World Bee Day 2020: Trinity’s research round up

Happy World Bee Day 2020! In Jane Stout‘s Plant-Animal Interactions Research group at Trinity College Dublin, we’ve been working hard for bees, other pollinators and biodiversity in general, so here’s a round up of what everyone’s up to at the moment…


Creating evidence base for protecting bees and other pollinators on farmland

Post-docs Stephanie Maher and Simon Hodge are working on the Farm-Ecos project assessing semi-natural habitats, such as hedgerows, on farms with different production intensities in Wexford and Sligo.  The next step in the project is to evaluate the quality of these habitats in terms of the abundance and diversity of the pollinating insects, such as wild bees and hoverflies, they support throughout the year.


Steph and Simon are also working on projects examining the ecology of solitary bees on Irish farms.

Steph is working on ground-nesting bees and aiming to better understand the soil conditions and types of substrates these bees prefer, and how well these habitats are provided for in environmental policy. Simon is investigating how stem nesting bees utilize artificial nests and how the success of these nests is affected by factors such as the diameter of the nesting tubes and their height above the ground.


New PhD student Ceri Green is researching pollinators on beef-farmland in Ireland, and how the implementation of biodiversity-friendly management actions can enhance pollinators. This project is co-funded by the IRC and Kepak as an Enterprise Partnership.


Bee Health

The PoshBee project is collecting data on the threats affecting bee health across Europe. Samples of honey bees, bumble bees, other pollinators and floral resources have been collected from oilseed rape and apples orchards, and will be assessed for contamination by pesticides and heavy metals, and the presence of diseases.  PhD student Irene Bottero is investigating how different habitats and floral resources available in field boundaries affect the pollinator communities in Irish mass-flowering crops.

irene montage
Irene in the field surveying flower visitors to Oilseed rape

Also as part of the PoshBee project, Jordan Chetcuti is working on creating a framework for Bombus sp. modeling within the ALMaSS framework (Animal Landscape and Man Simulation System). He will then parameterise the first ALMaSS Bombus sp. individual-based model for Bombus terrestris which will be used to assess the risks associated with different farming practices, as well as gaining insights into bumblebee ecology.

The PROTECTS project is investigating pesticide usage in Ireland and implications for bee health. The role of PhD student Elena Zioga is to detect and quantify the pesticide residues found in pollen and nectar of crops and wild plants.

Elena fieldwork
Elena in the field collecting flowers from Oilseed rape and Bramble to extract nectar and pollen


PhD student Sarah Gabel is researching agricultural impacts on the health of hoverfly pollinators, also called flower flies. She is looking at how hedges relate to hoverfly diversity, and how pesticides affect behaviour. #LoveIrishResearch

sarah montage
Sarah sampling hoverflies in oat fields


Urban bees

The Connecting Nature project aims to create Nature-based Solutions to many contemporary problems, from climate change and rising sea levels to social cohesion and health. PhD student Cian White has conducted research on urban wildflower meadows, looking at the multiple benefits they provide, both aesthetically and from a conservation of biodiversity point of view. Cian is also looking at how urban and agricultural landscapes impact plant and pollinator communities and the interaction networks they form.


Post-doc Aoibheann Gaughranis managing the team of Trinity ecologists completing a year-long biodiversity audit of Áras an Uachtaráin at the request of President Michael D Higgins and the Office of Public Works. The team will make recommendations on positive measures for biodiversity in the future management of the house and grounds. Habitats on-site include meadows, parkland, formal gardens and an organic vegetable garden and orchard, and surveys have already revealed a host of solitary and bumble bees including Andrena lapponica and Bombus pascuorum foraging on both wildflowers and planted cultivars.



All of this research helps to provide the evidence base for practical conservation of bees and other pollinators across farmland, (semi) natural and urban habitats, providing advice to stakeholders, and for developing policy. As Phase 1 of the All-Ireland Pollinator Plan (AIPP) draws to an end, Jane Stout is working with Úna FitzPatrick at the National Biodiversity Data Centre, and the AIPP Steering Group to develop AIPP II 2021-2025. Our efforts in Ireland feed into the EU Pollinators Initiative as well as global efforts via Promote Pollinators  and the International Pollinator Initiative. Together we can make a difference!






