| evolutionary relationships of three new species of enterobacteriaceae living as symbionts of aphids and other insects. | ecological studies on three bacterial lineages symbiotic in aphids have shown that they impose a variety of effects on their hosts, including resistance to parasitoids and tolerance to heat stress. phylogenetic analyses of partial sequences of gyrb and reca are consistent with previous analyses limited to 16s rrna gene sequences and yield improved confidence of the evolutionary relationships of these symbionts. all three symbionts are in the enterobacteriaceae. one of the symbionts, here given t ... | 2005 | 15933033 |
| aphid protected from pathogen by endosymbiont. | aphids are associated with several facultative bacterial endosymbionts that may influence their interactions with other organisms. we show here that one of the three most common facultative symbionts of pea aphid (acyrthosiphon pisum), the bacterium regiella insecticola, has a major effect on host resistance to a fungal pathogen. experimental establishment of the bacterium in uninfected aphid clones led to higher survival after fungal attack. the bacteria also increased the aphid's inclusive fit ... | 2005 | 16357252 |
| costs and benefits of symbiont infection in aphids: variation among symbionts and across temperatures. | symbiosis is prevalent throughout the tree of life and has had a significant impact on the ecology and evolution of many bacteria and eukaryotes. the benevolence of symbiotic interactions often varies with the environment, and such variation is expected to play an important role in shaping the prevalence and distributions of symbiosis throughout nature. in this study, we examine how the fitness of aphids is influenced by infection with one of three maternally transmitted bacteria, 'candidatus se ... | 2006 | 16537132 |
| symbiont modifies host life-history traits that affect gene flow. | the evolution of herbivore-host plant specialization requires low levels of gene flow between populations on alternate plant species. accordingly, selection for host plant specialization is most effective when genotypes have minimal exposure to, and few mating opportunities with individuals from, alternate habitats. maternally transmitted bacterial symbionts are common in insect herbivores and can influence host fecundity under a variety of conditions. symbiont-mediated effects on host life-hist ... | 2006 | 16600884 |
| genetic variation in the effect of a facultative symbiont on host-plant use by pea aphids. | ecological specialisation on different host plants occurs frequently among phytophagous insects and is normally assumed to have a genetic basis. however, insects often carry microbial symbionts, which may play a role in the evolution of specialisation. the bacterium regiella insecticola is a facultative symbiont of pea aphids (acyrthosiphon pisum) where it is found most frequently in aphid clones feeding on trifolium giving rise to the hypothesis that it may improve aphid performance on this pla ... | 2007 | 17415589 |
| impact of plant nutrients on the relationship between a herbivorous insect and its symbiotic bacteria. | the interactions between herbivorous insects and their symbiotic micro-organisms can be influenced by the plant species on which the insects are reared, but the underlying mechanisms are not understood. here, we identify plant nutrients, specifically amino acids, as a candidate factor affecting the impact of symbiotic bacteria on the performance of the phloem-feeding aphid aphis fabae. aphis fabae grew more slowly on the labiate plant lamium purpureum than on an alternative host plant vicia faba ... | 2008 | 18089538 |
| genetic variation and covariation of susceptibility to parasitoids in the aphid myzus persicae: no evidence for trade-offs. | parasitoids are an important mortality factor for insects. susceptibility to parasitoids should thus be under strong negative selection. nevertheless, ample genetic variation for susceptibility to parasitoids is commonly observed in natural populations, suggesting that trade-offs may constrain the evolution of reduced susceptibility. this can be studied by assessing genetic variation for susceptibility and its covariation with other components of fitness. in a set of 17 clones of the peach potat ... | 2008 | 18270153 |
