Nigel E. Stork

Many insect species are declining globally, yet they are largely overlooked in biodiversity conservation measures. This gap is most severe in the tropics, which harbor over 80% of insect species. To address this conservation gap, we assembled a global team of experts and identified four major challenges: limited global visibility, data shortfall, lack of infrastructure, and insufficient conservation actions. We propose a strategic framework that integrates diverse data sources, strengthens regional expertise, and links evidence to policy—highlighting an application in Bangladesh, a densely populated tropical country facing multiple conservation barriers. Centered on insects, our framework provides a pathway to measurable conservation outcomes, builds local capacity for delivery, and helps tropical countries meet biodiversity commitments.

Tropical forests harbour a large proportion of Earth’s insect biodiversity. Tropical forest structure produces layers of habitat from the cooler, wetter understorey to the hotter, drier canopy, which provide stratified resources for inhabitants. This gradient of biotic and abiotic factors results in vertically stratified insect communities, often with different assemblages in the understorey and canopy. Vertical distributions of insect taxa are shaped by their niche requirements, with narrower vertical ranges for species with more specialised life history strategies and abiotic requirements. Many studies of vertical stratification focus on single taxonomic orders, often overlooking less well-worked orders, such as Hemiptera, and comparisons of the responses of different taxa sampled at the same time under the same conditions are rare. Here we examine light-trapped samples of adult Lepidoptera (moths), Hemiptera: Auchenorrhyncha (leafhoppers and relatives) and Coleoptera (beetles) collected at 0 m, 10 m, 20 m and 30 m from the ground within a primary tropical forest in Daintree, Queensland, Australia. We found different assemblages of insects in the canopy (20–30 m above ground) and in the understorey (0–10 m) for moths and beetles, but not for Auchenorrhynchs. Species diversity of moths was higher in the canopy than in the understorey, while beetles showed the opposite pattern. In contrast, Auchenorrhyncha did not vary in species diversity between the canopy and the understorey. This may be because the resources used by moths are mostly higher in the canopy and vice versa for beetles. Auchenorrhycha are sap-sucking insects so, provided their host plants can be found throughout the vertical gradient, they might not face the resource availability pressure that drives stratification in moths and beetles. We suggest that future studies of vertical stratification in multiple taxa need to test for such drivers of diversity.

Insect species are declining globally, yet they are often overlooked in biodiversity conservation measures. The tropics harbour > 80% of all insect species; however, information on their ecology and conservation status is largely lacking. It is imperative to identify solutions to the issues of data availability and integration of scientific findings with conservation policy for tropical insects. To achieve this, we assembled a global team of experts and identified four major challenges: global visibility, data shortfalls, lack of infrastructure, and insufficient conservation action. We developed a framework for potential solutions to conserve tropical insects and tested it in Bangladesh, a densely populated tropical country. Our framework applies broadly to governmental obligations for biodiversity conservation in tropical countries worldwide.

Tropical elevation gradients support highly diverse assemblages, but competing hypotheses suggest either peak species richness in lowland rainforests or at mid‐elevations. We investigated scolytine beetles—phloem, ambrosia and seed‐feeding beetles—along a tropical elevational gradient in Papua New Guinea. Highly standardised sampling from 200 to 3700 m above sea level (asl) identified areas of highest and lowest species richness, abundance and other biodiversity variables. Using passive flight intercept traps at eight elevations from 200 to 3500 m asl, we collected over 9600 specimens representing 215 species. Despite extensive sampling, species accumulation curves suggest that diversity was not fully exhausted. Scolytine species richness followed a unimodal distribution, peaking between 700 and 1200 m asl, supporting prior findings of highest diversity at low‐to‐mid elevations. Alternative models, such as a monotonous decrease from lowlands to higher elevations and a mid‐elevation maximum, showed lesser fit to our data. Abundance is greatest at the lowest sites, driven by a few extremely abundant species. The turnover rate—beta diversity between elevation steps—is greatest between the highest elevations. Among dominant tribes—Dryocoetini, Xyleborini and Cryphalini—species richness peaked between 700 and 2200 m asl. Taxon‐specific analyses revealed distinct patterns: Euwallacea spp. abundance uniformly declined with elevation, while other genera were driven by dominant species at different elevations. Coccotrypes and phloem‐feeding Cryphalus have undergone evolutionary radiations in New Guinea, with many species still undescribed. Species not yet known to science are most likely to be found at lower and middle elevations, where overall diversity is highest.

Only 20% of the estimated 5 million species of insects on Earth are named and yet insects are poorly represented in protected area assessments, and insect declines are of concern globally. Here, we explore how to increase the discovery of new species and understanding of this group through analysis of 10,097 tropical rainforest bark beetles (Scolytinae) from eight different ecological studies between 2000 and 2018 in the Australian Wet Tropics. Of the 107 species identified, 58 are undescribed: an increase of 37% on the 156 species known from Australia. Rarefaction indicates doubling sampling would increase the number of species by 17. As hypothesised, new species are significantly smaller, less abundant and less widespread than described species making them more extinction‐prone than named species. Flight interception traps collected 84% of individuals and 98% of species confirming the effectiveness of a single sampling method for some beetles. Increased locations and collection from the canopy may sample further species rather than additional collecting methods. Scolytines are relatively well studied with taxonomists at the forefront of using modern methods to resolve formerly intractable groups. Hence, these new species are more likely to be named than others in many other beetle groups where taxonomy has largely stalled. To increase species description rates and to avoid most species becoming extinct before being named, we call on taxonomists to use new character systems provided by DNA methods and advances in the rapidly developing field of artificial intelligence.

