Insights into the origin of the invasive populations of Trioza erytreae in Europe using microsatellite markers and mtDNA barcoding approaches

Omar Ruíz-Rivero,Dina Cifuentes,Fathiya M Khamis,Borja Rojas-Panadero,Meritxell Pérez-Hedo,Kerstin Kruger,José Carlos Franco,Alejandro Tena,Alberto Urbaneja,Pablo Bielza,Andrés Garcia-Lor

doi:10.1038/s41598-021-97824-0

Abstract

The African citrus psyllid Trioza erytreae is one of the major threats to citrus industry as the vector of the incurable disease known as huanglongbing (HLB) or citrus greening. The psyllid invaded the northwest of the Iberian Peninsula 6 years ago. The invasion alarmed citrus growers in the Mediterranean basin, the largest citrus producing area in Europe, which is still free of HLB. Before our study, no research had been carried out on the genetic diversity of T. erytreae populations that have invaded the Iberian Peninsula and the archipelagos of the Macaronesia (Madeira and the Canary Islands). In this study, combining microsatellites markers and mtDNA barcoding analysis, we characterize the genetic diversity, structure and maternal relationship of these new invasive populations of T. erytreae and those from Africa. Our results suggest that the outbreaks of T. erytreae in the Iberian Peninsula may have derived from the Canary Islands. The populations of T. erytreae that invaded Macaronesia and the Iberian Peninsula are likely to have originated from southern Africa. We anticipate our results to be a starting point for tracking the spread of this invasive pest outside of Africa and to be important for optimizing contingency and eradication plans in newly invaded and free areas.

Highlights

The African citrus psyllid Trioza erytreae (Del Guercio) (Hemiptera: Triozidae) is an invasive pest that has become one of most severe threats to the Mediterranean citrus industry[1,2,3]
We found that the total number and frequency of T. erytreae SSR markers (428,342 SSRs and 1 SSR/1.09 Kb) are about 3.6 and 3.8 times lower, respectively, compared to D. citri (1,547,487 SSRs and 3.8 SSR/1 Kb)[38]
Since the genome of T. erytreae is not yet fully annotated, we could not estimate the total number of SSRs in exons, introns or intergenic regions, but it was possible to get information for most of the SSR loci selected for further analysis

Summary

Introduction

The African citrus psyllid Trioza erytreae (Del Guercio) (Hemiptera: Triozidae) is an invasive pest that has become one of most severe threats to the Mediterranean citrus industry[1,2,3]. In Florida, the largest orange growing area in the United States of America, the spread of HLB by D. citri caused citrus production decline by 74%, resulting in losses of about USD 4554 m illion[7,8] Besides their role as HLB vectors, the nymphs of both psyllid species excrete large amount of honeydew that facilitates the growth of sooty moulds on infested trees[2,9]. In Spain, the distribution of T. erytreae has expanded in a north-eastern direction throughout to the Cantabrian coast, and specific outbreaks have been reported recently in Asturias, Cantabria and the Basque C ountry[19]. It is still unknown how T. erytreae reached the Iberian Peninsula. A T. dryi-assisted biological control program against T. erytreae was carried out successfully in the Indian Ocean island of Réunion 24 and Mauritius[25]

Objectives

Methods

Results

Conclusion