Toxicity of green tree frog (Litoria caerulea) skin secretion to the blowflies Calliphora stygia (Fabricius) and Lucilia cuprina (Wiedemann) (Diptera: Calliphoridae)

Abstract

Many instances of attack by flies (Diptera) upon adult amphibians have been reported. The green tree frog (Litoria caerulea) produces a skin secretion that protects the frog from infection and predation. In this laboratory study, we tested the secretion for its effect on two calliphorids, the Australian sheep blowfly, Lucilia cuprina, and the eastern goldenhaired blowfly, Calliphora stygia, to investigate the role of frog skin secretion in defence against dipteran attack. Topical application to L. cuprina larvae caused mortality, resulting in the eclosion of fewer flies. Direct application upon C. stygia adults caused mortality, whereas introducing the secretion into food caused mortality as well as reduced feeding rates. Results suggest that both physical and chemical properties of the secretion play a role in its toxicity. The skin secretion of L. caerulea may be effective in the defence of this frog against Diptera in general; however, it may have evolved initially in response to attack by particular flies of parasitic genera.