Agroforestry has an impact on nocturnal predation by ground beetles and Opiliones in a temperate organic alley cropping system

Abstract The sustainability of organic vegetable cropping relies on ecosystem services such as biocontrol. Vegetable agroforestrycan combine perennial woody crops and non-woody crops, which may alter ground predatoractivity-density and predationpotential. We used living sentinel prey ( Cydia pomonella) to assess predationin two different months, as a function of three levels of canopy openness in an agroforestrysystem combining lettuce crops and grassy strips. Ground beetlesand arachnidswere sampled throughout the year and we analyzed summer data conjointly to assess potential differences in the activity-density of these major predatorsbetween treatments. We found significantly higher predationpotential in June in all agroforestrytreatments compared to the control. In August, however, no differences were observed. Ground beetlesand Opilioneswere the major predatorsinvolved in observed predationevents at both sampling periods. Differences in predationpotential in June (−35% in the control compared to agroforestrytreatments) could be due to differences in Pterostichus madidusand Opilionesactivity-density, which may have increased due to warmer temperatures under trees compared to the control plot.