Document Type

Publication - Article

Mitochondrial and Wolbachia phylogenetics of the introduced Joro spider, Trichonephila clavata (Araneae: Araneidae) in North America

Department

Biology

Date of Activity

9-15-2025

Abstract

The introduction of Trichonephila clavata (L. Koch, 1878) (Araneae: Araneidae: subfamily Nephilinae) in the United States was first recorded in Georgia in 2014. Since its introduction, T. clavata has become a prominent feature of the arthropod fauna in several southeastern US states. Many questions regarding the introduction event(s) remain unanswered; for instance, was the introduction a single discrete event followed by rapid spread, or were there multiple introductions? The mitochondrial cytochrome c oxidase subunit one gene region (COI), which was used to characterize the initial T. clavata observation in the US, has also been used to characterize within- and between-population genetic variation. One confounding factor for COI as a population genetic molecular marker, though, is the presence of cytoplasmic agents of selection such as intracellular bacteria in the genus Wolbachia. Given that Wolbachia infections have been detected in potential source populations of T. clavata, the present study sought to characterize mitochondrial genetic diversity and the status of Wolbachia infection in the North American population(s) closest to the originally proposed introduction site in Georgia. DNA sequencing revealed no mitochondrial genetic variation in the T. clavata population sampled in North America, and an exact sequence match to the previously reported T. clavata in Georgia and a sequence sample from Yunnan, China. Wolbachia was detected in the North American samples. However, phylogenetic analysis on a concatenated multi-locus type sequence suggested two distinct Wolbachia clades, one represented by samples collected in Georgia and another represented by a single sample collected in South Carolina. Sequence analyses of the multi-locus gene regions suggested that the Georgia T. clavata may be infected with two strains of Wolbachia (super-infection), and the South Carolina sample represented a separate single infection. The study’s results emphasize the need for further research, including expanded sampling in the introduced and potential source population regions, as well as a more detailed molecular characterization of the populations.

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