Zhang, Q.H., Byers, J.A., & Schlyter, F. 1992. Optimal
attack density in the larch bark beetle, Ips cembrae
(Coleoptera: Scolytidae). Journal of Applied Ecology
29:672-678. pdf
Abstract--
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 m2 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. The results show that there is a
positve 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 resistance. The exponential
relationships are attributed to intraspecific competition between
female parent adults for breeding space and between larvae for
limited food resources. In addition, there are two optimal attack
densities 13.9 attacks per 0.1 m2 and 8.7 attacks per 0.1 m2, at
which the number of egg niches (935) and offsprign adults (496) are
maximal, respectively. An upper threshold of attack density, 31.8
attacks per 0.1 m2, beyond which the number of offspring adults
produced from a bark area become less than the input of parent adults
was also found.
Chemical Ecology