Bees: common myths and misunderstandings

There are >20,000 different species of bee worldwide. They are a diverse group, encompassing the tiny 2mm long Perdita minima and the massive 38mm long Megachile pluto. They all* have one thing in common: their larvae feed on pollen from flowers. The protein in the pollen is necessary for larval growth and development, and thus for producing healthy adult bees. When visiting flowers to collect pollen and nectar to fuel flight, adult bees transfer that pollen from flower to flower, thus making them brilliant pollinators.

And bees are ever-increasing in popularity across many sectors including conservation, gardening, fashion, marketing, and public/corporate strategies. Their popularity means that there has been an increase into bee research, and lots of excellent conservation strategies (including our own All-Ireland Pollinator Plan), but it also means there has been a lot of mis-use of bees in corporate and even well-meaning conservation strategies (see Charlotte de Keyzer’s excellent “bee-washing” website). And as their popularity spreads, so does the amount of incorrect information about them, which makes an Melittologist (someone who studies bees), buzz with frustration…

So here’s a blog I’ve been meaning to write for some time** – six statements about bees that are often used, but aren’t true…


1. One in three bites of food (or one third of food) depends on bee pollination: this one pops up on my twitter feed, in articles, talks, publications all the time…

The source of this “one in three” or “one third” quote is thought to be a 1976 Pollination Handbook, which says “it appears that perhaps one-third of our total diet is dependent, directly or indirectly, upon insect-pollinated plants.”

In 2007, an excellent paper by Alex Klein and co-authors was published, which states in its abstract “60% of global production comes from crops that do not depend on animal pollination, 35% from crops that depend on pollinators, and 5% are unevaluated”. But if you read the paper properly, you will see “Production of 39 of the leading 57 single crops increases with pollinating animals… account[ing] for 35% (23×108 Mt) of global food production”. But the authors acknowledge that not all crops are entirely dependent on animal pollination, i.e. animal pollination can increase fruit or seed production, but exclusion of animal pollinators does not inhibit it entirely for all crops. Thus the amount of production directly attributable to animals is probably lower. And the data were only taken from crops that produce fruits or seeds for direct human use as food.

So the “one-third/one-in-three bites depending on bees” is wrong for several reasons:

i) it’s not just bees that pollinate food crops, and certainly not just honey bees – wild and unmanaged pollinators, including insects that aren’t bees, are important for crop production.

ii) these crops aren’t 100% dependent on animal pollination – the level of dependency varies among crop types and even varieties within crops and across with geographic context, and so the plants aren’t “dependent” on animal pollination, but benefit from it in terms of increased quantity and/or quality of yields

iii) we get food from sources other than directly from crops – this study only included crops that are used directly as human food – it does not include fodder crops for animals (which are then consumed by humans), it does not include processed foods.

The other thing to remember is that bees and other flower-visiting animals are responsible for pollinating the vast majority of all flowering plant species on earth – they aren’t just important because they contribute to the human food system. They have many other values to us, and are an intrinsic part of functioning ecosystems.


2. Einstein quote: “If the bee disappeared off the face of the earth, man would only have four years left to live”. There is no evidence that Einstein ever said this – according to Quote investigator, he was linked with bees in the Canadian Bee Journal in 1941, and the 4-year deadline was attributed to him by a French publication ten years after this death. But there is no evidence Einstein ever calculated the fate of humanity in the absence of bees. Jeff Ollerton has a nice blog on this topic here and I don’t need to repeat.


3. The bee is in decline and needs our help: which bee are we talking about here? This is a massive over-generalisation of a group which comprises >20,000 different species worldwide (see excellent blog by Manu Saunders), and the point is that not all of them are in decline. In fact, some are doing very well, thank you very much, particularly the ones that can thrive in human-modified landscapes (whether urban or agricultural). One species that has been spreading its distribution westwards over the past two decades is Bombus hypnorum, the tree bumblebee (see pages 70-71 of Rasmont et al. 2015) – I first saw one individual of this species in southern England in 2000 (I wasn’t quick enough to catch it!), so it was first officially recorded in 2001, and spread rapidly northwards after that. In 2017, it turned up in Dublin.

