Location: Fruit and Vegetable Insect Research
2013 Annual Report
A series of field experiments on Tinian Island tested a variety of known wasp attractants and baits, and fermented sweet baits and fruit juices to determine if the pest Polistes stigma could be trapped with any of these materials. All of these experiments yielded negative results. Subsequent observation of Polistes stigma on Tinian Island showed a consistent feeding by the wasp at several species of flowers. Work on chemical attractants then shifted to consideration of possible wasp orientation to the volatile chemicals produced by these plants and flowers. Chemical samples of flower odors were obtained using a field-portable volatile collection system. The flower chemistry was then characterized for a Euphorbia species, Colubrina asiatica, and an Ipimorpha species, using combined gas chromatography and mass spectroscopy. Subsequent analysis using GC-EAD, combined gas chromatography/electroantennography, showed consistent responses by wasp antennae to several of the compounds from each of the three species of plant. Additional work is planned to test for wasp attraction to those compounds, using both a laboratory olfactometer assay, and field testing using traps. The makeup of the species of social or stinging wasps was determined for Tinian and Saipan of the Northern Marianas Islands, at four times over the life of the project. This was accomplished by the netting of large numbers of wasps on and about vegetation, and the collection and analysis of over 100 wasp nests. Polistes stigma was always dominant on Tinian Island, with small numbers of Ropalidia marginata. On Saipan, Ropalidia marginata appeared to be dominant, with fewer numbers of Polistes stigma present.