Insects from the southwest Australia biodiversity hotspot: a barometer of diversity and threat status of nine host-dependent families across three orders

The mass loss of insects is gaining momentum in the twenty-first century, compared with the previous 100 years. The loss is coinciding with accelerating threats, including megafires, flooding, temperature extremes, urbanisation, and habitat loss. In global diversity hotspots, where endemism is high, and native vegetation highly impacted, many insect species would likely be both endemic and threatened. However, insect diversity, endemicity and threat status are largely unknown in these regions. Here we assess the biodiversity and status of host-dependent insects in the southwest Australian (SWWA) hotspot. We selected nine insect families across three orders; Tingidae, Achilidae, Derbidae, Dictyopharidae, Triozidae (Hemiptera), Micropterigidae, Heliozidae (Lepidoptera), Boopidae, and Philopteridae (Psocodea). These families had 632+ species, of which 255 (~ 40%) were described. One species was formally listed as threatened, but a further 245 species potentially require conservation management. Threatening processes include coextinction (through loss or reduction in host populations), climate change, altered fire regimes, habitat loss, and fragmentation of host populations. Taxonomic and resourcing bias has inhibited attempts to describe the diversity and biogeography of the region, precluding comprehensive conservation assessments for the majority of insect families.
Implications for insect conservation

Given the scale and intensity of threats faced by a hyperdiverse insect fauna in the southwest Australia biodiversity hotspot, a systematic approach to manage habitats at a landscape scale is most likely to succeed in conserving species in the short-term. Longer term solutions require addressing these knowledge gaps, thus increasing our understanding of the diversity and conservation needs of insect families in southwest Australia.