Only 20% of the estimated five million species of insects on Earth are named despite over 240 years of taxonomy. Yet insects are poorly represented in protected area assessments, and insect declines are of concern globally. Here we explore how to increase the discovery of new species and understanding of this group through analysis of 10,097 tropical rainforest bark beetles (Scolytinae) from eight different ecological studies using beetles between 2000 and 2018 in the Australian Wet Tropics. Of the 107 species identified, 58 are undescribed: an increase of 35% on the 166 species known from Australia. As hypothesised, new species are significantly smaller, less abundant and less widespread than described species making them more extinction prone than named species. Rarefaction indicates doubling sampling would increase the number of species by 17. Flight Interception Traps (FIT) collected 84% of individuals and 98% of species confirming the effectiveness of a single sampling method for some beetles. Increased locations and collection from the canopy may sample further species rather than additional collecting methods. Scolytines are relatively well studied with a cadre of taxonomists at the forefront of using modern methods to resolve formerly intractable groups. These new species are more likely to be named than others in many other beetle groups where taxonomy has largely stalled. To increase species description rates and to avoid most species becoming extinct before being named, we call on taxonomists to use new character systems provided by DNA methods and to look at working with Artificial Intelligence tools. Significance Statement In an era of rapid biodiversity loss, current conservation decisions for insects will continue to be based on a small and almost certainly biased sample of the world’s biota until more species are named. We demonstrate how large-scale sampling can dramatically increase the number of species discovered for one group of beetles and how these undescribed species are significantly smaller, less abundant and less widespread than named species. The identification and determination of undescribed species is rarely possible except when taxonomic expertise is available, as in the present study. Addressing the insect taxonomic bottleneck and increasing the rate of description will require the adoption of new and developing tools.

Climate warming is considered to be among the most serious of anthropogenic stresses to the environment, because it not only has direct effects on biodiversity, but it also exacerbates the harmful effects of other human‐mediated threats. The associated consequences are potentially severe, particularly in terms of threats to species preservation, as well as in the preservation of an array of ecosystem services provided by biodiversity. Among the most affected groups of animals are insects—central components of many ecosystems—for which climate change has pervasive effects from individuals to communities. In this contribution to the scientists' warning series, we summarize the effect of the gradual global surface temperature increase on insects, in terms of physiology, behavior, phenology, distribution, and species interactions, as well as the effect of increased frequency and duration of extreme events such as hot and cold spells, fires, droughts, and floods on these parameters. We warn that, if no action is taken to better understand and reduce the action of climate change on insects, we will drastically reduce our ability to build a sustainable future based on healthy, functional ecosystems. We discuss perspectives on relevant ways to conserve insects in the face of climate change, and we offer several key recommendations on management approaches that can be adopted, on policies that should be pursued, and on the involvement of the general public in the protection effort.

Aims: Terrestrial biodiversity is threatened by land use change. Modelling suggests that the remaining, potentially arable areas of natural intact vegetation (rNIV) of 9 of 35 global biodiversity hotspots may be converted to agriculture by 2050, committing their endemic species to extinction. Studies have shown that if the global population adopted a healthy, mostly plant based diet, agricultural area expansion can be reduced. We want to examine to what degree this applies to the regions covered by biodiversity hotspots.Location: Global.Time period: 2020–2050.Major taxa studied: No particular taxa.Methods: For every biodiversity hotspot, we simulate climate change impacts on agricultural productivity, and estimate food demand shifts from 2010 to 2050 by processing population and income growth projections. We quantify the net change in rNIV by 2050 in all hotspots by calculating the agricultural area necessary to meet the food demand under a business as usual, a healthy diet, a healthy diet plus agricultural intensification, and a healthy diet plus agricultural intensification plus crop change scenario.Results: In the healthy diet scenario, the rNIV of 16–21 hotspots can be preserved entirely, but 5–6 hotspots in less developed regions may lose all rNIV to agricultural area expansion. In these regions, a healthy diet implies an increase in consumed calories and no change in the already high share of plant‐based calories. When combined with agricultural intensification, these hotspots will still lose 7%–92% of rNIV. Only an additional change in crop mix patterns may preserve all.Main conclusions: While a change in dietary habits may be sufficient for preservation of rNIV in many hotspot regions, a healthy diet actually puts more pressure on rNIV in other hotspot regions. Intensifying agriculture and optimizing crop selection should be priorities in those regions to mitigate the expected loss of rNIV to agricultural expansion.

The analysis of forest cover change at different scales is an increasingly important research topic in environmental studies. Forest Landscape Restoration (FLR) is an integrated approach to manage and restore forests across various landscapes and environments. Such restoration helps to meet the targets of Sustainable Development Goal (SDG)–15, as outlined in the UN Environment’s sixth Global Outlook, which includes the sustainable management of forests, the control of desertification, reducing degradation, biodiversity loss, and the conservation of mountain ecosystems. Here, we have used time series Landsat images from 1996 to 2016 to see how land use, and in particular forest cover, have changed between 1996 and 2016 in the Lumbini Province of Nepal. In addition, we simulated projections of land cover (LC) and forest cover change for the years 2026 and 2036 using a hybrid cellular automata Markov chain (CA–Markov) model. We found that the overall forest area increased by 199 km² (2.1%), from a 9491 km² (49.3%) area in 1996 to 9691 km² (50.3%) area in 2016. Our modeling suggests that forest area will increase by 81 km² (9691 to 9772 km²) in 2026 and by 195 km² (9772 km² to 9966 km²) in 2036. They are policy, planning, management factors and further strategies to aid forest regeneration. Clear legal frameworks and coherent policies are required to support sustainable forest management programs. This research may support the targets of the Sustainable Development Goals (SDG), the land degradation neutral world (LDN), and the UN decade 2021–2031 for ecosystem restoration.