Vegetation Cover Management and Landscape Plant Species Composition Influence the Chrysopidae Community in the Olive Agroecosystem

Abstract

Habitat manipulation through the promotion of semi-natural habitats such as cover and patch vegetation is a possible means of offsetting the negative impacts of the agricultural practices. A baseline situation is crucial before any successful habitat manipulation is attempted. We studied the effects that current vegetation cover management practices have on plant composition and the potential attraction that the plant families from the semi-natural habitats could have on the Chrysopidae community, a key pest control agent, in five olive farms in Granada (Spain). Vegetation cover was assessed using a point quadrat methodology in eight transects per farm. In addition, the patch vegetation was characterized with 60 transects using a line intercept methodology. The woody patch vegetation and olive tree canopies were vacuumed using a field aspirator to collect adult Chrysopidae. In the cover vegetation we observed great variability in both the richness and diversity of plant communities caused by the vegetation cover management techniques and the transect position (in the middle of the rows or beneath the tree canopy). The plant families with the greatest plant cover were the Asteraceae and Fabaceae, where Asteraceae was favoured by tillage and Fabaceae by grazing, while in the patch vegetation, the predominant families were the Rosaceae and Fagaceae. Our results indicate that the genus Chrysoperla was mostly correlated with the Plantaginaceae, Brassicaceae and Asteraceae plant families in the cover vegetation, and with the Caryophyllaceae and Rosaceae families in the patch vegetation. The genera Apertochrysa and Pseudomallada were associated with the families Malvaceae and Poaceae in the cover vegetation, and with the families Cupressaceae, Poaceae and Pinaceae in the patch vegetation. Our study shows to the farmers the possibilities of vegetation cover management to select plant families for the cover vegetation.

Ant Community Is Not Influenced by the Addition of Olive Mill Pomace Compost in Two Different Olive Crop Managements

“…Other studies have been carried out on the olive crop in Spain (but also in other countries with extensive olive areas) to analyze the effect of different variables (such as crop and soil management from a broad point of view, landscape complexity, and others) on the diversity and complexity of soil and canopy inhabitants to maximize and strengthen resilience [14][15][16][17][18], natural biological control of some olive pests [19][20][21][22][23][24][25] or improve the presence of some particular natural enemies [26,27]. A general common result of these studies indicates that higher landscape complexity [17,18], organic management [19], the use of cover crops [16], and no-tillage [14,15] help to increase biodiversity, which ultimately can help to improve the control of some olive pests; the most important and cited are Prays oleae Bernard (Lepidoptera: Praydidae) [21,22,24] and Bactrocera oleae (Rossi) (Diptera, Tephritidae) [19,20].…”