Insights into social organization and population genetics of introduced Odontomachus troglodytes in Taiwan
Abstract
Supercoloniality and unique reproductive strategies are critical factors driving the ecological dominance of invasive ant species. However, their role in the post-introduction success of species belonging to the Ponerinae subfamily remains largely unexplored. Odontomachus troglodytes, a ponerine ant native to sub-Saharan Africa, has been recently reported to have established populations in southern Taiwan. In the present study, we conducted behavioral assays and developed 11 novel polymorphic microsatellite markers to investigate the social organization, breeding system, and population structure of O. troglodytes in its introduced range. Genotypic analyses indicated sexual reproduction with no evidence of clonal propagation. Both field observations and genetic data revealed high levels of polygyny and polyandry, accompanied by a notable frequency of diploid males, likely resulting from inbreeding. Our findings suggest that the Kaohsiung population exhibits some supercolonial traits, including polygyny, polydomy, and the absence of inter-nest aggression across distances of several kilometers. This marks the first reported case of such a social structure in the Odontomachini tribe. While workers from different nests displayed tolerance, genetic data suggest incomplete homogenization across nests. The present study offers new insights into the colony structure and reproductive biology of O. troglodytes in an introduced context and highlights the potential role of social structure in supporting population persistence and spread.
Methodology and Implementation Steps
Our study aims to investigate the social structure and dispersal potential of the invasive trap-jaw ant, Odontomachus troglodytes, following its establishment in Taiwan. Although this species has been recorded in southern Taiwan since 2017, empirical data regarding supercolony formation within the subfamily Ponerinae remain scarce. Consequently, we conducted behavioral experiments and molecular genetic analyses on populations in Chiayi and Kaohsiung starting in 2023. By developing 11 microsatellite markers and performing 107 inter-colony aggression tests, our results demonstrate that O. troglodytes exhibits distinct supercolony characteristics in Taiwan. Notably, the Kaohsiung population maintained high inter-colony tolerance across distances of up to 6.8 kilometers, characterized by polygyny and polydomy. Genetic analyses revealed that the species reproduces sexually; although diploid males potentially resulting from inbreeding were detected, this did not compromise their polydomous structure or low aggression, which grant them strong resource-monopolizing capabilities. Ultimately, this study indicates that the Taiwanese populations have differentiated into two distinct genetic units (Chiayi and Kaohsiung), with the Kaohsiung population forming a nascent supercolony. As the first evaluation to integrate behavioral and genetic evidence, these findings bear critical significance for monitoring biodiversity risks and formulating biosecurity and management strategies.
Innovation and Cross-Disciplinary Collaboration
Published in Myrmecological News, a top-tier Q1 journal in entomology, this study holds a benchmark status in both academic originality and practical application value. As the first instance within the tribe Odontomachini to integrate behavioral and genetic evidence in support of its 'supercolonial traits,' this project not only challenges the conventional view that the social structure of the subfamily Ponerinae is relatively conservative, but also validates its data quality through rigorous international peer review (published in 2025). The rapid assessment framework established in this study, which combines behavioral assays with microsatellite markers, provides a highly reproducible scientific model for emerging invasive ponerine ants. Consequently, it offers far-reaching theoretical implications and practical reference value for understanding the evolution of social behaviors, population genetic mechanisms, and formulating cross-species invasive ecological control strategies.
Expected Results and Contributions
This study offers significant practical and policy contributions. First, by demonstrating kilometer-scale inter-colony tolerance and a polygynous structure in the Kaohsiung population, it provides critical risk warnings for the government, highlighting the species' high potential to expand rapidly and suppress native arthropods. Second, it delineates Chiayi and Kaohsiung as distinct genetic management units, establishing a scientific foundation for localized monitoring and regional control. This 'early intervention' model, which assesses genetic risks during the initial stages of invasion, effectively mitigates future ecological impacts and management costs. Looking ahead, this rapid assessment framework can integrate environmental DNA (eDNA) technology to construct a national population genetic database and an invasion risk-rating system. This will serve as a benchmark model for responding to other emerging invasive social insects, ultimately strengthening national biosecurity.
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