Host plant predictability and the feeding patterns of monophagous, oligophagous, and polyphagous insect herbivores.

Host plant preferences for 34 insect herbivore species are reported. Most polyphagous herbivores feeding on annuals, herbaceous perennials, and woody perennials show distinct preferences for the least abundant plant species among their various host plants. In addition, some populations of widely distributed polyphagous species are much more specialized in their diet than host plant lists alone would suggest. The high level of polyphagy on annuals and herbaceous perennials is suggested to be strongly influenced by the unpredictability of the host plant that is, in turn, controlled by environmental variability. Oligophagous herbivores preferred the least abundant woody perennials on the study sites. Ten of the 22 monophagous herbivores preferred the rarest of all the plant species on the same sites.