During the 2020 lockdown caused by the COVID-19 pandemic, I coordinated an international network of pollination ecologists who used standardised methods to collect data in their gardens. I blogged about it at the time – see here and here for instance – and also put up a post when the data paper from that work was published.
Several research groups are now working with that huge data set and interrogating it for answers to a wide range of questions. The first group to actually publish a paper from the data is a largely Chinese set of researchers from the Key Laboratory of Plant Resources, Conservation and Sustainable Utilization, at the South China Botanical Garden in Guangzhou, assisted by Kit Prendergast and myself.
In this paper we’ve considered how robust these plant-pollinator networks are to simulated extinctions of species, and how this is affected by the elevation, latitude, and plant species diversity of the network.
Here’s the full reference with a link to the study:
If you can’t access it and need a PDF, please send me a request via my Contact page.
Here’s the abstract:
Plant-pollinator interactions play a vital role in the maintenance of biodiversity and ecosystem function. Geographical variation in environmental factors can influence the diversity of pollinators and thus, affect the structure of pollination networks. Given the current global climate change, understanding the variation of pollination network structure along environmental gradients is vital to predict how global change will affect the ecological interaction processes. Here, we used a global plant-pollinator interaction data collection by the same sampling method at the same period to explore the effects of elevation, latitude, and plant richness on the structure and robustness of pollination networks. We analyzed a total of 87 networks of plant-pollinator interactions on 47 sites from 14 countries. We conducted a piecewise structural equation model to examine the direct and indirect effects of elevation, latitude, and plant richness on the network robustness and analyzed the function of network structure in elucidating the relationship between robustness and these gradients. We found that plant richness had both positive effects on robustness under random and specialist-first scenarios. Elevation, latitude, and plant richness affected network connectance and modularity, and ultimately affected network robustness which were mediated by nestedness under specialist-first and random scenarios, and by connectance under the generalist-first scenario. This study reveals the indirect effects of elevation, latitude, and plant richness on pollination network robustness were mediated by nestedness or connectance depended on the order of species extinctions, implying that communities with different pollination network structures can resist different extinction scenarios.
Yesterday I received an email containing the following press release. I thought it might interest readers of the blog so I am copying it in full with no edits. I had a quick look over the report and it’s amazingly detailed and comprehensive. It’s a shame that the report only covers insects, but that probably reflects my current bias given that my next book, due out in February, is about pollinating birds! Press release follows:
Governor Polis and the Department of Natural Resources Release Pollinator Report
BROOMFIELD – Today, Governor Polis in partnership with The Colorado Department of Natural Resources (DNR), Colorado State University Extension, Xerces Society for Invertebrate Conservation, and University of Colorado Museum of Natural History released the Colorado Native Pollinating Insects Health Study which is the most robust and detailed account of pollinator health ever undertaken in Colorado history. As directed by SB22-199, Native Pollinating Insects Protection Study, sponsored by Senators Sonya Jaquez Lewis and Kevin Priola, and Representatives Cathy Kipp and Meg Froelich, signed by Governor Polis on May 27, 2022, the study assesses the health of Colorado’s native pollinators, evaluates state policies for safeguarding pollinators, and makes recommendations on how to preserve and protect pollinators in Colorado.
“Pollinators play a critical role in Colorado life. From Crested Butte’s beautiful spring meadows to Palisade Peaches and Rocky Ford melons, Colorado’s pollinators sustain our flora and enable many foundational industries in every corner of the state. As our climate changes, we must safeguard the pollinators that generate and regenerate the Colorful Colorado we love,” said Governor Polis
Colorado is home to various native insects and bats whose pollinating services are at the heart of healthy environments and economies. Pollinators are critical to Colorado’s economy and our agricultural production and food systems, and they are essential for flowering plants that support the state’s wildlife ecosystem and add color to Colorado’s beautiful landscapes.
“Colorado is fortunate to have a tremendous diversity of plants and animals, but pollinating insects are perhaps the least studied but most beneficial for our ecosystems, economy and quality of life,” said Dan Gibbs, Executive Director, Colorado Department of Natural Resources. “I greatly appreciate the time and effort of the study authors who truly did a deep dive into the current state of pollinating insects and state policies and structures. I look forward to working with Colorado legislators and stakeholders in pursuing the best policies to ensure pollinating insect protection and long-term health.”
