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

Climate change is real, and the use of synthetic chemicals in agrosystems is becoming increasingly restricted due to environmental and human concerns. Modern agricultural systems have been designed by strategies aimed at maximizing the crop productivity, while there are increasing calls for healthy agroecosystems. 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 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. Understanding how habitat manipulation patterns influence natural enemies is essential to predicting how landscape alters biological control services. 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 the destructive pear psylla Cacopsylla pyri L. in organic pear orchards. To answer this question, seasonal abundance and presence frequency measurements were used to determine 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 in one orchard, and with intervals of 3-4 weeks in the second orchard. 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.