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Under the supervision of Muriel Valantin-Morison (INRAE), Antoine Gardarin (AgroParisTech) and François Chiron (ESE Lab - AgroParisTech and Paris-Saclay University)

The defense of Lola Serée's PhD thesis will take place on March 23 in Paris:practical information

Summary:

Agriculture's dependence on pesticides is struggling to reduce and biodiversity in agricultural areas continues to decline. Today's cropping systems must progress towards strengthening ecological processes to move towards agro-ecological management of crop health, which requires a deeper understanding of the regulation by predators and parasitoids, and their determinants. Moreover, very little knowledge exists on the multifunctionality of arable crop systems.
The objectives of this thesis are to evaluate (i) how perennial flower strips, inserted in contrasting cropping systems, modify multitrophic communities, biological regulations, and the resulting ecosystem goods and services, and (ii) the multifunctionality of cropping systems supported by a flower strip.

To this end, a network of 31 farmers implementing organic, conservation tillage or conventional cropping systems is being mobilized in the Parisian basin. Within this network, we compared pairs of field crop plots with and without flower strips, and characterized biodiversity, biological regulation services on several crops, cultural service, and agronomic and economic performance.

First of all, our results show that the effect of flower strips depends on the type of cropping system in which they are implemented and on the taxon considered. The regulation of oilseed rape pests is little affected by the presence of a flower strip but it increases with the trophic resources provided by weeds in the field. On faba bean, trophic resources at the edge of the field increased the abundance of hoverflies and green aphid mummies, but this did not result in increased aphid regulation. Food web analysis suggests that birds are poorly connected to epigean arthropods and do not predate predators. Our results also indicate an important role of carabid beetles in the biological regulation of phytophagous insects.

In a second step, a survey of citizens on the aesthetic and biodiversity perception of agricultural fieldsrevealed a strong preference for cropping systems with the most soil cover and diverse vegetation, both cultivated and uncultivated. These systems are similar to those in conservation agriculture.

Finally, we evaluated the multifunctionality of cropping systems, in plots with and without flower strips. Cropping systems with high biodiversity use show a more balanced profile between the goods and services provided. Cropping systems with conservation tillage or high diversity are slightly less efficient in terms of yield and profits but are more efficient in terms of cultural services, and seem to be more favorable to biodiversity when associated with a flower strip.

In conclusion, we show a complementarity between the presence of a flower strip and the different cropping systems in the supply of ecosystem goods and services. They suggest that biodiversity-based systems, in the plot and its surroundings, strengthen the multifunctionality profile of cropping systems.

CV de Lola Seree