Celebrating the bees on the World Bee Day – Getting to know them better!

This blog was written by 3rd-year PhD students Elena Zioga and Irene Bottero and first appeared on the TCD EcoEvo Blog.

The 20th of May is declared as the ‘World bee day’ and its purpose is to acknowledge the importance of bee pollinators in our ecosystem. Animal pollinators play an important role in the reproduction of many plant species (90% benefit from animal pollination), including food crops (crops pollinated by animals make up 35% of global food production), ensuring the abundance and good quality of fruits, nuts, and seeds, which are crucial for human nutrition. Beyond food, pollinators also contribute directly to medicines, biofuels, fibers (e.g. cotton and linen), and construction materials.

Among all pollinators, bees are considered the dominant pollinators in many habitats across the world, as they depend on flowers to fuel all stages of their life cycle. There are over 20,000 bee species worldwide and they are found in all types of climates, from forests in Europe to deserts in Africa – even in the Arctic Circle. Bees belong to the great insect order of Hymenoptera – that also involves wasps, sawflies and ants – and to the suborder Apocrita, subclade Aculeata. We can say that bees are hunting wasps that changed their habits, shifting from a predatory or carnivorous diet to a herbivorous one based on nectar and pollen. This also had consequences on the physical aspect of bees, which evolved a hairy body to be more functional at holding pollen. In Ireland there are overall 99 bee species, including one honeybee species, 21 bumblebee species and 77 solitary bee species.

The honeybee (Apis mellifera L.) is the main species commercially exploited by humans for its various products (e.g. honey, pollen, royal jelly, propolis and wax). Honeybees are social insects, forming colonies with large numbers of individuals. Each colony consists of a single queen, hundreds of male drones and 20,000 to 80,000 female worker bees. The queen honeybee is the largest bee in the colony and the only one capable of laying fertilized eggs (between 1,500 to 2,000 eggs per day). Drones have no sting and they do not collect pollen or food. Their main purpose is to leave the colony and mate with new queens; if the colony becomes short of food, they are the first to be kicked out! The workers are all females and they are the smallest bees of the colony. They produce wax and they use it to build the honeycomb cells where the eggs are then laid by the queen. They are also responsible for feeding the newborn larvae which are initially fed with royal jelly, and later with honey and pollen. Their responsibilities in the hive change depending on their age: the young worker bees clean the hive and feed the larvae. Then, they start building comb cells and as they become older, they progress into cleaning and guard duties. Their last job is foraging for nectar, pollen, other plant exudates and water. Nectar is collected in their “honey stomach” while pollen is collected in their “pollen baskets”. The forager bees leave the hive each morning to source the best nectar within a 5 km radius. On return to the hive, foragers perform the ‘waggle dance’ to communicate the source of food, distance, and direction. Only female workers may sting, sacrificing themselves for the rest of the colony as they die afterwards.

A forager honeybee, Apis mellifera, covered with pollen (Photo by Irene Bottero)

Bumblebees are large, hairy bees and you can tell when you see one from its loud buzzing sound. All species of bumblebee live in colonies, but their colonies are much smaller than those of honeybees and do not survive over winter. The bumblebee colony will only consist of around 50-150 individuals. Bumblebees will only sting to defend themselves and their colony, but unlike honeybees, they can sting more than once. Bumblebees do not store honey to survive the winter. The little food they do store is saved to feed the larvae and the egg-producing queen. Bumblebees feed on nectar and collect pollen to feed their young. The bumblebee colony will die off at the end of summer and only the new queens will find somewhere to hibernate during the winter, usually underground, and emerge to find new nesting ground ready to start a new colony in spring. They like to nest underground in disused nests of small mammals, or just above the ground, in undisturbed areas with tall grasses and plenty of leaf litter. Bumblebees are very important pollinators to many plants, from herbaceous wildflowers, to shrubs and trees. They can pollinate plants that other pollinators cannot due to their longer proboscis (tongue) and they don’t mind going out on overcast days. They also perform the so called ‘buzz pollination’ by sonicating the male plant parts (stamens) to release pollen which is firmly held by the anthers.

Commercial bumblebee colonies are used for pollination in greenhouses with tomatoes, peppers, squash, strawberries, blueberries, cranberries, and many other crops.

