We are currently researching the pollination requirements/restrictions/deficiencies and other potential threats impacting on an endangered plant species, Astrotricha roddii, Rodd’s Star Hair (Fig. 1), a species that has been in decline for many years in response to droughts and over-grazing by goats. This project is a collaboration between researchers at the University of New England (Australia) and the NSW Department of Planning Infrastructure and Environment.
Figure 1. Astrotricha roddii in its natural habitat, in sclerophyllous woodland on granite in north-western New South Wales.
In November 2020 we visited the only known, vigorous population (fenced off from goats) that was in flower to begin our investigation of the plant’s pollination ecology.
We saw three species of bees at the Astrotricha roddii flowers. The most common species was a Lipotriches species, possibly L. phanerura; one was a Megachilid species (Fig. 2), yet unidentified; and the third was a small black bee!, probably a Halictid but I saw only one and very briefly – it was eating the pollen into a crop like some Halictids do, so unlikely to be a good pollinator. Oh, there were also some honeybees competing with the native bees at the flowers 😦
I have never seen so many Lipotriches together at the same time! It was amazing! This certainly supports our idea that these bees can survive in stasis underground – as pupae probably – for extended periods (multiple years) to survive through drought periods. We didn’t see these bees before or after the Astrotrichas were in flower. Interestingly, there were some Haemodorum plants just coming into flower – which we know are pollinated by Lipotiches spp. – and there were also Dianella and Hibbertia species in flower, co-occurring with the Astrotrichas – these two plant genera don’t produce nectar, just pollen, so are dependent on co-occurring nectar-producing flowering species (such as the Astrotichas :)) to supply pollinators with nectar/energy. The pollinators of Dianellas and Hibbertias need to be bees such as Lipotriches species that are capable of buzz-pollinating plants like these that have poricidal anthers … which is all rather neat 🙂 and very exciting for pollination-ecology nerds.
Figure 2. A megachilid bee on Astrotricha roddii, with a great load of pollen.