John H. Hawking’s research while affiliated with Murray-Darling Freshwater Research Centre (MDFRC) and other places

The Australian Odonata fauna is reviewed. The state of the current taxonomy and ecology, studies on biodiversity, studies on larvae and the all identification keys are reported. The conservation status of the Australian odonates is evaluated and the endangered species identified. In addition the endemic species, species with unusual biology and species, not threatened yet, but maybe becoming critical in the future are discussed and listed.

The status and trends of global biodiversity are often measured with a bias towards datasets limited to terrestrial vertebrates. The first global assessment of an insect order (Odonata) provides new context to the ongoing discussion of current biodiversity loss. A randomly selected sample of 1500 (26.4%) of the 5680 described dragonflies and damselflies was assessed using IUCN’s Red List criteria. Distribution maps for each species were created and species were assigned to habitat types. These data were analysed in respect to threat level for regions and habitat types. We have found that one in 10 species of dragonflies and damselflies is threatened with extinction. This threat level is among the lowest of groups that have been assessed to date, suggesting that previous estimates of extinction risk for insects might be misleading. However, Odonata only comprise a small invertebrate order, with above-average dispersal ability and relatively wide distribution ranges. For conservation science and policy to be truly representative of global biodiversity a representative cross-section of invertebrates needs to be included.

Dragonflies and damselflies are conspicuous insects – many are large and brightly coloured. Here for the first time is a comprehensive guide to the Australian dragonfly fauna. The book includes identification keys not only for adults but also for their larvae, commonly known as ‘mud eyes’ and often used as bait for freshwater fish. With stunning full-colour images and distribution maps, the book covers all 30 families, 110 genera and 324 species found in Australia. Dragonflies are valuable indicators of environmental well-being. A detailed knowledge of the dragonfly fauna and its changes is therefore an important basis for decisions about environmental protection and management. Their extraordinary diversity will interest entomologists and amateur naturalists alike.

In this article we report underwater oviposition and epilithic oviposition in Anisoptera. We observed Notoaeschna sagittata totally submerged ovipositing on bare rock in the fast current of a rapid. Dendroaeschna conspersa oviposited also underwater, but into wood submerged in very clear water.

In order to evaluate single-occasion sampling in compiling inventories for Odonata, larvae were sampled on 20 occasions from 1987–1990 at a site on Middle Creek, north-eastern Victoria, and adults sought also on each visit to more fully evaluate the diversity of the asemblage, and limitations of depending on a single life stage for this purpose. A total of 18 species (7 Zygoptera, 11 Anisoptera) included 15 species collected as larvae and 16 as adults. Few species were common as larvae, and about half the 2806 specimens identified were Austrogomphus cornutus Watson. Orthetrum caledonicum (Brauer) and Ischnura heterosticta (Burmeister) were also abundant, and these three species were also the most common as adults. The number of species obtained ranged from 2–9 on different occasions, and represent different 'habitat groups' within the local fauna. The Middle Creek odonate fauna appears to be much richer than that of a nearby site on the Kiewa River (12 species), and reasons for this are discussed. Seasonal variation in species representation and relative abundances are noted. Any single sample occasion provided insufficient knowledge of the total assemblage to interpret odonate diversity reliably.

Sampling of larval and adult Odonata from 16 sites along the Kiewa River, Victoria, yielded 34 species: 10 Zygoptera, 24 Anisoptera. Patterns of larval and adult incidence were appraised, and showed that most species were restricted in incidence to several consecutive sites along the river, and that there is clear distinction also between the faunas of the potamon, rhithron and eucrenon regions. Different species of some genera of Anisoptera displayed different zonational distributions, and patterns of incidence and relative abundance of larvae and adults confirmed zonational occupancy. For larvae, these distribution patterns transcended the mode of collection, although many species were found most abundantly in one microhabitat or by one of several sampling methods employed at each site. Sampling of the two stages separately showed considerable concurrence of distributional patterns, so that either stage alone may provide data of value in faunal and conservation assessment.

The macroinvertebrate communities of large lowlandrivers are little studied, partly because of the lackof suitable collection methods. In this study, fourmacroinvertebrate collecting methods: two artificialsubstrates, snags and onion-bag baskets; air-liftsampling of soft sediments; and sweep net sampling ofedges (including macrophyte stands where theyoccurred) were trialed in four lowland rivers withinthe Murray-Darling Basin in southeastern Australia. The subset of the macroinvertebrate communitycollected by each method was determined and the numberof replicates needed for a given degree of precisionwas estimated. Sweep samples were dominated byhemipterans and were the best method for collectingdecapods and beetles. The other three methodscollected mostly chironomid, caenid mayfly and ecnomidcaddisfly larvae and oligochaetes. The artificialsnag and basket samples had surprisingly similarcompositions but the snag samples did contain sometaxa, such as Dicrotendipes, Paratanytarsus andwood-boring beetles, that basket samples did not. Thedensities of macroinvertebrates collected byartificial snags, sweep and air-lift samples weresimilar. We concluded that each of the methods couldbe used in lowland rivers but for different purposes. For example, if quantitative data are needed, onlyair-lifts and snags would be appropriate, whereas ifa species list is required, snags and sweeps would bemost effective.

Developmental stages of larvae of eight species of Anisoptera from the Kiewa River and Middle Creek, Victoria, were determined and their phenology investigated. The last six to nine instars of each species were distinguished by size frequency and scatter plots, using labium width, metafemur and wing-pad measurements, and the early instars were estimated from Dyar's Law. This suggested between 11 to 14 instars. Four species appeared to be univoltine and four species semivoltine.

The development of the eggs of six species of Anisoptera from the Kiewa River and Middle Creek, Victoria was studied by incubating eggs over a range of temperatures, comparable to that found in the two streams. The eggs of each species developed directly, with an increase in development rate with increase in temperature. There appeared to be differences in the lower developmental threshold temperatures of coexístíng species of Gomphidae and Libel‐Iulidae.