scholarly journals Elucidation of the Transmission Patterns of an Insect-Borne Bacterium

2003 ◽  
Vol 69 (8) ◽  
pp. 4403-4407 ◽  
Author(s):  
A. C. Darby ◽  
A. E. Douglas
Keyword(s):  
Vertical Transmission ◽  
Acyrthosiphon Pisum ◽  
Deterministic Model ◽  
Transmission Rate ◽  
Horizontal Transmission ◽  
Natural Populations ◽  
Oral Route ◽  
Pea Aphid ◽  
Diagnostic Pcr ◽  
Modes Of Transmission

ABSTRACT Quantitative data on modes of transmission are a crucial element in understanding the ecology of microorganisms associated with animals. We investigated the transmission patterns of a γ-proteobacterium informally known as pea aphid Bemisia-like symbiont (PABS), also known as T-type, which is widely but not universally distributed in natural populations of the pea aphid, Acyrthosiphon pisum. The vertical transmission of PABS to asexual and sexual morphs and sexually produced eggs was demonstrated by a diagnostic PCR-based assay, and the maximum estimated failure rate was 2%. Aphids naturally lacking PABS acquired PABS bacteria administered via the diet, and the infection persisted by vertical transmission for at least three aphid generations. PABS was also detected in two of five aphid honeydew samples tested and in all five siphuncular fluid samples tested but in none of 15 samples of salivary secretions from PABS-positive aphids. However, PABS-negative aphids did not acquire PABS when they were cocultured with PABS-positive aphids; the maximal estimated level of horizontal transmission was 18%. A deterministic model indicated that the force of infection by a horizontal transmission rate of 3% is sufficient to maintain a previously described estimate of the prevalence of PABS-positive aphids (37%), if the vertical transmission rate is 98%. We concluded that PABS infections in A. pisum can be maintained by high vertical transmission rates and occasional horizontal transmission, possibly via the oral route, in the absence of selection either for or against aphids bearing this bacterium.

scholarly journals Simulated folivory increases vertical transmission of fungal endophytes that deter herbivores and alter tolerance to herbivory in Poa autumnalis

2020 ◽  
Vol 125 (6) ◽  
pp. 981-991 ◽  
Author(s):  
Pedro E Gundel ◽  
Prudence Sun ◽  
Nikki D Charlton ◽  
Carolyn A Young ◽  
Tom E X Miller ◽  
...  
Keyword(s):  
Vertical Transmission ◽  
Transmission Rate ◽  
Horizontal Transmission ◽  
Fungal Endophytes ◽  
Natural Populations ◽  
Plant Tolerance ◽  
Hyphal Density ◽  
Symbiotic Fungi ◽  
Symbiont Transmission ◽  
Fitness Benefits

Abstract Background and Aims The processes that maintain variation in the prevalence of symbioses within host populations are not well understood. While the fitness benefits of symbiosis have clearly been shown to drive changes in symbiont prevalence, the rate of transmission has been less well studied. Many grasses host symbiotic fungi (Epichloë spp.), which can be transmitted vertically to seeds or horizontally via spores. These symbionts may protect plants against herbivores by producing alkaloids or by increasing tolerance to damage. Therefore, herbivory may be a key ecological factor that alters symbiont prevalence within host populations by affecting either symbiont benefits to host fitness or the symbiont transmission rate. Here, we addressed the following questions: Does symbiont presence modulate plant tolerance to herbivory? Does folivory increase symbiont vertical transmission to seeds or hyphal density in seedlings? Do plants with symbiont horizontal transmission have lower rates of vertical transmission than plants lacking horizontal transmission? Methods We studied the grass Poa autumnalis and its symbiotic fungi in the genus Epichloë. We measured plant fitness (survival, growth, reproduction) and symbiont transmission to seeds following simulated folivory in a 3-year common garden experiment and surveyed natural populations that varied in mode of symbiont transmission. Key Results Poa autumnalis hosted two Epichloë taxa, an undescribed vertically transmitted Epichloë sp. PauTG-1 and E. typhina subsp. poae with both vertical and horizontal transmission. Simulated folivory reduced plant survival, but endophyte presence increased tolerance to damage and boosted fitness. Folivory increased vertical transmission and hyphal density within seedlings, suggesting induced protection for progeny of damaged plants. Across natural populations, the prevalence of vertical transmission did not correlate with symbiont prevalence or differ with mode of transmission. Conclusions Herbivory not only mediated the reproductive fitness benefits of symbiosis, but also promoted symbiosis prevalence by increasing vertical transmission of the fungus to the next generation. Our results reveal a new mechanism by which herbivores could influence the prevalence of microbial symbionts in host populations.

