Search results for "Facultative"
showing 9 items of 29 documents
Vector Transmission of a Plant-Pathogenic Bacterium in the Arsenophonus Clade Sharing Ecological Traits with Facultative Insect Endosymbionts
2009
Bressan, A., Semetey, O., Arneodo, J., Lherminier, J., and BoudonPadieu, E. 2009. Vector transmission of a plant-pathogenic bacterium in the Arsenophonus clade sharing ecological traits with facultative insect endosymbionts. Phytopathology 99:1289-1296. The planthopper Pentastiridius leporinus (Hemiptera: Cixiidae) is the major vector of a nonculturable plant-pathogenic γ-3 proteobacterium associated with a disease of sugar beet called syndrome “basses richesses” (SBR). The bacterium, here called SBR bacterium, belongs to the Arsenophonous clade, which includes mostly insect-associated facultative symbionts. Assays using field-collected planthopper nymphs and adults were carried out to inve…
Epibiont communities of loggerhead marine turtles (Caretta caretta) in the western Mediterranean: influence of geographic and ecological factors
2014
This study reports for the first time on the whole epibiont fauna of loggerhead marine turtles,Caretta caretta, in the western Mediterranean, analysing the factors that account for the predictability and composition of the assemblage. A total of 104 loggerhead turtles stranded along the coasts of eastern Spain during 1995–2006 were surveyed for epibionts. A total of 39 epibiont taxa were identified, three of them being new records for loggerhead turtles:Bittiumsp.,Idotea metallicaandJassasp. The assemblage was composed of a group of 27 facultative taxa that use turtles as any inanimate buoyant substrate, and 12 taxa that have developed more specific associations to marine turtles, including…
Side-stepping secondary symbionts: widespread horizontal transfer across and beyond the Aphidoidea.
2003
To elucidate the co-evolutionary relationships between phloem-feeding insects and their secondary, or facultative, bacterial symbionts, we explore the distributions of three such microbes--provisionally named the R-type (or PASS, or S-sym), T-type (or PABS), and U-type--across a number of aphid and psyllid hosts through the use of diagnostic molecular screening techniques and DNA sequencing. Although typically maternally transmitted, phylogenetic and pairwise divergence analyses reveal that these bacteria have been independently acquired by a variety of unrelated insect hosts, indicating that horizontal transfer has helped to shape their distributions. Based on the high genetic similarity b…
Settling Down: The Genome of Serratia symbiotica from the Aphid Cinara tujafilina Zooms in on the Process of Accommodation to a Cooperative Intracell…
2014
Particularly interesting cases of mutualistic endosymbioses come from the establishment of co-obligate associations of more than one species of endosymbiotic bacteria. Throughout symbiotic accommodation from a free-living bacterium, passing through a facultative stage and ending as an obligate intracellular one, the symbiont experiences massive genomic losses and phenotypic adjustments. Here, we scrutinized the changes in the coevolution of Serratia symbiotica and Buchnera aphidicola endosymbionts in aphids, paying particular attention to the transformations undergone by S. symbiotica to become an obligate endosymbiont. Although it is already known that S. symbiotica is facultative in Acyrt…
The Genome of Cardinium cBtQ1 Provides Insights into Genome Reduction, Symbiont Motility, and Its Settlement in Bemisia tabaci
2014
International audience; Many insects harbor inherited bacterial endosymbionts. Although some of them are not strictly essential and are considered facultative, they can be a key to host survival under specific environmental conditions, such as parasitoid attacks, climate changes, or insecticide pressures. The whitefly Bemisia tabaci is at the top of the list of organisms inflicting agricultural damage and outbreaks, and changes in its distribution may be associated to global warming. In this work, we have sequenced and analyzed the genome of Cardinium cBtQ1, a facultative bacterial endosymbiont of B. tabaci and propose that it belongs to a new taxonomic family, which also includes Candidatu…
Interspecific extrinsic and intrinsic competitive interactions in egg parasitoids
2012
Interspecific competitive interactions can occur either between adult parasitoids searching/exploiting hosts (extrinsic competition) or between parasitoid larvae developing within the same host (intrinsic competition). Understanding how interspecific competition between parasitoids can affect pest suppression is important for improving biological pest control. The purpose of this work was to review both extrinsic and intrinsic competition between egg parasitoid species. These are organisms that are often candidates for biological control programs due to their ability to kill the pest before the crop feeding stage. We first reviewed the literature about interspecific competitive abilities of…
Landscape and anti-predation determinants of nest-site selection, nest distribution and productivity in a Mediterranean population of Long-eared Owls…
2006
Nest predation is an important determinant of owl breeding success. We studied Long-eared Owl Asio otus productivity and attributes of nest-sites at the microhabitat and landscape scales in a Mediterranean locality over an 8-year period. We examined the effect on nest location and productivity of protective cover in concealing the nest from aerial and terrestrial predators. A dense cover of ivy and tree-foliage at canopy level favoured nest location but not productivity. By contrast, high shrub cover beneath the nest was selected by Owls and was positively related to both the site reoccupancy rate and the overall number of young fledged. Pre-fledging Owls use the ground, where they are expo…
Intraguild interactions between egg parasitoids: window of opportunity and fitness costs for a facultative hyperparasitoid.
2013
We investigated intraguild interactions between two egg parasitoids of Nezara viridula (L.) (Heteroptera: Pentatomidae), Ooencyrtus telenomicida (Vassiliev) (Hymenoptera: Encyrtidae) and Trissolcus basalis (Wollaston) (Hymenoptera: Platygastridae), as the former has the potential to be a facultative hyperparasitoid of the latter. We assessed the suitability of N. viridula eggs for the development of O. telenomicida as a function of egg age when they were unparasitized, or had been attacked by T. basalis at different times prior to exposure to O. telenomicida females. Ooencyrtus telenomicida can exploit healthy N. viridula host eggs up to 5 days of age, just prior to the emergence of N. viri…
Sex Allocation Theory for Facultatively Sexual Organisms Inhabiting Seasonal Environments: The Importance of Bet Hedging
2018
Adaptive explanations for dormancy often invoke bet hedging, where reduced mean fitness can be adaptive if it associates with reduced fitness variance. Sex allocation theory typically ignores variance effects and focuses on mean fitness. For many cyclical parthenogens, these themes become linked, as only sexually produced eggs undergo the dormancy needed to survive harsh conditions. We ask how sex allocation and the timing of sex evolve when this constraint exists in the form of a trade-off between asexual reproduction and sexual production of dormant eggs—the former being crucial for within-season success and the latter for survival across seasons. We show that male production can be tempo…