The bumblebee Bombus lapidarius feeding on oilseed rape flower (Photo by Irene Bottero)

Solitary bees make up the largest percent of the Irish bee fauna. Solitary bees do not form a colony. Instead, they create nests in hollow reeds or twigs, holes in wood, or, most commonly, in tunnels in the ground. The female solitary bee typically creates a cell that she lays an egg into and places some food (nectar and pollen mix) for the larva when it hatches, then seals the cell off. A nest may consist of numerous cells. The adult solitary bee does not provide care for the brood once the egg is laid and usually dies after making one or more nests. Solitary bees take one whole year to pass through a complete life cycle and may only survive as adults for a few weeks. This isn’t long enough for them to raise their offspring, so the young bees must fend for themselves. The males usually emerge first and are ready for mating when the females emerge.

Andrena spp. bee with pollen on its legs. (Photo by Irene Bottero)

Bees are a large group of insects with various morphological characteristics and diverse nesting and food preferences. Here are some cool facts about those magnificent creatures!

To bee or not to bee

Some groups of insects can be very similar to bees, like flies (hoverflies) or wasps. Flies can adopt a mimic “bee pattern” to trick the predators, that will avoid them for fear of painful stings! Some Irish examples of this mimicry are represented by Eristalis tenax that looks like a honey bee and Volucella bombylans similar to a bumble bee. In other groups the similarity is less evident, but still present, like in Syrphus ribesi and in many Cheilosia species.

Comparison between an Eristalix tenax (on the left) and a honey bee (on the right, photo by Irene Bottero)
Comparison between a Volucella bombylans (on the left) and a bubmble bee (on the right, photo by Irene Bottero)

To distinguish bees from flies it could be useful pay attention to their eyes (much larger in flies) and to their wings (4 in bees and only 2 in flies). Antennae and mouth also have different aspects.

In wasps, the differences are more related to the shape of the body, and to the presence of branched hairs on bees. Some genus of bees are very similar to wasps and distinguishing them might be very tricky and might require the use of microscopes!

Comparison between a wasp (on the left) and a honey bee (on the right)

Same species but many forms!

Within the same species we can find big differences between the individuals, depending on their gender, age, and social role.

Many bees show differences between females and males – sexual dimorphism. In some cases, the differences can be particularly emphasised, and the two genders can appear as belonging to different species (i.e. Bombus lapidarius, Osmia bicolor, Andrena and Lasioglossum species).

Bombus lapidarius male and female. The male is identified by yellow hair, a characteristic that is absent in the female

The first important difference is the sting, that only can be found in females, because of its origin; the sting in fact evolved from the ovipositor system. It can be often be retracted inside the abdomen and thus not being visible at a first sight – so be careful petting a bee!

Another important difference between the genders are the hairy pollen baskets or brushes, only evident in females, on the hind legs or under the abdomen (except the cleptoparasite species that don’t collect pollen themselves, but parasite nests of other bee species).

The size and the colours also differ between gender. Usually males are smaller and less colourful than females. Moreover, their antennae are longer (13 segments instead of 12).

Some tricks can also help to quickly identify the male from the female. In honey bees for example, the eyes of the drones are much bigger than the eyes of workers (females), and if a bumble bee has yellow hair on its head is for sure a male (yes, you can pet it!!).

Another huge difference is at chromosome level: males only have half of the normal number of chromosomes because they originate from unfertilized eggs. This phenomenon, called haplodiploidy, is very rare in nature and it seems to be one of the drivers of the social behaviour in eusocial bees. In fact, the males have no fathers (even though they have grandfathers – weird!) and they share only their mother’s genetic material; the females (workers) share the 75% of their genes (25% from mother and 50% from the father – we only share 50% of our genetic material with our siblings!)

In those eusocial species, differences can be spotted between different castes: queens are usually bigger than workers and males. The workers have poorly developed ovaries and although they can in some cases lay unfertilized eggs, they cannot give birth to female individuals. 

Aging can also affect the appearance of the bees. The sun can bleach bright hairs turning them into greyish/whitish/brownish. Some other individuals can lose some hair and look smaller or darker than normal.