scholarly journals Intraspecific variation in symbiont density in an insect-microbe symbiosis

2020 ◽  
Author(s):  
Benjamin J. Parker ◽  
Jan Hrček ◽  
Ailsa H.C. McLean ◽  
Jennifer A. Brisson ◽  
H. Charles J. Godfray
Keyword(s):  
Intraspecific Variation ◽  
Fungal Pathogens ◽  
Acyrthosiphon Pisum ◽  
Natural Populations ◽  
Pea Aphid ◽  
Optimal Density ◽  
Evolutionary Forces ◽  
Standing Variation ◽  
Dramatic Decline

AbstractMany insects host vertically-transmitted microbes, which can confer benefits to their hosts but are costly to maintain and regulate. A key feature of these symbioses is variation: for example, symbiont density can vary among host and symbiont genotypes. However, the evolutionary forces maintaining this variation remain unclear. We studied variation in symbiont density using the pea aphid (Acyrthosiphon pisum) and the bacterium Regiella insecticola, a symbiont that can protect its host against fungal pathogens. We found that relative symbiont density varies both between two Regiella phylogenetic clades and among aphid ‘biotypes’. Higher-density symbiont infections are correlated with stronger survival costs, but variation in density has little effect on the protection Regiella provides against fungus. Instead, we found that in some aphid genotypes, a dramatic decline in symbiont density precedes the loss of a symbiont infection. Together, our data suggest that the optimal density of a symbiont infection is likely different from the perspective of aphid and microbial fitness. Regiella might prevent loss by maintaining high within-host densities, but hosts do not appear to benefit from higher symbiont numbers and may be advantaged by losing costly symbionts in certain environments. The standing variation in symbiont density observed in natural populations could therefore be maintained by antagonistic coevolutionary interactions between hosts and their symbiotic microbes.

scholarly journals Context-dependent vertical transmission shapes strong endosymbiont community structure in the pea aphid, Acyrthosiphon pisum

2017 ◽  
Vol 27 (8) ◽  
pp. 2039-2056 ◽  
Author(s):  
Danielle I. Rock ◽  
Andrew H. Smith ◽  
Jonah Joffe ◽  
Amie Albertus ◽  
Narayan Wong ◽  
...  
Keyword(s):  
Community Structure ◽  
Vertical Transmission ◽  
Acyrthosiphon Pisum ◽  
Pea Aphid ◽  
Context Dependent

scholarly journals Spiroplasma Symbiont of the Pea Aphid, Acyrthosiphon pisum (Insecta: Homoptera)

2001 ◽  
Vol 67 (3) ◽  
pp. 1284-1291 ◽  
Author(s):  
Takema Fukatsu ◽  
Tsutomu Tsuchida ◽  
Naruo Nikoh ◽  
Ryuichi Koga
Keyword(s):  
Acyrthosiphon Pisum ◽  
Natural Populations ◽  
Laboratory Strain ◽  
Pea Aphid ◽  
Endosymbiotic Bacterium ◽  
Negative Effects ◽  
Central Japan ◽  
16S Ribosomal Dna ◽  
Molecular Phylogenetic ◽  
Successive Generations

ABSTRACT From a laboratory strain of the pea aphid, Acyrthosiphon pisum, we discovered a previously unknown facultative endosymbiotic bacterium. Molecular phylogenetic analysis based on 16S ribosomal DNA revealed that the bacterium is a member of the genusSpiroplasma. The Spiroplasma organism showed stable vertical transmission through successive generations of the host. Injection of hemolymph from infected insects into uninfected insects established a stable infection in the recipients. TheSpiroplasma symbiont exhibited negative effects on growth, reproduction, and longevity of the host, particularly in older adults. Of 58 clonal strains of A. pisum established from natural populations in central Japan, 4 strains possessed theSpiroplasma organism.

scholarly journals Rickettsia Symbiont in the Pea Aphid Acyrthosiphon pisum: Novel Cellular Tropism, Effect on Host Fitness, and Interaction with the Essential Symbiont Buchnera

