Original paper
Invasive beetleMerizodus soledadinusmeets unexpected clinicalAcinetobacter baumanniiin subantarctic Kerguelen Archipelago soil
Tasiemski, Aurélie; Boidin-Wichlacz, Céline; Massol, François; Audebert, Christophe; Bonardi, Franck; Hadjadj, Linda; Ferchiou, Sophia; Caza, France; St-Pierre, Yves; Diene, Seydina M.; Rolain, Jean-Marc; Renault, David
Entomologia Generalis Volume 46 Number 2 (2026), p. 533 - 541
published: Apr 29, 2026
published online: Apr 20, 2026
manuscript accepted: Jan 25, 2026
final revised version received: Jan 6, 2026
manuscript revision requested: Oct 7, 2025
manuscript received: Jun 16, 2025
Open Access (paper may be downloaded free of charge)
Abstract
The South American beetleMerizodus soledadinusoffers a compelling model of biological invasion. Since its accidental introduction to the Kerguelen Islands in 1913, its spread has been closely monitored. While its ecological and physiological traits are well studied, microbial interactions remain poorly understood. We investigated this aspect by isolating a bacterium from soil inhabited by Merizodus, identified through whole-genome sequencing, Oxford multilocus sequence typing (MLST), and resistome profiling asAcinetobacter baumanniiclonal complex 2, sequence type 78 (CC2-ST78), encoding the OXA-90 (oxacillinase) β-lactamase, a resistance gene indicative of a human-mediated introduction. Quantitative PCR (qPCR) data showed thatMerizodusis not a reservoir for this bacterium. Survival assays revealed no correlation between tolerance toA. baumanniiinfection and the temporal gradient of beetle invasion. However, beetles at the invasion front, often found in low-density, high-altitude populations, had reduced survival. In contrast, at low altitudes, beetles from areas with greater human presence better survived infection and exhibited basal anti-A. baumanniiactivity. These findings reveal the presence of a human-associated pathogen in sub-Antarctic soil and suggest that immune plasticity inMerizodusmay contribute to invasion success, though limited at the invasion front.
Keywords
insect • invasion • polar • immunity • microbe • environment • sub-Antarctic ecosystems • human-mediated introduction