LIFE HISTORY STUDIES OF THE PINE SCALE, CHIONASPIS HETEROPHYLLAE COOLEY, AND THE PINE NEEDLE SCALE, CHIONASPIS PINIFOLIAE (FITCH) (ILLINOIS, INDIANA, KENTUCKY, MICHIGAN)
Abstract
Life histories of the Pine Scale, Chionaspis heterophyllae Cooley, and the Pine Needle Scale, C. pinifoliae (Fitch) (Homoptera:Diaspididae), were determined on separate plantings of Scots Pine, Pinus sylvestris. Although both species were bivoltine and overwintered primarily as eggs, a portion of the population for each species completed a partial third generation, overwintering as mated adult females. C. heterophyllae general seasonal development and summer crawler emergence preceeded that of C. pinifoliae. Blooming of Spiraea x vanhouttei and pollen release of P. sylvestris coincided with spring crawler activity, while Cotinus coggygria and Campsis radicans were blooming as summer crawlers emerged. Accumulation of 250-270 heat units (base 50 F) had occurred before crawlers emerged in the spring and 1330-1470 heat units accumulated prior to summer emergence. C. pinifoliae settled preferentially on the concave needle surface on P. sylvestris, whereas C. heterophyllae settled on concave and convex surfaces. The male:female ratio was 40:60 for C. pinifoliae and 25:75 for C. heterophyllae. Fecundity estimates of first (ca. 25 eggs/female) and second (ca. 55 eggs/female) generation were the same for both scale species. Natural enemies were listed with estimates of percent predation or parasitism and pertinent biological observations. National host ranges and geographic distributions were recorded. A new host record for C. heterophyllae was Picea abies and new state records of Illinois, Indiana, Kentucky and Michigan were discussed. Prepupal, pupal and adult male descriptions for C. heterophyllae and C. pinifoliae were made studying materials from several areas of the United States. Scales were determined to be in two distinct morphological groups, C. pinifoliae males being larger than those of C. heterophyllae. Adult males of both species were smaller when feeding on Pinus mugo than when on P. sylvestris. Presence of individuals with 8-segmented antennae and absence of wingless males distinguished C. heterophyllae and C. pinifoliae from other described Chionaspis species.
Degree
Ph.D.
Subject Area
Entomology
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