The potential of genotypically diverse cultivar mixtures of wheat for controlling aphid populations

Productivity in agricultural fields may be maintained with fewer pesticides by increasing the diversity within these agroecosystems. While there are some major challenges to increasing plant-species diversity in agricultural landscapes, little research appears to have considered pest-control benefits associated with increased genotypic diversity in field crops even though crop fields tend to have low intraspecific diversity. Recent research in “natural” plant systems has revealed that plant genotypic diversity can strongly influence arthropod diversity and primary production, but it is unclear if these findings can extend to insect pest management in field crops. To assess the pest-management potential of increased genetic diversity in field crops, we performed greenhouse experiments with wheat monocultures and cultivar mixtures in the absence and presence of bird cherry-oat aphids (Rhopalosiphum padi). In the absence of aphids, pots planted with genotypically diverse six-line mixtures grew significantly more biomass than those planted with monocultures, while three-line mixtures had intermediate biomass. Mixtures also released more complex volatile blends and more total volatiles than monocultures. In the presence of aphids, mixtures and monocultures produced similar amounts of biomass, but aphid populations on mixtures were significantly moderated relative to those on monocultures. Moreover, peak aphid population size on the six-line mixture was approximately half of the aphid population that developed on monocultures. Our results support the hypothesis that more diverse plant communities are more resilient in the face of pest populations and suggest that genotypically diverse cultivar mixtures hold much potential to contribute to improved insect pest management in field crops.