Orchard management practices may lead to changes in diversity of spiders

Apple orchards are a source of income for many farmers around the world. In France, they comprise approximately 54 000 hectares and are maintained with intensive spraying of pesticides. Orchard treatment practices can be split up into three approaches: conventional, integrated pest management (IPM), and organic. The conventional approach uses synthetic, non-selective chemical pesticides and is the most frequently implemented. IPM utilises lower impact environmental approaches, such as restricted pesticide application and pheromones that disrupt mating in pests. Finally, the organic approach also uses mating-disruption pheromones as well as biological insecticides, e.g. viruses that only affect certain pests.

Spiders play an important role in an ecosystem as natural pest controllers. They are also good indicators of habitat quality because they are generalist predators, present in most ecosystems, and fill many ecological niches. Many pesticides can directly and indirectly affect organisms other than the targeted pests, including spiders.

To see how ground (epigeal) spiders are affected by different orchard management strategies, researchers sampled 597 spiders using pit traps in 19 orchards in southeast France. The sampling took place in 2009 and 2010 in 19 orchards — five under each of the three management types, and four abandoned orchards used as controls. The researchers measured the abundance and number of spider species in each orchard, and also carried out a trait-based assessment to see how pesticides affected the individual traits of those species in each area.

To read the full article, follow this link.

Source:  "Science for Environment Policy": European Commission DG Environment News Alert Service, edited by SCU, The University of the West of England, Bristol.