Real or fake bumble bee?

Within our 21 bumble bee species, 6 of them are called cuckoo bumble bees. These are cleptoparasites, exploiting the nest of other bumble bees. The cuckoo bumble bee females usually look like the queens of the host species. They enter the nest of true bumble bees and replace the queen, subjecting the workers, that will feed the new “queen” and her offspring. Despite looking very similar to true bumble bee species at first glance, some hints can help us to distinguish cuckoo bees. Bumble bees are usually very hairy, and their legs are modified to better collect pollen grains. In true bumble bee female, the lower portion of their hind legs (hind tibia) is flat and smooth with long hair on the borders (this is the “pollen basket”). Cuckoo bumble bees do not collect pollen and thus their bodies look different: they are less hairy and the hind tibia are “dull, convex and slightly hairy”. Moreover, their wings might look darker and smoky, compared to ones of the true bumble bees.

Leg differences between true female and male of bumble bee and cuckoo bumble bee from “Identification guide to Ireland’s bumblebees” National Biodiversity Data Centre

Cuckoo bumble bees are not the only cleptopasite bees. The cuckoo behaviour is present throughout the bee groups, even though the way each taxon behaves can differ. Some species wait for the host to leave the nest to place an egg inside an open cell. When the parasite hatches, it feeds on the provisions collected by the host, and the host grubs themselves. Other parasites lay the eggs in sealed cells, breaking the cell wall or penetrating it with their long and sharp ovipositor organs, or make their way through the nest killing the host if it is present.

Cleptoparasites differ from their hosts because have different habits and aspects. They do not have parental care; they develop a stalker attitude and waiting for the best moment to occupy the nest and they visit flowers only for their own need. For these reasons their bodies can lose their pollen-collecting characteristics, ending up in some cases, to be very similar to wasps – e.g. Nomada species.

Nomada spp. – the body is not hairy and is wasp-shaped. Photo by Irene Bottero

Nest sweet nest

When we think about bee nests, we can think about the hives, an anthropogenic solution to manage the honeybees. But in nature there are very different types of nests, and every group of bee has its peculiar home.

Nests can be located in the ground or be aerial. In Ireland, the majority of the solitary bees (such as Andrena, Colletes and Lasioglossus) and the totality of bumble bees are ground nesters. The only exception between bumble bees is represented by Bombus hypnorum, new to Ireland (first spotted in 2017), that nests above the ground in tree holes. Ground nester can be found in different types of dry and sun-exposed surfaces – flat, slopes or vertical – and despite some species can be found in different soils, other just nest in very peculiar ones (like for example clay or sand). The ground nests, that can be isolated or aggregated, consist in tunnels that terminates with cells. Bees found incredible solutions to make their nests waterproof, thanks to waxy or cellophane secretions.

Andrena cineraria emerging from the ground nest
Internal structure of a ground solitary bee nest

The above ground nests (or aerial) have a different structure because they are located inside holes (in trees, walls, bee hotels).

An artificial solution to provide aerial nests for solitary bees. The tubes closed that we see in the bottom suggests that some insects nested inside. Photo by Irene Bottero

These nests have different cells organised in a line, where the males larvae are laid closer to the entrance and the females in the inner part. The cells are filled with provision and they separated by walls that can be constituted by different materials. Sometimes it is possible to recognise the species the nest belongs to thanks to the materials used to make the cells – e.g. Megachile species, as the common name suggests (leaf cutter bee) uses leaves, Osmia bicornis uses mud etc.

Internal organisation of an Osmia nest. Eggs (upper part of the photo) and larvae (bottom) lie on pollen provision.

A very particular and weird type of nest is the one belonging to some Osmia species. They use empty snail shells to lay their eggs in, and that can hide them to protect them (e.g. in Ireland, Osmia aurulenta).

Some shells used as nests by different Osmia species

Save the bees!

In Ireland, six species of bumble bees are critically endangered, seven are endangered, sixteen are vulnerable and thirteen are near threatened. In the last 80 years, three species of bees have become extinct, and the distribution and forty-two species of solitary bee has decreased of approximately 50% (six species critically endangered, ten endangered, fourteen vulnerable, twelve near threatened and thirty-eight of least concern).

