Three-quarters of insect species are insufficiently represented by protected areas

Nearly 2% of insects do not overlap at all with PAs

Insects are declining in many parts of the world, yet they constitute only 8% of the assessed species in the IUCN Red List. While protected areas (PAs) could play a key role in safeguarding many insect species from extinction, coverage of insect distributions by PAs remains undocumented. We show that about 76% of insect species are inadequately represented in protected areas globally and that nearly 2% of species do not overlap with protected areas at all. The Post-2020 Global Biodiversity Framework that will likely drive PA growth provides a unique opportunity for nations to designate new areas that specifically consider insects’ needs.

Insects dominate the biosphere, yet insect populations are plummeting worldwide. Massive conservation efforts will be needed to reverse these declines. Protected areas (PAs) could act as a safeguard against extinction, but documented coverage of insect representation across the PA estate is limited. Here, we show that 76% of 89,151 insect species assessed globally do not meet minimum target levels of PA coverage. Nearly 1,900 species from 225 families do not overlap at all with PAs. Species with low PA coverage occur in North America, Eastern Europe, South and Southeast Asia, and Australasia. The Post-2020 Global Biodiversity Framework provides a guide to PA designations that require taking account of the needs of insects. Mapping important biodiversity areas must be upscaled to ensure nations capture insect diversity.

Here, we measure insect representation in the global PA system using occurrence data from the Global Biodiversity Information Facility (GBIF).We mapped the distribution of all extant insect species with at least three occurrence records in GBIF (n = 89,151) and compared their coverage by PAs with a target threshold(see experimental procedures ) set according to the geographic range size of each species. We developed species-specific range maps representing (1) the extent of occurrence (EOO; area within the shortest continuous boundary encompassing all known occurrence records) and (2) area of occupancy (AOO; the area within the EOO estimated to be occupied using alpha hulls), in both cases excluding records of known vagrant individuals.We report AOO results in the main article and EOO results in Figure S3 . We show that over 75% of insect species are inadequately represented in PAs globally. We call for an expansion of the global PA network that is insect smart, a key agenda item for the Convention of Biological Diversity’s Post-2020 Global Biodiversity Framework.

Protected areas are generally effective in safeguarding habitats from loss and degradation; therefore, ensuring adequate protected area (PA) coverage for insect species (especially those that are endangered) could help prevent insect extinctions worldwide.PAs are defined by the International Union for Conservation of Nature (IUCN)as “a clearly defined geographical space, that is recognized, dedicated, and managed through legal or other effective means, to achieve the long term conservation of nature.” There have been numerous gap analyses on different taxonomic groups,but the extent to which the distributions of insect species are represented by PAs remains poorly understood.Some local studies have reported relatively high PA coverage of insects. For example, PAs contain 80% of freshwater insect species in Spain,and butterfly species richness is greater in German PAs than in surrounding areas.Yet, in contrast, other local studies find the opposite, with PAs in Bangladesh covering less than 2% of the geographic ranges of butterflies,83% of migratory butterflies inadequately represented by PAs globally,PAs in Europe representing only 42% of the suitable habitat of the threatened beetle Rosalia alpina,and 40% of insect species reported to be entirely absent from PAs in Costa Rica, the USA, and Mexico.Given this substantial local variation, the extent to which insect species are covered by PAs globally remains obscure, meaning we are unable to track the progress of insect conservation globally.

Nature protection areas of Europe are insufficient to preserve the threatened beetle Rosalia alpina (Coleoptera: Cerambycidae): evidence from species distribution models and conservation gap analysis.

Protected areas and insect conservation: questioning the effectiveness of Natura 2000 network for saproxylic beetles in Italy.

Convention on Biological Diversity Update of the Zero Draft of the Post-2020 Global Biodiversity Framework.

