Summary
A bioRxiv preprint reports that the palm pest Rhynchophorus ferrugineus established on mainland America through Uruguay, spread across nearly 80,000 square kilometres and reached Argentina. The weevil is now attacking several native South American palms.
A population of the palm pest Rhynchophorus ferrugineus has established on mainland America through Uruguay, according to a bioRxiv preprint. The weevil was first detected in Uruguay in 2022, spread across an area of nearly 80,000 square kilometres over the following four years and reached Argentina in January 2026.
The study combines morphological and molecular identification, genetic analysis, records of attacked palms and ecological-niche modelling. It describes the Uruguayan population as the first established mainland-American population of the species, following earlier records from the islands of Curaçao and Aruba.
From introduced ornamental palms to native species
During the first two years after its detection, attacks in Uruguay focused on Phoenix canariensis, commonly known as the Canary Island date palm. The researchers now report attacks on three of Uruguay’s most common native palms: Butia odorata, Butia yatay and Syagrus romanzoffiana.
This shift matters because an invasive pest affecting only introduced palms presents a different management challenge from one that can also use native hosts. The authors identify the presence of susceptible palms across Uruguay and neighbouring areas of Argentina and Brazil as a factor that could support further spread.
In January 2026, the weevil reached two locations in Argentina near the Uruguayan border. The source describes these detections as part of the continuing expansion of the Uruguayan invasion.
Genetic evidence points to a separate introduction
The researchers used DNA sequences alongside physical characteristics to identify the beetles. Their phylogenetic analysis placed the Uruguayan sequences in a single genetic clade most closely related to sequences from southern China. The Uruguayan sequences were clearly distinct from those obtained from Curaçao and Aruba.
That separation indicates that the mainland and island populations arose through at least two independent introductions into the Americas, from different source regions. It also means that the Uruguayan population is not simply an extension of the previously recorded island lineage.
The study provides a practical way to distinguish R. ferrugineus from Rhynchophorus palmarum, a native species. The proposed diagnostic key uses three features: the shape of the rostrum tip, the tegminal plate and the ratio between the space between the eyes and the width of the rostrum at its base. The rostrum is the elongated snout-like structure characteristic of these weevils.
Areas considered suitable for further spread
The ecological-niche models identify Uruguay and neighbouring parts of Argentina and Brazil as suitable for R. ferrugineus. Such models estimate whether environmental conditions could support a species; they complement, rather than replace, field detections.
The predicted suitable areas overlap with the distribution of P. canariensis and the three native palms already being attacked. On that basis, the authors say neighbouring countries should prepare for short-term expansion of the weevil.
The findings come from a preprint, which reports the authors’ analyses before formal journal peer review. Its central evidence is the combination of specimen identification, genetic relationships, observed host attacks and geographic modelling. Continued field surveillance will determine how closely the predicted expansion matches future infestations.