Constructing a lower-bound estimate of the global number of insect species on a hyperdiverse empirical foundation

Authors

• Robert Colwell, Department of Ecology and Evolutionary Biology, University of Connecticut,
• Laura Melissa Guzman, Department of Entomology, Cornell University, Ithaca, NY 14853-2601
• Dirk Steinke, Centre for Biodiversity Genomics, Department of Integrative Biology, University of Guelph, Guelph, ON N1G2W1, Canada
• Anne Chao, Institute of Statistics, National Tsing Hua University, Hsin-Chu 30043, Taiwan;
• Daniel H. Janzen, University of Pennsylvania
• Winnie Hallwachs, University of Pennsylvania
• Austin Baker, Department of Entomology, Natural History Museum of Los Angeles County, Los Angeles, CA 90007;
• Jose L Fernández-Triana, hCanadian National Collection of Insects, Ottawa, ON K1A 0C6, Canada
• Paul D.N. Hebert, Centre for Biodiversity Genomics, Department of Integrative Biology, University of Guelph, Guelph, ON N1G2W1, Canada
• Frank Joyce, Monteverde Institute, Monteverde, Puntarenas 60109, Costa Rica
• Robert Puschendorf, School of Biological and Marine Sciences
• Donald L.J. Quicke, Center of Excellence in Integrative Insect Ecology, Department of Biology, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand
• Rodolphe Rougerie, Department of Origins and Evolution, Institut de Systématique, Évolution, Biodiversité, Muséum National d’Histoire Naturelle, CNRS, École Pratique des Hautes Études – Université Paris Sciences & Lettres, Sorbonne Université, Université des Antilles, Paris F-75005, France
• M. Alex Smith, University of Guelph
• Nelson Zamora, Escuela de Ingeniería Forestal, Instituto Tecnológico de Costa Rica, Cartago 159-7050, Costa Rica
• Michael J. Sharkey, The Hymenoptera Institute, Lexington, KY 40502

ORCID

• Robert Puschendorf: 0000-0002-8105-171X

Abstract

Estimating the number of insect species on Earth is a daunting challenge. The current consensus estimate—about six million species—is likely far too low, as we will show. Our estimate of the global number of insect species rests on a sample of more than 1,600,000 DNA-barcoded insect specimens representing 53,945 species from 15 “core” Malaise traps deployed in dry forest, cloud forest, and rainforest ecosystems of the Área de Conservación Guanacaste (ACG) in Costa Rica. Even this massive sample fails to reveal the full extent of ACG insect species richness. To estimate total ACG insect richness, we adjust the observed count of insect species by an “undersampling ratio,” computed for a hyperdiverse subfamily of parasitoid wasps (Braconidae: Microgastrinae). The ratio compares microgastrine richness from the core Malaise traps to a lower-bound estimate of true microgastrine richness—including undetected species—based on 21,669 specimens from three sources: the 15 core Malaise traps, 15 “peripheral” Malaise traps spanning all three ecosystems, and 11,373 DNA-barcoded specimens reared from some 1,500 species of microgastrine-parasitized caterpillars (Lepidoptera). To estimate global insect richness, we apply Earth/ACG ratios for tree species and several animal taxa to upscale our estimate of ACG insect richness (nearly 333,000 species). Adopting conservative assumptions, we reach an estimate of 14 to 20 million insect species on Earth, depending on the upscaling group—two to three times the current consensus estimates. Upscaling instead from a point estimate of ACG richness with a wide CI, global estimates reach nearly 30 million species.

DOI Link

10.1073/pnas.2524283123

Publication Date

2026-07-07

Publication Title

Proceedings of the National Academy of Science

Volume

123

Issue

27

Acceptance Date

2026-05-11

Deposit Date

2026-07-01

Funding

This study was made possible, in part, by awards from Canada’s New Frontiers in Research Fund (NFRFT-2020-00073) and the Canada Foundation for Innovation’s Major Science Infrastructure program (MSI 42450). These awards sustained the analytical capacity and informatics platforms at the Centre for Biodiversity Genomics at Guelph, Canada, needed to advance the overall BIOSCAN research program and its key initiatives such as BioAlfa and BOLD (Barcode of Life Data System). We are also grateful to the Walder Foundation of Chicago for supporting the barcode analyses of millions of ACG specimens and to the government of Costa Rica for approving this research program. We thank the ACG parataxonomists for sharing biological data and providing specimens. All yy-SRNP-nnnnn and DNAPARnnnnn vouchered specimens were collected, exported, and DNA-barcoded under Costa Rican government permits issued to BioAlfa (Collection Permits: Janzen and Hallwachs, 2019; R-054-2022-OT-CONAGEBIO; R-019-2019-CONAGEBIO; National Published Decree #41767), JICASAPI #0328497 (2014) and D.H.J. and W.H. (ACGPI-036-2013; R-SINAC-ACG-PI-061-2021; Resolución No001-2004 SINAC; PI-028-2021). L.M.G. acknowledges funding from the University of Southern California and Cornell University. Work on the saturniid reference library was funded by a grant to R.R. by the French Foundation for Research on Biodiversity (CESAB/ACTIAS). We thank Waldy Medina and the SIG-ACG for the layers needed to create the maps for Fig. 1. We thank Isidro Chacón for estimating the number of butterfly and odonate species in the ACG. We thank Nigel Stork, the Editor, and three peer reviewers for comments.

Keywords

DNA barcodes, species richness, biodiversity, hyperdiverse taxa, Microgastrinae, DNA barcodes | species richness | biodiversity | hyperdiverse taxa | Microgastrinae

Creative Commons License

This work is licensed under a Creative Commons Attribution 4.0 International License.

Recommended Citation

Colwell, R., Guzman, L., Steinke, D., Chao, A., Janzen, D., Hallwachs, W., Baker, A., Fernández-Triana, J., Hebert, P., Joyce, F., Puschendorf, R., Quicke, D., Rougerie, R., Smith, M., Zamora, N., & Sharkey, M. (2026) 'Constructing a lower-bound estimate of the global number of insect species on a hyperdiverse empirical foundation', Proceedings of the National Academy of Science, 123(27). Available at: 10.1073/pnas.2524283123