The Invasion of South-Western Australia by the Orange Palmdart (Cephrenes augiades sperthias (Felder), Lepidoptera, Hesperiidae) and its Positive Effect on Species Richness
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Media type:
E-Article
Title:
The Invasion of South-Western Australia by the Orange Palmdart (Cephrenes augiades sperthias (Felder), Lepidoptera, Hesperiidae) and its Positive Effect on Species Richness
Description:
<p>The eastern Australian hesperiid, the orange palmdart (Cephrenes augiades sperthias (Felder), has spread throughout much of the Perth metropolitan are (Western Australia) and to several country centres in south-western Australia, since it was first recorded near Wanneroo, a northern suburb of Perth, in 1977. The dispersal pattern of this species suggests that it has been aided by humans carrying infested palms to several points, from where it has been able to diffuse (in the adult stage) into adjacent areas containing the larval foodplant. The success of this invasion can probably be attributed to Cephrenes pre-adaptation to the environment in which it found itself. The maximum area that this species can successfully invade in south-western Australia is limited by its oligophagy and possibly by winter minimum temperatures. Canary Island date palms (Phoenix canariensis Hort. and D. Chabaud), with fronds uninfested by C. augiades sperthias, in common with most exotic plants, have a depauperate associated fauna. The fronds of P. canariensis invaded by C. augiades sperthias tend to have a more diverse associated fauna than the fronds of palms that remain uninvaded. Evidence suggests that this is because the shelters constructed by C. augiades sperthias larvae are utilized by additional species and because new food webs are establihed. C. augiades sperthias appears to be performing the role of a keystone species, as defined by Vitousek (1986).</p>