Comparing host-plant resistance to herbivory between domesticated and wild highbush blueberry populations in southern New Jersey
The effects of domestication on resistant traits against herbivory are poorly understood in general, and not at all for highbush blueberry (Vaccinium corymbosum). Theory predicts that selective breeding for increased growth and yield leads to negative tradeoffs in defense. V. corymbosum is one of the most economically important crops in New Jersey and is native to the Pinelands region of the state. Pest management is handled overwhelmingly by the conventional application of insecticides, which is environmentally hazardous and concerning to consumers. However, the utilization of natural plant defenses in pest management has not been fully explored. This study addresses these questions: 1. Does arthropod community composition differ between neighboring domesticated and wild populations? 2. Does performance of a generalist herbivore differ on domesticated and wild plants? To answer them, we sampled insect communities on 15 paired populations of wild and domesticated V. corymbosum in the field. Under greenhouse conditions, we grew gypsy moth larvae (Lymantria dispar), and measured differences in insect success and plant damage.
A principle components analysis of community composition revealed that insect communities are much more varied on wild blueberry populations than on domesticated, cultivated plants. Gypsy moth had significantly improved larval growth and reduced mortality on domesticated plants, while wild plants experienced significantly less leaf damage. This suggests future pathways for the study of underlying genetic mechanisms of resistance in V. corymbosum, and the results will be important for the selection of resistant traits against insect herbivores.