S14 - Session O1 - Different management strategies for non-cropping plants in pear orchards and their impact on biological control

Authors: Tim Belien, Ammar Alhmedi *, Dany Bylemans

Climate change is real, and the use of synthetic chemicals in agrosystems is becoming increasingly restricted due to several environmental concerns. Modern agricultural systems have been designed by strategies aimed at maximizing the crop productivity, while there are increasing calls for healthy agroecosystems or so-called, green marketing systems. The suppression of pest populations in fruit tree crops by natural enemies can help in providing such kind of healthy environment. However, the role of natural enemies in maintaining pest control in field condition is controversial and needs more scientific support via practical research to be accepted and adopted by farmers. Functional biodiversity is of major value for pest control. The provision of flowering plants in horticultural cropping systems to enhance natural enemies is a key practice for pest control. However, natural enemies are influenced by non-crop habitat and understanding how habitat manipulation patterns influence natural enemies is essential to predicting how landscape alters biological control services. Here we focus on biological control of pear psylla, Cacopsylla pyri L., a destructive pear pest. The key question addressed in the present work is whether the temporal variation in management strategies applied by growers on the non-cropping plants can make difference in term of natural control provided by natural enemies against C. pyri in organic pear orchards. To answer this question, we assessed the impact of two different management types on natural control level of pear psylla. Flowering plants and weeds growing in study orchards were fortnightly managed (or so-called short-term management type) in one orchard, and with intervals 3-4 weeks (or so-called long-term management type) in the second orchard since the second half of May until the harvest. There was a significant impact of management type on the infestation level of pear psylla. A clear impact of the short-term management tactic on psylla population was observed since the second half of June onwards. Moreover, higher severe-infestation levels of C. pyri were observed in the orchard associated with long-term management, while more healthy, slight to moderate infestation levels were found in the orchard associated with sort-term management of non-crop plants. Our study provides new insights into the impact of management types of non-crop habitat on the natural control of C. pyri in organic pear orchards. Conclusion. Weather conditions and plant-insect interactions, and thus the appropriate management tactic of non-crop plants, vary between years. To cope with unpredictable changes in environmental conditions, there is need to an adaptive management strategy based on the predictive mathematical models that can help the farmers facilitate the monitoring of pests and their natural enemies, and thus the related efficient management type in space and time.