| 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 |
| variation in resistance to parasitism in aphids is due to symbionts not host genotype. | natural enemies are important ecological and evolutionary forces, and heritable variation in resistance to enemies is a prerequisite for adaptive responses of populations. such variation in resistance has been previously documented for pea aphids (acyrthosiphon pisum) attacked by the parasitoid wasp aphidius ervi. although the variation was presumed to reflect genotypic differences among the aphids, another potential source of resistance to a. ervi is infection by the facultative bacterial symbi ... | 2005 | 16120675 |
| the players in a mutualistic symbiosis: insects, bacteria, viruses, and virulence genes. | aphids maintain mutualistic symbioses involving consortia of coinherited organisms. all possess a primary endosymbiont, buchnera, which compensates for dietary deficiencies; many also contain secondary symbionts, such as hamiltonella defensa, which confers defense against natural enemies. genome sequences of uncultivable secondary symbionts have been refractory to analysis due to the difficulties of isolating adequate dna samples. by amplifying dna from hemolymph of infected pea aphids, we obtai ... | 2005 | 16195380 |
| population dynamics of defensive symbionts in aphids. | vertically transmitted micro-organisms can increase in frequency in host populations by providing net benefits to hosts. while laboratory studies have identified diverse beneficial effects conferred by inherited symbionts of insects, they have not explicitly examined the population dynamics of mutualist symbiont infection within populations. in the pea aphid, acyrthosiphon pisum, the inherited facultative symbiont, hamiltonella defensa, provides protection against parasitism by the wasp, aphidiu ... | 2008 | 18029301 |
| 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 |
| inherited intracellular ecosystem: symbiotic bacteria share bacteriocytes in whiteflies. | symbiotic relationships with bacteria are common within the arthropoda, with interactions that substantially influence the biology of both partners. the symbionts' spatial distribution is essential for understanding key aspects of this relationship, such as bacterial transmission, phenotype, and dynamics. in this study, fluorescence in situ hybridization was used to localize five secondary symbionts from various populations and biotypes of the sweet potato whitefly bemisia tabaci: hamiltonella, ... | 2008 | 18285399 |
| diverse phage-encoded toxins in a protective insect endosymbiont. | the lysogenic bacteriophage apse infects "candidatus hamiltonella defensa," a facultative endosymbiont of aphids and other sap-feeding insects. this endosymbiont has established a beneficial association with aphids, increasing survivorship following attack by parasitoid wasps. although apse and "ca. hamiltonella defensa" are effectively maternally transmitted between aphid generations, they can also be horizontally transferred among insect hosts, which results in genetically distinct "ca. hamilt ... | 2008 | 18791000 |
| almost there: transmission routes of bacterial symbionts between trophic levels. | many intracellular microbial symbionts of arthropods are strictly vertically transmitted and manipulate their host's reproduction in ways that enhance their own transmission. rare horizontal transmission events are nonetheless necessary for symbiont spread to novel host lineages. horizontal transmission has been mostly inferred from phylogenetic studies but the mechanisms of spread are still largely a mystery. here, we investigated transmission of two distantly related bacterial symbionts--ricke ... | 2009 | 19274091 |
| hamiltonella defensa, genome evolution of protective bacterial endosymbiont from pathogenic ancestors. | eukaryotes engage in a multitude of beneficial and deleterious interactions with bacteria. hamiltonella defensa, an endosymbiont of aphids and other sap-feeding insects, protects its aphid host from attack by parasitoid wasps. thus h. defensa is only conditionally beneficial to hosts, unlike ancient nutritional symbionts, such as buchnera, that are obligate. similar to pathogenic bacteria, h. defensa is able to invade naive hosts and circumvent host immune responses. we have sequenced the genome ... | 2009 | 19451630 |
| bacteriophages encode factors required for protection in a symbiotic mutualism. | bacteriophages are known to carry key virulence factors for pathogenic bacteria, but their roles in symbiotic bacteria are less well understood. the heritable symbiont hamiltonella defensa protects the aphid acyrthosiphon pisum from attack by the parasitoid aphidius ervi by killing developing wasp larvae. in a controlled genetic background, we show that a toxin-encoding bacteriophage is required to produce the protective phenotype. phage loss occurs repeatedly in laboratory-held h. defensa-infec ... | 2009 | 19696350 |
| 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 |
| co-infection and localization of secondary symbionts in two whitefly species. | whiteflies are cosmopolitan phloem-feeding pests that cause serious damage to many crops worldwide due to direct feeding and vectoring of many plant viruses. the sweetpotato whitefly bemisia tabaci (gennadius) and the greenhouse whitefly trialeurodes vaporariorum (westwood) are two of the most widespread and damaging whitefly species. to complete their unbalanced diet, whiteflies harbor the obligatory bacterium portiera aleyrodidarum. b. tabaci further harbors a diverse array of secondary symbio ... | 2010 | 20462452 |