On the other hand, there are some species that have rapidly declined: 30% of Irish species are threatened, and a whopping 77 species of bee face extinction across Europe, including 22 species that don’t occur anywhere else in the world. Some are threatened by climate change: for example, Bombus polaris, which is restricted to the mountains of Scandinavia and tundra of the Arctic, is likely to lose suitable habitat and to be extinct by 2050 (see pages 102-103 of Rasmont et al. 2015). But others are threatened by the familiar drivers of biodiversity decline: habitat loss, destruction, degradation and fragmentation, agrochemicals, parasites and diseases and other invasive species, and the combination of these stressors.

In fact, we don’t know nearly enough about most bee species to know whether they are in decline or not. Of the 1,942 species in Europe, more than half (1,101) were deemed “Data Deficient” during the Red-Listing process of 2015. That means that for more than half our bees, their extinction risk is officially unknown. However, studies from Europe and North America have shown declines in species richness and distributions of bees (Biesmeijer et al. 2006, Kosior et al. 2007), shifts in community compositions (Bommarco et al. 2011, Dupont et al. 2011), and declines in abundance (Cameron et al. 2011). A shocking report published recently (Zattara and Aizen 2019), using GBIF data, showed steep downward trends in bee species globally since 1990s.  The body of evidence thus suggests that bee decline is a widespread phenomenon in many species, even if we don’t yet have all the data.


4. Honey bees are most threatened and in need our help: Honey bees (and one species in particular, the “Western” or “European” honey bee, Apis mellifera) are managed by beekeepers worldwide, having been introduced by European colonists. And the number of beehives worldwide is not in decline, with numbers increasing steadily across the world, and in the EU (see graph below).

honeybee hives

Honey bees are the most widely used managed bees for crop-pollination, despite not always being the best pollinators. With the increasingly popularity of bees as a flagship for conservation, and well-intentioned increases in urban beekeeping, numbers will probably continue to rise.

urban beekeeping.png

Beekeeping is of course not a solution to decline in wild bee species, and can sometimes actually exacerbate problems for wild bees (I’m not going to go into this now, but for example see Hannah Hamilton’s Irish Times article, and articles in Science and The Conversation).

Whether wild populations of Apis mellifera are in decline is less well known: Apis mellifera was deemed “Data Deficient” in the European Red List process (see Page 17 of the report), and wild, feral colonies, formed by bees escaping from managed colonies, are often not self-sustaining. Because Apis mellifera has been managed by beekeepers for hundreds of years, and selected for honey production and docility rather than resilience to environmental pressures, they may be less able to cope with environmental change (climate, parasites, disease etc.). And some authors are arguing that, in their native range, honey bees do need conserving (see Requier et al. 2019)

5. Bees die when they sting: only honey bees die when they sting – most other bees can happily sting and fly away unharmed. The reason that honey bees die when they sting, is because their sting is barbed, meaning it gets lodged in the flesh of the creature it stings, and when it attempts to fly away, its stinger and parts of its digestive tract, muscles and nerves get left behind. Unfortunately, the honey bee does not survive this damage to its abdomen.

The bees’ stinger is actually more like a hollow needle, but attached to the sting is a venom sack – it is this venom that causes the reaction when it enters your body. The venom contains a cocktail of chemicals that cause pain, stop blood flow, histamines that give an allergic reaction and also pheromones, which stimulates a defence response to nestmates, who may also sting.

And why on earth have honey bees evolved to die when they sting you? Well, one reason is that there are no selection pressures to stop them from dying, as worker honey bees do not reproduce anyway – for more detail see here.

Did you know that it’s only female bees, ants and wasps that can sting? That’s because the sting has evolved from a modified ovipositor – the egg-lying tool of insects – and males don’t lay eggs.

6. Bees live in colonies in hives: Only approximately 10% of the world’s bee species are social and live in colonies. The vast majority of bee species are solitary, which means that a single female constructs her own nest, defends it from predators, lays eggs, and collects all the food for her offspring. Although many females can nest in aggregations, each has her own nest. These nests can be constructed in a wide variety of places, many of them in the ground, but others create or use cavities in wood, sandstone, snail shells or even within the nests of other social insects. The brood cells in these nests can be incredible feats of engineering, using mud, resin, leaves flower petals, plant fibers and even, in some urban environments, rubbish, like old plastic bags.

