The Plant Vigor Hypothesis and Herbivore Attack

Four sources of evidence are used to support the Plant Vigor Hypothesis that many herbivore species feed preferentially on vigorous plants or plant modules, as opposed to the Plant Stress Hypothesis arguing that stressed plants ae beneficial to herbivores. Evidence includes patterns of within-plant species utilization by galing insects where females select large plant modules and larvae survive better than on smaller modules. Independent evidence concerns patterns of herbivory between plant species habitually growing in rich resource environments which are heavily utilized, compared with low-resource adapted species. A third source of evidence is the forestry literature in which many cases are known of most attacks by insect herbivores occurring on young and open-grown trees