The decline is driven by many threats including climate change, pesticide application, habitat disruption and introduction of new species (including some parasites species). Since bees play an important role in our ecosystem and they are such amazing creatures, it should be everyone’s responsibility to protect them and prevent their decline. Even small things of our everyday life can have a big impact on bee health, and everyone can contribute protecting them by following the All-Ireland Pollinator Plan guide of simple actions towards that cause. Trying to reduce herbicide, insecticide and fungicide application in our gardens can be a first step, as these substances were proven to have a negative impact on bees. Avoiding mowing the lawn, or at least leaving some patches with flowers, will help to preserve food resources (flowers) that pollinator will use to feed on. Allowing native species to grow in our gardens and parks or planting specific plants with different flowering periods, will sustain populations of pollinators through the seasons, helping them to feed their larvae and establish colonies. Preserving hedgerows is also fundamental since they represent a semi-natural feature particularly important in the agricultural landscape, that provides food and nest resources and enables the movement of the individuals across the landscape. Moreover, preserving our soil and providing bee hotels will help to create a suitable environment for the bees to nest.

The All-Ireland Pollinator Plan provides all the guidelines for easy actions that everyone (farmers, local authorities, schools and every citizen) can adopt to preserve the bee biodiversity.


Steven Falk and Richard Lewigton (2019) Field guide to the bees of Great Britain and Ireland. Bloomsbury.

National biodiversity data centre –

Identification guide to Ireland’s bumblebees – National biodiversity Data Centre –

Wikipedia – Haplodiploidy –

All-Ireland Pollinator Plan 2021-25 –

Fitzpatrick et al. (2006) –

Fitzpatrick et al. (2007) –

IUCN Red List –

About the Authors:

Irene and Elena are PhD students in the Plant-Animal Interactions Research group, in the School of Natural Sciences at Trinity College Dublin, and are supervised by Jane Stout.

Irene Bottero is a 3rd year PhD student in Botany (Trinity College Dublin). She is part of PoshBee project and in her thesis she is evaluating the impact of different habitat types on pollinators, specifically, honeybees, bumblebees, solitary bees, hoverflies, and butterflies.
Elena Zioga is a 3rd year PhD student in Botany (Trinity College Dublin). She is part of PROTECTS project and in her thesis she is evaluating the levels of pesticide residues in pollen and nectar of plants growing in Ireland.

Previous World Bee Day blogs:

2018 World Bee Day – are we preaching to the converted?

2019 World Bee Day 2019

2020 World Bee Day 2020: Trinity’s research round up and Bees: common myths and misunderstandings

How understanding the buff-tailed bumblebee could help save the bees

This article, by PhD student Sarah Larragy, first appeared on RTE BRAINSTORM on 27 April 2021

“Save the bees”; This phrase has been meandering through various media platforms and trending hashtags for a while now. But who are these bees? And why should we to save them?

This mirrors a much wider decline in insect populations observed in many regions around the globe. For instance, a 27-year-long study by Hallman et al. (2017) in Germany found that insect biomass had declined by three quarters in this time period. Unfortunately, the suspected culprits of insect pollinator declines are all too familiar: habitat loss, pesticide use, disease spread and climate change.

Most people are aware of the critical link between bees and pollination. About three quarters of crops produced globally require animal pollination to some degree, meaning insect pollinator declines could threaten the food supply of our already crowded planet.

To put a number on this, the recent Pollival report estimated that global pollination services are worth between €260 billion and €1.1 trillion every year.

My research focuses on Bombus terrestris, also known as the buff-tailed bumblebee. It is not an endangered species, but a model-organism for pollinator research, much like mice or Drosophila melanogaster, the common fruit fly. Buff-tailed bumblebees are naturally found across Europe and Northern Africa.

Bombus terrestris, the Buff-Tailed Bumblebee, Dublin. Photo © Jane Stout

Across its range, this species has pocketed itself away in several geographically isolated areas, like Ireland, the Canaries, and Sardinia. Evolution has already caused variances in how this bee acts and looks in many of these places and several of these are classified as unique subspecies.

Buff-tailed bumblebee colonies have also become a commodity; they are grown and exported around the world by commercial companies. In Ireland, these colonies are used to pollinate crops like apples, strawberries, blackberries and cranberries.

