STAGE‐SPECIFIC MORTALITY IN TWO FIELD POPULATIONS OF IMMATURE CHRYSOPHTHARTA BIMACULATA (OLIVIER) (COLEOPTERA: CHRYSOMELIDAE)

Abstract

A population census of the immature stages of 2 widely separated field populations of the Tasmanian eucalyptus leaf beetle, Chrysophtharta bimaculata was conducted to determine the level of mortality occurring in each stage. Analysis of census figures for stage specific mortality showed that the egg stage was the most vulnerable with mortality ranging from 66% to 84%. Total mortality of the immature stages up to fourth instar larvae ranged from 95 to 97%. Similar mortality factors were seen to operate in each of the 2 populations with the greatest single factor being predation by coccinellids. The implications of this level and timing of natural biological control are discussed in relation to control strategies for C. bimaculata. Copyright © 1990, Wiley Blackwell. All rights reserved