Mealybug species from Chilean agricultural landscapes and main factors influencing the genetic structure of Pseudococcus viburni.

Margarita C G Correa,Didier Crochard,Tania Zaviezo,Eric Lombaert,Thibaut Malausa,Ferran Palero,Andrés Alvear

doi:10.1038/srep16483

Abstract

The present study aimed to characterize the distribution of mealybug species along Chilean agro-ecosystems and to determine the relative impact of host plant, management strategy, geography and micro-environment on shaping the distribution and genetic structure of the obscure mealybug Pseudococcus viburni. An extensive survey was completed using DNA barcoding methods to identify Chilean mealybugs to the species level. Moreover, a fine-scale study of Ps. viburni genetic diversity and population structure was carried out, genotyping 529 Ps. viburni individuals with 21 microsatellite markers. Samples from 16 localities were analyzed using Bayesian and spatially-explicit methods and the genetic dataset was confronted to host-plant, management and environmental data. Chilean crops were found to be infested by Ps. viburni, Pseudococcus meridionalis, Pseudococcus longispinus and Planococcus citri, with Ps. viburni and Ps. meridionalis showing contrasting distribution and host-plant preference patterns. Ps. viburni samples presented low genetic diversity levels but high genetic differentiation. While no significant genetic variance could be assigned to host-plant or management strategy, climate and geography were found to correlate significantly with genetic differentiation levels. The genetic characterization of Ps. viburni within Chile will contribute to future studies tracing back the origin and improving the management of this worldwide invader.

Highlights

(between Coquimbo and Maule regions) and 20 fruit species concentrating about 90% of the cultivated area[13]
In the Norte Chico area (26° S to 32° S), which includes the administrative regions of Atacama and Coquimbo, there are semi-desert conditions with extreme climate variations
Correct identification is essential for pest management, previous reports on mealybugs have evidenced considerable difficulties when using morphology-based methods[17,18,19]

Summary

Introduction

(between Coquimbo and Maule regions) and 20 fruit species concentrating about 90% of the cultivated area[13]. The Norte Chico climate is mostly favorable to vineyards, while the Central Chile area includes both vineyards and fruit orchards (e.g. orange trees, apple trees, plum trees and pears). In a preliminary study using a DNA barcoding approach, Correa et al.[20] found Pseudococcus viburni (Signoret) to be the most common mealybug species in Chilean vineyards, followed by Pseudococcus meridionalis Prado and Pseudococcus cribata González. The present study aimed at characterizing the diversity and distribution of mealybug species infesting Chilean agro-ecosystems, including both vineyards and deciduous fruit crops. In order to achieve this goal, we completed an extensive survey between Atacama and the Northern part of Biobío (covering most cultivated areas in Chile) and using DNA barcoding methods to identify mealybug samples to the species level. A comprehensive analysis of Ps. viburni samples allowed us to determine the relative impact of host plant, management strategy, geography and micro-environment on shaping the distribution and genetic structure of the pest

Methods

Results

Conclusion