There is much less known about solitary bees, compared with their social cousins, but a wonderful book has just been published, which I thoroughly recommend if you are interested in getting to know more about solitary bees.

laura mining bees 3
Solitary mining bee (photo by Laura Russo)



So, there you go, six things that have been bugging me and I felt the need to share! I am sure there are many others out there, so feel free to comment!


*Except Vulture bees, which are a small group of three closely related North American stingless bee species in the genus Trigona that feed on rotting meat. They substitute meat for pollen, but still make honey from nectar. This unusual behavior was only discovered in 1982, nearly two centuries after the bees were first classified.

**It took me so long to finish this, that Úna FitzPatrick, leader of the All-Ireland Pollinator Plan, beat me to it and published this excellent blog, with lots of myth busting and good advice about how to conserve bees.

About the author: Professor in Botany, Jane Stout leads the Plant-Animal Interactions research group at Trinity College Dublin and is co-founder of the All-Ireland Pollinator Plan.

Natural Capital, Investment Banking and Biodiversity

PhD student, Andrew Neill, reflects on his summer placement at the European Investment Bank…


If you had asked me a year ago if I had any interest in banking, I probably would have said no. As a natural sciences graduate passionate about sustainable development, it just wasn’t a path I associated with my interests. Yet in March 2019, I set off for Luxembourg to undertake a traineeship at the European Investment Bank (EIB). Not just any bank, the biggest multilateral bank in the world, responsible for lending over EUR 50 billion in 2018 alone.

The reason for this sudden change in direction was discovering a new pilot program at EIB called the “Natural Capital Financing Facility” (NCFF). It seemed like a unique project attempting to use traditional investments to support and conserve Europe’s ecosystems and biodiversity. The interdisciplinary aspect of combining finance with biodiversity, economics with environmental sustainability, really appealed to me and was too good an opportunity to miss. I applied for a traineeship position with the NCFF, crossed my fingers, and a few months later, had packed my bags for Luxembourg!

Andrew 1.png

Natural Capital and the Business Case for Biodiversity

Natural capital is a tool that captures the valuable benefits provided by nature, termed ecosystem services. These services, such as food provision, water regulation and retention, nutrient cycling, clean air provision and waste decomposition, are the fundamental building blocks for society and economy. The estimated value of these services provided by natured is 125-140 trillion USD per year, over 1.5x the global GDP (OECD, 2019). The global economic system is embedded within the Earth’s stock of natural capital, and so future development and growth depends upon preserving natural capital and its associated services.

Despite the vital importance of ecosystem services, natural capital is being lost and biodiversity eroded away. Over one million species are threatened by extinction making this the greatest mass extinction event in natural history (IPBES 2019). Once natural capital has been lost, it can be very costly or even impossible to replace it. To preserve biodiversity, an investment of USD 150-400 bn per year is required but only USD 50 bn per year is currently mobilised (CBD, 2012, UNDP BIOFIN, 2018). There is a financial gap for nature and biodiversity and until that gap is closed, natural capital will continue to be lost.

While the scale of the problem appears to be insurmountable, the biodiversity financial gap is equal to only 0.2-0.6% of global GDP. The costs of replacing these services provided freely by nature far outweigh the investment required to maintain the natural assets we currently have. There is a clear business case for investing in nature, spending 0.2-0.6% global GDP in order to safeguard the world stock of natural capital that provides over 150% global GDP in ecosystem services!

What is the NCFF project?

The NCFF project housed at EIB contributes to bridging this financial gap for nature in Europe. By acknowledging the financial need to safeguard nature, and the vast potential of private finance, it brings together two disciplines that traditionally are viewed in opposition.

The NCFF is a collaboration between the European Commission (EC) and EIB. It consists of a sum of EUR 125 m to be invested across a portfolio of natural capital based projects in Europe. The key component is a EUR 50 m contribution sourced from the EC LIFE budget (public finance), while the remainder is sourced from EIB’s capital (private finance). The public finance envelope acts as a first-loss guarantee for investments, essentially “de-risking” a project that would traditionally be viewed as too risky for private investors. This is an example of a blended financial model that can combine the strengths and advantages of both public and private financial streams in order to mobilise capital for nature.

