Trade-offs between Colorado potato beetle resistance and late blight resistance in commercial potato varieties

Plant defense theory predicts that plants have to allocate their limited resources to reproduction, growth, and defense. With respect to defense, it has been suggested that if a plant allocates resources to defenses against pathogens there will be a trade-off in terms of resources allocated to prevent insect herbivory. To test if there are trade-offs between pathogen and herbivore defenses, we compare resistance to Late Blight (LB), Phytophthora infestans, to resistance to Colorado potato beetle (CPB) Leptinotarsa decemlineata (Say) in potato. For this study we selected 14 potato varieties along a gradient from susceptible to highly resistant to LB. For each variety, we characterized the resistance to CPB through various herbivore performance measures. Our initial analysis suggests that resistance in terms of CPB larval survival to adulthood was not different among varieties and we did not find any evidence of a trade-off between LB and CPB resistance. However, there was a difference in resistance in terms of pupal size among varieties: Sebago, Green Mountain, and Snowden were the most resistant varieties while Superior was the most susceptible variety. When we measured resistance as pupal size, we did not find any evidence of a trade-off between LB and CPB resistance. Overall we found no trade-offs between herbivore and pathogen resistance, indicating that selecting for increased resistance to both herbivores and pathogens seems possible in this system.