Microsatellites reveal extensive geographical, ecological and genetic contacts between invasive and indigenous whitefly biotypes in an insular environment

Abstract

SummaryHuman-mediated bioinvasions provide the opportunity to study the early stages of contact between formerly allopatric, divergent populations of a species. However, when invasive and resident populations are morphologically similar, it may be very difficult to assess their distribution in the field, as well as the extent of ecological overlap and genetic exchanges between invasive and resident populations. We here illustrate the use of data obtained from a set of eight microsatellite markers together with Bayesian clustering methods to document invasions in a group of major tropical pests, Bemisia tabaci, which comprises several morphologically indistinguishable biotypes with different agronomic impacts. We focus on the island of La Re´union, where an invasive biotype (B) has recently been introduced and now interacts with the resident biotype (Ms). The temporal and spatial distribution, host-plant range and genetic structure of both biotypes are investigated. We showed (i) that, without prior information, clustering methods separate two groups of individuals that can safely be identified as the B and Ms biotypes; (ii) that the B biotype has invaded all regions of the island, and showed no signs of genetic founder effect relative to the Ms biotype ; (iii) that the B and Ms biotypes coexist in sympatry throughout most of their geographical ranges, although they tend to segregate into different host plants ; and finally (iv) that asymmetrical and locus-specific introgression occurs between the two biotypes when they are in syntopy.

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

“…Human activities in glasshouses (for example pesticide spraying, pruning, harvest and so on) may favour whitefly flight and serve as passive transport, hence increasing within-glasshouse mixing. Conspicuously high levels of F IS were reported in previous B. tabaci population genetic studies Delatte et al, 2006), which contrast with our results at first glance. De argued that these high heterozygote deficiencies could at least partially result from high insecticide pressures.…”

“…Second, individuals from the two entities were assigned to genetic groups B or Q according to the match between their CO1 sequences and Genbank CO1 sequences of individuals from known genetic groups taken as references. The high F ST value we found between genetic groups B and Q was consistent with the F ST value documented in Moya et al (2001), F ST ¼ 0.34) using random amplified polymorphic DNA markers, and between genetic group B and the Indian Ocean group Ms (F ST ¼ 0.32) (Delatte et al, 2006) using microsatellite markers.…”

“…Genetic structure of B. tabaci in glasshouses A Dalmon et al enriched for AC nucleotide repeats described by Delatte et al (2006). As B. tabaci is a haplo-diploid species, only females were analysed due to their diploid state.…”

“…Markers 68, 145 and 177 are described here for the first time. They were prepared as described by Delatte et al (2006). When a repeat unit is interrupted, it is considered as imperfect (imp).…”

Estrutura genética populacional de Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) utilizando marcadores microssatélites

“…O valor médio encontrado de F IS pode ser considerado nulo nas populações de B. tabaci, sugerindo que a espécie aproxima-se da panmixia, e indica que as frequências alélicas dessas populações podem se encontrar nas proporções de equilíbrio de Hardy-Weinberg, para a geração. Esse resultado é semelhante ao observado por Delatte et al (2006), onde a estimativa foi de 0,18, indicando um pouco de endogamia intrapopulacional. Porém, vale ressaltar que foram utilizados diferentes locos microssatélites.…”