Scientists' warning to humanity on insect extinctions

Here we build on the manifesto ‘World Scientists’ Warning to Humanity, issued by the Alliance of World Scientists. As a group of conservation biologists deeply concerned about the decline of insect populations, we here review what we know about the drivers of insect extinctions, their consequences, and how extinctions can negatively impact humanity. We are causing insect extinctions by driving habitat loss, degradation, and fragmentation, use of polluting and harmful substances, the spread of invasive species, global climate change, direct overexploitation, and co-extinction of species dependent on other species. With insect extinctions, we lose much more than species. We lose abundance and biomass of insects, diversity across space and time with consequent homogenization, large parts of the tree of life, unique ecological functions and traits, and fundamental parts of extensive networks of biotic interactions. Such losses lead to the decline of key ecosystem services on which humanity depends. From pollination and decomposition, to being resources for new medicines, habitat quality indication and many others, insects provide essential and irreplaceable services. We appeal for urgent action to close key knowledge gaps and curb insect extinctions. An investment in research programs that generate local, regional and global strategies that counter this trend is essential. Solutions are available and implementable, but urgent action is needed now to match our intentions.Peer reviewe

Solutions for humanity on how to conserve insects

The fate of humans and insects intertwine, especially through the medium of plants. Global environmental change, including land transformation and contamination, is causing concerning insect diversity loss, articulated in the companion review Scientists' warning to humanity on insect extinctions. Yet, despite a sound philosophical foundation, recognized ethical values, and scientific evidence, globally we are performing poorly at instigating effective insect conservation. As insects are a major component of the tapestry of life, insect conservation would do well to integrate better with overall biodiversity conservation and climate change mitigation. This also involves popularizing insects, especially through use of iconic species, through more media coverage, and more inclusive education. Insect conservationists need to liaise better with decision makers, stakeholders, and land managers, especially at the conceptually familiar scale of the landscape. Enough evidence is now available, and synthesized here, which illustrates that multiple strategies work at local levels towards saving insects. We now need to expand these locally-crafted strategies globally. Tangible actions include ensuring maintenance of biotic complexity, especially through improving temporal and spatial heterogeneity, functional connectivity, and metapopulation dynamics, while maintaining unique habitats, across landscape mosaics, as well as instigating better communication. Key is to have more expansive sustainable agriculture and forestry, improved regulation and prevention of environmental risks, and greater recognition of protected areas alongside agro-ecology in novel landscapes. Future-proofing insect diversity is now critical, with the benefits far reaching, including continued provision of valuable ecosystem services and the conservation of a rich and impressive component of Earth's biodiversity.Peer reviewe

