Monday, December 10, 2007 - 9:41 AM

Evaluation of the impact of exotic parasitoids on the native Hawaiian moth Udea stellata (Lepidoptera: Crambidae)

Leyla V. Kaufman,, University of hawaii at Manoa, Plant and Environmental Protection Sciences, 3050 Maile Way. Room 310, Honolulu, HI and Mark G. Wright,, University of Hawaii - Manoa, Plant and Environmental Protection Sciences, 3050 Maile Way. Room 310, Honolulu, HI.

The impact of alien species on native organisms is a cause for concern worldwide, with biological invasions commonplace today. Suppression efforts targeting many invasive species have included introductions of biological control agents. The numerous releases of biological control agents in the Hawaiian archipelago have resulted in considerable concern for non-target impacts, due to high level of parasitism. This study investigated the impact of introduced Hymenoptera parasitoids on a Hawaiian moth. The endemic Hawaiian moth Udea stellata (Butler) has seven alien parasitoids associated with it, two purposely introduced, three adventive, and two of uncertain origin. The objective of this study was to determine the relative contribution of parasitoid species, to the population dynamics of U. stellata by constructing partial life tables. Marginal attack rates and associated k-values were calculated to allow comparison of mortality factors between experimental sites. Sentinel larvae were exposed on host plants in the field, where they were exposed to parasitoids and other sources of mortality for three-day intervals in open and exclusion treatments. Results showed that the factor that consistently had the most contribution to total mortality at all sites was larval disappearance, which in large part is the result of predation, but also larval migration. Adventive parasitoids inflicted greater total larval mortality attributable to parasitism than purposely introduced species.

Species 1: Lepidoptera Crambidae Udea stellata