Leaf element content and utilization of maple and elm as hosts by the potato leafhopper (Homoptera: Cicadellidae)

Abstract

Feeding injury and performance of the potato leafhopper, Empoasca fabae (Harris), was measured on two red maple clones (Acer rubrum L.), a Freeman maple cultivar (A × freemanii E. Murray), two elm cultivars (Ulmus spp.), and an American elm clonal selection (U. americana L), and was related to the leaf content of important nutritional elements. Significantly more eggs were laid and more nymphs became adults on American and Patriot elms than on the other clones. Although the mean number of eggs laid was not significantly different among the maple clones, nymphal survivorship was significantly higher on red maple 56026 than on the other maple clones. Although the number of eggs laid was linearly related to foliar nitrogen and phosphorus, survival of nymphs to adulthood was linearly related to foliar nitrogen. Significantly more leafhoppers from the wild population were collected from American elm, followed by Patriot elm and red maple 56026. Although none of the elms showed any evidence of feeding injury, the maple trees varied from tolerant (i.e., 'Indian Summer') to susceptible (i.e., red maple 56026). Leafhoppers may need to increase feeding on red maple 56026 as a compensatory response to the limited nutritional quality of this clone. Because the sex ratio of the wild population was close to 1:1, and consistent across clones, it appears that differences in the behavior of the potato leafhopper among clones were not a function of gender bias associated with each species. Resistance against the potato leafhopper among maples and elms is influenced, in part, by the nutritional content of the leaves. Yet, feeding injury is not a good indicator of host resistance against the potato leafhopper.