2005 ◽  
Vol 71 (7) ◽  
pp. 4069-4075 ◽  
Author(s):  
Makiko Sakurai ◽  
Ryuichi Koga ◽  
Tsutomu Tsuchida ◽  
Xian-Ying Meng ◽  
Takema Fukatsu
Keyword(s):  
Acyrthosiphon Pisum ◽  
Natural Populations ◽  
Pea Aphid ◽  
Host Cells ◽  
Pcr Analysis ◽  
Bacterial Cells ◽  
Host Fitness ◽  
Host Aphid ◽  
Sheath Cells

ABSTRACT In natural populations of the pea aphid Acyrthosiphon pisum, a facultative bacterial symbiont of the genus Rickettsia has been detected at considerable infection frequencies worldwide. We investigated the effects of the Rickettsia symbiont on the host aphid and also on the coexisting essential symbiont Buchnera. In situ hybridization revealed that the Rickettsia symbiont was specifically localized in two types of host cells specialized for endosymbiosis: secondary mycetocytes and sheath cells. Electron microscopy identified bacterial rods, about 2 μm long and 0.5 μm thick, in sheath cells of Rickettsia-infected aphids. Virus-like particles were sometimes observed in association with the bacterial cells. By an antibiotic treatment, we generated Rickettsia-infected and Rickettsia-eliminated aphid strains with an identical genetic background. Comparison of these strains revealed that Rickettsia infection negatively affected some components of the host fitness. Quantitative PCR analysis of the bacterial population dynamics identified a remarkable interaction between the coexisting symbionts: Buchnera population was significantly suppressed in the presence of Rickettsia, particularly at the young adult stage, when the aphid most actively reproduces. On the basis of these results, we discussed the possible mechanisms that enable the prevalence of Rickettsia infection in natural host populations in spite of the negative fitness effects observed in the laboratory.

scholarly journals Vertical transmission of zika virus in Aedes albopictus

2020 ◽  
Vol 14 (10) ◽  
pp. e0008776
Author(s):  
Zetian Lai ◽  
Tengfei Zhou ◽  
Jiayong Zhou ◽  
Shuang Liu ◽  
Ye Xu ◽  
...  
Keyword(s):  
Vertical Transmission ◽  
Aedes Albopictus ◽  
Reverse Transcription ◽  
Zika Virus ◽  
Transmission Rate ◽  
Horizontal Transmission ◽  
Infection Rates ◽  
Transmission Rates ◽  
Suckling Mice ◽  
Reverse Transcription Pcr

Background Zika virus (ZIKV) is an arthropod-borne flavivirus transmitted by Aedes mosquitoes. Aedes albopictus is an important vector of ZIKV worldwide. To date, most experiments have focused on the vertical transmission of ZIKV in Ae. aegypti, while studies on Ae. albopictus are very limited. To explore vertical transmission in Ae. albopictus, a series of laboratory studies were carried out. Methodology/Principal findings In this study, Ae. albopictus were blood-fed with ZIKV-infectious blood, and the ovaries and offspring viral infection rates were analyzed by reverse transcription PCR (RT-PCR), real-time reverse transcription PCR (RT-qPCR) and immunohistochemistry (IHC). ZIKV was detected in the ovaries and oviposited eggs in two gonotrophic cycles. The minimum filial egg infection rates in two gonotrophic cycles were 2.06% and 0.69%, and the effective population transmission rate was 1.87%. The hatching, pupation, and emergence rates of infected offspring were not significantly different from those of uninfected offspring, indicating that ZIKV did not prevent the offspring from completing the growth and development process. ZIKV was detected in three of thirteen C57BL/6 suckling mice bitten by ZIKV-positive F1 females, and the viremia persisted for at least seven days. Conclusions/Significance ZIKV can be vertically transmitted in Ae. albopictus via transovarial transmission. The vertical transmission rates in F1 eggs and adults were 2.06% and 1.87%, respectively. Even though the vertical transmission rates were low, the female mosquitoes infected via the congenital route horizontally transmitted ZIKV to suckling mice through bloodsucking. This is the first experimental evidence of offspring with vertically transmitted ZIKV initiating new horizontal transmission. The present study deepens the understanding of the vertical transmission of flaviviruses in Aedes mosquitoes and sheds light on the prevention and control of mosquito-borne diseases.

scholarly journals Unravelling the genomic basis and evolution of the pea aphid male wing dimorphism