But why would a conservation or nature-based project consider an investment from the private sector?

The majority of biodiversity finance comes from public sources such as grants, subsidies or development assistance (Global Canopy Program 2012). While this is attractive because it does not require repayment, it is highly competitive with uncertain supply, and a lack of long-term reliability.  Grant finance often comes with specific targets and objectives that lead to project design optimised for securing grants rather than achieving the best outcomes for nature. On the other hand, private finance can be reliable, flexible, long-term and less competitive to secure. Private sector actors can also unlock a new realm of expertise, networks and resources that would otherwise be unavailable. For these reasons, private finance may sometimes be a better fit for a particular nature-based project.

So far this all seems sensible and straight forward. There are advantages from diversifying investment for nature, and benefits for business and industry to support the preservation of ecosystem services and natural capital assets. But there is one major stumbling block that I am sure has become obvious…

How can private investors earn any returns on their investments? How can nature-based projects repay a loan or equity investment?

This is what makes the NCFF so interesting. It aims to demonstrate how nature-based projects can have sustainable, profitable business models. The value from the benefits derived from nature are internalised and central to the evaluation of these potential investments. This is a shortcoming of traditional economic evaluations that treat the environment (and its services) as an externality. The NCFF outlines four potential models for natural capital focused activities that generate revenue or provide cost savings for business, municipalities, NGOs, financial partners or public bodies (further details here):

  1. Payments for ecosystem services e.g. flood defence.
  2. Pro-biodiversity or pro-climate adaptation businesses e.g. ecotourism.
  3. Habitat banking e.g. offset essential infrastructure projects.
  4. Green infrastructure e.g. green roofs for city cooling.

Since 2015, the NCFF has successfully signed 5 investments totalling EUR 40 m, benefitting environmental projects across Europe. Examples include continuous cover forestry in Ireland, urban climate resilience in Athens, and habitat restoration in France. The NCFF program also includes EUR 10 m as a technical assistance package (a maximum of EUR 1 m per investment) for project partners to fully unlock the potential of their project through appropriate training and resources.

Reflecting on my NCFF experience

As a pilot program, the NCFF was, and remains, an ambitious venture. The first of its kind to demonstrate blended environmental financing at a large scale to tackle some of the biggest challenges for society today. The program is not due to finish its investment window until 2021 but there are some considerations for the future.

First is the financial demand from environmental projects in Europe. The EIB and the NCFF are specialised at delivering large scale investments of EUR 5+ million. However, many environmental organisations and businesses may be better suited to smaller investments or struggle to meet the oversight of such large sums. A more nuanced understanding of the demand characteristics of environmental financing would allow for more tailored solutions. Supporting financial intermediaries that can disburse more specialised investment sizes, finding new ways to connect the demand and supply actors of environmental finance, and building capacity for natural capital investments across sectors will be key considerations moving forward.

Secondly, many environmental business models depend on stable, long-term policy support which is not always present, and can differ within countries or across borders. It is hoped that the new EU Biodiversity strategy 2020+ can provide support and guidance on this issue and further strengthen the united approach to nature conservation across the EU. The recent green-wave observed in the 2019 European Elections is a promising sign combined with the strong sustainability commitment of the incoming European president.

Finally, there is a need to raise awareness and connect different stakeholders that may be unaware of the opportunities within the NCFF. Many stakeholders may be unaware of the opportunities of the NCFF or lack the financial experience to engage with private investors. Creating networks of stakeholders and building capacity within the environmental sector will be important for unlocking new key partnerships and investment for nature. As I have learned over the past year, when thinking of ecology, financial institutions should not be forgotten, ignored or discounted.

Conclusion and Reflection

The five months I spent at EIB opened my eyes to the importance of interdisciplinary approaches to environmental problems. I learnt a lot from working in an office of investment bankers, and I hope I was able to provide some useful insights as a natural scientist. We are inclined to think of nature and biodiversity focused projects as ecologists wearing wellington boots, surveying plants and animals in the most remote wilderness but this is no longer the norm. Important project discussions are going on in offices with people wearing suits rather than wellies (and with much less exciting scenery I must admit). But these less traditional actors for environmental conservation may prove to be vital for closing the gap for nature.