Colorado is home to over 1,000 species of bees—nearly 30% of North America’s and approximately 5% of the world’s bee species—and nearly 300 species of butterflies, representing over 40% of the diversity of butterflies in North America north of Mexico, some of which are already listed under the federal Endangered Species Act. This report underscores the importance of the Polis administration’s goals to tackle Colorado’s greenhouse gas emissions, prepare industries for the impending effects of climate change, and create more sustainable living in Colorado for pollinator populations.
“Our ecosystems rely on pollinators, which is why I’ve championed measures that limit toxic chemicals from harming pollinators and put forth a statewide assessment to better understand the problems our pollinators face and identify practices to better sustain them,” said Senator Sonya Jaquez Lewis, D-Longmont. “Today’s report shows that there’s plenty to do moving forward, and I am looking forward to continuing our work to protect pollinators and the ecosystems that are dependent on them.”
“I’m excited that we have this report to help us understand the extent of pollinator decline in Colorado. While Colorado ranks fifth nationally for the rate of honey-bee die-offs, we haven’t known as much about native pollinating insects. This threatens our food production, biodiversity and health of our ecosystems,” said Rep. Cathy Kipp, D-Fort Collins. “We created the Native Pollinating Insects Protection Study in 2022 to identify ways to better protect and support the native Colorado pollinators, like different bee species, butterflies, and moths, that are also essential to maintaining a healthy environment. These findings will help direct future legislation to create a safer environment for our pollinators, protect our food supply and support biodiversity.”
Promoting policies that benefit native pollinating insects represents an opportunity to foster healthy and sustainable pollinator populations, especially in agricultural and urban habitats. This includes enhancing pollinator-friendly native plantings along I-76 following its designation as a Colorado Pollinator Highway by the Colorado Department of Transportation and other existing state plans such as the state’s Natural Areas Program, and Wildlife Action Plan among others.
“Working on the Pollinator Health Study has been an amazing opportunity to collaborate with so many locally, nationally, and internationally recognized experts in the field of pollinator conservation. In addition to the immense amount of information within the report, this study highlights the importance of collaboration between scientists and land management agencies to bring together the many facets needed for conserving native pollinating insects,” said Deryn Davidson, Sustainable Landscape State Specialist, Colorado State University Extension. “Having the existing research on Colorado pollinators paired with recommended land management practices in one, comprehensive document is an incredible tool for policy makers, land managers, and really anyone interested in actionable steps for pollinator conservation.”
Areas of immediate action and priorities highlighted by the Pollinator Report include:
Priority 2: Protect, restore, and connect pollinator habitats.
Priority 3: Mitigate environmental changes that negatively impact pollinators and their habitats.
Priority 4: Reduce the risks from pesticides to pollinating insects.
Priority 5: Monitor and support native and managed pollinator health.
Governor Polis announced his annual budget proposal on November 1, focusing on ensuring Colorado is more affordable, sustainable, and liveable. The Governor included $100,000 to support education and incentives to encourage the use of pesticide alternatives in agricultural production and residential or commercial landscaping. On May 17, 2023, Governor Polis signed Neonic Pesticides as Limited-Use Pesticides, sponsored by Senators Kevin Priola and Sonya Jaquez Lewis and Representatives Kyle Brown and Cathy Kipp, which protects pollinators from harmful toxins.
Obviously the title of this post is click-bait, as there’s LOTS of things that I wish more people knew about pollination! But here’s one that really gets my (Yule) goat.
I’ve lost track of the number of times that I’ve read statements in books and research papers such as “bees collect lots of pollen from flowers therefore they are good pollinators”. Even worse, I sometimes see studies where pollen has been removed from “pollen baskets” or other scopae, then used as a measure of the importance of those bees as pollinators.
In both cases it seems to have been forgotten that bees are collecting pollen to feed their larvae and pollen that ends up in scopae is generally not available for pollination.
That’s the purpose of the Venn diagram at the top of this short post, to remind us that there can be a disconnect between what bees are doing and what plants require: foraging for pollen only partly correlates with flower pollination. Indeed, the same argument applies to any animal that feeds itself or its young on pollen, including pollen wasps (Maserinae), Heliconia butterflies, and some flower-visiting hoverflies, birds and bats.
It’s not only loss of pollen from reproduction that’s important here: depending on the size and behaviour of the bees relative to the shape and size of the flower, they may go nowhere near the stigma, so even if they are carrying viable pollen, it can be lost as far as the plant is concerned.
Note also that many bee species will collect pollen from wind-pollinated plants such as grasses, oaks, etc. Indeed in some species the availability of such pollen is extremely important – see Manu Saunders’ review on this topic and more recent papers that cite it. Again, it emphasises the partial disconnect between pollen collecting by bees and pollination of flowers by bees.
