Global convergence of dominance and neglect in flying insect diversity

Abstract

Most of arthropod biodiversity is unknown to science. For this reason, it has been unclear whether insect communities around the world are dominated by the same or different taxa. This question can be answered through standardized sampling of biodiversity followed by estimation of species diversity and community composition with DNA sequences. This approach is here applied to flying insects sampled by 39 Malaise traps placed in five biogeographic regions, eight countries, and numerous habitats (>220,000 specimens belonging to >25,000 species in 463 families). Unexpectedly, we find that 20 insect families account for >50% of local species diversity regardless of continent, climatic region, and habitat type. These consistent differences in family-level dominance explain two-thirds of variation in community composition despite massive levels of species turnover, with most species (>97%) in the top 20 families encountered at a single site only. Alarmingly, the same families that dominate global insect diversity also suffer from extreme taxonomic neglect with little signs of increasing activities in recent years. Tackling the biodiversity of these "dark taxa" thereby emerges as an urgent priority because the arthropod groups comprising most of the global flying insect diversity are particularly poorly known.

Global determinants of insect mitochondrial genetic diversity

“…The remaining 2.8% of OTUs belong to 20 additional insect orders. Although Coleoptera has more described species than the other three megadiverse orders, it comprises less than 10% of OTUs represented in the data, possibly due to the common practice of using Malaise traps in flying insect surveys, where Diptera and Hymenoptera dominate sampling 86 . Across orders, 74.7% of all OTUs occupied a single grid cell with less than one percent occupying more than 11 grid cells ( Supplementary Fig.…”

Legume integration for biological control deserves a firmer scientific base

“…Those shortfalls are apt to be exacerbated in the Global South (Steward et al, 2014). Not only are insect biodiversity discovery and description lagging in the tropics (Eisenhauer et al, 2019; Srivathsan et al, 2023), but most plant x invertebrate functional linkages and their underlying traits most certainly wait to be uncovered (Moretti et al, 2013). Other limiting factors are the lower likelihood of actual publication and the lower visibility of scientific outputs – with the latter mirrored in the omission of popular bibliographic databases such as Scielo in WoS Core Collection (Fox et al, 2023; Gomez et al, 2022).…”

“…In the Global South, absence of these interaction records reflects the paucity of data on invertebrate biodiversity - which can only be filled through additional discovery and description. In the Global Biodiversity Information Facility (GBIF), only 0.17 G of the 2.16 G records i.e., 7.9% pertain to arthropods (Srivathsan et al, 2023). Though sufficient data may already be available in Europe or North America, our work demonstrates that these are not necessarily accessible at scientists’ fingertips.…”

Surprising morphological diversity in ceraphronid wasps revealed by a distinctive new species of Aphanogmus (Hymenoptera: Ceraphronoidea)

“…At the same time, certain taxa, particularly those termed 'dark taxaʼ due to their taxonomic inaccessibility, have remained vastly understudied and are still neglected altogether in current conservation efforts. The two largest insect orders, Hymenoptera and Diptera, jointly constitute over half of the German entomofauna (Klausnitzer 2005) and together make up 76.2% of insects caught in Malaise trap samples (Chimeno et al 2022;Srivathsan et al 2022). At the same time, these are the two orders that contain the highest number of dark taxa and that suffer from the most severe gaps in species knowledge (Shaw & Hochberg 2001;Geiger et al 2016;Hausmann et al 2020;Chimeno et al 2022).…”

“…Proposals to re-think current conservation strategies and instead apply a more holistic approach would benefit both common taxa (Hallmann et al 2021) and the numerous dark taxa that remain yet to be discovered and whose biology and morphological adaptations remain to be worked out (Shaw 2006). To effectively preserve insect biodiversity, future conservation efforts must be accompanied by long-term biodiversity monitoring and solid integrative taxonomic research that includes also those taxa that show the highest diversity and abundance (Srivathsan et al 2022).…”