Commercial bumblebee colonies in a fruit orchard. Photo © Jane Stout

They are much-loved by growers as bumblebees can forage in our grubby Irish weather and can provide buzz pollination to plants that can’t be pollinated without it.

Although these colonies are a great resource for growers looking for pollination services, it’s possible that they may pose some risks to wild bees, including pathogen spill-over, hybridisation and competition for floral resources.

My PhD research is funded by the Irish Research Council and is based in the Applied Proteomics lab in Maynooth University. In a nutshell, the aim of my research is to characterise the native population Irish buff-tailed bumblebee from the genetic level all the way up to the behavioural.

Sarah Larragy (L) and Merissa Cullen (R), bumblebee researchers in the Applied Proteomics Research Group, Maynooth University

Genetic distinctions can indicate when a population may be on track to diverge from the larger species group and perhaps evolve into a new sub-species or species. Although Ireland is often considered species poor next to Britain & mainland Europe, there are several genetically unique species populations here, such as the native black Irish honeybee rediscovered just a few years ago.

Ireland may host many more distinctively ‘Irish’ species populations. Through whole genome sequencing supported by the Department of Agriculture’s Genetic Resources Grant Aid Scheme, our project team hopes to evaluate the genetic uniqueness of Irish buff-tailed bumblebees.

This is a collaborative project involving my supervisor Dr James Carolan (MU), Prof Jane Stout (TCD) and Dr Joe Colgan (JGU, Mainz). Should we find that Irish buff-tailed bees are a genetic resource, we will need to consider how best we can conserve one of our most important native pollinator bee species.

I plan to evaluate how our Irish buff-tailed bees respond on a molecular level to pathogens and pesticides. We do this by identifying which proteins become up or down-regulated in, for example, haemolymph (the insect equivalent of blood) in response to a stressor. This is called proteomics and can let us know what could be happening on a functional level in the body of the bumblebee.

It’s possible that pollination and foraging efficiency may differ across subpopulations of bees, especially those with different genetic backgrounds or those living in different climatic regimes. I want to assess this behavioural aspect of Irish buff-tailed bumblebees to see how they compare with imported colonies in the Irish environment.

It may be that imported colonies provide excellent pollination services to crops and while they may be necessary to sustain food production, they could compete with our wild bumblebees for pollen and nectar.

I am hoping that my research will show the importance of understanding the diversity within different populations of the same species. I anticipate that this research will shed some light on the risks associated with imported bumblebees and I don’t think it is possible to remove every potential threat to our biodiversity.

Anywhere humans and wildlife co-exist, conflicts of interest are sure to crop up. However, we can try to strike a balance. In this light, I believe my research will lead to evidence-based solutions and management strategies that will help achieve the best of both worlds i.e. getting the best pollination services we can while also reducing any risks posed to wild pollinators.

And, perhaps, this will be one step towards how we will save the bees.

About the Author: Sarah Larragy is a PhD student at Maynooth University, supervised by Jim Carolan and Jane Stout. Her work is funded by the Irish Research Council. She led the development of the All-Ireland Pollinator Plan guidelines for users of imported bumblebee colonies.

My Shea Story

From pollinators to policy – the story of applied ecological research across continents

Back in 2015, I had a blast from the past when a former colleague (we did our PhDs together at Southampton University in the late 1990s) got in touch to ask whether I’d like to work on pollination of shea (Vitellaria paradoxa) in West Africa. I had done very little tropical ecology work, and had to google shea, but said “Sure, why not?”. Before I knew it, I was in Ghana, learning about shea growth, production and markets as part of a team including scientists, international and national NGO workers, and representatives from the shea industry.

Shea “nuts” drying (L), prior to being boiled and processed into Shea butter (R), July 2015

We designed an experiment across six sites in Ghana and southern Burkina Faso, and the following year, I was back setting up the experiment. We did pollinator exclusion trials to test for pollinator dependency, and surveyed which insects were visiting the flowers and actually doing the pollinating. This pilot study showed that the majority of flower visitors to shea (88%) were bees, most frequently small social stingless bees (Hypotrigona gribodoi), but native honey bees (Apis mellifera adansonii) were also common visitors to flowers early in the morning. The number of fruit produced per inflorescence was significantly lower when insects were excluded during flowering by bagging, but any fruits and seeds that were produced in bagged treatments were of similar weight to un-bagged ones. This work was published in the Journal of Pollination Ecology.

