Effects of Prior Herbivory on Aphid Colonization of Solidago Altissima Clones

To determine the effects of genetic variation and initial herbivore damage on Solidago altissima and subsequent aphid colonization, I conducted a common garden experiment with greenhouse-grown clones induced by Trirhabda virgata. Seventy-five days after planting larvae-damaged and undamaged clones in a common garden, I determined Uroleucon nigrotuberculatum abundance, measured plant biomass, and collected leaves for water content, nitrogen, carbon, and terpene analysis. I found significant differences among clones for bornyl acetate, ß-elemene, azulene, ledene oxide, and bicyclo[4.4.0]dec-5-ene, and significant interaction effects between clone and damage for a-pinene, limonene, caryophyllene, and ?-elemene. Some clones, but not others, produced higher quantities of terpenes in plants that had not been previously damaged. Aphid measures were significantly different among clones but were not significantly different between damage. Though SLW, N and C:N were significantly different among clones and between damage, aphid colonization only correlated with terpenes. Aphid abundance was positively related to the sesquiterpenes azulene, ledene oxide, and bicyclo[4.4.0]dec-5-ene. I conclude that U. nigrotuberculatum colonization of S. altissima is due to genetic differences in terpene production among clones, and these differences are affected by prior damage and other environmental factors.