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Sammanfattning

Ecological intensification aims to sustain crop yields by enhancing ecosystem functions, yet its performance across the diverse environments of sub-Saharan Africa is not well understood. Drawing on data from four East African countries, this thesis investigates how push-pull (PP) cropping system interacts with soil conditions and landscape structure to influence natural enemy communities, lepidopteran pest regulation and Striga weed suppression. Across countries, natural enemy communities were dominated by ants, and the overall abundance and diversity of natural enemies varied with landscape heterogeneity, cropping season and elevation. However, landscape effects were only present in Kenya. The push-pull system increased natural enemy abundance only in landscapes with high forest cover, while reduced crop cover, greater grass cover and configurational heterogeneity tended to reduce natural enemy abundance. Reduced crop cover, greater grass cover and configurational heterogeneity were also associated with lower pest damage, most likely due to mechanisms other than predation. PP cropping increased pest suppression in Uganda and Ethiopia, whereas no effects were detected in Kenya or Rwanda, although pest damage varied with seasons in Rwanda. At the soil level, PP fields with high Desmodium cover had elevated SOM, N, and P, but responses differed among countries. Field age produced divergent soil trajectories, with some older PP fields showing acidification and others accumulating SOM. Striga weed suppression demonstrated context dependency: PP was most effective in uniformly nutrient-poor or physically constrained soils, while in countries with limited soil variation or low seedbank pressure, soil interactions could not be detected. These findings highlight that PP is a context-dependent system whose effectiveness varies across ecological gradients. Aligning PP with local agroecological conditions is therefore essential for achieving consistent and sustainable outcomes in smallholder farming systems.

Nyckelord

biocontrol; ecological intensification; fall armyworm; landscape; natural enemies; pests; soil fertility; stemborer; Striga; biologisk bekämpning; ekologisk intensifiering; höstarmélarv (Spodoptera frugiperda); landskap; naturliga fiender; skadegörare; markbördighet; stamborrare; Striga (häxaört)

Publicerad i

Acta Universitatis Agriculturae Sueciae
2026, nummer: 2026:7
Utgivare: Swedish University of Agricultural Sciences

SLU författare

UKÄ forskningsämne

Markvetenskap
Jordbruksvetenskap

Publikationens identifierare

  • DOI: https://doi.org/10.54612/a.mnr64efddg
  • ISBN: 978-91-8124-204-1
  • eISBN: 978-91-8124-224-9

Permanent länk till denna sida (URI)

https://res.slu.se/id/publ/145003