The pollination team in Ghana, January 2016

Of course, this study generated as many questions as it delivered answers, and so we sought more funding. Fortunately, we were successful and between 2016 and 2019, we were partners on a U.K government Darwin Initiative funded project researching both the impact of habitat diversity upon pollination services in shea parklands of southern Burkina Faso, and also how farmer led agro-ecological interventions, referred to as the ‘Trees Bees and Birds strategy’ can increase on-farm biodiversity, and improve parkland habitat at landscape level.

This time, I was lucky enough to go back to Burkina Faso with Dr Aoife Delaney, who had just completed her PhD with me. We set up an experiment to compare pollination and fruit production in landscapes with different levels of biodiversity, to try and understand whether in more degraded sites, the shea was adequately pollinated. Aoife stayed in Burkina Faso for six months to complete the field study, working with our local partners and farmers.

We found that in the more biodiverse sites, honey bees were observed more frequently, whereas other bee species were generally widespread, but they did visit trees in greater numbers at diverse sites. We also found that shea fruit production was significantly limited due to lack of pollination and that the degree of pollination limitation was greater in sites with lower levels of tree and shrub diversity. This work was published in Journal of Applied Ecology. See our blogs on The Applied Ecologist and RSPB sites for more.

Aoife Delaney, meeting local partners in Burkina Faso, January 2017

So, the ecological conclusion was to maintain or improve habitat level biodiversity to optimise levels of pollination for shea, and presumably other plants in the Parklands. This biodiversity would then provide multiple benefits to people, including forage and shelter for livestock, firewood, building materials and traditional medicines. The presence of trees helps to bind the soil, reducing organic matter loss, and leguminous tree species in the parklands including acacia and African locust bean improve soil fertility. The populations of insect and bird species helps to provide pollination and pest control functions.

However, these are heavily populated landscapes and increased demand for land under active cultivation has led to more land clearance, shorter fallow periods and smaller fallow areas in the Parkland. With less time and space for natural regeneration to occur, the trees and shrubs in the shea parklands have become less diverse and less abundant. Thus there are trade-offs to be made in land-management, and sustainable solutions need to be found.

To address this issue, together with Elaine Marshall the Project Leader at BirdLife International, we highlighted these issues at a “Lessons Learned” workshop in June 2019 at the David Attenborough Building in Cambridge, focusing on partner-led community conservation approaches around the world, including the Trees Bees and Birds strategy. We summarised the challenges and solutions in terms of tackling ecological restoration as follows..


  1. We need solutions to reverse the drivers of biodiversity decline
  2. Nature appears to be invisible in a lot of decision-making
  3. Loss of biodiversity and ecosystem degradation damages the flows of benefits we get from nature
  4. There are conflicts and trade-offs in ecosystem restoration
  5. Research and education efforts are currently inadequate


  1. Research and (importantly) knowledge transfer
  2. Facilitation of Indigenous Local Knowledge (ILK) sharing
  3. Target messages and roll out across sectors
  4. Build on international initiatives for restoration and frameworks for accounting for the benefits from nature

And we concluded this was all URGENT…

Jane Stout, Elaine Marshall and Aoife Delaney in Cambridge

And in 2020, we published a Policy Briefing on ” Building Resilient Landscapes and Livelihoods in Burkina Faso’s Shea Parklands” to try and address some of the issues that had been raised during the project. This highlighted the outcomes of our research, and made policy-relevant recommendations. This Briefing can be downloaded below.

And we are continuing to do the research. Latif Nasare, Lecturer at University for Development Studies in Tamale, Ghana, is conducting his PhD on shea pollination, and I’m co-supervising him. He’s investigating patterns of shea flowering phenology, how pollinator abundance varies with climate, the effects of honey bee keeping on shea yields, and forage resources for pollinators outside of the shea blooming period.

