Genetic structure of the invasive pest Bemisia tabaci: evidence of limited but persistent genetic differentiation in glasshouse populations

Abstract

The geographic range of plant pests can be modified by the use of glasshouses. Bemisia tabaci, originating from warm to hot climates, has been shown to be a complex of distinct genetic groups with very limited gene flow. The genetic structure of this pest was studied in glasshouses in southern France, a region beyond the northern limit of its open-field development area in Europe. Seven microsatellite loci were scored in 22 populations sampled from various regions over 3 years. Two genetic groups were distinguished using a Bayesian clustering method and were assigned to the socalled biotypes B and Q using the gene sequence of cytochrome oxidase 1 (CO1). All but one population corresponded to biotype Q, even though only biotype B was previously reported. Despite the enclosed environment of glasshouses and their expected isolation due to low outdoor survival during the winter, only limited differentiation among biotype Q glasshouses was observed. A single sample site was notable for a decrease in expected heterozygosity and the mean number of alleles over the years. The lack of spatial genetic structure among biotype Q populations was indicative of a recent colonization event combined with large dispersal at all spatial scales. This migration pattern of biotype Q populations was further supported by additional CO1 sequences, since individuals from France, Asia and America exhibited 100% nucleotide identity. The evolution of genetic diversity observed in glasshouses in France is part of the worldwide invasion of biotype Q, which is discussed in light of human activities.

Population variability of Bemisia tabaci (Genn.) in different hosts

“…A low level of genetic polymorphism was observed in the present study, compared to previous study on biotype B (Simón et al, 2007;Dalmon et al, 2008;do Valle et al, 2011). However, 50 alleles were found in the 13 polymorphic loci.…”

Spatial and host‐plant partitioning between coexisting Bemisia tabaci cryptic species in Tunisia

“…However, putative MEAMI and Med species have sometimes been reported to co-occur with other species of the B. tabaci complex in the field, and particularly in the Mediterranean basin. But after a period of co-existence, Med has often been reported to rapidly displace or eliminate the other B. tabaci species, including MEAMI (Tahiri et al 2006;Simón et al 2007;Tsagkarakou et al 2007;Dalmon et al 2008). Only a few Mediterranean countries including Tunisia have been reported to still ''host'' the highly competing Med and MEAMI B. tabaci, at least in some localities (Chermiti et al 1997;Bel-Kadhi et al 2008).…”

Tools and Recent Progress in Studying Gene Flow and Population Genetics of the Bemisia tabaci Sibling Species Group

“…Finally, another study looked at the genetic structure of 22 B. tabaci populations sampled from vegetable and ornamental glasshouses in southern France (Dalmon et al 2008). This study tested the hypothesis that the enclosed environment and patchy distribution of glasshouses in combination with the limited outdoor survival of whiteflies in the winter would promote genetic differentiation among populations.…”

“…Complementing markers from these two different genomes having different natural histories can also help detect past hybridization events between biotypes by testing for discrepancies between the generated nuclear and mitochondrial phylogenies (Lowe et al 2004). Moreover, use of microsatellite loci can add significant information because they are examined as multilocus markers and a good number of polymorphic loci are already available in the literature for B. tabaci (Dalmon et al 2008;De Barro et al 2003;Delatte et al 2006;Gauthier et al 2008;Schwartz et al unpubl. data;Tsagkarakou and Roditakis 2003;Tsagkarakou et al 2007).…”