Variation of sperm length and heteromorphism in drosophilid species

International audienc

Phenetic distances in the Drosophila melanogaster-subgroup species and oviposition-site preference for food components

Oviposition-site preferences (O.S.P.) have been investigated in females of six sibling species of the Drosophila melanogaster subgroup. O.S.P. were determined for standard food components and yeast genotypes. Females of all species showed a strong preference for complete medium and avoidance of pure agar as an egg-deposition site.\ud \ud Ecological trees of the species on the basis of rank correlations were constructed. In ‘no-choice’ situations they agree with phylogenetic trees obtained by different means but in ‘choice’ situations they do not agree too well.\ud \ud All species showed a high egg production on live yeast compared with standard medium (with killed yeast) and D. erecta females demonstrated discrimination between yeast genotypes. Niche breadth calculated from survival on the sterol mutant yeasts correlated fairly well with phylogenetic trees

Fenhexamid Resistance in the Botrytis Species Complex, Responsible for Grey Mould Disease

International audience1.1 Chemical control of grey mould in French vineyardsThe three major fungal pests of grapevine, powdery and downy mildew and grey mould aremostly controlled through the application of fungicides. Some of those are particularlyactive against the grey mould agent Botrytis cinerea. The panel of fungicides authorized inFrance comprise since many years anilinopyrimidines, benzimidazoles, dithiocarbamates,dicarboximides, phenylpyrroles and pyridinamines. Lately, the panel has been completedby fenhexamid, a sterol biosynthesis inhibitor (SBI) and the pyridine boscalid, a succinatedehydrogenase inhibitor (SDHI). In addition, a biofungicide based on the Bacillus subtilisstrain QST 713 (Serenade) has been authorized in 2010 against grey mould in vineyards. Thecompounds authorized against grey mould in French vineyards are listed in Table 1.Since grey mould may infect grapevine from flowering until harvest, optimal protectionneeds to be obtained during this period. Nowadays up to three treatments per season arerecommended in vineyards, corresponding to the stages A-C (A: flower cap falling – B:bunch closure – C: veraison). To reduce pesticide applications along with the general trendof reduction of chemical inputs in agriculture chemical treatments against grey mould arepositioned according to epidemiological and meteorological parameters. Grey mould notonly affects quantity of harvest but also the wine quality. Therefore, treatments also dependon the economic value of the wine. The number of treatments is variable between regionsand years according to the factors cited above.In those regions with regular applications of anti-Botrytis fungicides, especially in theNorthern regions, resistant strains have been selected which can ultimately lead totreatment failure. In order to reduce the risk of specific resistance development each antiBotrytis mode-of-action is limited to one application/season in France since the 90’s,involving alternations of different chemical families to combat grey mould in the vineyards

Patterns of nucleotide diversity at the regions encompassing the Drosophila insulin-like peptide (dilp) genes: demography vs positive selection in Drosophila melanogaster.

In Drosophila, the insulin-signaling pathway controls some life history traits, such as fertility and lifespan, and it is considered to be the main metabolic pathway involved in establishing adult body size. Several observations concerning variation in body size in the Drosophila genus are suggestive of its adaptive character. Genes encoding proteins in this pathway are, therefore, good candidates to have experienced adaptive changes and to reveal the footprint of positive selection. The Drosophila insulin-like peptides (DILPs) are the ligands that trigger the insulin-signaling cascade. In Drosophila melanogaster, there are several peptides that are structurally similar to the single mammalian insulin peptide. The footprint of recent adaptive changes on nucleotide variation can be unveiled through the analysis of polymorphism and divergence. With this aim, we have surveyed nucleotide sequence variation at the dilp1-7 genes in a natural population of D. melanogaster. The comparison of polymorphism in D. melanogaster and divergence from D. simulans at different functional classes of the dilp genes provided no evidence of adaptive protein evolution after the split of the D. melanogaster and D. simulans lineages. However, our survey of polymorphism at the dilp gene regions of D. melanogaster has provided some evidence for the action of positive selection at or near these genes. The regions encompassing the dilp1-4 genes and the dilp6 gene stand out as likely affected by recent adaptive events