We just published a paper showing pollinators experienced higher levels of reproductive success in isolated trees at a fig species’ expanding range margin, in spite of there being lower numbers of pollinators in these isolated trees (half as many) as there were in larger populations of fig trees. This increase in reproductive success was partly a consequence of parasitoid release (Mackay KD, Gross CL, Ryder DS., Increased reproductive success through parasitoid release at a range margin: Implications for range shifts induced by climate change. J Biogeogr. 2020;00:1–15. https://doi.org/10.1111/jbi.13795).
Ficus rubiginosa female-stage fig with pollinator wasps, Pleistodontes imperialis, entering the narrow opening or ostiole of the fig syconium to pollinate some of the enclosed female flowers and lay their eggs within others. One wasp has already entered, her torn-off wings left sticking out of the ostiole, as another one enters. A pollinator parasitoid, Philotrypesis sp., is sitting on the leaf edge at the lower right. She might be about to lay her own eggs after the pollinators have laid theirs.
I am starting here with a quote from Jeff Ollerton’s Biodiversity Blog – “A recent assessment by ecologists at the University of Sydney has suggested that almost half a billion reptiles, mammals and birds have been killed so far by the fires.” This assessment by University of Sydney ecologists was made in December before the devastating fires raged through south-eastern NSW and eastern Victoria over the New Year period, so the true figures are likely to have grown substantially since than and will continue to grow over this devastating fire season. Losses of insects, including pollinators, will be even greater. These losses will number in the billions of individuals but what we will never know will be how many locally-endemic species are lost forever, and how much genetic biodiversity is lost in the surviving species. Our lab is working in several areas monitoring pollinator recovery after fire but recovery of both plants and pollinators is being hampered by the ongoing drought conditions. In the Howell Shrubland Endangered Ecological Community, for example, where we have been working since 2007, neither plants nor pollinators are recovering.
Howell Shrubland in a good yearHowell Shrubland nine months after fire in 2019 – without the shrubs! The recovery of this community is being hampered by drought.
We recorded a very low spike of pollinator numbers in the burnt area that correlated with the growth and flowering of very small numbers of fire-ephemeral plants. In fact, we recorded more pollinators in the burnt area than in the adjoining unburnt area (where there were no fire ephemerals and the other plants were not flowering in spite of the fact that it was the normal flowering season). We presented this information at the Ecological Society of Australia meeting in Launceston in November 2019. It will be very interesting to see what recovery occurs once normal rains return.
The ‘insect apocalypse’ is a theme that has been taken up as a popular discussion point lately, driven in part by recent papers such as ‘Worldwide decline of the entomofauna: A review of its drivers’ by Sánchez-Bayo and Wyckhuys. Those of us who work in this area – entomologists, insect ecologists and others – have been aware of declines in insect abundance and diversity for decades. Unfortunately, because our understanding of these declines is limited there are multiple views, and multiple claims and counter-claims made concerning the geographic and taxonomic extents of these declines; and the discussion has become somewhat emotional at times…like all worthwhile discussions! What I think we can all agree on is that old chestnut: ‘more work needs to be done’. In the meantime, as more work is done and our understanding improves, let’s welcome all the sources of information available and all the different points of view and let’s keep the discussion going!
A preprint of a very interesting paper was published this month on the subject of bee decline: Eduardo E. Zattara and Marcelo A. Aizen, Global Bee Decline. Dec. 10, 2019; doi: http://dx.doi.org/10.1101/869784. They found the numbers of collected bee species recorded in global occurrence records sourced from the Global Biodiversity Information Facility have decline today to half of those recorded in the 1950s.
A book I did with the poet, John Charles Ryan, has just been launched as an open-access, online book at https://hdl.handle.net/1959.11/27909 The book is called ‘Between Art and Poetry: New Perspectives on Tablelands Flora’. It is a cross-disciplinary look at the diversity of the vegetation on the New England Tablelands of NSW, Australia. It combines poetry by John, paintings by me, notes on the early botanical exploration of the region by John and environmental-science notes by both of us. We picked out six different ecosystems among the diverse assemblage on the tablelands and explored the flora in those those six systems. Do please have a look and feel free to download/copy/use/cite 🙂
The image above is of Exoneura bicolor on a flower of Leptospermum novae-angliae, the New England Tea-tree. This tea tree (a shrub) is a ‘co-factor’ in the pollination ecology of a threatened species on native mint, Prostanthera staurophylla – known as a co-factor because it provides nectar to pollinators on which P. staurophylla depends and is therefore an important component of P. staurophylla‘s plant-pollinator network. There are only about 100 plants of P. staurophylla left in the wild. We are currently working out the species’ pollination needs and also working closely with the Department of Planning, Industry and Environment on a translocation experiment to establish some back-up populations of this endangered plant.