Scientists' warning on climate change and insects

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

Abiotic and biotic drivers of African aquatic insect distribution

Thesis (PhDConsEcol)--Stellenbosch University, 2020.ENGLISH ABSTRACT: Freshwater habitats are disproportionately rich in biodiversity, and are among the most threatened, yet poorly protected ecosystems. Aquatic insects make up much of the total freshwater fauna and contribute greatly to ecosystem functioning. At the broad-scale, aquatic insect distribution is driven by combinations of traits, as well as regional climate gradients and historical landscape context. Locally, both aquatic insect species richness and diversity are driven by various aspects related to vegetation and to physiochemical environments. Effective conservation requires thorough understanding of species distribution patterns at various spatial scales. My overall aim here is to combine broad-scale, theoretical biogeography, and local-scale empirical ecology to investigate drivers of aquatic insect distribution across Africa. Species are often binarily classified as ‘widespread generalists’ or ‘narrow-range specialists’ based on their ecological traits. Results in Chapter 2 show that ecological and biological traits are highly interactive among dragonflies, and inferring geographical range size based on ecological preference and/or biotope specialization alone should be approached with caution. Biological traits related to phenology and mobility were also strong drivers of dragonfly range size, indicating that conservation efforts should include multiple species across all habitat types. Regional climates show considerable variation across latitudinal and longitudinal gradients, and determine areas of high species richness and diversity. In Chapter 3, I show strong latitudinal and longitudinal gradients for South-African dragonfly species richness and endemism. Dragonfly assemblage-turnover boundaries coincided with significant geographical features and/or areas where contemporary climate changed from one condition to another. However, these dragonfly assemblage turnover-boundaries were gradual rather than discrete throughout South Africa. At the local scale, natural and artificial ponds contribute greatly to overall biodiversity, especially when they are of high quality and occur in networks across the landscape. I show that ponds characterized by high heterogeneity support diverse aquatic insect assemblages (Chapters 4 and 5). Chapter 4 showed artificial reservoirs, occurring alongside natural ponds in ecological networks, to expand the area of occupancy for most widespread dragonflies, aquatic beetles and true bugs. Some species with specific habitat requirements were confined to natural ponds, suggesting the significance of natural ponds for conserving the full range of insects. Dragonflies, aquatic beetles and true bugs occupy low-quality artificial reservoirs at low abundance to survive the adverse effects of drought (Chapter 5). However, many insects exclusively occupied natural ponds, emphasizing the overall importance of naturalness, and suggests that there is merit in improving artificial reservoirs. This would most likely be by having macrophytes and vegetated banks similar to those of natural ponds.Investigating aquatic insect distribution patterns is important for conservation, and here, I demonstrate the value of dragonflies as model organisms for investigating the drivers of broad-scale distribution patterns. Studying other taxa is also appropriate, as I have demonstrated at the local scale, but not always possible due to limited distribution knowledge. I recommend broad-scale investigations of other complementary taxa to determine their added value for elucidating the drivers of overall insect distribution patterns, and so address our current shortfalls to improve insect conservation.AFRIKAANSE OPSOMMING: Varswaterhabitatte is besonders biodivers, en val onder die mees bedreigde, onder-beskermde ekosisteme. Varswaterinsekte vorm ‘n groot deel van alle varswaterdiere, en het hoë waarde vir ekosisteem-werking. Breë-skaalse waterinsekverspreiding word aangedryf deur kombinasies van eienskappe, sowel as streeksklimaat en historiese landskap-konteks. Oor plaaslike skale word beide waterinsek spesierykheid en diversiteit aangedryf deur verskeie aspekte van plantegroei, en chemiese omgewings. Effektiewe bewaring vereis goeie begrip van spesieverspreidingspatrone oor verskeie ruimtelike skale. My algehele doel is om breë-skaalse, teoretiese bio-geografie, en fyn-skaalse empiriese ekologie te kombineer, om sodoende die dryfkragte van waterinsekverspreiding oor Afrika te ondersoek. Spesies word dikwels op ‘n binêre wyse geklassifiseer as ‘wyd-verspreide generaliste’ of ‘streeksgebonde spesialiste’, gebaseer op hul ekologiese eienskappe. Bevindinge in Hoofstuk 2 toon dat ekologiese en biologiese eienskappe onder naaldekokers hoogs interaktief is. Afleidings van geografiese verspreiding, gebaseer op ekologiese voorkeur en/of biotoop spesialisme, hoort versigtig benader te word. Biologiese eienskappe verwant aan fenologie en beweeglikheid was ook beduidende dryfkragte van geografiese verspreiding onder naaldekokers, wat aandui dat bewaringspogings verskeie spesies vanaf alle habitat moet betrek. Streeksklimaat verskil aansienlik oor breedte- en lengtegradiënte, en bepaal waar areas van hoë spesierykheid en diversiteit voorkom. Ek bewys in Hoofstuk 3 dat sterk breedte- en lengtegradiënte vir Suid-Afrikaanse naaldekoker spesierykheid en inheemsheid bestaan. Naaldekoker gemeenskapsomsetgrense stem ooreen met beduidende geografiese strukture en/of areas waar kontemporêre klimaat verander tussen streke. Hierdie naaldekoker gemeenskapsomsetgrense is egter geleidelik eerder as diskreet oor Suid-Afrika. Natuurlike en kunsmatige damme dra by tot algehele biodiversiteit oor die plaaslike skaal, veral wanneer dié damme van hoë kwaliteit is, en aangetref word in netwerke wat strek oor die landskap. My bevindinge bewys dat damme wat gekenmerk word deur hoë variasie diverse waterinsek-gemeenskappe ondersteun (Hoofstukke 4 en 5). Bevindinge in Hoofstuk 4 bewys dat kunsmatige damme, tesame met natuurlike damme in ekologiese netwerke, die besettingsarea van meeste wyd-verspreide naaldekokers, waterkewers en ware watergoggas vergroot. Sommige spesies met spesifieke habitatvereistes was beperk tot natuurlike damme, wat aandui dat natuurlike damme belangrik is vir die bewaring van die volle spektrum van waterinsekte. Naaldekokers, waterkewers en ware watergoggas beset lae-gehalte kunsmatige damme in lae hoeveelhede, om die ongunstige toestande van droogte te oorleef (Hoofstuk 5). Heelwat waterinsekte word egter slegs in en rondom natuurlike damme aangetref, wat beklemtoon dat die natuurlikheid van damme belangrik is. Hierdie bevindinge dui aan dat daar meriete is om kunsmatige damme te verbeter, waarskynlik deur om plantegroei wat soortgelyk aan dié van natuurlike damme is, te stimuleer. Om ondersoek in te stel op waterinsek-verspreidingspatrone is belangrik vir natuurbewaring, en hier bewys ek dat naaldekokers waardevol is om die drywers van breë-skaalse verspreidingspatrone aan te dui. Om ander insek-groepe te ondersoek is hoogs gepas, soos hier aangedui vir plaaslike studies, alhoewel dit nie altyd moontlik is nie, as gevolg van beperkte kennis met betrekking tot hul verspreidingspatrone. Ek beveel breë-skaalse studies aan vir ander ooreenstemmende insek-groepe, om te bevestig wat hul bydraende waarde is om die dryfkragte van algehele insekverspreiding te verklaar. Sodoende kan ons huidige tekortkominge aanspreek om insekbewaring te verbeter.Doctora

