Optimal Attack Density in the Larch Bark Beetle, Ips cembrae (Coleoptera: Scolytidae)

Abstract

1. The effects of attack density of the larch bark beetle, Ips cembrae (Heer) (=Ips subelongatus Motsch.) on the gallery length, egg and offspring adult production and mortality were studied in 0.1 m 2 bark samples from 100 larch trees (Larix dahurica Turcz) during the summer of 1989 in a burned area of the Tu Qiang Forest' District, Great Xingan Mountains, P.R. China. 2. The results show that there is a positive linear relationship between gallery length and number of egg niches. The number of egg niches and offspring adults produced per gallery declined exponentially with attack density, and the egg to adult mortality increased exponentially as the attack density increased in the absence of host resistances