Biocontrol in insecticide sprayed crops does not benefit from semi-natural habitats and recovers slowly after spraying

1. To enhance biological pest control in crop fields, it is recommended to increase semi-natural area on farm and decrease insecticide spraying. While the benefits of semi-natural area for biocontrol in unsprayed fields are often demonstrated, it remains largely unknown if there are any benefits in real world, commonly sprayed crops. 2. Here, we explored the combined effects of semi-natural field margins and insecticide spraying on pest (cotton bollworm) egg predation in 53 Australian cotton fields and semi-natural field margins across two years. We used predation experiments close to field edges to exclude functional groups of predators depending on their spatio-temporal activity (diurnal vs. nocturnal and ground vs. canopy dwelling) and digital cameras to record natural enemy taxa responsible for predation. 3. Ground predation was substantially higher than canopy predation and its magnitude in unsprayed crops with semi-natural margins was similar to that within semi-natural areas. In ...