Ants of Mexico: Distribution and species richness in environments with varying levels of human impact

Abstract Background Anthropogenic disturbance, primarily driven by land-use changes, has caused alterations in ecosystems and biodiversity, including the ant community. Therefore, the aim of this study was to analyse the current landscape of ant species richness and distribution in environments with varying degrees of disturbance in Mexico. Additionally, we sought to identify ant species of ecological, economic and health significance within the country. New information The present study shows that Mexico has a total of 33,286 records of 1,104 ant species belonging to 10 subfamilies. These species were recorded in a wide variety of environments with different levels of human impact. It was observed that both highly-disturbed environments and undisturbed environments had the highest number of ant records. In undisturbed environments, greater species richness was recorded, with a total of 704 species. Furthermore, the most representative ant species for the country were identified in ecological, economic and human health contexts. Within these species, a group composed of four exotic species (Tapinomamelanocephalum, Paratrechinalongicornis, Wasmanniaauropunctata and Linepithemahumile) deserves special attention, as they have achieved extensive dispersion throughout the country and have been associated with negative impacts in ecological, economic and human health realms.


Introduction
Ants are one of the most successful groups of insects in terrestrial environments, with nearly 13,000 species described worldwide and 887 species reported in Mexico (Dáttilo et al. 2020).They hold significant importance within ecosystems, participating in various ecological processes, such as seed dispersal (Hölldobler and Wilson 1990), organic matter decomposition, and nutrient recycling, which are essential for soil fertility and plant growth (Andersen and Sparling 1997).Additionally, they play a role in the pollination process of plants such as cacti and orchids.Furthermore, ants are involved in a wide range of trophic interactions, as they have a broad feeding spectrum and associate with numerous species (Redolfi et al. 2004, Parker andKronauer 2021).From an economic standpoint, certain species are considered pests, with a negative impact on crops, while others are used to control pests and improve soil quality (Rojas-Fernández 2001, Rojas-Fernández 2011, Murguía-González et al. 2018), reducing the need for pesticide use.On the other hand, some ant species have medical significance due to their potential as carriers of pathogens (Olivera and Porras-Villamil 2021).Nevertheless, certain ant species are of importance in the pharmaceutical industry because they contain various compounds, such as antimicrobial peptides, biogenic amines, alkaloids and flavonoids, which are used for the treatment of various diseases, including asthma, cancer and microbial infections (Agarwal et al. 2022).
In Mexico, ants are particularly diverse due to topographic complexity, climatic diversity and the convergence of two biogeographic zones (Nearctic and Neotropical) (Halffter andMorrone 2017, Dáttilo et al. 2020).However, in recent years, approximately 50% of natural ecosystems have been lost due to the impact of human activities (González-Abraham et al. 2015).The areas with the highest potential for productivity and greatest accessibility are the first to be utilized for human benefit.The expansion of agricultural frontiers, livestock farming (Aguilar et al. 2000), deforestation (Palacio-Prieto et al. 2000) and human settlements are the main activities leading to the loss of the original environment, increased isolation, and reduction of remaining areas (Lozano et al. 2009).These changes have repercussions for the physical environment, causing indirect effects on the composition, abundance, and dispersal of many species (Bustamante and Grez 1995), resulting in alterations in biological interactions, increased occurrence of pests and a decline in crop pollination (Buczkowski and Richmond 2012).Furthermore, human-induced disturbance favors the establishment of exotic and invasive ant species that can displacenative species (Sobrinho andSchoereder 2007, Rosas-Mejía et al. 2021).
The diversity and distribution of ants in Mexico have been extensively studied and documented (Vásquez-Bolaños 2015, Dáttilo et al. 2020, Rocha-Ortega et al. 2023).However, there is a need for a comprehensive analysis of ant distributions in environments with varying degrees of disturbance throughout Mexico.This research aims to review the current status of these dispersal patterns of ant species in environments with different degrees of disturbance in Mexico, as well as to highlight the species of ecological, economic and health importance to humans present in the country.

General description
Purpose: This study provides information on the current status of the diversity and distribution of ant species in environments with varying degrees of disturbance in Mexico, collected between 1700 and 2022.These data were obtained from the Global Biodiversity Information Facility (GBIF), as well as entomological collections in Mexico.The review highlights the significance of the most representative species in the country in terms of ecological, economic and human health impacts.