Shea flowers being visited by tiny “stingless bees”

Latif is just completing his first field season, and I’m anxiously waiting for news of how he has got on, and for travel restrictions to be lifted so that I can go back to this wonderful part of the world to continue my shea story.

About the Author: Dr Jane Stout is Professor in Botany at Trinity College Dublin, and leads the Plant-Animal Interactions Research Group. She is co-founder of the All-Ireland Pollinator Plan and Natural Capital Ireland.

Irish Pollinator Research Network meeting 2021

Despite the global pandemic, lockdown and geographic dispersion of researchers (who are currently scattered across Ireland, UK, Zambia, Ghana, Italy…), the Irish Pollinator Research Network (IPRN) gathered for its annual research symposium on 20th January 2021. Smoothly organised by TCD postdocs Jordan Chetcuti and Stephanie Maher, the meeting featured 16 presentations, with 26 participants at any one time (not always the same 26!).

The IPRN was established in 2017. Since then, we’ve met at TCD in 2018, DCU in 2019 and MU in 2020.

This year, researchers from TCD, UCD, MU, DCU, NUIG, and NBDC gathered to share research outputs, plans and ideas. Presentations covered a range of topics (listed below with my own personal take-home note!), and there was lively and constructive discussion after each one:

  • modelling bees and their responses to pressures (is difficult because so many parameters to include and we still don’t know enough about basic biology of bees to parameterise models perfectly)
  • how pollinators interact with plants and soil communities (ecological interactions are complicated, and we need to know more about soils and species traits)
  • how bees are affected at a proteomic level by stressors such as pesticides and pathogens (we need to know more about bee immune systems, commercial formulations need more testing, and proteins/pathways have weird names!)
  • analysing pesticide residues in soils, nectar and pollen (chemical extraction methods depend on both the matrix and the analytes of interest)
  • how bees are affected at an individual behavioural and colony level by pesticides and climate (bees don’t always do what you expect in flight cages!)
  • pollinators and pollination of flowering crops in Ireland (landscape surrounding fields/orchards can influence pollinators and pollination services)
  • schemes to promote pollinators on Irish farmland (with relatively little effort, farms can become much more pollinator-friendly)
  • pollination in African woodlands (although many woodland species are valuable to locals, role of pollination is not well understood, and different plant species react differently to pollination).

One thing that was apparent was the huge amount of work that has continued over the past year, despite the pandemic. A massive round of applause for all researchers for continuing to do amazing research despite restrictions, illnesses, constraints and other personal and national traumas…

Another thing that struck me was that there is so much synergy, collaboration and friendship in this network. We are there to support, help and advise each other, not to compete with one another, and that was apparent. This is so refreshing and I am feel very proud and privileged to work in this group. Keep it up everyone and looking forward to gathering at UCD next year!

To find out more about the IRPN members, see links to PIs below:

Jane Stout, TCD: Pollination ecology, plant-pollinator interactions, pollinator diversity and drivers of decline, landscape and agroecology, pollinator conservation, valuing pollinators and pollination services

Dara Stanley, UCD: Plant-pollinator diversity, interactions and conservation, pollinator behavioural ecology, agroecology, impacts of pesticides on bee behaviour and provision of pollination services.

Jim Carolan, NUI Maynooth: Cellular and molecular level effects of various stressors (pathogens, parasites and pesticides) in both native and commercial bees, bumblebee conservation, DNA barcoding and genomics.

Blanaid White, DCU: Analytical chemistry, honey chemistry, pesticide contamination of soils/floral resources.

Grace McCormack, NUI Galway: Disease tolerance/resistance in native Irish honeybees, wild honey bees.

Una Fitzpatrick, National Biodiversity Data Centre: All-Ireland Pollinator Plan


About the Author: Jane Stout is a Professor in Botany in the School of Natural Sciences at Trinity College Dublin and leads the Plant-Animal Interactions Research Group. She is co-founder of the All-Ireland Pollinator Plan.

What do insects have to do with eating, drinking and kissing this Christmas?

We don’t see many insects during the winter, but their legacy is evident in terms of the fruits and seeds that they have helped to produce earlier in the year. Without insects, we wouldn’t have many of our Christmas foods, drinks and decorations. This is because many of the plants that produce our Christmas treats rely on insects pollinating flowers earlier in the year.

