Exploring social justice in ecosystem restoration

Elaine Marshall has just started her PhD research with Jane Stout (Botany) and Susan Murphy (Geography), School of Natural Sciences. Here she describes what her research will focus on…

Global biodiversity loss and increasing awareness of the multiple values of biodiversity for people, has resulted in an array of mechanisms, actions, policy, legislative and financial incentives for ecosystem restoration. 2021-2030 is declared the UN Decade on Ecosystem Restoration, to prevent, halt and reverse degradation of ecosystems worldwide. Efforts such as the international “Bonn challenge” – to restore 350 million hectares of degraded land by 2030 – will take place in the context of sustainable development decision-making and COVID-19 pandemic recovery.

Ecosystem restoration is place-based – interventions in landscapes where people live and derive livelihoods can result in trade-offs and conflicts with existing land uses and land users. It imperative to engage the full participation of local communities around restoration decision-making to promote fair and equitable benefit sharing over the longer term. The natural capital approach frames social-well being within the context of provisioning goods and services from nature, but we seek to build a more inclusive approach, drawing from environmental and climate justice theories, to address the historical eco-centric or anthropocentric dichotomy. We will evaluate and synthesise existing International Development and Ecological Restoration approaches to develop a new conceptual framework that balances ecological, social and economic considerations for restoration, recognising different ideological motivations for restoring and maintaining biodiverse landcapes, and the differentiated impacts of interventions upon different stakeholders. Of particular interest is how restoration effectiveness varies according to the demographic and socio-economic status of recipients (power dynamics, well-being, gender, age, access to education, religion, and race inter and intra-generational differences, gender etc.), and allows us to consider which people and whose views are taken on board when decisions are made, and who is impacted by those decisions.


Provisional research questions have been defined in order to enable the social dimensions of ecological restoration to be explored in depth.

  1. What are the most effective incentives underpinning successful ecosystem restoration outcomes?
  2. What are the social justice implications of ecosystem restoration important in ensuring success?
  3. What are the key opportunities to strengthen incentive mechanisms to ensure effective and successful ecosystem restoration?

It is envisaged that a combination of mixed methods approaches inlcuding desk-based analysis and in-field engagement with relevant stakeholders, will be employed. Methods will be refined and developed, taking a global view initially, and then focussing on case-studies for in-depth analysis:

  1. In-depth literature review of incentives for ecosystem restoration and evaluation of their effectiveness where possible; of social justice implications of restoration; the key incentives for ensuring compliance. Peer-reviewed or published (from bi and multilateral funded initiatives, UN, NGO, Academic) and grey literature will be included. Different mechanisms will be recorded and categorised; and social justice, inclusion and participation elements extracted.
  2. Including multiscale policy and regulatory analyses of international conventions around biodiversity and restoration to better understand the place-based specifics of biodiversity conservation and restoration.
  3. Stakeholder identification and consultation with case study communities (to be identified). Questionnaires and semi structured interviews based around key research questions to elicit quantitative and qualitative data on effectiveness, compliance and impacts of established and contrasting restoration initiatives. Robust, felixble methods to allow for field travel / non travel:
    • Expert opinion consultations with key informants, authors and thinkers: donors, conservation and development practitioners, private sector business, to collect their perspectives on what is successful ecosystem restoration.
    • Participatory research in communities or a combination of (in person / remote) focal group conversations and semi structured interviews to explore incentives from historical, gender, intergenerational, ethnic, perspectives; what incentives are in place for costs, benefits, rights, responsibilities, and risk sharing; perceptions of effectiveness of these incentives; barriers to implementation; and other demographic and socio-economic factors perceived as affecting successful restoration.       
  4. Analysis will focus on effectiveness of mechanisms across a range of parameters, enabling recommendations to be made around approaches and incentives for delivering effective, sustainable and ultimately successful restoration outcomes.
  5. Output: Develop a typology of incentives, or new conceptual framework, around environmental rights based and social justice to address different and diverse elements of equity, including distributional (sharing conservation and restoration costs and benefits) and procedural (involvement and participation in decision-making at different levels).

