Master's Student Eastern Illinois University Baton Rouge, Louisiana, United States
Plant genetic diversity (PGD) is related to population success, pathogen resistance and arthropod communities in many natural systems. This effect however is not universal across cultivated systems and environmental gradients. Plant genetic diversity in crops is expected to generate variation in plant defensive traits, so diverse populations should generate turnover in associated arthropod communities. In contrast, genetically uniform crops would be expected to be equally susceptible to herbivores, generating more uniform arthropod communities. We explored arthropod communities on hazelnuts (Corylus spp), a potential commercial crop for the Midwestern US, to determine if PGD affected associated arthropod communities.
We sampled the arthropod communities of two genetically diverse seedling lines and two genetically uniform clonal lines, planted in three model agroecosystems across central Illinois, USA. We assessed measures of arthropod abundance, diversity, and composition across trophic levels. Non-metric multidimensional scaling analysis and associated permutational MANOVAs were used to determine if arthropod community composition varied between hazelnut varieties and across sites.
There was strong variation in arthropod community composition and diversity across sites and some hazelnut varieties, with site driving much of that variation. Despite significance among varieties, there was no consistent pattern to arthropod community variation across diverse and clonal hazelnut varieties. Clonal lines supported both the most and lease diverse arthropod communities, while composition only varied within seedling lines. Multivariate dispersion analysis found one clonal line supported higher compositional variation than either of the seedling lines or the other clonal line. Herbivore composition and diversity varied among hazelnut varieties; however only one seedling line differed in composition to the other seedling line, and the same clonal line that supported greater relative abundance supported lower herbivore diversity than all other lines. Predator and parasite composition and diversity varied among hazelnut varieties, but differences were only between seedling lines. While this study does suggest that hazelnut varieties drive arthropod community composition, plant genetic diversity did not have the expected direct effect of consistently increasing arthropod abundance and diversity compared to the genetically identical lines.