KZN pondscape full dataset and species matrices

This is the full dataset of species data(dragonflies, beetles and bugs), diversity index data, environmental data and vegetation data. R-ready

A Review of the Impacts and Opportunities for African Urban Dragonflies

Urban settlements range from small villages in rural areas to large metropoles with densely packed infrastructures. Urbanization presents many challenges to the maintenance of freshwater quality and conservation of freshwater biota, especially in Africa. There are many opportunities as well, particularly by fostering contributions from citizen scientists. We review the relationships between dragonflies and urbanization in southern Africa. Shifts in dragonfly assemblages indicate environmental change, as different species are variously sensitive to abiotic and biotic water and bank conditions. They are also conservation umbrellas for many other co-occurring species. Major threats to southern African dragonflies include increasing infrastructure densification, frequent droughts, habitat loss, pollution, and invasive alien vegetation. Mitigation measures include implementation of conservation corridors, maintenance of healthy permanent ponds, pollution reduction, and removal of invasive alien trees. Citizen science is now an important approach for supplementing and supporting professional scientific research

Larva of one of the world's rarest and most threatened damselflies: Spesbona angusta (Odonata: Platycnemididae)

Charl Deacon, Michael J. Samways (2016): Larva of one of the world's rarest and most threatened damselflies: Spesbona angusta (Odonata: Platycnemididae). Odonatologica 43 (3): 225-234, DOI: 10.5281/zenodo.16345

Artificial reservoirs complement natural ponds to improve pondscape resilience in conservation corridors in a biodiversity hotspot.

Natural ponds are rich in biodiversity, contributing greatly to regional aquatic biodiversity. Artificial reservoirs used for irrigation can be significant additional features of the landscape. They infill the local natural pondscape, and are attractors for aquatic insects. Here, we determine the extent to which artificial reservoirs represent the local natural pond biota, and how they contribute to the pondscape in conservation corridors used to mitigate the impact of plantation forestry in a global biodiversity hotspot. We did this by: 1) identifying the environmental factors, including plants, that drive dragonfly, water beetle, and water bug species richness, diversity and composition, and 2) determining the value of natural ponds vs. artificial reservoirs for maintaining the population size and expanding the area of occupancy for dragonflies, beetles and bugs in conservation corridors. While vegetation cover was central for maintaining species richness and composition of the assemblages in general, many other environmental variables are necessary to encourage the full suite of local diversity. Artificial reservoirs are attractive habitats to many species, overall increasing area of occupancy for 75% of them (ranging from 62-84% for different taxa). These reservoirs provide complementary alternative habitats to natural ponds, leading to improved ecological resilience across the pondscape. We conclude that maintaining a diverse and heterogeneous pondscape is important for conserving local aquatic insect diversity, and that artificial reservoirs increase the local area of occupancy for a range of pond insects in conservation corridors, and improve the biodiversity value of these pondscapes

Artificial reservoirs complement natural ponds to improve pondscape resilience in conservation corridors in a biodiversity hotspot

CITATION: Deacon, C., Samways, M. J. & Pryke, J. S. 2018. Artificial reservoirs complement natural ponds to improve pondscape resilience in conservation corridors in a biodiversity hotspot. PLoS ONE, 13(9):e0204148, doi:10.1371/journal.pone.0204148.The original publication is available at https://journals.plos.org/plosoneNatural ponds are rich in biodiversity, contributing greatly to regional aquatic biodiversity. Artificial reservoirs used for irrigation can be significant additional features of the landscape. They infill the local natural pondscape, and are attractors for aquatic insects. Here, we determine the extent to which artificial reservoirs represent the local natural pond biota, and how they contribute to the pondscape in conservation corridors used to mitigate the impact of plantation forestry in a global biodiversity hotspot. We did this by: 1) identifying the environmental factors, including plants, that drive dragonfly, water beetle, and water bug species richness, diversity and composition, and 2) determining the value of natural ponds vs. artificial reservoirs for maintaining the population size and expanding the area of occupancy for dragonflies, beetles and bugs in conservation corridors. While vegetation cover was central for maintaining species richness and composition of the assemblages in general, many other environmental variables are necessary to encourage the full suite of local diversity. Artificial reservoirs are attractive habitats to many species, overall increasing area of occupancy for 75% of them (ranging from 62–84% for different taxa). These reservoirs provide complementary alternative habitats to natural ponds, leading to improved ecological resilience across the pondscape. We conclude that maintaining a diverse and heterogeneous pondscape is important for conserving local aquatic insect diversity, and that artificial reservoirs increase the local area of occupancy for a range of pond insects in conservation corridors, and improve the biodiversity value of these pondscapes.Mondi Grouphttps://journals.plos.org/plosone/article?id=10.1371/journal.pone.0204148Publisher's versio