Genetic variation of lodgepole pine physical and chemical defenses associated with each step in host selection behavior sequence by mountain pine beetle

Abiotic and biotic stressors exert selective pressures on plants, and over evolutionary time lead to the development of specialized adaptations and specific responses to stresses (Safranyik and Carroll 2006, Wallin and Raffa 2002). In this way, the environment in which plants evolve shapes their life cycles, range, growth, reproduction, and defenses. Insects and diseases are particularly potent plant stressors. Insect herbivores exert pressure on plants by feeding on plant parts and using them to reproduce by forming galls and cysts. Some insect species carry mutualistic pathogens on their bodies, which exert pressure on plants in the form of disease.