Agriculture, climate change, urbanization, habitat loss, and habitat degradation are primarily driving insect declines.Although species-specific conservation actions—such as captive rearing of Schaus’ swallowtail Papilio aristodemusand the wide-scale planting of host plants for Richmond birdwing Ornithoptera richmondia—are important for preventing some extirpations, the sheer scale of insect diversity renders such intensive care too expensive and too slow to avert mass insect extinctions.

Threatened species could be more vulnerable to climate change in tropical countries.

Insects underpin the functioning of the biosphere, mediating pollination, herbivory, detritivory, plant architecture, and nutrient cycling among many other vital ecosystem processes.They also influence the physiology and population dynamics of plants and provide a major food source for thousands of vertebrate species.Insects pollinate some 80% of plant species, while at least 60% of bird species use insects as food.Approximately 5.5 million species of insects occur worldwide, yet insect richness and abundance are collapsing,with insect biomass down by 76% over 26 years in Germanyand insect abundance declining by 75%–98% over 35 years in Puerto Rico.

More than 75 percent decline over 27 years in total flying insect biomass in protected areas.

Breakpoints in butterfly decline in Central Europe over the last century.

How many species of insects and other terrestrial arthropods are there on Earth?.

The decline of butterflies in Europe: problems, significance, and possible solutions.

We detected substantial variation in PA coverage among insect families (n = 827). Mean PA coverage across the species in the family was 100% for only one (Mengenillidae), <15% for 28% of families, and there was no coverage for seven families (Ametropodidae, Ateluridae, Cecidosidae, Mnesarchaeidae, Monomachidae, Palingeniidae, and Styloperlidae). There were 22 families for which 100% of species met the representation target, but the proportion of species meeting the representation target was very low for the remaining families ( Tables S1 and S2 ). For about 27% of families (n = 227), no species achieved the representation target, and 525 families had at least 75% of their species missing the representation target ( Figure 1 ). Of the highly diverse orders that comprise at least 10,000 species in GBIF (e.g., Lepidoptera, Coleoptera, Diptera, and Hymenoptera), Coleoptera had the greatest proportion of families meeting target levels of protection (29%; Figure 1 ).

Relatively high proportions of insect species achieved target PA coverage in Amazonia, Africa, Saharo-Arabia, Europe, Western Australia, the Neotropics, Afrotropics, and Eastern and Central Europe, but protection fell short of target levels for many species in North America, Eastern Europe, South and Southeast Asia, and Australasia ( Figure 2 ). If this is caused by under-estimation of geographic range size in tropical regions, our results of PA overlap are likely to under-estimate true coverage.

Some example species for which the target representation was not achieved are given (CC-BY licenses). The source of these photographs are the following: California Academy of Sciences (Adetomyrma venatrix); Alejandro Santillana (Phanaeus vindex); Charles J. Sharp (Pseudochazara cingovskii); Seabrooke Leckie (Apantesis phalerata); US Fish & Wildlife Service – Pacific Region (Megalagrion leptodemas); Ajay Narendra (Nothomyrmecia macrops); Cuthrelld (iNaturalist user ID, Oecanthus laricis); and Kyli00 (Wikipedia user ID, Trechus terrabravensis). CR, Critically Endangered; EN, Endangered; NE, Not Evaluated. The color ramp represents the percentages of species not meeting the representation target, which increases from blue to yellow.

Insect representation in PAs showing the percentage of insect species not meeting the representation target (using the AOO) at 1 km 2 pixel resolution

Figure 2 Insect representation in PAs showing the percentage of insect species not meeting the representation target (using the AOO) at 1 km 2 pixel resolution

Species with very small geographic ranges usually occurred either completely within PAs (very high coverage) or mostly outside them (no or very low coverage), while species with large geographic range size approximated the overall terrestrial PA coverage in their degree of representation inside the PA network ( Figure S1 ). Mean coverage of AOO by PAs across all insect species was 19.24% (89,151 species). This is greater than the overall proportion of the terrestrial surface that is covered by PAs (15.73%), suggesting either biases of PAs toward insect distributions or biases in the available occurrence records of insects toward PAs.

