The life-history and host specificity of Comostolopsis germana Prout (Lepidoptera: Geometridae), a biological control agent of Chrysanthemoides monilifera (Compositae).
Larvae of the southern African geometrid Comostolopsis germana feed on the shoot apices and axillary buds of Chrysanthemoides monilifera, a serious alien weed of native vegetation in Australia. The insect was found in low abundance throughout the distribution of its hosts, C. incana and C. monilifera, in southern Africa. Larvae were present throughout the year in subtropical Natal, but were absent in winter in the cooler, Mediterranean type climate of Cape Province. In host-specificity tests using 65 plant species from 26 families, Comostolopsis germana completed development only on Chrysanthemoides monilifera monilifera and C. monilifera rotundata. Insignificant, exploratory feeding occurred on Olearia axillaris (Compositae) and pea (Leguminosae). In multiple-choice oviposition tests eggs were laid on 41 species, but a strong preference was shown for the foliage and stems of C. monilifera. Larvae grazing the flower buds, pedicels and peduncles of C. monilifera may reduce the reproductive capcity of their host and contribute to its control. Comostolopsis germana has been approved for release as a biological control agent of Chrysanthemoides monilifera in Australia.