Abstract/Summary

Conservation biological control has been proposed as a practice that can improve the sustainability of farming by reducing the need for synthetic chemical insecticide use and increasing resources for insect conservation. However, measures to help implement conservation biological control often do not result in increased delivery of pest control in crops and require land to be taken out of production. Carrot growers are keen to investigate how flower strips can be included in their fields to control insect pests and support pollinating insects but want to optimise the use of these strips. This thesis evaluates the efficacy of various annual seed mixes, tested over three seasons in attracting key ecosystem service providers and delivering pest regulation in the crop. Critically, the effects of the mixes on yield and quality variables at harvest were also assessed. Finally, the commercial implications of these flower strips are investigated. Invertebrate sampling in trials across the plot, field and commercial-scale revealed that seed mix composition manipulated insect community composition, but cannot be linked with direct evidence for pest control delivery as assessed by pest aphid numbers, sentinel prey predation, and insect-damaged carrots. There was, however, indirect evidence for pest control delivery, suggesting that flowering strips can increase net carrot yield. However, these benefits were most apparent at the field edge and depended on spray regime and any existing edge effect strength. Furthermore, when the commercial implications of flower strips are subsequently analysed, flower strips incur significantly more cost in the field interior. The analysis of flower-insect visitor networks across all three trials shows that the Phacelia and Cornflower mixes best support flower visitors. This thesis demonstrates that flower strip plant composition can be tailored for pest control and insect conservation aims, and their spatial placement can be optimised to minimise barriers to adoption from growers.