| effects of bacterial secondary symbionts on host plant use in pea aphids. | aphids possess several facultative bacterial symbionts that have important effects on their hosts' biology. these have been most closely studied in the pea aphid (acyrthosiphon pisum), a species that feeds on multiple host plants. whether secondary symbionts influence host plant utilization is unclear. we report the fitness consequences of introducing different strains of the symbiont hamiltonella defensa into three aphid clones collected on lathyrus pratensis that naturally lack symbionts, and ... | 2011 | 20843842 |
| symbiont infection affects aphid defensive behaviours. | aphids harbour both an obligate bacterial symbiont, buchnera aphidicola, and a wide range of facultative ones. facultative symbionts can modify morphological, developmental and physiological host traits that favour their spread within aphid populations. we experimentally investigated the idea that symbionts may also modify aphid behavioural traits to enhance their transmission. aphids exhibit many behavioural defences against enemies. despite their benefits, these behaviours have some associated ... | 2011 | 21490007 |
| only helpful when required: a longevity cost of harbouring defensive symbionts. | maternally transmitted symbionts can spread in host populations if they provide a fitness benefit to their hosts. hamiltonella defensa, a bacterial endosymbiont of aphids, protects hosts against parasitoids but only occurs at moderate frequencies in most aphid populations. this suggests that harbouring this symbiont is also associated with costs, yet the nature of these costs has remained elusive. here, we demonstrate an important and clearly defined cost: reduced longevity. experimental infecti ... | 2011 | 21569156 |
| 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 |
| molecular characterization of bemisia tabaci populations in tunisia: genetic structure and evidence for multiple acquisition of secondary symbionts. | a survey was conducted during 2009-2010 seasons to identify the distribution of bemisia tabaci (gennadius) biotypes in tunisia. the genetic affiliation of collected populations was determined by polymerase chain reaction (pcr)-restriction fragment-length polymorphism (taqi) of the mitochondrial cytochrom oxidase i (mtcoi) gene. results, validated by sequencing and phylogenetic analysis, allowed the clustering of sampled sweetpotato whiteflies into b and q biotypes. as b. tabaci harbors the obli ... | 2011 | 22251681 |
| 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 |
| combining next-generation sequencing strategies for rapid molecular resource development from an invasive aphid species, aphis glycines. | aphids are one of the most important insect taxa in terms of ecology, evolutionary biology, genetics and genomics, and interactions with endosymbionts. additionally, many aphids are serious pest species of agricultural and horticultural plants. recent genetic and genomic research has expanded molecular resources for many aphid species, including the whole genome sequencing of the pea aphid, acrythosiphon pisum. however, the invasive soybean aphid, aphis glycines, lacks in any significant molecul ... | 2010 | 20614011 |
| 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 |
| facultative symbionts in aphids and the horizontal transfer of ecologically important traits. | aphids engage in symbiotic associations with a diverse assemblage of heritable bacteria. in addition to their obligate nutrient-provisioning symbiont, buchnera aphidicola, aphids may also carry one or more facultative symbionts. unlike obligate symbionts, facultative symbionts are not generally required for survival or reproduction and can invade novel hosts, based on both phylogenetic analyses and transfection experiments. facultative symbionts are mutualistic in the context of various ecologic ... | 2010 | 19728837 |
| impact of environmental stress on aphid clonal resistance to parasitoids: role of hamiltonella defensa bacterial symbiosis in association with a new facultative symbiont of the pea aphid. | resistance to endoparasitoids in aphids involves complex interactions between insect and microbial players. it is now generally accepted that the facultative bacterial symbiont hamiltonella defensa of the pea aphid acyrthosiphon pisum is implicated in its resistance to the parasitoid aphidius ervi. it has also been shown that heat negatively affects pea aphid resistance, suggesting the thermosensitivity of its defensive symbiosis. here we examined the effects of heat and uv-b on the resistance o ... | 2009 | 19545573 |
| genotypic variation and the role of defensive endosymbionts in an all-parthenogenetic host-parasitoid interaction. | models of host-parasite coevolution predict pronounced genetic dynamics if resistance and infectivity are genotype-specific or associated with costs, and if selection is fueled by sufficient genetic variation. we addressed these assumptions in the black bean aphid, aphis fabae, and its parasitoid lysiphlebus fabarum. parasitoid genotypes differed in infectivity and host clones exhibited huge variation for susceptibility. this variation occurred at two levels. clones harboring hamiltonella defens ... | 2009 | 19228189 |
| evolutionary genetics of a defensive facultative symbiont of insects: exchange of toxin-encoding bacteriophage. | the facultative endosymbiont of aphids, hamiltonella defensa, kills parasitoid wasp larvae, allowing aphid hosts to survive and reproduce. this protection may depend on toxins that are encoded by the genomes of h. defensa and of its bacteriophage (apse). strains of h. defensa vary in degree of protection conferred upon acyrthosiphon pisum (pea aphid). although h. defensa is known to undergo some horizontal transmission among aphid maternal lineages, divergence, recombination, and population stru ... | 2008 | 18179430 |
