Population genetic structure of the lettuce root aphid, Pemphigus bursarius (L.), in relation to geographic distance, gene flow and host plant usage

Abstract

Microsatellite markers were used to examine the population structure of Pemphigus bursarius, a cyclically parthenogenetic aphid. Substantial allele frequency differences were observed between populations on the primary host plant (collected shortly after sexual reproduction) separated by distances as low as 14 km. This suggested that migratory movements occur over relatively short distances in this species. However, the degree of allele frequency divergence between populations was not correlated with their geographical separation, indicating that isolation by distance was not the sole cause of spatial genetic structuring. Significant excesses of homozygotes were observed in several populations. Substantial allele frequency differences were also found between aphids on the primary host and those sampled from a secondary host plant after several parthenogenetic generations at the same location in two successive years. This could have been due to the existence of obligately parthenogenetic lineages living on the secondary host or genetically divergent populations confined to different secondary host plant species but sharing a common primary host.

Genetic structure of populations of Aphis gossypii (Hemiptera: Aphididae) on citrus trees in Northern Iran

“…The same results are also reported for other species of pest aphids (e.g. Sunnucks et al, 1996;Miller et al, 2003;Vorburger et al, 2003;Vorwerk & Forneck, 2006;Aradottir et al, 2012).…”

Gene Flow Among <I>Cydia pomonella</I> (Lepidoptera: Tortricidae) Geographic and Host Populations in South Africa

“…Our results are consistent with findings in South Africa, northern Italy and Switzerland, where limited gene flow and significant genetic differentiation between different local geographic regions were found (Timm et al 2006;Thaler et al 2008;Chen & Dorn 2010). Similar results were also reported in the closely related species with small flight capacity, Grapholita molesta (Timm et al 2008;Torriani et al 2010;Kirk et al 2013 a, b;Zheng et al 2013 ), as well as in aphids (Loxdale et al 1993;Miller et al 2003). We found similar genetic diversities and similar genetic structures within each region in this study.…”

Host-associated populations in the lettuce root aphid, Pemphigus bursarius (L.)

“…A recent study of microsatellite variation in the hostalternating aphid Pemphigus bursarius (L.) demonstrated substantial allele frequency differences between samples taken from its primary host, Populus nigra, in the spring and on Lactuca sativa, one of the secondary hosts, in summer at the same location (Miller et al, 2003). This divergence may be explained by the population on Lactuca being composed largely of obligate parthenogens that do not complete the sexual part of the life cycle on Populus.…”