Does pecan population structuring predict resistance to pecan aphids? Aphid performance and plant physical defenses across a broad sample of native pecans

Host plant resistance is considered a cornerstone of pecan IPM and also an obvious way to increase profitability while minimizing environmental impacts of pecan production. The goals of our study were to: (i) characterize resistance to aphids and other insects in indigenous pecan populations from across the USA and Mexico, and; (ii) address whether known patterns of genetic structuring of pecan populations are correlated with patterns of insect resistance. Indigenous pecan populations are genetically structured into three “Groups”: Southern (<23 ° N latitude), Central (>23 ° to <33 °), and Northern (> 33 °), and trees corresponding to each of these groups are available in a common-garden at the USDA Provenance Orchard, Somerville, TX. Resistance in each of nine indigenous populations (three per Group) will be characterized through assessments of aphid performance (abundance, body weight) and plant physical defense traits (trichomes, leaf specific weight and dry matter). We will use Multivariate ANOVA and other statistical methods to address structuring and resistance traits among the nine indigenous pecan populations.