title: Physiological mechanisms of dehydration tolerance contribute to the invasion potential of Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) relative to its less widely distributed congeners.
abstract: BACKGROUND
  The Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) is a highly invasive species now with an almost cosmopolitan distribution. Two other damaging, polyphagous and closely-related species, the marula fruit fly, Ceratitis cosyra (Walker), and the Natal fly, Ceratitis rosa Karsch, are not established outside of sub-Saharan Africa. In this study, adult water balance traits and nutritional body composition were measured in all three species at different temperatures and levels of relative humidity to determine whether tolerance of water stress may partially explain their distribution.
  
  
  RESULTS
  Adult C. capitata exhibited higher desiccation resistance than C. rosa but not C. cosyra. Desiccation resistance of C. capitata was associated with lower rates of water loss under hot and dry conditions, higher dehydration tolerance, and higher lipid reserves that were catabolised during water stress. In comparison with C. capitata, C. cosyra and C. rosa lost water at significantly higher rates under hot, dry conditions, and did not catabolise lipids or other sources of metabolic water during water stress.
  
  
  CONCLUSIONS
  These results suggest that adult physiological traits permitting higher tolerance of water stress play a role in the success of C. capitata, particularly relative to C. rosa. The distribution of C. cosyra is likely determined by the interaction of temperature with water stress, as well as the availability of suitable hosts for larval development.
authors.affiliation: Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield, 0028 South Africa.
authors.forename: Christopher W
authors.initials: CW
authors.lastname: Weldon
authors.affiliation: Centre for Invasion Biology, Department of Conservation Ecology and Entomology, Stellenbosch University, Private Bag X1, Matieland, 7602 South Africa ; Present address: Department of Entomology and Nematology, University of Florida, PO Box 110620, Gainesville, FL 32611-0620 USA.
authors.forename: Leigh
authors.initials: L
authors.lastname: Boardman
authors.affiliation: Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield, 0028 South Africa ; Present address: School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, 1 Jan Smuts Avenue, Braamfontein, 2000 South Africa.
authors.forename: Danica
authors.initials: D
authors.lastname: Marlin
authors.affiliation: Centre for Invasion Biology, Department of Conservation Ecology and Entomology, Stellenbosch University, Private Bag X1, Matieland, 7602 South Africa.
authors.forename: John S
authors.initials: JS
authors.lastname: Terblanche
keywords: Body composition; Dehydration tolerance; Desiccation resistance; Starvation; Water loss