Beyond the olive grove: exploring forest use and microclimatic associations of the olive fruit fly in a Mediterranean landscape

Abstract The olive fruit fly ( Bactrocera oleae (Rossi)) is a key pest of olive cultivation in Mediterranean agroecosystems and is traditionally studied almost exclusively within olive groves. However, under increasingly variable climatic conditions, particularly rising summer temperatures, this orchard-centred perspective may overlook important aspects of olive fly spatial behaviour. This study explores whether olive flies occur within adjacent forest habitats and whether such occurrences vary with distance from the grove and microclimatic conditions. Moreover, it examines whether microclimatic conditions are associated with occurrences outside the grove. Using a pilot field experiment, olive fly activity was monitored along a grove - forest gradient, including the grove interior, the grove - forest border, and pine forest habitats at 100 m and 300 m from the grove. Olive fly adults were detected not only within olive groves but also at the grove edge and inside the forest, with captures recorded up to 100 m and sporadically at 300 m from the grove. Activity declined sharply beyond the grove boundary, yet extra-grove occurrences were consistently observed. Microclimatic contrasts between olive groves and forest habitats were evaluated using temperature-based indices calculated for the five days preceding each sampling round. Differences in cool-hour exposure (< 23 °C) between grove and forest at 100 m were associated with the presence of olive flies inside the forest, whereas contrasts in extreme heat exposure (> 31 °C) showed no significant association. Although limited in scope, these pilot results support the feasibility of a landscape-based approach to olive fly ecology and provide a conceptual basis for investigating how adjacent forest habitats may influence OLF activity under different microclimatic conditions and at increasing distances from olive groves.