The natural capital concept may not be applicable to every biodiversity focused project, but it can contribute significantly by connecting otherwise unrelated stakeholders. These different groups possess different skills, resources, capital and expertise for the preservation of nature. Success stories from the NCFF signal to the market that these types of investments are viable, profitable and attractive, hopefully mobilising much greater sums of money to safeguard our stock of natural capital.

More Information:

EIB NCFF webpage – here

EC NCFF webpage – here

Investing in Nature Guide – here

NCFF Application Guide – here

Literature cited:

CBD, 2012 Convention on Biological Diversity, Resourcing The Aichi Biodiversity Targets: A First Assessment Of The Resources Required For Implementing The Strategic Plan For Biodiversity 2011-2020.

IPBES. 2019. Summary for policymakers of the global assessment report on biodiversity and ecosystem services of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services.

Global Canopy Program, 2012,  Parker, C., Cranford, M., Oakes, N., Leggett, M. ed., 2012. The Little Biodiversity Finance Book, Global Canopy Programme; Oxford.

OECD (2019), Biodiversity: Finance and the Economic and Business Case for Action, report prepared for the G7 Environment Ministers’ Meeting, 5-6 May 2019.

UNDP (2018). The BIOFIN Workbook 2018:Finance for Nature. The Biodiversity Finance Initiative. United Nations Development Programme: New York.


About the Author: Andrew Neill is a first year PhD student in Prof. Jane Stout’s group, working on a natural capital approach to the bioeconomy, as part of the SFI Beacon centre

Post-doc position – Developing risk assessment models for bees

We are seeking programmers for a post-doctoral research assistant (PDRA) position to develop an agent-based model for bumble bees, to complement similar models for honey bees and solitary bees, contribute to integrative analysis of bee health and production of tools for risk assessment, and develop a multi-species Environmental Risk Assessment tool, as part of an EU Horizon 2020 research project. The successful applicant will be based in the research group of Professor Jane Stout in the School of Natural Sciences, Trinity College Dublin, will work closely Professor Chris Topping and his team in the Department of Bioscience, Aarhus University, and will join the dynamic and interdisciplinary PoshBee[1] team. The PDRA is required to: design (create a formal model), develop (implement the formal model), and test an agent-based model for bumble bees (Bombus) within the ALMaSS framework[2], utilising landscape simulation models for a large part of the EU. The final model should integrate multiple stressors, including explicit incorporation of pesticide-related effects to predict impacts of changed agricultural management on bumblebees. The model is to be developed in cooperation with ALMaSS researchers associated with PoshBee and EcoStack H2020 projects, to create a simulation modelling system to inform risk assessment procedures for bees in agricultural systems.


Key skills


  • Proven programming ability in an object-oriented language, ideally C++.
  • Experience in developing scientific programming and/or modelling projects.
  • Good communication abilities will be important to be able actively engage the geographically distributed team.
  • Structured approach to project planning and execution
  • Languages skills – must be fluent in English.


  • Ecological/behavioural knowledge of bees, particularly bumblebees.
  • Programming in Python, GIS skills, experience with R, and application of mathematical and statistical analysis will all be helpful skills to have.
  • Knowledge of pesticide environmental risk assessment, or toxicology.
  • Flexibility to be able spend periods in Denmark.


Salary: This appointment will be made at point 1 of the PDRA scale from the Irish Universities Association Researcher Salary Scales i.e. €37,874 per annum (gross) for 18 months from 1st January 2020.


To apply: please send letter of application, outlining suitability for the post, and a CV, to Prof. Stout


Project description

Pollinators face multiple threats including agrochemicals, pathogens, habitat loss and climate change. A major project PoshBee (Pan-European Assessment, Monitoring and Mitigation of Stressors on the Health of Bees) aims to understand the impacts of these multiple pressures on a range of bee species and develop novel tools to help reduce risks and negative impacts. Our findings will help to ensure that pesticides can be used safely while protecting wildlife, health and the environment, both in Ireland and internationally.

The PDRA will contribute to a workpackage on systems and agent-based modelling approaches to assess the synergistic effects of multiple stressors on bee health.

poshbee logo

[1] This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 773921


Wildflowers – to plant or not to plant?

