Spatial structure of olive groves and scrublands affects Bactrocera oleae abundance: a multi-scale analysis

Abstract

Environmentally friendly measures are needed to achieve natural pest control. A relationship between landscape structure and Bactrocera oleae, the main olive grove pest, indicated a general association between complex landscapes and reduced abundance of the insect. In this work we have characterised the relationship between spatial structure of specific land uses and the olive fruit fly abundance at different scales (from 600 to 2000 m radius). We paid special attention to the dominant land use in the studied area, the olive crop, and the surrounding natural land uses. In the landscape analysed the spatial arrangement of olive and scrubland patches showed a gradient of situations from areas with an abundance of olive area distributed in very few patches close to each other to landscapes with less olive area arranged in many patches and with larger scrubland areas. Linear mixed-effects models showed that the abundance of B. oleae is positively related to the proximity of olive patches at all studied scales. However, other landscape characteristics (total area of olive groves and scrublands) were differentially related to pest abundance depending on considered scales. According to the obtained results it is advisable to plan olive groves at a 1000–1500 m radius spatial scale, in which the role of scrublands regarding B. oleae population is favoured. The best planning option for the olive grove landscape is discussed in the “Land sharing-Land sparing” context.