Sampling description:
The assessment of the current status of ant species diversity and dispersion in environments with varying degrees of anthropogenic influence in Mexico was conducted, based on documented records from 1700 to 2022.Ant species records were obtained from the GBIF database and the National Collection of Insects at the Institute of Biology, National Autonomous University of Mexico, as well as collections from the Institute of Applied Ecology at the Autonomous University of Tamaulipas and the National Technological Institute of Mexico, Victoria Campus, Tamaulipas.The localities and geographic coordinates were verified using the Google Earth programme.Duplicate records, non-georeferenced records or records for which the latitude and longitude coordinates had fewer than two decimal places (0.0) were eliminated during the classification process.Additionally, a review of current taxon status was conducted to verify the validity of each name, grouping taxa treated as synonyms of another species with the taxon with the validated current name (Bolton 2023, AntWeb 2022).With the obtained information, two maps were created using ArcGIS 10.8 software (ESRI (Environmental Systems Research Institute) 2020): 1.
to represent the dispersion of ant species in Mexico; 2.
to determine the degree of anthropogenic environmental disturbance under which the highest number of species and records are found.For the latter, the human A review of specialised literature was carried out, composed of scientific articles that address ant species in Mexico.The main objective was to collect comprehensive information about these species, focusing on their ecological and economic aspects and their impact on human health, regardless of the year of publication of the studies.For this search, keywords that spanned the breadth and depth of these topics were carefully selected.Terms such as "ant species", "ecological importance", "economic significance", "human health impact", "distribution", "records" and "Mexico" were used to ensure thorough collection of relevant information.During this selection process, priority was given to those species that demonstrated a wide geographic distribution or a considerable number of documented records.In relation to health, a verification of the existence of pathogens that were associated with the ant species registered in the country was carried out and their scientific name was validated using the Catalogue of Life (https:// www.catalogueoflife.org/).

Quality control:
The scientific name of each ant species was verified using the online catalogue of world ants maintained by Barry Bolton (AntCat) (https://antcat.org/)and the largest online ant database, AntWeb (https://www.antweb.org/).The scientific name of pathogens associated with ant species was validated using the Catalogue of Life (https:// www.catalogueoflife.org/).The location of ant species records was corroborated using Google Earth, ensuring that the records fell within the extent considered in the human footprint layer (González-Abraham et al. 2015).

Geographic coverage
Description: Mexico spans a territorial extent of 1,964,375 km , of which 1,959,248 km constitute continental land (i.e.mainland within the country) and 5,127 km comprise island territory (i.e.islands belonging to the country) (    1 and Fig. 2).Furthermore, it was determined that the most investigated environments amongst ant species studies in the country are those without human impacts, followed by environments with high anthropogenic influence.The species that were mainly found in environments with high human impact are Atta mexicana, Pseudomyrmex gracilis and Pogonomyrmex barbatus, while in untransformed environments, they are Wasmannia auropunctata, Camponotus sericeiventris and Strumigenys brevicornis.In the case of W. auropunctata, despite being an invasive exotic species, it exhibits unique behaviour within untransformed environments.In these areas, where ecosystems remain largely intact and have not been altered by human activity, it has adopted a role more similar to that of a native species.Additionally, in untransformed environments, W. auropunctata appears to have a lower population density than in disturbed ecosystems (Salguero et al. 2011).However, it is of vital importance to continue monitoring and controlling the expansion of this invasive species in all ecosystems, with the aim of minimising its negative impact and protecting local biodiversity.Of the species recorded in the country, 12 are of great relevance in the medical field; six of these cause direct health problems, while eight carry pathogens that cause diseases or discomfort to humans (Tables 2, 3).In ecological terms, ant species play a fundamental role in ecosystems.In the country, there are species that participate in seed dispersal ( Aphaenogaster rudis) and in the pollination process (species of the genus Formica), as well as species that serve as indicators of environmental health, species diversity and population changes (Table 4).(Pérez-Espona 2021)

Pogonomyrmex imberbiculus
Indicators of semi-arid environments where there is little vegetation cover, such as shrublands and grasslands.
( Economically-important species are those considered pests that cause significant losses in crop yields, such as A. mexicana, as well as species that have mutualistic interactions with other insect pests.However, it is important to note that there are also species with positive economic impacts, such as Tapinoma melanocephalum, an exotic species in the country that is used to control the red spider mite (Tetranychus urticae), a pest that affects various crops.Additionally, the presence of Liometopum apiculatum has been recorded in Mexico, as well as species belonging to the genus Atta, which play a crucial role in various areas as they are consumed as food.These ants provide a valuable source of proteins, vitamins, minerals and essential fatty acids (FAO (Food and Agriculture Organization) 2015, Reyes-Prado et al. 2016, Gallardo-López et al. 2022) (Table 5).From an environmental perspective, the rearing and collection of ants for food purposes is considered a sustainable practice that contributes to the conservation of natural resources and a reduction in environmental impacts.
This study identified one native species (Solenopsis geminata) and four exotic species of significant importance in Mexico.Amongst the exotic species, T. melanocephalum stands out as the most prominent and representative species for the country due to its ecological, economic and human health impacts.Furthermore, the importance of the species Paratrechina longicornis and W. auropunctata has been determined in both human health and ecosystems.Finally, Linepithema humile stands out for its ecological and economic significance (Tables 2, 3, 4, 5).

Economic importance Reference
Dorymyrmex flavus Mutualistic interactions with the mealybugs that are pests of sugar-cane.(Murguía-González et al.