2017 ◽  
Author(s):  
Binshuang Li ◽  
Ryan D. Bickel ◽  
Benjamin J. Parker ◽  
Neetha Nanoth Vellichirammal ◽  
Mary Grantham ◽  
...  
Keyword(s):  
Complex Traits ◽  
Acyrthosiphon Pisum ◽  
Natural Populations ◽  
Pea Aphid ◽  
Specific Gene ◽  
Regulatory Change ◽  
Wing Dimorphism ◽  
Wing Polymorphism ◽  
Male Wing ◽  
Mechanistic Basis

SummaryWing dimorphisms have long served as models for examining the ecological and evolutionary tradeoffs associated with alternative morphologies [1], yet the mechanistic basis of morph determination remains largely unknown. Here we investigate the genetic basis of the pea aphid (Acyrthosiphon pisum) wing dimorphism, wherein males exhibit one of two alternative morphologies that differ dramatically in a set of correlated traits that inclused the presence or absence of wings [2-4]. Unlike the environmentally-induced asexual female aphid wing polyphenism [5], the male wing polymorphism is genetically determined by a single uncharacterized locus on the X chromosome called aphicarus (“aphid” plus “Icarus”, api) [6, 7]. Using recombination and association mapping, we localized api to a 130kb region of the pea aphid genome. No nonsynonymous variation in coding sequences strongly associated with the winged and wingless phenotypes, indicating that api is likely a regulatory change. Gene expression level profiling revealed an aphid-specific gene from the region expressed at higher levels in winged male embryos, coinciding with the expected stage of api action. Comparison of the api region across biotypes (pea aphid populations specialized to different host plants that began diverging ~16,000 years ago [8, 9]) revealed that the two alleles were likely present prior to biotype diversification. Moreover, we find evidence for a recent selective sweep of a wingless allele since the biotypes diversified. In sum, this study provides insight into how adaptive, complex traits evolve within and across natural populations.

Diversity and geographic distribution of secondary endosymbiotic bacteria in natural populations of the pea aphid, Acyrthosiphon pisum

2002 ◽  
Vol 11 (10) ◽  
pp. 2123-2135 ◽  
Author(s):  
Tsutomu Tsuchida ◽  
Ryuichi Koga ◽  
Harunobu Shibao ◽  
Tadao Matsumoto ◽  
Takema Fukatsu
Keyword(s):  
Geographic Distribution ◽  
Acyrthosiphon Pisum ◽  
Natural Populations ◽  
Pea Aphid ◽  
Endosymbiotic Bacteria

scholarly journals Infection Patterns and Fitness Effects of Rickettsia and Sodalis Symbionts in the Green Lacewing Chrysoperla carnea

Insects ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 867
Author(s):  
Rebekka Sontowski ◽  
Michael Gerth ◽  
Sandy Richter ◽  
Axel Gruppe ◽  
Martin Schlegel ◽  
...  
Keyword(s):  
Pest Control ◽  
Transmission Rate ◽  
Natural Populations ◽  
Chrysoperla Carnea ◽  
Green Lacewing ◽  
Biological Pest Control ◽  
Diagnostic Pcr ◽  
Vertical Transmission Rate ◽  
Laboratory Populations ◽  
Ecological Importance

Endosymbionts are widely distributed in insects and can strongly affect their host ecology. The common green lacewing (Chrysoperla carnea) is a neuropteran insect which is widely used in biological pest control. However, their endosymbionts and their interactions with their hosts have not been very well studied. Therefore, we screened for endosymbionts in natural and laboratory populations of Ch. carnea using diagnostic PCR amplicons. We found the endosymbiont Rickettsia to be very common in all screened natural and laboratory populations, while a hitherto uncharacterized Sodalis strain was found only in laboratory populations. By establishing lacewing lines with no, single or co-infections of Sodalis and Rickettsia, we found a high vertical transmission rate for both endosymbionts (>89%). However, we were only able to estimate these numbers for co-infected lacewings. Sodalis negatively affected the reproductive success in single and co-infected Ch. carnea, while Rickettsia showed no effect. We hypothesize that the fitness costs accrued by Sodalis infections might be more tolerable in the laboratory than in natural populations, as the latter are also prone to fluctuating environmental conditions and natural enemies. The economic and ecological importance of lacewings in biological pest control warrants a more profound understanding of its biology, which might be influenced by symbionts.

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