Effects of leaf and sap feeding insects on photosynthetic rates of goldenrod.

摘要: Herbivory can alter the balance between sources and sinks within a plant, changes in source-sink ratio often lead to plant photosynthetic rates. We investigated how feeding by three insect herbivores affected rates growth of goldenrod (Solidago altissima). One, phloem-sap aphid (Uroleucon caligatum), creates an additional sink, other two, leaf-chewing beetle (Trirhabda sp.) xylem-sap spittlebug (Philaenus spumarius) both reduce source supply decreasing leaf area. Plants were grown outside large pots insects placed on them at predetermined densities, with undamaged plants included as controls. All removed after 12-day period. measured damaged leaves that produced removal. Photosynthetic per unit area reduced feeding, but not or feeding. Conductance spittlebugdamaged did differ from controls, internal carbon dioxide concentrations increased. These results indicate does cause stomatal closure, impairs fixation leaf. Effects persisted plants. removal spittlegug-damaged lower than control levels, even though measurements taken 12 days The measurement was 27% relative specific (leaf area/leaf weight) increased 18%. Because shift area, also examined weight, when this done there no significant differences spittlebug-damaged Beetle had effects rate Plant (in terms height) spittlebugs during period Relative above levels removal, these still shorter controls 17 Beetles aphids affect height. Feeding beetles effect more severe beetle. show herbivory cannot be predicted simply considering ratio, is damaging host