Influence of Habitat Structure and Resource Availability on the Movements ofRhagoletis indifferens(Diptera: Tephritidae)

Abstract

Habitat structure and resources availability may differentially influence movement between habitat patches. We examined fly movement decisions (stay or leave) at the scale of individual trees by measuring the response of marked Rhagoletis indifferens (Diptera: Tephritidae) to sweet cherry trees (Prunus avium) that were manipulated by changing the shape of the tree (structure treatment = normal or reduced) and the fruit load (fruit treatment = augmented, normal, or reduced). More than 600 observations were made at two field sites that differed in the average inter-tree distance: Senger site, 10.1 +/- 4.5 m; Tuemp site, 29.0 +/- 19.3 m. At the Senger site, flies were resighted most often in the normal structure-augmented fruit trees. At the Tuemp site, however, there were fewer transfers between trees, unusual tree preferences, and significant treatment interaction terms. Using a first principles diffusion model of attraction and by varying fly perceptual range to limit tree choice, we generated unusual tree preferences based on differential attraction to individual trees. Our results suggest that manipulating tree attractiveness may be a viable pest management strategy for closely spaced trees but not for dispersed trees. Further study into the relationship between the spatial arrangement of trees and the flies' ability to detect specific tree characteristics is warranted.