The Spider Assemblage of Olive Groves Under Three Management Systems.

Olives, Olea europaea L., are one of the most important crops in Spain. They are currently produced under three management systems that involve different aspects of soil and pest management, productivity, and crop economy: organic, (integrated pest management-IPM), and conventional. Here, we studied how these systems affect the spiders, the natural enemies of olive grove pests, and performed a detailed analysis of their assemblage. The study was performed during one season in 18 olive groves in Andalusia, Spain, and included both ground-dwelling and canopy species. We found that the organic system supported a significantly higher level of abundance and diversity of canopy spiders than the IPM and conventional systems. Plowing had a negative effect on spider abundance and diversity. However, the presence of hedge vegetation had a positive effect on the spiders. The practices affected the guild structure differently, with some guilds supported by organic and others by IPM. It is suggested that sustainability (in terms of pest control) in olive grove agroecosystems may be obtained by maintaining hedge vegetation regardless of the management system.