Assessing which flower visitors are actually pollinators is not technically demanding but it can be time consuming. The minimum that you need is single visit deposition (SVD) experiments in which you expose unvisited flowers to one visit by the potential pollinator. Then you assess how much pollen has landed on the stigma or (better) whether the visit results in seed set.
If you want to know more about the evidence that’s required to determine if a flower visitor is or is not a pollinator, they are codified in the “Cox-Knox Postulates” that I discuss in my book Pollinators & Pollination: Nature and Society.
Biodiversity Net Gain (or BNG) promises to transform the way that we approach nature conservation in the UK. I’ve been giving a lot of thought to what this might mean for insect pollinators and have produced a new report that summarises the opportunities that BNG presents and how we can make the most of them. You can download a copy of that report by following this link.
This is meant to be a working document and as BNG progresses, and our understanding of its impacts on pollinators increases, I will update it. In the meantime, please do feel free to comment.
There’s an estimated 350,000 described species of pollinators, and many, many more undescribed. Only about 20,000 of these (i.e. less than 6%) are bee species, although you wouldn’t know it from the media obsession with bees. It’s important and and timely, therefore, that a team of South American scientists have come together to propose a special issue of the Journal of Applied Entomology that focuses on these “other” insects.
The special issue will be called “The Neglected Pollinators: Understanding the Importance of Lesser-Known Insect Taxa in Pollination”. Consider submitting a manuscript if you work on anything except bees! Here’s the link to the details of how to submit your work:
As part of our roles as ambassadors of the new conservation organisation Restore (more of which later this year), several of us including Dave Goulson, George McGavin, and myself, are promoting this online petition to get the government to take the issue of neonicotinoid pesticides seriously. Here’s some text from Dave explaining the situation with a link to a petition that you can sign:
“For three years in a row our government has granted farmers special permission to use banned neonicotinoid pesticides on sugar beet. This is contrary to the expert advice of their own Expert Committee on Pesticides, who specifically recommended that permission should not be granted. It also flies in the face of a huge body of scientific evidence showing that these chemicals are phenomenally toxic to all insect life, and that their use on any crop contaminates soils, hedgerow plants, and nearby streams and ponds for years to come. We are in a crisis, with insect populations in freefall. It is about time our government woke up to this, and acted accordingly. This petition https://petition.parliament.uk/petitions/631948 is a necessary means of holding the government to account. Please sign and share, as signing will ensure the issue is debated in Parliament.”
This petition now has more than 15,000 signatures which ensures that it gets a response from the Government. If it reaches 100,000 mark, it will trigger a debate in Parliament. Please sign and promote this important initiative!
It’s been a couple of years since I last did a talk or workshop for the Wildlife Trust for Bedfordshire, Cambridgeshire & Northamptonshire. But I’m pleased to say that they’ve invited me back and you can join me tomorrow evening for an online introductory talk about pollinators and pollination in the UK.
The talk starts at 7pm UK time and full details of how to sign up are in the link below:
It’s been quite a while since I posted about the Chequered Skipper Reintroduction Project – see my earlier posts here and here. But my involvement has continued, albeit geographically removed from Northamptonshire, and I thought I’d give a brief update with two good news stories.
The headline story is, of course, the success of the project. Since its reintroduction in summer 2018, the Chequered Skipper population has thrived and grown and is now the first self-sustaining population in England since it went extinct there in 1976. Not only that, but the management within Rockingham Forest that was designed to improve the habitat for this butterfly has also benefitted a range of other species, including plants, insects and birds.
How do we know this? Well, the situation on the ground is being intensively monitored by the project team and the passionate volunteers who are helping to count butterflies and other species every year. The data collected from these activities has fed into Jamie Wildman’s PhD thesis where he’s collated and analysed the results. And that’s the second item of good news: yesterday Jamie successfully defended his PhD thesis and was awarded a pass with very minor corrections!
I’m actually not surprised because it’s a great thesis with some fascinating results that not only document this reintroduction but also rewrite the history of the decline and extinction of the English populations of Chequered Skipper. The first paper from that is out – see this post – and there’s more to follow shortly.
Once again, huge congratulations to Jamie and thanks to the project team and the other supervisors for their hard work. Here’s my favourite photo of Jamie, second from the left and just starting out on his PhD journey back in 2018.