About the author: Elaine has 20+ years of experience managing collaborative relationships for research, impact assessment, communication and policy implementation across the natural resource, rural livelihoods and health sectors. She has an established interest in community based resource management and trade, poverty alleviation, governance and gender empowerment, and has worked more recently on ecosystem restoration and farmer-led interventions for mainstreaming biodiversity on farm. Wider experience includes evaluating climate change mitigation policies on agricultural systems and human health, and opportunities for sustainable energy solutions for health care provision in resource constrained settings. Her first degree was in Agriculture and the Environment, she holds a Masters in Resource Management and she believes that making progress on environmental and sustainable development ambitions relies on the engagement of local communities to ensure that enabling conditions are in place to support effective outcomes at a local scale. She hopes her PhD research will provide an exciting and timely opportunity to bring her experience and interests into a space where components of justice and equity can be more explicitly evaluated.

Researcher in Ecosystem Services and Natural Capital Accounting

Trinity College Dublin is seeking a highly motivated, collaborative researcher, with interests in Ecosystem Services and Natural Capital Accounting, to join the interdisciplinary Farm Zero C project

Farm Zero C is an SFI-funded collaboration between industry and academia, which aims to deliver a range of strategies to help to create a more sustainable and resilient dairy sector. The ultimate aim of the project is to develop a replicable net zero emissions model for dairy farmers. The Farm Zero C team is led by SFI BiObic Centre and Carbery Group, with partners including University College Dublin, Trinity College Dublin, Munster Technological University Kerry, Teagasc and GRASSA B.V. The project builds on previous work at Shinagh Dairy Farm (in West Cork), as a ‘demonstrator’, and will develop tools to be deployed through a technological platform (Climate Neutral App) that will allow farmers to design climate and biodiversity strategies that best suits their needs.

Trinity College Dublin is leading work on habitat mapping and natural capital accounting, and is seeking a researcher to:

  1. Build natural capital accounts (extent, condition and services) at farm level using the UN System of Environmental Economic Accounting – Ecosystem Accounting (SEEA-EA) approach. Accounts will focus on extent, condition, and services (carbon sequestration and storage, runoff pollution remediation and aesthetic services), and will be built for Shinagh and 10 farms in the Greener Dairy Programme.
  2. Develop and test indicators for farmland habitat condition and assess the link farmland between habitat condition and service provision for integration into natural capital accounts.  
  3. Work with other members of the Farm Zero C team to integrate accounting into an interactive app-based interface (Climate Neutral App), so that accounts are informative, useful and intuitive to use by farmers.
  4. Write and publish peer reviewed scientific papers and present results at national and international conferences.

The researcher will join the group of Professor Jane Stout in the School of Natural Sciences at Trinity College Dublin, who leads the INCASE project developing Natural Capital Accounting (NCA) approaches for Ireland, and who is a lead PI on the Nature+Energy project, developing NCA for the wind-energy industry. As part of the Farm Zero C project, the researcher will also benefit from training and collaboration with Professor Lars Hein at Wageningen University who was one of the main authors of the UN SEEA-EA framework.   

Qualifications and experience required

Candidates must demonstrate the following

  • Minimum 2 years experience (which may include experience gained during a Masters/PhD) in a relevant field, such as environmental sciences, agricultural ecology, ecological economics, environmental resource economics, or related discipline, with an interest in Natural Capital Accounting, and ecosystem services.
  • Research expertise and excellent written communication skills as evidenced by, for example, publications in international peer-reviewed journals
  • Excellent oral communication and team work skills for transdisciplinary collaboration with other researchers and partners in industry
  • Strong organisation skills and self-motivation
  • Driving licence

The following is desirable

  • Understanding of Irish dairy or related agricultural systems
  • Direct project or work experience developing tools for habitat assessment and/or using SEEA-EA approach
  • Understanding of habitat assessment and related policy within the agricultural sector
  • Experience participating in collaborative research projects

Details of the position


This post is full time 18-24 months’ duration, with an annual salary of €38,632 (gross).