| biotype-dependent secondary symbiont communities in sympatric populations of bemisia tabaci. | the sweet potato whitefly, bemisia tabaci, harbors portiera aleyrodidarum, an obligatory symbiotic bacterium, as well as several secondary symbionts including rickettsia, hamiltonella, wolbachia, arsenophonus, cardinium and fritschea, the function of which is unknown. bemisia tabaci is a species complex composed of numerous biotypes, which may differ from each other both genetically and biologically. only the b and q biotypes have been reported from israel. secondary symbiont infection frequenci ... | 2007 | 17645822 |
| costs and benefits of a superinfection of facultative symbionts in aphids. | symbiotic associations between animals and inherited micro-organisms are widespread in nature. in many cases, hosts may be superinfected with multiple inherited symbionts. acyrthosiphon pisum (the pea aphid) may harbour more than one facultative symbiont (called secondary symbionts) in addition to the obligate primary symbiont, buchnera aphidicola. previously we demonstrated that, in a controlled genetic background, a. pisum infected with either serratia symbiotica or hamiltonella defensa (calle ... | 2006 | 16720402 |
| identification and localization of a rickettsia sp. in bemisia tabaci (homoptera: aleyrodidae). | whiteflies (homoptera: aleyrodidae) are sap-sucking insects that harbor "candidatus portiera aleyrodidarum," an obligatory symbiotic bacterium which is housed in a special organ called the bacteriome. these insects are also home for a diverse facultative microbial community which may include hamiltonella, arsenophonus, fritchea, wolbachia, and cardinium spp. in this study, the bacteria associated with a b biotype of the sweet potato whitefly bemisia tabaci were characterized using molecular fing ... | 2006 | 16672513 |
| 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 |
| aphid clonal resistance to a parasitoid fails under heat stress. | parasitoid virulence and host resistance are complex interactions depending on metabolic rate and cellular activity, which in aphids additionally implicate heritable secondary symbionts among the enterobacteriaceae. as performance of the parasitoid, the aphid host and its symbionts may differentially respond to temperature, the success or failure of aphid parasitism is difficult to predict when temperature varies. we tested the hypothesis that resistance of the pea aphid acyrthosiphon pisum to t ... | 2006 | 16307754 |
| rickettsia 'in' and 'out': two different localization patterns of a bacterial symbiont in the same insect species. | intracellular symbionts of arthropods have diverse influences on their hosts, and their functions generally appear to be associated with their localization within the host. the effect of localization pattern on the role of a particular symbiont cannot normally be tested since the localization pattern within hosts is generally invariant. however, in israel, the secondary symbiont rickettsia is unusual in that it presents two distinct localization patterns throughout development and adulthood in i ... | 2011 | 21712994 |
| symbiont diversity and non-random hybridization among indigenous (ms) and invasive (b) biotypes of bemisia tabaci. | the whitefly bemisia tabaci (hemiptera: aleyrodidae) is a worldwide pest and a vector of numerous plant viruses. b. tabaci is composed of dozens of morphologically indistinguishable biotypes and its taxonomic status is still controversial. this phloem-feeder harbours the primary symbiont portiera aleyrodidarum and potentially six secondary symbionts: cardinium, arsenophonus, hamiltonella, rickettsia, wolbachia and fritschea. in the southwest indian ocean, la réunion hosts two biotypes of this sp ... | 2011 | 21476990 |
| further insights into the strange role of bacterial endosymbionts in whitefly, bemisia tabaci: comparison of secondary symbionts from biotypes b and q in china. | the percentage infection of secondary symbionts (ss) (wolbachia, arsenophonus, rickettsia, hamiltonella, fritschea and cardinium) in the exotic bemisia tabaci (genn.) invaders, commonly known as biotypes b and q from china, were determined by pcr. in total, 373 biotype b and 1830 biotype q individuals were screened for the presence of ss. biotype b was more abundant than biotype q from 2005 to 2006, and biotype q was more abundant from 2007 to 2009. each of the ss, with the exception of fritsche ... | 2011 | 21329550 |
| rapid evolution of parasitoids when faced with the symbiont-mediated resistance of their hosts. | insects harbour a wild diversity of symbionts that can spread and persist within populations by providing benefits to their host. the pea aphid acyrthosiphon pisum maintains a facultative symbiosis with the bacterium hamiltonella defensa, which provides enhanced resistance against the aphid parasitoid aphidius ervi. although the mechanisms associated with this symbiotic-mediated protection have been investigated thoroughly, little is known about its evolutionary effects on parasitoid populations ... | 2011 | 21261770 |
| the transmission efficiency of tomato yellow leaf curl virus by the whitefly bemisia tabaci is correlated with the presence of a specific symbiotic bacterium species. | tomato yellow leaf curl virus (tylcv) (geminiviridae: begomovirus) is exclusively vectored by the whitefly bemisia tabaci (gennadius) (hemiptera: aleyrodidae). tylcv transmission depends upon a 63-kda groel protein produced by the vector's endosymbiotic bacteria. b. tabaci is a species complex comprising several genetically distinct biotypes that show different secondary-symbiont fauna. in israel, the b biotype harbors hamiltonella, and the q biotype harbors wolbachia and arsenophonus. both biot ... | 2010 | 20631135 |