Interactions between conservation agricultural practice and landscape composition promote weed seed predation by invertebrates

Assuring future crop yields whilst minimising impacts of agriculture on the environment requires that we adopt managements that replace pesticides by fostering pest regulation. However, large-scale empirical evidence for in-field and landscape properties supporting natural enemy abundance and their regulation of pests, as an ecosystem service in agriculture, is scarce. Using data from 67 arable fields, we examined whether the duration of adoption of in-field conservation agricultural practices (CA) and the landscape context of those arable fields explains the levels of in-field weed seed predation. Our results indicate that landscape and CA, in interaction, do indeed explain a large proportion of the observed variation in weed seed predation in-field. CA practice maintains high in-field abundances of carabids, but only after a period of four years of adoption. Prior to this, carabid abundance was only high for fields in landscapes with high percentage cover of arable crops and/or permanent grassland. Our work shows that the effect of landscape composition is conditional on local in-field management and that both local and landscape scales can be used to enhance the abundance of carabid beetles and the amount of seed predation in arable fields.