Sampling plan for Adelges cooleyi (Hemiptera: Adelgidae) in spruce seed orchards

Abstract

AbstractWithin-plant and between-plants distributions of the Cooley spruce gall adelgid, Adelges cooleyi (Gillette), fundatrices were measured in “interior spruce”, Picea glauca × P. engelmannii (Moench) Voss. & Parry (Pinaceae), seed orchards in central British Columbia to develop a quantitative sampling plan. Adelgids (number of fundatrices per shoot) were abundant at the lower and middle crown heights of the tree crowns but scarce at the upper crown height, and more abundant on the ends and central one-third of branches than on the inner portions. The northern and eastern aspects of trees had slightly but significantly more adelgids than did the southern and western aspects, and terminal shoots had more adelgids than did distolateral shoots. Variance was much greater between than within trees. These data were used to create a sampling plan with a sample unit consisting of a single 1-year-old shoot selected from the ends or central area of main branches in the lower or middle portion of each sample tree. Collecting 104 samples required 69 min, and yielded an estimate of the mean number of fundatrices per shoot with a standard error of 10% of the mean.