Within‐plant distribution of a galling adelgid (Homoptera: Adelgidae): the consequences of conflicting survivorship, growth, and reproduction

Abstract

Abstract. 1. Adelges cooleyi (Gil.) was rarely found in the top‐most whorl of shoots in its host plant Engelmann spruce.2. The survivorship of the few Adelges fundatrices which did colonize the top whorl was at or near zero for the 3 years in which survivorship was assessed, while survivorship in the bottom whorls was at least 60%.3. In contrast, when an Adelges fundatrix did survive in the top whorl, her growth and reproductive output, and the growth of her progeny, the gallicolae, were at least double that of bottom whorl fundatrices.4. The distribution of fundatrices within spruce trees was strongly correlated (R2=0.934) with fundatrix fitness (=survivorship × fecundity × growth).5. We hypothesize that the vigorous growth of top whorl shoots promotes Adelges growth and fecundity, but the earlier growth of these shoots results in low temperature mortality of fundatrices.