Wheat genotypic diversity and intercropping to control cereal aphids.

• Cultivar mixture was more infested by aphids than the least susceptible cultivar. • Intercrops tended to be less infested by aphids than wheat monoculture. • Combining genetic and species diversity did not better than each individual practice. • Wheat yields were reduced in intercropping, but not in cultivar mixtures. Increasing intrafield plant diversity has been shown to regulate pest populations. Mixing wheat cultivars and intercropping winter wheat and white clover are both promising agroecological practices. On field experiments over two growing seasons, we combined both practices and examined the impact on aphid populations and on wheat production. Results show that combining intra- and interspecific diversity did not outperform each practice individually in reducing aphid populations. Taken separately, intercropping tended to have lower aphid infestation, while it was intermediate in cultivar mixtures. Yearly variation in climatic conditions impacted wheat and clover development, as well as the appearance of aphid peaks. Wheat yields and grain nitrogen content were reduced in intercropping by 10% and 7%, respectively, but not in cultivar mixtures. Our findings suggest that intrafield diversification may regulate wheat aphids to some extent, but combining two diversification practices did not result in an attractive trade-off between pest regulation and wheat production in real farming conditions. [ABSTRACT FROM AUTHOR]