Ant community potential for pest control in olive groves: management and landscape effects

Ants are important pest control agents in many agroecosystems worldwide. However, little is known about how management, ecological contrast generated by different agricultural practices, and landscape complexity affect their communities and the potential pest control that they can provide. Here, we surveyed ant communities in 40 paired olive groves with different ground-herb cover management across 20 localities spanning a wide range of landscape complexity at the regional scale. We also conducted experiments with dummy plasticine models in 18 of these groves to explore the ant potential to control the two main pests of the olive tree (olive moth and olive fly). In addition, we calculated an index, the Ant-community Predation Function (APF), which informs about the predation pressure exerted by ant communities over these pests. Results show that: a) extensive management at intermediate landscape complexity maximizes the abundance and pest control by ants; b) the ecological contrast affects ant abundance and ant richness but does not impact the predation function; c) APF is a good measure of pest control potential at the community level; and, d) Tapinoma nigerrimum is an important ant species for pest control in our system, which seems little affected by local or landscape heterogeneity. This study advances our knowledge about local management and landscape effects on ants and their potential contribution to pest control in olive groves. Extensive herb cover management and landscape heterogeneity increased ant predation pressure in olive groves.