Natural pest control in heterogeneous agricultural landscapes ultimately results from a network of trophic interactions among pest species and their predators. These interaction networks are not constant but vary across different spatial and temporal scales in dependence on the landscape context (Martin et al., 2013).

Important factors driving the dynamics of interaction networks are on the one hand spatial and temporal variation in the availability of different habitats and plant resources (crops, field weeds, non-crop habitats) and on the other hand the spatial population dynamics of pests and predators that determine how heterogeneous resource landscapes are utilized (e.g. reservoir effects, hibernation sites).

The effectiveness of natural pest control does thus not only depend on the character of the local cropping system, but also on neighborhood effects at the landscape scale (Tscharntke et al., 2016).

The research project aims at improving our understanding of how spatio-temporal variation of resource landscapes drives biotic interaction networks and consequently natural biological pest control in heterogeneous agricultural landscapes.

We will specifically address the following hypotheses:

• The NOcsPS variants support a higher local abundance, biomass and functional diversity of aphids' natural enemies than the conventional cropping system.
• At the landscape scale the spatial co-occurrence patterns of the study species are further determined by (i) field sizes, (ii) landscape structures and (iii) land use dynamics.
• The understanding of these effects on dynamic interaction networks enables the development of scenarios that optimize the predicted potential for natural pest control in the large-scale NOcsPS cropping systems.

The monitoring of aphids and antagonistic insects (Coccinellidae, Chrysopidae, Syrphidae) will be conducted at different spatial scales within the cropping system trials and on‐farm. In the first two years of our project we will then also collect data on farms that already apply pesticide‐free cropping systems. We will use a backpack insect aspirator to collect biomass samples that will be evaluated with respect to the abundance of the focal insects (aphids, Coccinellidae, Chrysopidae, Syrphidae).

Analyses are expected to show the effect of NOcsPS variants on the occurrence of aphids and natural enemies as well as the effects of landscape structure and landscape dynamics on the occurrence of aphids and natural enemies.

As a result, the assessment of landscape scenarios for the implementation of NOcsPS cropping systems will be evaluated.