Mature female apple maggot flies, Rhagoletis pomonella (Walsh) were released individually onto a single fruitless hawthorne tree in the center of an open field. This tree was surrounded by four 1 m$\sp2$ plywood host tree models painted green or white, with or without synthetic host fruit odor (butyl hexanoate), placed at one of several distances from the release tree. Each fly was permitted to forage freely on the release tree for up to 1 hour, or until it left the tree. Flies left the tree significantly sooner when green models with host fruit odor were present at 0.5 m, 1.5, or 2.5 m distance from the release tree than when these models were placed at a greater distance (4.5 m) from the release tree or when no models were present. These results suggest that female apple maggot flies did not detect green 1 m$\sp2$ models with odor 4.5 m away or models without odor 2.5 m or more away. Increasing model size to 2 m$\sp2$ increased the distance at which flies responded to green models without odor. Decreasing model size to 0.5 m$\sp2$ reduced fly responsiveness. The presence of host-fruit odor alone did not influence residence time on the release tree. Rate of movement and upwind orientation ($\pm$22.5$\sp\circ$) of individually-caged R. pomonella flies increased significantly over no-odor conditions in the presence of a stationary point source of butyl hexanoate at a distance of 12 m (P $\le$ 0.03) in an open grassy field, but not at 24 m. Increasing the rate of butyl hexanoate release from ca. 500 ug per hour to ca. 6000 ug per hour did not significantly increase distance of response. Take-off direction of R. pomonella from a platform in the center of a large open field was random with respect to wind direction when no host odor stimulus was present. Take-off direction was significantly biased upwind ($\pm$67.5$\sp\circ$) when 8 evenly spaced butyl hexanoate-filled vials surrounded the release platform in a circle with a radius 6 m (P $\le$.03), and downwind ($\pm$67.5$\sp\circ$) when the same number of vials encircled the platform at 12 m (P $\le$ 0.01). Similarly, take-off direction tended towards upwind when 16 evenly spaced butyl hexanoate-filled vials surrounded R. pomonella at 12 m (P $\le$ 0.10), and was significantly biased downwind at 24 m (P $\le$ 0.01).
| Identifer | oai:union.ndltd.org:UMASS/oai:scholarworks.umass.edu:dissertations-8376 |
| Date | 01 January 1992 |
| Creators | Green, Thomas Anthony |
| Publisher | ScholarWorks@UMass Amherst |
| Source Sets | University of Massachusetts, Amherst |
| Language | English |
| Detected Language | English |
| Type | text |
| Source | Doctoral Dissertations Available from Proquest |
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