The benefits within: Can increased crop genotypic diversity help manage insect pests?

Ecosystems with high plant diversity benefit from complex ecological interactions that can help improve the system’s productivity and resistance to perturbation. Modern agricultural fields often lack the ability to take advantage of these interactions because they primarily consist of low diversity monocultures of a single variety of a single crop species. Promisingly, mounting evidence suggests that plant intraspecific (i.e. genotypic) diversity can be as important as interspecific (i.e. species) diversity in structuring arthropod communities and lowering herbivore abundance. We expanded upon promising work from our lab to further test the pest management potential of increased genotypic diversity. We increased genotypic diversity and intraspecific plant-plant interactions within a wheat model system by increasing variety diversity. In a combination of greenhouse  and lab experiments, we compared plant biomass and populations of bird cherry oat aphid (Rhopalosiphum padi) in pots with low and high genotypic diversity. Low diversity treatments consisted of monocultures of a single variety, while high diversity treatments contained all possible four-variety mixtures chosen from a pool of six varieties. In addition, we measured the response of natural enemies of the aphid to the diversity treatments to assess the effect of genotypic diversity on top-down control of insect pests. Our results thus far appear to indicate that the intraspecific plant-plant interactions in variety mixtures can affect herbivorous pests. Importantly, our results build upon recent work in natural and agricultural systems that has exposed the significance of plant intraspecific diversity and suggest that increasing crop genotypic diversity has potential as a readily adoptable pest management tactic.