Population Dynamics of a Pernicious Parasite: Density‐Dependent Vitality of Red Pine Scale

Abstract

The relationships between biotic and climatic factors and three parameters of fitness (survival, developmental rate, fecundity) and population density were examined for the exotic red pine scale, Matsucoccus resinosae (Homoptera: Margarodidae), in a plantation of red pine, Pinus resinosa, in Connecticut, USA, over a period of population increase and decline from 1975 to 1980. When scale density was relatively low and injury to trees was minor, measures of fitness were not correlated with density. However, when density increased markedly, each measure of fitness was significantly negatively correlated with scale density. Also, as scale density increased so too did injury to trees indicated by an increasing percentage of branches exuding resin. A greater percentage of nymphs dispersed and died as branches became resinous and unsuitable for colonization. Even though scale density decreased sharply after 1977, survival, developmental rate, and fecundity continued to decline, indicating that deterioration of red pine as a host was progressive and irreversible. The scale killed all trees in the plantation within 7 yr of its initial colonization.The single most important factor leading to the collapse of the red pine scale population was change in the magnitude of overwintering mortality incurred by nymphs. Drastic reductions in scale numbers during winter more than offset population growth during the rest of the year and resulted in overall annual population decline. Steadily increasing overwintering mortality from year to year was due to density-dependent reduction in developmental rate which resulted in nymphs overwintering in a developmental substage incapable of surviving even relatively mild winter temperatures.Natural enemies were not important to the population dynamics of M. resinosae. The only such species encountered, the cecidomyiid fly Lestodiplosis nr. grassator, consumed only 5-7% of the scale ovisacs in each year, showing no response to the changes in scale population density.

Strategies to reduce browse damage on eastern white pine (Pinus strobus) in southern New England, USA

“…In response to the loss of red pine (Pinus resinosa) initiated by red pine scale (Matsucoccus matsumuraein) and red pine adelgid (Pineus borneri) in Connecticut (McClure, 1983), we began a series of experiments in 1989 to develop a practical system of growing eastern white pine in areas with large deer herds. Our earlier work found tree shelters increased survival of eastern white pine (Ward, 1996), but did not increase height growth (Ward et al, 2000).…”

Histological Studies of Pinus Halepensis Stem Xylem Affected by Matsucoccus Josephi (Homoptera: Margarodidae)

“…(Homoptera: Margarodidae) are parenchyma feeders which develop only on pines. Several species of this genus are serious pests of pine forests throughout the northern hemisphere (McClure, 1983, U. S.A.; Carle, 1974, France;Golan et aI., 1983, Israel;Li et aI., 1980, China). Most investigators share the opinion that feeding behaviour is the primary cause of the typical deterioration of buds, twigs and stem bark portions.…”

<I>Matsucoccus macrocicatrices</I> (Hemiptera: Matsucoccidae): First Report, Distribution, and Association With Symptomatic Eastern White Pine in the Southeastern United States

“…For example, in the southwestern United States, the pinyon needle scale, Matsucoccus acalyptus Herbert, can cause defoliation and mortality of pinyon pine (Pinus edulis Engelmann) after repeated feeding (McCambridge and Pierce 1964). The nonnative M. matsumurae was responsible for foliage discoloration (Bean and Godwin 1955) and mortality of plantation-grown P. resinosa in Connecticut (McClure 1983). M. gallicolus was responsible for killing terminal leaders on Ͼ63% of pitch pine (Pinus rigida Miller) trees in Pennsylvania, and caused Ͼ50% mortality in pitch pine stands in Massachusetts (Parr 1939).…”