Bringing Nature Home: How You Can Sustain Wildlife with Native Plants

by Douglas W. Tallamy

So far I have described well-accepted hypotheses about how evolution has molded most insect herbivores to become “specialists”: insects that are adapted to find, eat, digest, and survive on plant lineages that produce particular types of phytochemicals. I have said little, though, about the species that are not specialists on particular host plants, about 10 percent of the insect herbivores in a given ecosystem. In contrast to specialists, “generalist” insects have evolved the ability to eat several types of plants. Toxicologists have learned that one of the adaptations that permit some insects to generalize on many host plants is the ability to produce very powerful gut enzymes called mixed-function oxidases (Brattsten, Wilkinson & Eisner 1977). These enzymes are so good at detoxifying different classes of plant-defensive chemicals that generalists can eat lots of unrelated plants with no measurable reduction in their ability to grow and reproduce.