Worldwide distribution and phylogeography of the agave weevil Scyphophorus acupunctatus (Coleoptera, Dryophthoridae): the rise of an overlooked invasion

Abstract

Global plant trade represents one of the main pathways of introduction for invertebrates, including insects, throughout the world. Non-native insects include some of the most important pests affecting cultivated and ornamental plants worldwide. Defining the origins and updating the distribution of non-native invasive species is pivotal to develop effective strategies to limit their spread. The agave weevil, Scyphophorus acupunctatus (Coleoptera, Dryophthoridae), is a curculionid beetle native to Central and North America, although it also occurs in Eurasia, Africa, Oceania and South America as a non-native species. Despite being widespread, the extent of occurrence and origins of European populations of the agave weevil have been overlooked. In the present study, the current and potential worldwide distribution of S. acupunctatus was assessed and an analysis of its genetic diversity in the native and non-native ranges was performed. By analysing occurrences from local phytosanitary bulletins and citizen-science platforms, the agave weevil was confirmed to be widely distributed and to occur on all continents, except Antarctica. Additionally, there is potential for expansion throughout the world, as estimated by species distribution models. Nucleotide and haplotype diversity of the COXI mitochondrial gene (about 650 bp) was lower in the non-native (n = 39 samples) than native populations (n = 26 samples). The majority of introduced individuals belonged to the same haplotype, suggesting that most introductions in Europe might have occurred from a small geographical area in Central America. Constant transboundary monitoring and national laws must be considered to reduce the spread of the agave weevil, given that a bridgehead effect may occur from non-native populations to new suitable areas.