Management trials of Australian insects threatened with coextinction

A project undertaken at The University of Western Australia and supervised by Melinda Moir

The world is facing the sixth mass extinction event, due to human disturbance. Recent estimates suggest that 1 in 5 species of the world’s invertebrates are committed to extinction. Insects constitute two-thirds of global terrestrial biodiversity, however, only 5.5% of threatened terrestrial animals on the international Red List are insects, due primarily to a paucity of taxonomic, ecological and biogeographical knowledge. Indeed, insect management is an increasingly daunting prospect as their conservation becomes more urgent under rapid and culminating anthropogenic disturbance. This project will develop practical applications for the management and conservation of herbivorous insects. We will do this by:

A. investigating where the highest loss of plant-dwelling insects is likely to occur, and

B. developing broadly applicable, effective management strategies with a network of endusers. This project is of profound international significance as providing management strategies to combat extinction is critical for allocating the limited resources available to mitigate the loss of global biodiversity.

Outcomes from the project as of 17th November 2016:
  • We have analysed a very large insect-plant dataset (>30,000 insects, >3,500 plants) and we are drafting a manuscript of the potential loss through coextinction in the southwest of Western Australia (itself a global biodiversity hotspot of plant diversity),
  • We have collated >4 years of fine-scale weather data within the southwest to determine whether there are hotspots of coextinction at small spatial scales, and expect a paper to follow,
  • We have been investigating different possible management strategies, broadly through a 2015 workshop with academics and endusers (e.g., how interaction type determines management options; Plein et al. 2016), and specifically through case by case management trials of multiple insect and plant pairs (e.g., how genetic congruence between insect and host plant populations influences management decisions; Moir et al. 2016),
  • We are providing land managers with on-going recommendations on how to incorporate the conservation of co-threatened insects into management strategies for threatened plants with minimal resources.
Publications

Moir, M.L., Coates, D.J., Kensington, W.J., Barrett, S. and Taylor, G.S. (2016). Concordance in evolutionalry history of threatened plant and insect populations warrant unified conservation management approaches. Biological Conservation, 198, 135 - 144.

Plein, M., Bode, M., Moir, M.L. and Vesk, P.A.. (2016). Translocation strategies for multiple species depend on interspecific interaction type. Ecological Applications. 25, 1186 - 1197.
Figure 1. Refugial areas are often found on mountains as the peaks provide moister conditions than surrounding regions. Photo: ML Moir

Figure 2. The critically endangered lerp insect Acizzia veski (IUCN red list 2013) on its host plant Acacia veronica. Photo: ML Moir

Figure 3. Translocation trials for threatened plant-dwelling insects on critically endangered host plants. Photo: MC Leng

Figure 4. The influence of host plant abundance and fire history on the critically endangered lerp insect Trioza barrettae (Moir et al., 2016)

Figure 5. The molecular congruence between critically endangered populations of lerp insect Trioza barrettae and its host plant, Banksia brownii. The larger the circle the higher the congruence. (Moir et al., 2016)