Unravelling pest infestation and biological control in low-input orchards: the case of apple blossom weevil

Abstract

Low input farming is an alternative production system that provides a great opportunity to disentangle the natural mechanisms regulating crop pests, since neither pests nor their natural enemies are disrupted by pesticides. Here we use a key apple pest in Europe, the apple blossom weevil (Anthonomus pomorum), as a model case to unravel the factors driving pest infestation and its biological control in a low input context, namely the cider apple orchards of NW Spain. We applied a holistic approach based on the complete life-cycle of the pest, and combined large-scale observation (23 orchards) with small-scale experimental assessment. Weevil attack (0.4-37.4% of flowers) increased with the proportion on apple trees in the immediate orchard neighbourhood, and with semi-natural woody habitat in the surrounding landscape, and decreased with tree distance to orchard edge and apple bloom level. Thus the prevalence of the pest depended on the availability of the various resources required for foraging, egg-lying and overwintering. Three types of natural enemies supplied complementary pest control by preying on weevils at different stages in their lifecycle: seven parasitoid species attacked immature weevils (6.4-81.5%) while the additive effects of birds and crawling arthropods were evident in terms of the removal of adult weevils (31-44%). We conclude that the effective biological control of A. pomorum can be achieved in low input systems to maintain the pest at non-harmful levels, through combined management of the pest, its habitat and its natural enemies.

Birds and human health: Pathways for a positive relationship and improved integration

“…2017). Another article presented evidence for birds as a promising alternative to pesticides for controlling weevils (Miñarro & García 2018).…”

“…One article found that the use of natural enemies, specifically raptors predating on vole populations, was as effective as rodenticide use with the added benefit of reduced costs for the farmer (Machar et al 2017). Another article presented evidence for birds as a promising alternative to pesticides for controlling weevils (Miñarro & Garc ıa 2018).…”

Review: Presence, distribution and current pesticides used in Spanish agricultural practices

“…This analysis was carried out in the three main maize growing areas in Spain: the northeast (Catalonia and Aragón), central Spain (Madrid and Castilla-La Mancha) and the southwest (Extremadura and Andalusia). Also, Miñarro and García (2018) carried out a comparative study distributed over a 600 km 2 area in Asturias, to determine the factors driving pest infestation, in which three of the orchards were organic, one applied the broad-spectrum insecticide Lambdacyhalothrin and the rest followed IPM guidelines. Additionally, Sánchez-Moreno et al (2018), assessed the effects of organic farming with Bacillus thuringiensis on pest control, soil diversity and functioning in Castilla La Mancha.…”

Morphological and olfactory tree traits influence the susceptibility and suitability of the apple species Malus domestica and M. sylvestris to the florivorous weevil Anthonomus pomorum (Coleoptera: Curculionidae)

“…Zabrodina et al (2020) call the apple blossom weevil “one of the most harmful insects in horticulture” and report yield losses for Russia and the Ukraine of 50–100 %. The increasing pest status of A. pomorum poses a serious threat to organic apple orchards and integrated pest management (IPM) systems currently in use in European apple orchards ( Miñarro & García, 2018 ; Shaw, Nagy & Fountain, 2021 ).…”