Further observations on the biology and host specificity of Prochoerodes truxaliata (Guenée) (Lepidoptera: Geometridae), a biological-control agent for Baccharis halimifolia L. in Australia.
The development and reproduction of Prochoerodes truxaliata were studied on Baccharis pilularis in California during 1988. In the laboratory at 25°C, the mean development time from egg to adult was slightly shorter for males than for females (49 and 50.6 days, resp.). The duration of the 4th and 5th larval instars and the pupal stage differed significantly between the sexes. There were 5 larval instars and measurement of head capsules revealed a relatively constant growth ratio (0.64-0.68). The longevity of adults was approximately 10 days. Following a short preoviposition period (approximately 2 days), females which laid fertile eggs produced an average of 489 eggs each but all the eggs were not always deposited before the death of the female. Other females laid only infertile eggs, despite exposure to males, 339 eggs/female being produced on average, a third of which were laid. In the field, adults active early in the evening laid predominately fertile eggs, while those active later in the evening laid predominately infertile eggs. In quarantine facilities in Australia, the specificity of larvae was tested on a range of economic and native plants. Larvae fed on a number of Asteraceae but did not complete development on any plant other than B. halimifolia. As a result, P. truxaliata was cleared for release in Australia to control B. halimifolia.