Abstracts Category : Other

Morphological and molecular characterisation of Australian pinhole borers (Coleoptera: Curculionidae, Platypodinae)

by James R Bickerstaff

Pinhole borers (Coleoptera: Curculionidae, Platypodinae) are ecologically important and evolutionary unique taxa of economic significance. They are the oldest known insect lineage that cultivates fungi, commonly referred to as ambrosia fungi, within galleries excavated into the heartwood of trees. Most species of pinhole borers inhabit dead or dying trees, however, several species attack living trees, which can have detrimental effects on these hosts. For example, wilt disease is a common disease of trees caused by fungal pathogens transmitted by some pinhole borer species. These beetle species inoculate fungal pathogens into tree hosts and this can lead to tree mortality. Not all pinhole borer species that attack living trees carry fungi that cause disease, but their tunnelling and fungiculture can still have adverse effects on tree vigour and timber quality. Despite the importance of pinhole borers, ecological information pertaining to this group is scarce and species identification is difficult due to highly conserved morphologies across species. This Master of Research project will help bridge this gap by reviewing the taxonomy, systematics, and biogeography of previously collected Australian Platypodinae and systematically characterise common DNA barcoding sequences. This project investigated the biogeography, host tree associations, and morphological diversity of Australian pinhole borers. This has culminated in comprehensive distribution maps for recorded and collected specimens of 25 species in Australia, as well as the distribution of their respective host trees. An electronic identification key of 37 Australasian pinhole borers, Australian native species and commonly intercepted species, was also developed, the first of its kind for this group of beetles. Additionally, a molecular study was performed on 98 individuals of 31 Australian pinhole borer morphospecies. Mitochondrial COI and nuclear 28S rDNA loci were amplified and sequenced, resulting in novel COI DNA barcodes for seven species, and new 28S rDNA sequences for six other species. Using these loci, in conjunction with published data, the systematics of Australian Platypodinae was explored and contextualised with species previously described from across the globe. Phylogenetic analyses of both loci were congruent with previous systematic and evolutionary investigations; however, the Platypus genus remained unresolved due to its polyphyletic status. This result highlights the need for further taxonomic work on Platypus, and on Platypodinae more broadly. Finally, results obtained in this study are discussed in a global context, and recommendations for future studies are outlined.Advisors/Committee Members: Western Sydney University. Hawkesbury Institute for the Environment (Host institution).