Tapinoma melanocephalum
Biological control of the red spider mite (Tetranychus urticae), a pest of various crops.Interactions with populations of phloem-feeding hemipteran insects, such as aphids, scale insects and mealybugs.

2018)
Linepithema humile Causes severe indirect damage to crops as it feeds on the honeydew secreted by various aphids.

Liometopum apiculatum
The larvae are used for human consumption.

Atta mexicana
Pest that causes significant losses in the yield of forest crops, citrus fruits, fruits, cocoa, coffee, corn and pastures.The queens of this species (known as chicatanas) are used for human consumption.

Temporal coverage
Notes: The distribution of ant species includes records from 1700 to 2022.

Collection data
Collection name: National Insect Collection of the Institute of Biology at the National Autonomous University of Mexico (CNIN-UNAM).Collection of the Institute of Applied Ecology at the Autonomous University of Tamaulipas (IEA-UAT) and the National Technological Institute of Mexico (TecNM), Victoria Campus, Tamaulipas.

Usage licence
Usage licence: Creative Commons Public Domain Waiver (CC-Zero) Table 5.
Economically-important ant species.

Data resources
Data package title: A dataset of the ant distribution in environments with varying human footprints in Mexico.

Number of data sets: 1
Data set name: A dataset of the ant distribution in environments with varying human footprints in Mexico.

Description:
The dataset (Suppl.material 1), compiled from the GBIF database and three entomological collections in Mexico from 1970 to 2022, reflects the distribution, species count and records of ant species in environments with varying human footprints.The scientific name of each species was verified using the online world ant catalogue maintained by Barry Bolton (AntCat) (https://antcat.org/)and the largest online ant database, AntWeb (https://www.antweb.org/).The database is presented in Darwin Core format.

Column label Column description
ocurrenceID An identifier for the dwc:Occurrence (as opposed to a particular digital record of the dwc:Occurrence).In the absence of a persistent global unique identifier, construct one from a combination of identifiers in the record that will most closely make the dwc:occurrenceID globally unique. basisOfRecord The specific nature of the data record.
Fig. 1).The political division of Mexico consists of 32 states.The human footprint layer incorporates digital vector maps from the National Institute of Statistics and Geography (INEGI) of Mexico and road maps from the Mexican Institute of Transportation (IMT).Taxonomic coverageDescription: The current taxonomy of ants, based on worldwide phylogenetic proposals, has led to significant and important changes in the classification of the family Formicidae.In this study, 33,286 records were obtained for Mexico, corresponding to 1,104 species belonging to 105 genera and 10 subfamilies (Fig.1, Suppl.material 1).These results represent an increase compared to the numbers in previous studies where 887 species ( Dáttilo et al. 2020) and 927 species (Vásquez-Bolaños 2015) were reported.In Mexico, the States with the highest number of ant species are Veracruz (474) and Chiapas (461), while the States with the lowest number of species are Tlaxcala (15) and Aguascalientes (23).The States with the highest number of records are Chiapas (7,509) and Veracruz (6,703).
Figure 1.Study area showing the distribution of ant species.The red dots represent the records of ant species in Mexico.
Figure 2. Human footprint in Mexico and the distribution of ants.

(
associatedReferences A list (concatenated and separated) of identifiers (publication, bibliographic reference, global unique identifier, URI) of literature associated with the dwc:Occurrence.institutionCode The name (or acronym) in use by the institution having custody of the object(s) or information referred to in the record.collectionCode The name, acronym, coden or initialism identifying the collection or dataset from which the record was derived.catalogNumber An identifier (preferably unique) for the record within the dataset or collection.kingdom The full scientific name of the kingdom in which the dwc:Taxon is classified.phylum The full scientific name of the phylum or division in which the dwc:Taxon is classified.class The full scientific name of the class in which the dwc:Taxon is classified.order The full scientific name of the order in which the dwc:Taxon is classified.family The full scientific name of the family in which the dwc:Taxon is classified.subfamily The full scientific name of the subfamily in which the dwc:Taxon is classified.
The subfamily with the highest numbers of species (612) and records (18,698) was Myrmicinae, while the subfamily with the lowest number of species was Agroecomyrmecinae, with Tatuidris tatusia.The States with the highest numbers of records and species in modified environments (high and very high human footprints) are Veracruz (3,546 records and 409 species), Oaxaca (1,211 records and 220 species) and Chiapas (1,035 records and 245 species).The highest numbers of records and species in untransformed environments were found in the States of Chiapas (3,048 records and 289 species), Quintana Roo (932 records and 162 species) and Veracruz (710 records and 144 species) (Table

Table 1 .
Numbers of records (rds) and species in each State as impacted by human footprint.

Table 2 .
Ant species that cause direct harm to human health.

Table 3 .
Species of ants carrying pathogens that affect human health.Ants of Mexico: Distribution and species richness in environments with ...