Start date

It is anticipated that the successful applicant will be in place as soon as possible.

Application procedure

Please submit a cover letter outlining suitability for the post and a CV (including details of experience and publications, and the names of two referees) via email to

Applications accepted until the position is filled.

The Cherry on Top? Flies as Alternative Crop Pollinators

PhD student Caroline Ponsonby may have been grounded by Covid-19 and unable to travel to Western Sydney University to start her PhD as planned, but she has been able to examine crop pollination by flies here in Ireland instead.

During 2021, Caroline has been examining cherry pollination, and investigating the role of flies as well as bees as pollinators. She has been determining the diversity of species that visit cherry flowers, looking at the pollen those visitors carry and deposit, and how those visitors behave within the cherry orchards. This will help inform management of pollinators in and around the cherry crops.

Caroline has just won the Western Sydney University Visualise Your Thesis competition with the video below, and now goes on to the the international competition in Melbourne.

Caroline is supervised by Prof James Cook and Dr Jon Finch at the Hawkesbury Institute for the Environment in Western Sydney University and Prof Jane Stout at Trinity College Dublin.

‘FOREST – Reimagining relations with nature’ – Five PhD Studentships available

An exciting new multi-disciplinary project is seeking to recruit 5 new PhD students. Students will work as a team to examine native woodland afforestation, which has become perceived as a key strategy to address climate and biodiversity challenges, and is attracting investment from public and private actors. However, the ecological, social, and financial risks of this are not always well considered. This project, FOREST, will use the increase in forestry in Ireland as a model system to explore the challenges associated with addressing climate and biodiversity issues, and examine potential solutions from a multi-disciplinary perspective. The aim is to develop socially just, ecologically sound and economically viable options. 

PhD 1: Climate justice through restorative development – primary supervisor Professor Murphy (Geography), co-supervisor Professor Denny (Economics). To explore the opportunities and barriers to community participation, social recognition, and fair distribution of the social, economic and ecological costs and co-benefits of offsetting through afforestation in Ireland

Phd 2: Blending nature-based & technology solutions – primary supervisor Professor McCormack (Engineering), co-supervisor Professor Stout (Botany). To examine optimisation of a blended approach, addressing the compatibility of nature-based solutions (long-term forestry) and technological solutions (e.g. solar farms) at different spatial and temporal scales in order to determine options for optimum climate action for Ireland.

PhD 3: Quantitative analysis/integration of metrics – primary supervisor Professor Brophy (Statistics), co-supervisor Professor Stout (Botany). To develop a statistical approach to exploring impacts of native afforestation, including a meta-analysis of ecological data (e.g. role of forests for pollinators in Ireland), integration of different metrics for value (monetary vs quantitative vs qualitative metrics) and methods for scaling individual actions to societal level. This project will also collaborate with the other four FOREST PhD students to develop a multivariate statistical analysis to jointly assess outcomes across the FOREST project.

PhD 4: Perspectives on value and financial incentives – primary supervisor Professor O’Hagan-Luff (Business), co-supervisor Professor Denny (Economics). To explore behavioural and financial incentives for increased forestry (restoration, afforestation, rewilding, offsetting) in Ireland.

PhD 5: Ecological value of new forests – primary supervisor Professor Jane Stout (Botany), co-supervisor Professor Fraser Mitchell (Botany). To determine the ecology and ecosystem services provided by newly planted forests, across a range of sites of different sizes, ages, and tree composition.

PhD students will work as a team and so excellent team working and communication skills are required. Each candidate will produce an independent piece of research in the form of a PhD thesis based on this research project.

