Spatial arrangement of intercropping impacts natural enemy abundance and aphid predation in an intensive farming system

Abstract

Crop diversification is an increasingly recognized management strategy to support biodiversity and ecosystem services, like pest and disease control, in agricultural systems. However, a significant obstacle to its adoption is the potential trade-off between ecosystem services and optimizing yields. We used a two year, on-farm study in Eastern Germany to test how different spatial arrangements of soy (Glycine max L.) and winter wheat (Triticum aestivum L.) can affect pest abundance, aphid predation, and natural enemy biodiversity as well as yields. We compared conventional sole cropping to three types of spatially diversified cropping systems: relay intercropping, wide strip cropping, and patch cropping. Strip cropping generally supported some of the highest levels of carabid abundance both years and spider abundance in 2022 without any yield penalties. While the relay system failed due to insufficient precipitation, strip cropping produced similar or higher yields than sole cropping (124 % and 96 % of the sole wheat yield and 96 % and 109 % of sole soy yield in 2022 and 2023, respectively). Strip cropping supported significantly more carabid beetles compared to sole cropped soy both years and sole cropped wheat in 2022. We found significantly different carabid community composition between wheat strips and patches and the corresponding soy strips and patches. There were no differences in aphid abundance between systems. Nevertheless, we found 51 % and 36 % higher aphid predation rates in wheat strips compared to wheat patches in 2022 and 2023. Our results provide initial insights into the potential of strip cropping to support both natural enemies and yields while also being an approachable diversification strategy for farmers.