Although we sometimes like to think that we have a “global” perspective on plant-pollinator interactions, in truth there are large parts of the world where we have little or no information. That’s especially true of biodiversity hotspots. One such hotspot is the Kashmir Himalaya, a relatively small area (just 135 km long by 32 km wide) that nonetheless contains an estimated 2,000 species of flowering plant, more than 150 of which are endemic to the area. In addition, over 1,280 insect pollinator species have been described, including at least 29 species of bumblebees and as many as 40 species of butterflies.
Recently I’ve been collaborating with Dr Zubair Rather from the University of Kashmir and his colleagues on a data set that represents the first network analysis of plant-pollinator interactions from the region. The network is presented at a large spatial scale – what is often termed a “meta-network”. As Dr Kit Prendergast and I noted in our recent paper, scale matters when it comes to analysing these sorts of networks. Nonetheless (to quote the current paper):
“meta-networks represent the “backbone” of plant-pollinator interactions to which smaller, local networks are attached”
Even at this very large scale we’re seeing some fascinating patterns emerging with respect to the plants, for example the importance of cultivated apples in supporting the wider network of flower visitors. Also notable, and I believe demonstrated for the first time, is the fact that both the indigenous Asian Honeybee (Apis cerana) and the introduced Western Honeybee (A. mellifera) utilise exactly the same, extremely broad array of plants from which to collect nectar and pollen.
Our Kashmir meta-network is, hopefully, the starting point for further work on plant-pollinator interactions in this fascinating and diverse part of the world. The paper is published in a special issue of the journal Flora that’s dedicated to the importance of natural history when considering the ecology and evolution of plant-pollinator relationships. The special issue is a celebration of the work of Professor Marlies Sazima and is edited by Dr Pedro Bergamo.
Here’s the reference with a link to download a free copy which should be valid up to and including 23rd January 2023:
Plant-pollinator studies are increasingly using network analysis to investigate the structure and function of such communities. However, many areas of high biodiversity largely remain unexplored in this way. Our study describes a plant-pollinator meta-network from an understudied biodiversity hotspot, the Kashmir Himalaya, where we specifically investigate plant-pollinator network nestedness and modularity, as well as the influence of alien species and the impacts of simulating species extinctions on network structure. Natural history observations were used to document the meta-network between 230 plant and 80 pollinator species forming 1958 (11% of the possible) interactions. Among the plants Malus domestica and among the pollinators Apis mellifera and A. cerana formed the largest number of interactions with significant influence over the whole network. Network cumulative degree distribution depicted a higher number of degree levels in pollinators than plants. A moderately high number of realized interactions were revealed, thereby indicating potential structural and functional stability in the network. Eight strongly defined modules were observed in the network which varied in their composition. For example, the Ephedra module exclusively comprised of native species whereas the Apis module comprised of all the four different types of interacting species (i.e. native and alien plants and pollinators) and also integrated the highest number of alien species. In the network overall, 40% of interactions were by alien species, reflecting how well these were integrated. Extinction simulations suggested that the network would collapse more quickly when the most connected pollinators are removed, rather than the most connected plant species. Our study is the first assessment of a plant-pollinator network from this Himalayan biodiversity hotspot; and will help to inform the ecological and economic implications of plant-pollinator interactions in an era of global biodiversity crisis.
During the lockdown period of the COVID-19 pandemic in 2020, many pollination ecologists were stuck at home: universities and research institutes were closed and restrictions on travel meant that it was not possible to get out and do field work. In order to keep active and motivated, and to turn adversity into an opportunity, an ad hoc network of more than 70 researchers from 15 different countries (see the map above) decided to collect standardised data on the plant-pollinator networks in their own gardens and nearby public spaces.
When combined with information about location, size of garden, floral diversity, how the garden is managed, and so forth, this would provide some useful data about how gardens support pollinators. For those with kids at home it could also be a good way of getting them out into fresh air and giving them something to do!
The resulting data set of almost 47,000 visits by insects and birds to flowers, as well as information about flowers that were never visited, is freely available and will be an invaluable resource for pollination ecologists. For example, analysing the links between ornamental flowers that share pollinators with fruits and vegetables such as apples and beans, will allow us to make recommendations for the best plants to grow in home gardens that can increase yields of crops.
There’s an old saying about turning adversity into a positive outcome: “When life gives you lemons, make lemonade”, and the researchers were pleased to find that there’s one record of Citrus limon in the data set!
The paper describing the data set has just been published in the Journal of Pollination Ecology and you can download a PDF of the paper and the associated data for free by following this link.
Sincere thanks to all of my co-authors for their commitment to the project!
Prof. Jeff Ollerton - ecological scientist and author 