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Research article - Peer-reviewed, 2023

Mixed effects of oak woodlands on biocontrol potential and pest pressure in olive orchards under management intensification

Vasconcelos, Sasha; Pina, Silvia; Jonsson, Mattias; Heleno, Ruben; Herrera, Jose M.; Moreira, Francisco; Silva, Bruno; Melguizo-Ruiz, Nereida; Daouti, Eirini; Jimenez-Navarro, Gerardo; Beja, Pedro


Public health and environmental concerns are increasing the pressure to reduce chemical pesticide usage, thereby requiring management alternatives to control pest damage to crops. Retaining semi-natural habitats within agricultural landscapes is often assumed to be one such alternative, by contributing to boost natural enemy populations and reduce pest abundance and spread. However, these potential benefits might be diluted or counteracted by intensive field management, thus limiting their effectiveness. We test these hypotheses, focusing on olive farming in southern Portugal, where we quantified the abundance of three pests, the olive fruit fly (Bactrocera oleae), olive moth (Prays oleae) and olive psyllid (Euphyllura olivina), and their parasitism and infestation rates in 17 orchards representing an intensification gradient and varying landscape cover by oak woodlands. Fly infestation was lower in more intensive orchards, there were no woodland effects, and parasitism was never detected. Psyllid infestation was also lower in more intensive orchards, but declined with woodland cover in more intensive orchards, while slightly increasing in less intensive ones. Psyllid parasitism rate could not be confidently estimated. Moth infestation declined with woodland cover in the most intensive orchards, while varying little in less intensive orchards. Moth parasitism rate declined with intensification and increased with woodland cover, particularly in less intensive orchards. Infestation by the moth was positively related to its abundance, albeit less so when parasitism rates were higher. Overall, our findings show mixed effects of oak woodlands, although retaining such habitats might still enhance biocontrol potential and reduce pressure by some pests, even under management intensification.


Agricultural intensification; Mediterranean; Olea europaea; Biological control; Parasitoids; Structural equation models

Published in

Journal of Pest Science