A global review of socioeconomic and environmental impacts of ants reveals new insights for risk assessment

Abstract

Risk assessments are fundamental to invasive species management and are underpinned by comprehensive characterization of invasive species impacts. Our understanding of the impacts of invasive species is growing constantly, and several recently developed frameworks offer the opportunity to systematically categorize environmental and socioeconomic impacts of invasive species. Invasive ants are among the most widespread and damaging invaders. Although a handful of species receives most of the policy attention, nearly 200 species have established outside their native range. Here, we provide a global, comprehensive assessment of the impacts of ants and propose a priority list of risk species. We used the Socioeconomic Impact Classification for Alien Taxa (SEICAT), Environmental Impact Classification for Alien Taxa (EICAT) and Generic Impact Scoring System (GISS) to analyze 642 unique sources for 100 named species. Different methodologies provided generally consistent results. The most frequently identified socioeconomic impacts were to human health. Environmental impacts were primarily on animal and plant populations, with the most common mechanisms being predation and competition. Species recognized as harmful nearly 20 years ago featured prominently, including Wasmannia auropunctata (little fire ant, electric ant), Solenopsis invicta (red imported fire ant), Anoplolepis gracilipes (yellow crazy ant), and Pheidole megacephala (African big‐headed ant). All these species except W. auropunctata have been implicated in local extinctions of native species. Although our assessments affirmed that the most serious impacts have been driven by a small number of species, our results also highlighted a substantial number of less well publicized species that have had major environmental impacts and may currently be overlooked when prioritizing prevention efforts. Several of these species were ranked as high or higher than some of the previously recognized “usual suspects,” most notably Nylanderia fulva (tawny crazy ant). We compared and combined our assessments with trait‐based profiles and other lists to propose a consensus set of 31 priority species. Ever‐increasing global trade contributes to growing rates of species introductions. The integrated approaches we used can contribute to robust, holistic risk assessments for many taxa entrained in these pathways.

Flower Visitation by Bees, Wasps and Ants: Revealing How a Community of Flower-Visitors Establish Interaction Networks in a Botanical Garden

“…Highlighting the core species of ants, Camponotus crassus belongs to the Formicidae subfamily and is a species which measures 20 mm and has no metapleural gland, being unable to produce harmful substances in the pollen (Del-Claro et al, 2019); it is a dominant forager in vegetation, exploits resources which do not come from flowers alone (Lange et al, 2019) and has already been associated with effective pollination (De Vega et al, 2014;Del-Claro et al, 2019). Finally, Wasmannia auropunctata is an ant from the subfamily Myrmicinae; the smallest of the key species, measuring 1.5 mm, it is invasive, commonly found in urban areas, often involved in cases of environmental impact and may have medical importance (Azevedo et al, 2022;Gruber et al, 2022). There are no studies relating this species to pollination, so it competes with pollinators once it recruits massively to dominate resources (Azevedo et al, 2022).…”

Genome-wide SNPs reveal the social structure and invasion pathways of the invasive tropical fire ant (Solenopsis geminata)

“…Despite being particularly useful to retrace the invasion history of invaders with low genetic diversity such as ants, RADseq has never been used to retrace global pathways of introduced ants to the best of our knowledge. Over 200 ant species are known to have established outside their native range with 31 species considered to have major environmental, economic, health, and social impacts (Angulo et al, 2022; Bertelsmeier et al, 2017; Gruber et al, 2022; Holway et al, 2002). Studies on the introduction history of global ant invaders using microsatellite markers and/or mitochondrial DNA gene sequences have all identified several main introduction pathways, but some population movements, especially between introduced populations, could not be reconstructed due to the low variability of the markers used in the ants’ introduced range (Ascunce et al, 2011; Foucaud et al, 2010; Vogel et al, 2010).…”

“…Solenopsis geminata (tropical fire ant) is one of the world’s six most widespread, abundant, and damaging invasive ants and is established globally throughout tropical regions (Gruber et al, 2022; Hodgson & Clarke, 2014; Holway et al, 2002; Wetterer, 2011). Colonies of S. geminata can be either monogyne or polygyne (Holway et al, 2002).…”

Invasive terrestrial invertebrate detection in water and soil using a targeted eDNA approach

“…Invasive ants are among the most harmful invasive species globally (Kenis et al, 2009); they threaten the environment, human health and livelihoods, and social amenity (Holway et al, 2002;Lach & Hooper-Bùi, 2010;Gruber et al, 2022). Millions of dollars are spent on prevention, treatment and control of ant invasions globally to avoid these impacts (Zenni et al, 2021).…”

“…In this study we test different methods to capture and detect terrestrial invertebrate eDNA. We use the yellow crazy ant, Anoplolepis gracilipes (Smith, 1857), one of the most environmentally and socioeconomically damaging invasive insect species in the world (Clarke et al, 2021; Gruber et al, 2022), as model species. We collected water and soil samples in field conditions to investigate whether yellow crazy ant eDNA can be detected in water from creeks or rivers adjacent to existing infestations; and to compare the efficiency of laboratory extraction methods for eDNA extraction from soil samples.…”