The evolution of maize farming explains maize-herbivore and maize-microbiome interactions: Implications for pest management

The processes of maize (Zea mays mays) domestication from teosinte (Zea mays parviglumis), spread of maize farming from western Mexico to North America, and improvement through breeding since the early 20^th century are well documented. We assessed whether host plant resistance to Western corn rootworm (WCR) (Diabrotica virgifera virgifera) was affected by those three processes. Respectively, those processes were represented by comparisons between teosinte and Mexican landrace maize, Mexican landrace maize and US landrace maize, and US landrace maize and US elite maize. We found that WCR resistance declined with maize domestication and northward spread and increased with modern breeding. This dynamic was explainable in terms of a plant productivity-herbivory defense tradeoff mediated by environmental variation relevant to plant survival and reproduction. Additionally, we assessed whether the aggregate teosinte-maize microbiome was affected by domestication, northward spread, and modern breeding. We found that the microbiome of US elite maize was shaped by domestication and modern breeding, and that teosinte and maize hosted clearly divergent microbiomes. We hypothesize that the teosinte microbiome enhances plant survival and reproduction in marginal (non-agricultural) environments. Finally, we discuss some implications of our findings for pest management. We suggest that the results of our studies on maize resistance to WCR and the maize microbiome provide insights and potential solutions for developing evolutionarily and ecologically sustainable pest management solutions.