The global distributions of 1,876 insect species (2%) do not overlap with PAs at all. These gap species were distributed across much of the world, with at least 100 gap species in the USA, Madagascar, Japan, Costa Rica, and Canada (see Figure S2 ). Gap species can occur because of sparse PA coverage, narrow species distributions, or a combination of both or simply under-recording of species distributions.Our results are strongly influenced by narrow species distributions, with nearly 85% of gap species having a known AOO of <1,000 km. Of course, many insect species are extremely poorly surveyed, and geographic range size is likely to be vastly under-estimated for many, and perhaps most, of the species in our dataset. For example, more than 50% of beetle species in a sample from taxonomic revisions were known from one locality, and roughly 15% were known from a single specimen.

PA coverage fell short of the target for 67,384 species (76%), indicating pervasive under-representation of insect distributions in the global PA system. The shortfall is much more severe than a similar global gap analysis conducted on vertebrate species, which found that 57% of 25,380 vertebrate species were inadequately covered.PA coverage varied markedly among insect orders ( Figure 1 ). Only three (Strepsiptera, Grylloblattodea, and Plecoptera) of the 28 orders had >25% PA coverage, with Strepsiptera having the highest coverage at 31.5%. There were three orders (Mantophasmatodea, Phthiraptera, and Thysanoptera) with <15% coverage, and the lowest was for Mantophasmatodea (12.12%; Tables S1 and S2 Figure S4 ).

Phylogenetic information is derived from TimeTree(see Figure S3 for the extent of occurrence results).

Taxonomic variation in PA coverage among insects using area of occupancy to depict geographic distribution

Figure 1 Taxonomic variation in PA coverage among insects using area of occupancy to depict geographic distribution

Discussion

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et al. Emerging technologies revolutionise insect ecology and monitoring. 49 Stork N.E. Measuring global biodiversity and its decline. Some insects are declining within PAs.Threats such as rapid environmental change; habitat alteration, fragmentation, and loss; human settlement; agricultural expansion and intensification; and loss of corridors and roads inside PAs suggest that insects are facing an existential risk,yet very little is known about their distribution and exposure to these threats. A new wave of surveys and monitoring is needed, perhaps fueled by the explosive growth of citizen science globally.Active management of threatening processes occurring within the existing PAs is critical, for example by planting nectar and larval-feeding plants, especially those that are suitable for threatened species, or restoring freshwater resources inside PAs.Insects utilize diverse vegetation structures and habitat requirements that vary markedly between and within families and orders.Management for insects may mean increasing landscape heterogeneity, reducing pollution, minimizing insecticide or pesticide use, reducing importing ecological harmful products, and avoiding introducing invasive species.Many insects bring joy to human visitors, and insects are often the target of citizen science participation and capacity-building workshops, enhancing restoration and conservation programs.Since most insects are herbivorous or are tied to plants, it has been suggested that the global biodiversity hotspots with more than 50% of endemic plant species could harbor a high proportion of terrestrial insect species and provide some protection if more PAs are placed within them.

5 Stork N.E. How many species of insects and other terrestrial arthropods are there on Earth?. This first global attempt to assess the performance of existing PAs in conserving insects reveals stark shortfalls, but our findings must be interpreted cautiously. First, of the estimated 5.5 million insect species globally,we could only model the distributions of 89,151 species. The unmodeled species might have much lower or higher PA coverage than those we were able to include here. Further research is needed to determine if estimated protection level varies systematically across species with dense versus sparse occurrence data after accounting for geographic range size. Second, it is possible that our results are affected by spatial variation in the extent to which occurrence records are themselves biased toward PAs. Habitats within some PAs might be unsuitable for particular insects even though the area is within the overall distribution of the species, and our maps of insect distributions will be overestimated for some species and under-estimated for others. Future studies can fine-tune estimates of the effectiveness of PAs for insect conservation by assessing habitat suitability within PAs and determine priorities for expansion of the global PA estate to efficiently increase insect protection.