One of the most common questions I get when talking about bee decline, what causes declines and the consequences, is “what can I do to help?”. Given that one of the key drivers of decline is loss of forage resources, i.e. flowers that provide nectar and pollen, which is food for bees and many other pollinating insects, then the obvious thing to do is to increase the number of flowers for these insects.

But…  it’s not quite that simple:  not all flowers are equal.

Our native insects have co-evolved with native flowering plants, and so respond to their colour, scent, size and location, and thrive on a particular suite of species. Just like us, bees and other insects need certain nutrients in their diets to keep them healthy and to stave off illness, as well as for basic growth and functioning. Bees also need food throughout their lifetimes, some from the first flushes of early spring, others later at the end of autumn. So, a diverse, season-long diet of native species is best.

Marketed as ‘pollinator-friendly’, wildflower seeds and ‘seed bombs‘ are widely available from many well-intentioned supporters. Should these be scattered across our gardens, roadsides and amenity areas to provide much-needed food for bees and other insects? Actually, in many cases, no, they should not. For several reasons:

  1. Seed mixes can contain non-native species (“wildflower” is not the same as “native species” – it’s just something that can grow in the wild), that could become invasive and reduce diversity in our native plant communities, and not provide the right kind of food at the right time of year for our native insects.
  2. Mixes could contain native species, but from genetically distinct populations that are not adapted to the local conditions. Any seed set from these plants, or gene-flow between local and non-local plants, could potentially swamp the locally-adapted populations, which can be better suited to the local environmental conditions and able to cope with local biological pressures (e.g. disease, competition and herbivory).
  3. Seed mixtures could contain horticultural varieties of native species, that are bred for their colour, hardiness, ease of growth rather than their nutritional value to native insects. Some of these varieties contain less nectar and pollen, or less of the essential nutrients that our native insects need.
  4. Mixtures may not contain species that provide flowers right through the season, providing a bounty of food at one time of year, but nothing at other times (e.g. see this study, although US-based, the principles apply).


So what’s the best way for people to make sure they provide the right kinds of flowers to support our native insects?

Firstly, the best source of seeds is the local soil seed bank. This is where seeds are naturally stored, often in a dormant state, in the soil of nearly all habitats. Given the opportunity, these seeds germinate and grow. What we need to do is give them that opportunity. To do this, we often just need to do less. Stop mowing the grass and see what comes up. This has been demonstrated as a really successful approach by projects like “Don’t Mow, Let it Grow” and local communities and other land managers who have reduced their mowing regime (e.g. see case studies here). You might be surprised at what will come up in a lawn that has been mown for decades.

This is a ‘wildflower meadow’. Unfortunately, thanks to lush images of cornflowers and other showy non-native varieties on the front of packets of wildflower seed, we tend not to recognise our own native wildflower meadows. Natural regenration from the existing seed bank is always the best option, so reducing grass-cutting and removing clippings to reduce fertility is the best and most economic way to encourage wildflowers to grow.


Secondly, if you are trying to create a wildflower patch in soil that has previously been planted with non-native/ornamental species, or is dominated by a single fast-growing species that crowds everything else out, then help might be needed with some additional locally-collected seed. The Collecting and using pollinator friendly wildflower seed guide from the All-Ireland Pollinator Plan contains great tips and advice on how to find the right seeds to collect, how to collect and store seeds, and how to sow them.

Finally, where there is no seed bank (e.g. if the soil has been covered by plastic or buildings for many years), then you can consider buying native, local-provenance seed. This is easier said than done, however, as there are not that many places we can buy such seed. Many online sites claiming to sell native wildflower seed have small-print somewhere that says it might not be from native sources. Check what you are buying carefully, and don’t use non-native, non-local seeds in wild areas (roadsides, farmland, brownfield/open sites). Small patches in urban gardens that are already full of non-native horticultural plants are probably ok.

For other pollinator conservation dos and don’ts, see my recent blog.



About the author: Jane Stout is a Professor in Botany at Trinity College Dublin, an ecologist who has studied bees and their foraging behaviour for >20 years. She was one of the instigators of the All-Ireland Pollinator Plan and is deputy Chair of its Steering Group.


This article originally appeared on the All-Ireland Pollinator Plan webpage on 19.09.19