ProjectPrimary supervisorContactRequirements
Climate justice through restorative developmentSusan MurphySusan.P.Murphy@tcd.ieMaster’s degree in geography, politics, economics, or other relevant social sciences area of study. Research / field experience in sustainable development research and practice is desirable
Blending nature-based & technology solutionsSarah McCormackmccorms1@tcd.ieMaster’s degree in engineering or natural sciences or a relevant area of study
Quantitative analysis/integration of metricsCaroline BrophyCaroline.Brophy@tcd.ieBachelors (upper second class or higher) or Master’s degree in Statistics, Mathematics or similar quantitative field; experience or interest in addressing environmental challenges desirable.
Perspectives on value and financial incentivesMartha O’Hagan Luffohaganm@tcd.ieMaster’s degree in business, finance or economics
Ecological value of new forestsJane Stoutstoutj@tcd.ieBachelors (upper second class or higher) or Masters degree in ecology, environmental sciences, or similar; experience in ecological fieldwork desirable; must have full-clean driving licence

This project is part of the Kinsella Challenge-Based E3 projects at Trinity College Dublin, and PhD students will have the opportunity to work alongside the other successful projects, particularly in terms of team-building and dissemination events.

The PhDs are all 4-year structured programmes, with an anticipated start date of September 2021.

Application Process

Applications can be made by clicking here…

Late applications will not be accepted. Informal enquiries should be made to the primary supervisor. Completed applications should be submitted via the above link and will require:

  1. A curriculum vitae (including the names of two referees, one of which must be an academic referee).
  2. A cover letter (maximum 1000 words) outlining the applicant’s research interests and why they are suitable for this project.

Applications will be jointly reviewed by project supervisors. Shortlisted applicants will be invited to video-interview. The successful applicant will subsequently apply to register as a PhD student through the Trinity College Dublin central portal but must meet all requirements for registration in order to be eligible for this funding award. Postgraduate admission requirements are available here: The successful applicant will be required to provide evidence of English language competence following the award offer and before registering.

About the Project

FOREST brings together research leaders across Botany, Economics, Engineering, Finance, Geography and Statistics to reimagine our relations with nature. People and nature are not separate – we are dependent on nature as our life support system. The systematic failure of economic, political, and financial systems to take nature into account has resulted in climate and biodiversity crises. Ireland is now seeking to transition away from highly carbon-dependent social and economic practices, towards sustainable practices, systems and behaviours that support the coexistence of flourishing human systems and natural environments.

This project will investigate how to assign value to the natural world to create investment initiatives with ecological benefits, to encourage investors to actively invest in assets with environmental and societal benefits.  It will examine the behavioural aspects and financial investment incentives that can be linked to the protection or restoration of forests.  However, placing a financial value on nature is not enough to preserve it, there must also be policy initiatives, and stronger legal mechanisms which recognise the multiple benefits of forests such as carbon capture, biodiversity habitat, and recreation. The financial industry is beset by a focus on short term gains, caused by performance metrics, remuneration incentives and incomplete measures of value.  Policy supports can to some extent address these market failures by creating incentives which incorporate the long term non-market and socio-cultural benefits of nature. 

To correctly design incentives, an understanding of different perspectives on the values and benefits of nature in the widest sense is key, particularly in terms of impacting on individual and collective action. Actions taken have consequences for environment, people, and economies, but are often only assessed through a single lens. Implementing the right action in the right place urgently requires a new kind of multi-disciplinary dynamic, and a way of integrating data measured on different scales.  This research challenge is inherently multidisciplinary in nature and will be conducted in conjunction with researchers across a range of relevant disciplines.

FOREST will use the increase in forestry in Ireland as a model system to explore the challenges associated with addressing climate and biodiversity issues, and examine potential solutions through a multi-disciplinary lens. It will recruit a team of PhD candidates to study as part of an interdisciplinary team to address complex human-nature relations and the social-economic-ecological challenges and opportunities associated with transitioning away from unsustainable to sustainable development pathways.

Projects are also advertised on – but please apply here

Climate Justice Through Restorative Development (with Susan Murphy and Eleanor Denny

Blending nature based technology solutions (with Sarah McCormack and Jane Stout

Quantitative Analysis Integration of Metrics (with Caroline Brophy and Jane Stout

Perspectives on Value and Financial Incentives (with Martha O’Hagan-Luff and Eleanor Denny

Ecological Value of New Forests (with Jane Stout

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