An initial investigation into the genetic diversity, phylogenetic relationships, and population structure of the Olive Psyllid Euphyllura olivina in Tunisia

The olive psyllid, Euphyllura olivina Costa (Hemiptera: Psyllidae), causes considerable damage in the olive groves of the Mediterranean area, resulting in significant loss in olive oil production. The present work aims to gain a first overview on the genetic diversity of this species in Tunisia by analyzing patterns of genetic variability in the mitochondrial cytochrome oxidase subunit 1 (COI) and the nuclear Internal Transcribed Spacer marker (ITS). Our analyses revealed low genetic differentiation among the studied populations, with low nucleotide and haplotype diversity. These results are associated with frequent rare variants and high gene flow exchange, suggesting recent colonization followed by population expansion across the invaded range. We cannot exclude the possibility that the low genetic diversity results in part from a reduction in the population size associated with poor performance under the current climatic conditions. Future investigations could benefit from the inclusion of additional genetic markers, including microsatellites, or population genomic approaches, to trace more accurately the demographic history and genetic differentiation of the olive psyllid.