Effects of total dietary nitrogen and nitrogen form on the development of xylophagous leafhoppers

Abstract

The influence of primary nutrients on the development of the leafhopper Homalodisca coagulata (Say) was examined using Glycine max (L.) Merrill subjected to treatments using different forms of nitrogen fertilization (urea and nitrate) and inoculation with Rhizobium bacteria. Concentrations of amino acids, organic acids, carbohydrates, and ureides in xylem fluid varied with treatment; differences were most pronounced in young plants (6 weeks after planting), and subsided as plants aged. Plants receiving urea fertilization had lower concentrations of organic nitrogen and carbon, but more balanced profiles of amino acids. Leafhoppers on urea-fertilized plants had much higher success in development (62 to 87% survival to adult stage) than H. coagulata developing on nitrate-fertilized plants (31-42%). The sex ratio of successfully developed adults varied greatly with treatments, indicating that female survival was much higher on urea-fertilized plants. Males and females utlilized diets differently as indicated by the carbon and nitrogen content of adult carcasses. Consumption rates and nitrogen assimilation efficiencies were higher for young (third instar) leafhoppers on urea-fertilized plants. Instar duration and total time of development were not affected by treatment. Highest rates of success in development on diets providing the lowest (yet most balanced) concentrations of total nitrogen, amino acids, and organic compounds underscored the importance of nutrient balance for leafhopper development. Arch. Copyright 1999 Wiley-Liss, Inc.