How Should Plant Resistance to Herbivores Be Measured?

Plant resistance is normally defined as the heritable ability of plants to escape attacking enemies, partially or fully, thus minimizing the amount of damage experienced by the plant (Painter, 1951; Mitchell et al., 2016). Plant resistance is pivotal in preventing crop yield loss to herbivores, and, thus, it is important to breed for (Hill et al., 2012). As many national and intergovernmental bodies have firmly endorsed Integrated Pest Management as the new paradigm for plant protection, the importance of resistant varieties is becoming even more important. However, measuring resistance is seldom straightforward, and many different approaches are being used, thus affecting biological interpretations. Choosing an appropriate measure for plant resistance is essential for engineering future varieties for improved plant production security, with less dependence on chemical pesticides. Here we suggest that the method selected to measure resistance should depend on the longevity of the crop (or culture) and the generation time of the herbivore.