Population genetic differentiation and structure analysis of the bean Weevil, Acanthoscelides obtectus (Say) based on mitochondrial COI DNA barcode sequences

The bean weevil, Acanthoscelides obtectus (Say), is a globally important storage pest which caused severe economic losses every year due to the erosion of legumes.

In order to reveal the genetic differentiation and population structure of A. obtectus.

We investigated the population geographical distribution, population genetic diversity and population genetic differentiation of 21 geographic populations from Asia, Europe, Africa, and South America based on mitochondrial COI DNA barcode sequences.

Geographical distribution analysis revealed widespread dispersal of A. obtectus populations across all four continents. Haplotype analysis showed there were 15 distinct haplotypes (H1~H15), and they were unevenly distributed, showing geographical preference. Genetic diversity analysis showed that A. obtectus populations had high haplotype diversity but low nucleotide diversity (Hd=0.665, Pi=0.00291), and there were differences among populations. Haplotype network and phylogenetic analysis showed that the population structure of A. obtectus was a multi-hub-and-spoke radiation pattern, and there was a certain degree of genetic differentiation among the populations, which were divided into three subgroups. Genetic differentiation and gene flow analysis revealed that there was a certain degree of genetic differentiation among the populations, and the degree of gene flow was greatly different (e.g., Fst=0.0851, Nm=2.6881 between Europe and Africa; Fst=0.7690, Nm=0.0751 between South America and Asia). There was no significant correlation between genetic differentiation and geographic distance (r=0.2102, P=0.031< 0.05). Neutral tests suggested recent population expansion in the Uganda population (Tajima's D= -1.79107, P<0.05), while the remaining 20 populations conformed to neutral mutation expectations with stable effective population sizes.

This study laid a foundation for further understanding the spread sources and invasion routes of A. obtectus at home and abroad, and building a sustainable prevention and control system.