Search results for "Aphids"
showing 10 items of 74 documents
Comparative Genomics of Serratia spp.: Two Paths towards Endosymbiotic Life
2012
Symbiosis is a widespread phenomenon in nature, in which insects show a great number of these associations. Buchnera aphidicola, the obligate endosymbiont of aphids, coexists in some species with another intracellular bacterium, Serratia symbiotica. Of particular interest is the case of the cedar aphid Cinara cedri, where B. aphidicola BCc and S. symbiotica SCc need each other to fulfil their symbiotic role with the insect. Moreover, various features seem to indicate that S. symbiotica SCc is closer to an obligate endosymbiont than to other facultative S. symbiotica, such as the one described for the aphid Acirthosyphon pisum (S. symbiotica SAp). This work is based on the comparative genomi…
Two Host Clades, Two Bacterial Arsenals: Evolution through Gene Losses in Facultative Endosymbionts.
2015
International audience; Bacterial endosymbiosis is an important evolutionary process in insects, which can harbor both obligate and facultative symbionts. The evolution of these symbionts is driven by evolutionary convergence, and they exhibit among the tiniest genomes in prokaryotes. The large host spectrum of facultative symbionts and the high diversity of strategies they use to infect new hosts probably impact the evolution of their genome and explain why they undergo less severe genomic erosion than obligate symbionts. Candidatus Hamiltonella defensa is suitable for the investigation of the genomic evolution of facultative symbionts because the bacteria are engaged in specific relations…
The evolution of the heat-shock protein GroEL from Buchnera, the primary endosymbiont of aphids, is governed by positive selection
2002
The heat-shock protein GroEL is a double-ring-structured chaperonin that assists the folding of many newly synthesized proteins in Escherichia coli and the refolding in vitro, with the cochaperonin GroES, of conformationally damaged proteins. This protein is constitutively overexpressed in the primary symbiotic bacteria of many insects, constituting approximately 10% of the total protein in Buchnera, the primary endosymbiont of aphids. In the present study, we perform a maximum likelihood (ML) analysis to unveil the selective constraints in GroEL. In addition, we apply a new statistical approach to determine the patterns of evolution in this highly interesting protein. The main conclusion d…
Neonicotinoids from coated seeds toxic for honeydew-feeding biological control agents
2021
Seed coating (‘seed treatment’) is the leading delivery method of neonicotinoid insecticides in major crops such as soybean, wheat, cotton and maize. However, this prophylactic use of neonicotinoids is widely discussed from the standpoint of environmental costs. Growing soybean plants from neonicotinoid-coated seeds in field, we demonstrate that soybean aphids (Aphis glycines) survived the treatment, and excreted honeydew containing neonicotinoids. Biochemical analyses demonstrated that honeydew excreted by the soybean aphid contained substantial concentrations of neonicotinoids even one month after sowing of the crop. Consuming this honeydew reduced the longevity of two biological control …
Ein Beitrag zur Kenntnis der Aphidenfauna Lettlands
1928
Izvilkums no: Latvijas Universitātes raksti = Acta Universitatis Latviensis XVIII, 1928.
Structure and evolution of the leucine plasmids carried by the endosymbiont (Buchnera aphidicola) from aphids of the family Aphididae.
1998
In all examined species of the family Aphididae, the bacterial endosymbiont Buchnera aphidicola carries a plasmid encoding the genes leuABCD (involved in leucine biosynthesis) along with repA1, repA2 and ORF1. The gene organisation of the leucine plasmids was conserved, except in Buchnera isolated from Pterocomma populeum, where ORF1 was located in a different position. An inverted repeat (LIR1) located between repA2 and leuA is found in all of the Buchnera leucine plasmids examined. The predicted secondary structure of the LIR1 transcript conforms to a long hairpin loop, suggesting an involvement in transcription termination or messenger stability. Phylogenetic reconstruction based on repA…
Insulin-like peptides involved in photoperiodism in the aphid Acyrthosiphon pisum
2019
Aphids were the first animals reported as photoperiodic as their life cycles are strongly determined by the photoperiod. During the favourable seasons (characterised by long days) aphid populations consist exclusively of viviparous parthenogenetic females (known as virginoparae). Shortening of the photoperiod in autumn is perceived by aphids as the signal that anticipates the harsh season, leading to a switch in the reproductive mode giving place to the sexual morphs (oviparae females and males) that mate and lay winter-resistant (diapause-like) eggs. The molecular and cellular basis governing the switch between the two reproductive modes are far from being understood. Classical experiments…
Virgins in the wild: mating status affects the behavior of a parasitoid foraging in the field
2008
In haplodiploid organisms, virgin females can produce offspring, albeit only sons. They may therefore face a trade-off between either: (1) searching for hosts and producing sons immediately; or (2) searching for mates and perhaps producing both sons and daughters later in life. Although this trade-off raises a theoretical interest, it has not been approached experimentally. The objective of this article is thus to document the effect of mating status on the foraging behavior of a haplodiploid parasitoid. For this, we recorded the behavior of virgin and mated female Lysiphlebus testaceipes (Hymenoptera: Braconidae) after being released, in the field, on a colony of their aphid hosts. Half of…
Seasonal photoperiodism regulates the expression of cuticular and signalling protein genes in the pea aphid
2007
International audience; Seasonal photoperiodism in aphids is responsible for the spectacular switch from asexual to sexual reproduction. However, little is known on the molecular and physiological mechanisms involved in reproductive mode shift through the action of day length. Earlier works showed that aphid head, but not eyes, directly perceives the photoperiodic signal through the cuticle. In order to identify genes regulating the photoperiodic response, a 3321 cDNA microarray developed for the pea aphid, Acyrthosiphon pisum was used to compare RNA populations extracted from heads of short- and long-day reared aphids. Microarray analyses revealed that 59 different transcripts were signifi…
The Striking Case of Tryptophan Provision in the Cedar Aphid Cinara cedri
2008
ABSTRACT Buchnera aphidicola BCc has lost its symbiotic role as the tryptophan supplier to the aphid Cinara cedri . We report the presence of a plasmid in this endosymbiont that contains the trpEG genes. The remaining genes for the pathway ( trpDCBA ) are located on the chromosome of the secondary endosymbiont “ Candidatus Serratia symbiotica.” Thus, we propose that a symbiotic consortium is necessary to provide tryptophan.