Document: STE-3-87-6

The invasion of the solanaceous fruit fly on the island of Maui: An example of an invasion cascade.

PECK, S.L.*

Brigham Young University, Provo, UT 84602 USA ¹

Abstract:
The presence of the solanaceous fruit fly (Bactrocera latifrons) in the Hawaiian Islands serves as a reservoir for introductions into subtropical areas of the U. S. mainland, therefore understanding its invasive abilities is imperative. The fly was first detected on Oahu in 1984 and has since been found on all of the major Hawaiian islands. Here, the question of whether the fly could have invaded the island without the prior invasion of two wild host plants Solanum sodomeum and Solanum torvum is examined using spatial stochastic simulation modeling. To parameterize the model and understand the population dynamics of the fly, two populations of B. latifrons were studied for six months using weekly protein bait and male lure trapping. In addition, fruit from the two species of invasive plants were gathered. Flies were then reared from the fruit in order to assess the infestation level. To examine the movement of the flies, individuals reared from wild host plants were marked with a vertebrate IgG protein and then released. Recaptured flies were assayed for the presence of the protein using ELISA. This method marks the fruit flies both internally and externally and has been found to be stable in the field for more than five weeks. Using this data, information on the movement and dispersal ability of the fly was quantified and used in the model. The model, written in the mathematical matrix language MatLab, suggests that the fly would have been unable to invade the islands if the prior invasion of the wild host plants had not reached the islands first. This study gives evidence of an "invasion cascade" where secondary invasions are predicated on prior invasions of other species.

Keywords: invasion biology, fruit flies, movement, dispersal, agricultural pests

This abstract is being presented at: 9:45 AM in session:
Oral Session #26: Invertebrate Herbivore - Plant Interactions.