| a strain of the bacterial symbiont regiella insecticola protects aphids against parasitoids. | aphids commonly harbour facultative bacterial endosymbionts and may benefit from their presence through increased resistance to parasitoids. this has been demonstrated for hamiltonella defensa and serratia symbiotica, while a third common endosymbiont, regiella insecticola, did not provide such protection. however, this symbiont was recently detected in a highly resistant clone of the peach-potato aphid, myzus persicae, from australia. to test if resistance was indeed conferred by the endosymbio ... | 2010 | 19776066 |
| two species of symbiotic bacteria present in the soybean aphid (hemiptera: aphididae). | aphids, which feed solely on plant phloem sap, have developed symbiotic associations with bacteria that provide them with the amino acids that are lacking in phloem. three soybean aphid (aphis glycines mat samura) populations were screened for the presence of buchnera aphidicola and three common species of secondary aphid symbionts (serratia symbiotica, hamiltonella defensa, and regiella insecticola). diagnostic polymerase chain reaction and subsequent dna sequencing showed the presence of two s ... | 2009 | 19791603 |
| dynamics of genome evolution in facultative symbionts of aphids. | summary aphids are sap-feeding insects that host a range of bacterial endosymbionts including the obligate, nutritional mutualist buchnera plus several bacteria that are not required for host survival. among the latter, 'candidatus regiella insecticola' and 'candidatus hamiltonella defensa' are found in pea aphids and other hosts and have been shown to protect aphids from natural enemies. we have sequenced almost the entire genome of r. insecticola (2.07 mbp) and compared it with the recently pu ... | 2009 | 19840097 |
| aphid reproductive investment in response to mortality risks. | aphids are striking in their prodigious reproductive capacity and reliance on microbial endosymbionts, which provision their hosts with necessary amino acids and provide protection against parasites and heat stress. perhaps as a result of this bacterial dependence, aphids have limited immune function that may leave them vulnerable to bacterial pathogens. an alternative, non-immunological response that may be available to infected aphids is to increase reproduction, thereby ameliorating fitness l ... | 2010 | 20716370 |
| interspecific symbiont transfection confers a novel ecological trait to the recipient insect. | in japan, pea aphids acyrthosiphon pisum mainly feed on vetch and clover, and many aphid clones produce more progeny on vetch than on clover. in this context, particular genotypes of the facultative symbiont regiella insecticola enhance reproduction of infected pea aphids specifically on clover, thereby broadening the suitable food plant range of the insect. a species that is sympatric to a. pisum, vetch aphids megoura crassicauda, are commonly found on vetch but not on clover. laboratory rearin ... | 2010 | 20880856 |
| genomic basis of endosymbiont-conferred protection against an insect parasitoid. | bacterial endosymbionts exert a variety of beneficial effects on insect hosts. in pea aphids (acyrthosiphon pisum), several inherited endosymbiont species protect their hosts against parasitoid wasps, which are major natural enemies. however, strains of these symbiont species vary in their ability to confer protection against parasitoids, with some conferring almost complete protection and others conferring almost none. in this study, two strains of the endosymbiont regiella insecticola (r. inse ... | 2011 | 21948522 |
| dynamics of genome evolution in facultative symbionts of aphids. | aphids are sap-feeding insects that host a range of bacterial endosymbionts including the obligate, nutritional mutualist buchnera plus several bacteria that are not required for host survival. among the latter, 'candidatus regiella insecticola' and 'candidatus hamiltonella defensa' are found in pea aphids and other hosts and have been shown to protect aphids from natural enemies. we have sequenced almost the entire genome of r. insecticola (2.07 mbp) and compared it with the recently published ... | 2010 | 21966902 |
| multiple origins of endosymbiosis within the enterobacteriaceae (gamma-proteobacteria): convergence of complex phylogenetic approaches. | abstract: background: the bacterial family enterobacteriaceae gave rise to a variety of symbiotic forms, from the loosely associated commensals, often designated as secondary (s) symbionts, to obligate mutualists, called primary (p) symbionts. determination of the evolutionary processes behind this phenomenon has long been hampered by the unreliability of phylogenetic reconstructions within this group of bacteria. the main reasons have been the absence of sufficient data, the highly derived nat ... | 2011 | 22201529 |