Without insects, we wouldn’t have bright red holly berries to decorate our Christmas puddings, mistletoe with its characteristic white berries to kiss under, cranberries to liven up our turkey, chocolate, marzipan or many of the spices and other goodies we associate with Christmas.

This is because insects are needed by most plants for cross-pollination, which results in the production of fruits and seeds. Since plants cannot move to find mates themselves, they rely on insects to bring male and female together.

Holly (Ilex aquifolium) is unusual in the plant world because male and female flowers occur on separate shrubs. As bees drink nectar from male flowers, they get pollen on their bodies and when they move to a female plant to continue to feed, they deposit that pollen on female flowers. The pollen causes the female flowers to be fertilized, and to form fruits (or berries) containing the fertilized seeds.

A bumblebee visits a Holly flower in Co. Wicklow in April to drink nectar. (Photo J. Stout)

Similarly, mistletoe (Viscum album) also holds its male and female flowers on separate plants. Plants are partially parasitic and live on the branches of other trees but still rely on insects (not just bees, but also flies, bugs and beetles) for pollination and thus berry production.

In fact, both mistletoe and holly fetch higher prices at market if they have berries on them, and so insect pollinators are of economic value at Christmas time as well.

Cranberry bushes (Vaccinium macrocarpon) produce both the male and female structures not just on the same plant, but in the same flower. However, they still need bees to transfer the pollen between flowers, because those male and female structures do not mature at the same time.  Large bees, such as bumblebees, which can shake the flowers in just the right way to dislodge the pollen (producing a distinctive buzzing sound) are the best pollinators. This is known as “buzz pollination” and is important in other crops too (including tomatoes and blueberries).

Chocolate-producing cocoa trees (Theobroma cacao) produce small flowers on their trunks, and although flowers don’t produce a scent to attract pollinators, they produce a small amount of nectar and are visited and pollinated by tiny flies (midges). Although flowers contain both male and female structures, they cannot fertilize themselves, and these midges are needed for the production of cocoa fruits, which contain the seeds from which we derive chocolate. These trees grow in the tropics and flowers and fruits are produced throughout the year, although it takes 5-6 months for them to mature before they are harvested.

Marzipan (almond paste) is made of ground almonds (and sugar). Almond (Prunus dulcis) trees bloom in early spring and are visited by bees – both managed honeybees and wild bees. In fact, almond trees in California (where most of the world’s almonds are produced) produce better yields when both honeybees and wild bees are present in orchards. This is because they complement each other in their foraging. If there are no bees at all visiting flowers, fruit set can plummet by up to 90%.

Honeybees are important pollinators of almond flowers (Photos J. Stout)

Many of our Christmas spices, including cinnamon (Cinnamomum spp.), cloves (Syzygium aromaticum) and nutmeg (Myristica fragrans), essential ingredients in Christmas cakes, puddings and mulled wine, also need pollinating by insects. In the case of cinnamon and cloves, this is done by bees, but for nutmeg, it’s beetles that do the pollinating job.

So, as you enjoy Christmas this year, raise a glass to the insects that made all of this possible.

For more information on pollinators, their value and conservation, see the All Ireland Pollinator Plan


FAO Crop pollination database

Adjaloo & Oduro (2013) Insect assemblage and the pollination system in Cocoa ecosystems. J. Appl. Biosci. 62: 4582 – 4594

Brittain, Williams, Kremen, Klein (2013) Synergistic effects of non-Apis bees and honey bees for pollination services. Proceedings of the Royal Society B-Biological Sciences 280(1754)

MacKenzie (1994) The foraging behaviour of honey bees (Apis mellifera L) and bumble bees (Bombus spp) on cranberry (Vaccinium macrocarpon Ait). Apidologie 25: 375-383

Ollerton, Rouquette, Breeze (2016) Insect pollinators boost the market price of culturally important crops: holly, mistletoe and the spirit of Christmas. Journal of Pollination Ecology 19: 93-97

This article first appeared in The Independent in 2015.

About the Author: Dr Jane Stout is Professor in Botany at Trinity College Dublin and leads the Plant-Animal Interactions Research Group. She is co-founder of the All-Ireland Pollinator Plan.