He says that when plants are under attack, they begin to ramp up production of their chemical defenses. This can mean releasing an aroma that attracts counter-attacking bugs (wasps for caterpillars, for instance), manufacturing something toxic or distasteful to the insects themselves, or producing an anti-fungal compound.
For us, these "defenses" translate directly into flavor and aroma. McGee says, "Because they're not protected by pesticides, organic plants that suffer from insect attack can accumulate higher level of flavor chemicals and other protective molecules, including antioxidants."
To put it plainly: more fight = heartier plants = more flavor and nutrition. Next time I find an aphid lurking in my kale, I'll try to remember to say "Thank you."
Do you think organic fruits and vegetables taste better?