‘The Little Things that run the world’: Ireland’s insect decline and an urgent call for action

Insects are the most diverse group of animals on the planet. With an estimated 5.5 million species, they play essential roles in the functioning of ecosystems. From recycling nutrients to ensuring crop pollination and biological pest control1, these invertebrates also constitute vital food sources for numerous vertebrates and are crucial to the survival of most life on Earth and the sustainable development of our societies.

Insects account for over one-third of Ireland’s species biodiversity2 and despite their critical importance, our knowledge regarding this group remains very limited. Current data show declining numbers of insect diversity and abundance from specific regions3, 4, 5, 6, including Ireland7, 2, 8, 9. The rapid insect population declines imply less abundance and a more restricted geographical distribution of species, representing the first step towards extinction5. We are potentially facing an undocumented extinction of thousands of Irish species, whose role in functioning of ecosystem we do not understand. Improving our insect knowledge is essential and urgent, particularly given widespread anthropogenic threats. To address this gap, this article aims to discuss how Ireland can develop a better understanding of insect conservation and ensure that these tiny creatures are fully addressed in effective biodiversity policies.

What is causing the insect extinction crisis and why should we worry about it?

The fast and undocumented loss of insect species and population decline can seriously impact ecosystem function10. However, it shows something even more disturbing in how we are changing the planet on such a broad scale that we are racing the extinction of many species. Many studies have proposed the main drivers of species declines11, 5, 12:

  • 1) Habitat loss, degradation and fragmentation (conversion to intensive agriculture and urbanisation)
  • 2) Deterioration of habitat quality (using polluting and harmful substances)
  • 3) Biological factors, such as pathogens and the spread of invasive species
  • 4) Climate change
  • 5) Direct overexploitation
  • 6) Coextinction of species dependent on other species

It is important to note that the number of studies on insect trends with sufficient replication and spatial coverage is limited and restricted to specific well-studied taxa12. Data from the ten major insect taxonomic orders indicate that an average of 37% of species is declining, while populations of 18% of species are increasing; the latter taxa mainly involve insect “pest” species5.

A dramatic decline in average airborne insect biomass of 76% (up to 82% in midsummer) was documented in 27 years for protected nature areas in Germany, parallel with reported declines in several taxa, such as butterflies, wild bees and moths, suggesting that the flying insect community as a whole has been decimated over the last few decades12. Unfortunately, efforts to protect insects are restricted to only a few groups.

Current biodiversity policies in Ireland and the UK have significant gaps in insect biodiversity protection13. While policies directly protect most UK mammalian species in the European IUCN Red List, insects remain largely unprotected. Moreover, there is a taxonomic bias whereby the majority (>50%) of insect species protected by current policies are Lepidopterans (moths and butterflies), while a minority are Coleopterans (beetles) and none are Hymenopterans (bees, ants, wasps). These findings are likely to occur worldwide, highlighting the need for more directive policies to manage and protect insect biodiversity.

What can be done to reverse the trend?

There is an urgent need to uncover the causes of biodiversity decline, its geographical extent and to understand the impacts of the decline on ecosystems and ecosystem services. Local, national and international efforts can help to minimise the biodiversity crisis, and it is important to understand whether current policies can effectively protect biodiversity.

Many solutions are now available to support insect populations at sustainable levels, especially through preserving and recovering natural habitats, which include: eliminating deleterious agricultural practices; implementing measures for avoiding or eliminating the negative impacts of invasive species; taking effective steps to reduce greenhouse gas emissions, and curbing the deleterious effects of overexploitation of many taxa11.

Such solutions involve a transformative change of our economy and society. To mitigate the effects of the biodiversity crisis, we need to adopt sustainable levels of consumption. In a global context, as human population growth has been the greatest challenge for natural systems10, social justice is another critical topic to discuss and the necessity to move away from global inequality if we wish to attain a sustainable world for future generations. Considering the current conditions, it will become increasingly difficult for emergent nations to maintain nature reserves or sustainable agricultural systems.

In the face of such trends, ecological restoration will become an essential strategy for preserving biodiversity. Restoring ecosystems is a crucial way to address the problem of slowing extinction, as it provides more options for organisms’ movement and dispersal, enhancing the possibility of their survival: “The greater the amount of natural habitat that we succeed in preserving now, the more options that we will have in the future10.

Designing agriculture in such a way as to preserve the existing biodiversity as much as possible is another key strategy that we should adopt widely. Maintaining natural or restored areas within or beside the fields and designing to be sustainable and productive under specific local conditions and the precise assessment of those conditions to find the best matches for them can be the key to maximising productivity and allowing for the preservation of other lands for preserving regional biodiversity10.

Political recognition of the need to establish long-term, standardised population monitoring for diverse orders will allow for setting priorities based on extinction risk, thereby targeting the most endangered species13. There is also a gap in our knowledge of how effective other environmentally relevant policies are for insect conservation, including protected area designations, pesticide regulations, and agricultural policies.

Investing in research programs that generate local, regional and global strategies that convert this trend is essential11. We must launch a major effort to measure biodiversity and improve our knowledge of insect diversity, distribution and ecology. Investing in a complete inventory of all the species of organisms and developing regional Red Lists to assess the changes these groups face are crucial steps.

To achieve these goals, we need to develop taxonomic expertise. More resources should be put into training for taxonomic research in museums and other institutions. It is worth mentioning that museums, parks and reserves deserve more support than they receive. More funding and staff are essential to the study and protection of biodiversity.

To address the communities, individuals can help through low-effort and impactful changes, taking meaningful steps to protect insects and their habitats:

  • Creating more insect-friendly spaces, cultivating native plants and a range of habitats and providing food and shelter wherever possible.
  • Reducing pesticide usage and substituting it with more sustainable practices.
  • Getting involved in citizen science initiatives. It will provide invaluable baseline monitoring data to support the inclusion or exclusion of species in priority species listings based on their conservation status.
  • Take action and spread the word!

The big challenge now is to halt the extinction of insect species, allowing the recovery of declining populations and consequently protecting the vital ecosystem services they provide. By preserving insect diversity, we are helping to secure benefits for our society while improving prospects for our civilisation’s future. Insects are very much “the little things that run our world”14, as Wilson (1987) referred to the crucial role these animals play in food webs and ecosystem services, generating and maintaining biological diversity.

To mitigate the effects of the biodiversity crisis that we have caused, solutions are available and implementable, and we must act upon them now before it is too late. Efforts to empower people to achieve shared biodiversity conservation goals are essential to meet this challenge. Our actions over the next decades will determine how many will still be alongside us and the future the next generations will face.

I thank Ken Bond, John O’Sullivan, Gill Weyman and Aislinn Ward Coelho for their useful comments made during the preparation of this article.