The Effect Of Solidago Altissima Cytotypes And Soil Nutrients On Terpene Production, Leaf Nutrients And Uroleucon Nigrotuberculatum Abundance

The specific factors that drive plant genotype choice by insects remain uncertain. I investigated the connection between tall goldenrod, Solidago altissima, cytotypes {diploid and hexaploid), phytochemistry (C, CN and terpenes) and soil nutrient level on the abundance of a specialist aphid Uroleucon nigrotuberculatum. Terpenes are one of the largest classes of secondary metabolites and can vary among plant genotypes. I hypothesized that chromosome number and available nutrients would affect leaf nutrients terpenes concentration in S. altissima and affect the abundance of U. nigrotuberculatum. A randomized common-garden design used sixty-four plants (32 diploid and 32 hexaploid representing four genotypes (cytotype), with eight plants per genotype. I added soil nutrients to four plants per treatment, while four plants had no nutrient addition. After allowing aphids to naturally colonize plants I quantified aphid abundance throughout a growing season. During peak aphid abundance I took estimates of plant biomass and leaf samples for phytochemical analyses. I found that soil nutrients had a significant effect on aphid abundance (P=0.0178) and no effects of cytotypes or cytotypes x nutrient interaction. The biomass of 2n plants were significantly larger than 6n plants (Cytotype effect=0.045) and high nutrient plants were significantly larger than ambient nutrient plants (nutrient effect, p>0.001). This study found nutrient and cytotype interactions with CN (p=0.0009). Chromosome number (cytotypes) had significant effects on three foliar terpenes: a- pinene (p=0.004), -pinene (p=0.003) and Bornyl acetate (p=0.027) of hexaploid plant with nutrient addition.