; E-mail: Kirsty.Moynihan@agric.wa.gov.au, Kirsty_V@yahoo.com.au known to transmit equine infectious anemia virus and bovine leukemia virus, both of which occur in Australia (Krinsky, 1979; Foil, 1989). Activity data for insect vectors are needed to identify periods when the risk of pathogen transmission might be highest. When used in combination with seasonal and spatial patterns of vector abundance, the data will help design strategies to minimize the risk of transmission, should surra be introduced. In addition, vector surveillance, feeding behavior studies and any studies  2010 The Authors Medical and Veterinary Entomology  2010 The Royal Entomological Society 17