Population genetic structure ofTomicus piniperdaL. (Curculionidae: Scolytinae) on different pine species and validation ofT. destruens(Woll.)

Abstract

Genetic diversity and population structure of Tomicus piniperda was assessed using mitochondrial sequences on 16 populations sampled on 6 pine species in France. Amplifications of Internal transcribed space 1 (ITS1) were also performed. Our goals were to determine the taxonomic status of the Mediterranean ecotype T. piniperda destruens, and to test for host plant or geographical isolation effect on population genetic structure. We showed that T. piniperda clusters in two mtDNA haplotypic groups. Clade A corresponds to insects sampled in continental France on Pinus sylvestris, P. pinaster and P. uncinata, whereas clade B gathers the individuals sampled in Corsica on P. pinaster and P. radiata and in continental France on P. pinea and P. halepensis. Insects belonging to clade A and clade B also consistently differ in the length of ITS1. Individuals belonging to both clades were found once in sympatry on P. pinaster. Genetic distances between clades are similar to those measured between distinct species of Tomicus. We concluded that clade B actually corresponds to the destruens ecotype and forms a good species, T. destruens. Analyses of molecular variance ( amova ) were conducted separately on T. destruens and T. piniperda to test for an effect of either geographical isolation or host species. Interestingly, the effect of host plant was significant for T. piniperda only, while the effect of geographical isolation was not. Pine species therefore seems to act as a significant barrier to gene flow, even if host race formation is not observed. These results still need to be confirmed by nuclear markers.

Genetic structure of the forest pest Hylobius abietis on conifer plantations at different spatial scales in Europe

“…A similar pattern (with 82-86% of variation within populations) was found using mitochondrial sequences in the Scolytid Tomicus piniperda L. (Kerdelhué et al, 2002). Similarly, RAPD analysis of the common pine sawfly Diprion pini L. also indicated that on average 84% of the genetic diversity comprised intrapopulation variation (Baumann et al, 2003).…”

Comparative population genetic study of two oligophagous insects associated with the same hosts

“…This pattern suggests that host specialization is not a strong factor influencing the evolution of the species, at least within this restricted group of host tree species. Yet, a previous study of host-plant specialization in T. piniperda using mitochondrial markers showed a weak but significant effect of host species as a barrier to gene flow (Kerdelhué et al, 2002). The different results obtained with nuclear and mitochondrial markers could be due to sex-biased dispersal.…”

Complex postglacial history of the temperate bark beetle Tomicus piniperda L. (Coleoptera, Scolytinae)

“…Thirty-four populations were found in sixteen countries and on six Pinus species, to complement the existing samples from France (Kerdelhué et al, 2002) and to obtain a representative sampling of the species across its distribution range in Europe. No insects were trapped in the southern part of the Iberian Peninsula, of Italy and of the Balkans, where only the congeneric T. destruens was found (Figure 1).…”

“…Mitochondrial DNA amplification T. piniperda specific primers were used to amplify a partial region of the cytochrome oxidase I and II genes (Kerdelhué et al, 2002). The annealing temperature was 50 1C, and a total of 30 cycles of amplification was carried out in 50 ml reaction volume.…”

“…All the obtained sequences, and sequences from France (GenBank accession numbers AF457799-AF457803, AF457804-AF457808, AF457819-AF457820, AF457822-AF457826; Kerdelhué et al, 2002), were aligned using ClustalW v1.4 (Thompson et al, 1994) as implemented in BIOEDIT v7.0.5.…”