Spider Diversity in the Olive Grove Agroecosystem (Türk___ye); Potential Bioindicators

Spiders, as a predatory group, are frequently encountered in agricultural areas and play a crucial role in maintaining ecological equilibrium. In European olive groves, spiders have been identified as significant contributors to the reduction of pest populations. However, there is a noticeable scarcity of studies focusing on spider diversity in Turkish olive groves, particularly within Balıkesir province, a region that holds considerable importance in olive cultivation. The determination of spiders, acting as natural areas to olive grove pests, has not been subject to research in this province. This study aims to address this research gap by investigating the diversity of spiders in olive groves across five regions in Balikesir province, situated in the North Aegean region of Türkiye. A total of 85 areas, encompassing both ground-dwelling and canopy species, were examined. Thomisidae, Salticidae, Araneidae and Philodromidae were identified as the dominant families, with Philodromus rufus (Walckenaer, 1826), Tmarus piochardi (Simon, 1866), Salticus noordami (Metzner, 1999), and Pseudicius palaestinensis (Strand, 1915) being the most frequently encountered specimens. An interesting observation pertains to the coexistence of the olive fly population, Bacterocea oleae (Rossi, 1790) (Diptera: Tephritidae), with spiders. It was revealed that the density of spiders exhibits an inverse relationship with the density of olive flies. While the species identified as dominant among spiders show potential as biological control agents against B. oleae, further research on this subject is warranted. Additionally, this study marks the first inclusion of Pseudeuophrys vafra (Blackwall, 1867) (Salticidae) in the spider list of Türkiye. We suggest that Philodromus rufus (Walckenaer, 1826), Tmarus piochardi (Simon, 1866), can be as a potential bioindicator for the olive grove.