Fly parasitism in Papuan frogs, with a discussion of ecological factors influencing evolution of life‐history differences

Abstract

Dipteran parasitism of frogs in the Papuan region is described and aspects of the ecological interaction are detailed. The fly involved, Batrachomyia krausi, is the largest known member of an otherwise Australian genus. Larvae of this species develop in the lateral lymph sacs of frogs of the genus Rana, feed on host blood tissues, occur with high incidence and moderate intensity, yet exhibit minimal virulence. Minimal virulence and high infestation rate seen in this host–parasite system contrast with those reported for Australian congeners. These differences are hypothesized to derive from interaction of the large size of the Papuan parasite with its phylogenetically constrained life‐history. Differences in virulence exhibited between parasitic chloropids versus calliphorids and sarcophagids are discussed as consistent with ecological predictions based on parasite transmission dynamics.

Keywords:

• Anura
• Batrachomyia
• fly parasitism
• New Guinea
• Rana
• virulence

Acknowledgments

I thank F. Malesa, D. Salepuna, and J. Tekwae for field assistance; D. Mitchell and Conservation International for logistical assistance in Milne Bay Province; D. Libai, F. Malesa, and B. Salepuna for logistical assistance on Fergusson Island; B. Evans for compiling the figures; G. Shea for providing critical literature; D. Duffy for comments on the manuscript; the PNG National Museum and Art Gallery for providing in‐country collaborative assistance; and the PNG Department of Environment and Conservation, PNG National Research Institute, and Milne Bay Provincial Government for permission to work in Milne Bay Province. This research was supported by National Science Foundation grant DEB 0103794. This is contribution 2007‐010 to the Pacific Biological Survey.