Temporal Genetic Stability Within and Restricted Migration (Gene Flow) Between Local Populations of the Blackberry-Grain Aphid Sitobion fragariae in South-East England

Host-associated genetic structure of Mexican populations of the cabbage aphid Brevicoryne brassicae L. (Homoptera: Aphididae)

“…The existence of host-mediated genetic differentiation is relevant for the analysis of the ecological causes that promote differentiation (Nason et al, 2002). The genetic structure of aphid species is maintained by selection adjusting populations to the local environmental conditions (Tomiuk and Wö hrmann, 1984;EggersSchumacher and Sander, 1988;Tomiuk et al, 1991), by reduced gene flow (Loxdale and Brookes, 1990;Loxdale et al, 1998;Johnson et al, 2002;Massonnet et al, 2002), itself a function of species-specific flight behaviour dependent on their tendency and their ability to fly (see Loxdale et al, 1993, for a review), and by genetic drift (De Barro et al, 1995a). Perhaps, as in the case of the aphid Methopolophium dirhodum, differentiation between hosts in the localities of Mitzitón and Balú n could be better explained if founder effects or genetic drift have occurred (see De Barro et al, 1995a).…”

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

“…The occurrence of both holocyclic and anholocyclic lineages in aphid populations has been demonstrated or inferred in several species (Loxdale and Brookes, 1990;Moran, 1991;Simon et al, 1999a, b). Allele frequency differences between holocyclic and anholocyclic aphids have been shown to be important in driving genetic divergence between populations of Sitobion avenae in France (Simon et al, 1999a) and Aphis pomi (de Geer) in Canada (Singh and Rhomberg, 1984) and have been suggested as a cause for genetic differences between populations of S. fragariae (Walker) on its primary and secondary hosts in southeast England (Loxdale and Brookes, 1990). The fact that the same multilocus genotypes were seen on lettuce in successive years suggests that some P. bursarius clones do persist throughout the winter and recolonise lettuce without an intervening sexual cycle.…”

Developmental differences of local populations of alfalfa weevil (Hypera postica) (Coleoptera: Curculionidae)

“…Geographic barriers and environmental differences may be responsible for the divergence between western and eastern populations. For most agricultural pests, the mixture of populations by human activity is undeniable (Loxdale and Brookes, 1990;Sakai et al, 2001;Sanaei et al, 2015c). Hamedan Province (the locality of the Hamedan and Tuyserkan populations) is one of the most important alfalfa-exporting sites that provide the feeding crop for livestock in many provinces of Iran.…”