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

Abstract

Pemphigus bursarius is a host-alternating aphid in which annual rounds of sexual reproduction on its primary host, Populus nigra, are interspersed with parthenogenesis on a range of secondary hosts. Evidence was sought for the existence of genetically distinct populations, associated with different secondary hosts, in P. bursarius. Microsatellite markers revealed that genetically distinct populations were present on three different secondary host species. Microsatellites were also used, in conjunction with mitochondrial DNA sequence variation, to investigate the relationships between aphids on Populus, following sexual reproduction, and those on the secondary hosts. Evidence was found for a distinct, cyclically parthenogenetic population that exploited Lactuca sativa as its secondary host. In contrast, populations associated with Matricaria inodora appeared to be largely composed of obligate parthenogens or may even have been another species of Pemphigus. Populations on Lapsana communis appeared to be a mixture of cyclical and obligate parthenogens and were more genetically heterogeneous than those on other secondary hosts, possibly due to founder effects. Experiments to measure the performance of P. bursarius clones on different secondary hosts were inconclusive, failing to demonstrate either the presence or absence of adaptations to secondary hosts. Heredity (2005) 94, 556-564.

Biotypic Diversity in Greenbug (Hemiptera: Aphididae): Microsatellite-Based Regional Divergence and Host-Adapted Differentiation

“…Host-based divergence of insect populations also was observed in the pea aphid (Via et al 2000, Simon et al 2003, Frantz et al 2006, Russian wheat aphid (Dolatti et al 2005); lettuce root aphid, Pemphigus bursarius (L.) (Miller et al 2005); and English grain aphid, Sitobion avenae (F.) (De Barro et al 1995, Sunnucks et al 1997. The molecular data herein based on 31 SSRs with 24 greenbug biotypes or isolates clearly supported the host-adapted nature of greenbug biotypes, but with a higher resolution.…”

Cross‐species transferability of microsatellite markers from six aphid (Hemiptera: Aphididae) species and their use for evaluating biotypic diversity in two cereal aphids

“…Common genetic factors exist among different biotypes, enabling them to predominate and thrive in monoculture crops (Zhu‐Salzman et al ., 2003). Host‐based divergence in populations was also observed in the pea aphid (Via et al ., 2000; Simon et al ., 2003; Frantz et al ., 2006), RWA (Dolatti et al ., 2005), lettuce root aphid, Pemphigus bursarius (L.) (Miller et al ., 2005) and English grain aphid, Sitobion avenae (De Barro et al ., 1995; Sunnucks et al ., 1997). The molecular data from 67 SSRs in the present study clearly support the earlier notion of the host‐adapted nature of the greenbug biotypes, but with higher resolution.…”

Evidence for an Invasive Aphid “Superclone”: Extremely Low Genetic Diversity in Oleander Aphid (Aphis nerii) Populations in the Southern United States

“…Prior to this study, it was not known if A. nerii populations inhabiting Oleander and Milkweed were genetically different. Several aphid species have “host races” or show non-random distribution of genetic variation among host plants, including the Pea aphid [14], [52], the Grain aphid, Sitobion avenae (F.) [54], [57], the Cotton /Melon aphid, Aphis gossypii Glover [15] and others [16], [17], [58]. This phenomenon undoubtedly results from habitat choice/host fidelity inhibiting interpopulation gene flow [14], [59].…”

“…Increased use of molecular markers to study aphid populations has revealed that host races are common [15], [16], [17]. There is currently no evidence of differential fitness for A. nerii inhabiting species of milkweed that differed in the amount cardiac glycosides that they possess [13].…”