Biological differences between mainland and Tasmanian Chrysophtharta agricola, a Eucalyptus leaf beetle

Chrysophtharta agricola collected from Tasmania and mainland Australia inDecember 2000 and January 2001, respectively, were compared for adult length, egg and larval batch size, and egg, larval and adult parasitism. Beetles originating from both regions were crossed and their offspring were reared to adulthood and assessed for fertility to confirm that collections were conspecific. 100 years of collection data from several state collections were collated to observe the frequency of collection across seasons, and relate this to the species’ differing voltinism in each region. Overall, the size of beetles, egg batches, larval batches and rate of larval parasitism did not differ significantly between regions. Larval parasitoids collected from Tasmania were the tachinid flies Paropsivora sp. and an undescribed tachinid species, and the braconid wasp Eadya paropsidis. The tachinid flies were also collected parasitising C. agricola larvae from mainland Australia. Eggparasitism rates differed significantly between mainland Australia and Tasmania: the pteromalid species Enoggera nassaui and Neopolycystus sp. developed from C. agricola eggs. Adult beetles were infected by the mites Leptus sp. and an undescribed genus of podapolipid mites in Tasmania, and by Chyzeria sp. in mainland Australia. Collection data revealed that the frequency of collection of adult C. agricola was similar between regions in spring and summer, but that beetles were collected more frequently in autumn in mainland Australia than in Tasmania