Assessment of pesticide susceptibility for Typhlodromus exhilaratus and Typhlodromus phialatus strains (Acari: Phytoseiidae) from vineyards in the south of France.

Two species of Phytoseiidae predominated in and around vineyards in an experimental site in the south of France: Typhlodromus exhilaratus is the dominant species on grapes, whereas T. phialatus occurs in the uncultivated areas surrounding these crops. To help understand their distribution, this study aims to determine their susceptibility to a fungicide (dimethomorph + mancozeb) and an insecticide (chlorpyriphos-ethyl), which have been widely used at the experimental site for at least four years.

Linking demography and host dispersal to Trichuris arvicolae distribution in a cyclic vole species.

Spatial structure in the distribution of pathogen infection can influence both epidemiology and host-parasite coevolutionary processes. It may result from the spatial heterogeneity of intrinsic and extrinsic factors, or from the local population dynamics of hosts and parasites. In this study, we investigated the effects of landscape, host dispersal and demography (population abundance and phase of the fluctuation) on the distribution of a gastro-intestinal nematode Trichuris arvicolae in the fossorial water vole Arvicola terrestris sherman.

Defining the limits of taxonomic conservatism in host-plant use for phytophagous insects: molecular systematics and evolution of host-plant associations in the seed-beetle genus Bruchus Linnaeus (Coleoptera: Chrysomelidae: Bruchinae).

In this study, we have investigated the limits of taxonomic conservatism in host-plant use in the seed-beetle genus Bruchus. To reconstruct the insect phylogeny, parsimony and multiple partitioned Bayesian inference analyses were conducted on a combined data set of four genes. Permutation tests and both global and local maximum-likelihood optimizations of host preferences at distinct taxonomic levels revealed that host-fidelity is still discernible beyond the host-plant tribe level, suggesting the existence of more important than previously thought evolutionary constraints, which are further discussed in details.

Microsatellite null alleles and estimation of population differentiation.

Microsatellite null alleles are commonly encountered in population genetics studies, yet little is known about their impact on the estimation of population differentiation. Computer simulations based on the coalescent were used to investigate the evolutionary dynamics of null alleles, their impact on F(ST) and genetic distances, and the efficiency of estimators of null allele frequency. Further, we explored how the existing method for correcting genotype data for null alleles performed in estimating F(ST) and genetic distances, and we compared this method with a new method proposed here (for F(ST) only).

Phylogeny of the genus Aphis Linnaeus, 1758 (Homoptera: Aphididae) inferred from mitochondrial DNA sequences.

Aphis is the largest aphid genus in the world and contains several of the most injurious aphid pests. It is also the most reluctant aphid genus to any comprehensive taxonomic treatment: while most species are easily classified into "species groups" that form well defined entities, numerous species within these groups are difficult to tell apart morphologically and identification keys remain ambiguous and mostly rely on host plant affiliation. In this paper, we used partial sequences of COI/COII and CytB genes to reconstruct the first phylogeny of Aphis and discuss the present systematics.

Host ecology and variation in helminth community structure in Mastomys rodents from Senegal.

We studied patterns of variation in parasite communities of 2 closely related species of Mastomys rodents. These 2 species live in sympatry in South-eastern Senegal, but differ drastically in their habitat choice. We asked (a) whether the host species have the same parasites; (b) whether there is any observable pattern relative to the host species/habitat type in the structure of parasite communities; (c) whether the variability in parasite community for each host species is related to habitat characteristics.

Rare sexual reproduction events in the clonal reproduction system of introduced populations of the little fire ant.

A unique reproductive system has previously been described in Wasmannia auropunctata, a widespread invasive ant species, where males are produced clonally, female queens are parthenogens, and female workers are produced sexually. However, these findings were mostly based on samples originating from only a limited part of the native range of the species in South America. We used microsatellite markers to uncover the reproductive modes displayed by a large number of nests collected in various invasive W.

Immunocompetence does not correlate with resistance to helminth parasites in house mouse subspecies and their hybrids.

A central point not yet elucidated in immuno-ecological studies is whether the different ways to assess the immune status of individuals are good indicators of parasite resistance of the host. We investigate the relationship between immunocompetence and the resistance/susceptibility phenotype of five strains of two European subspecies of the house mouse and their hybrids derived from natural populations. The assessment of immunocompetence was measured indirectly by the mass of the spleen and directly by the phytohaemagglutinin (PHA) test.

A note on the accuracy of PAC-likelihood inference with microsatellite data.

Stephens and Donnelly have introduced a simple yet powerful importance sampling scheme for computing the likelihood in population genetic models. Fundamental to the method is an approximation to the conditional probability of the allelic type of an additional gene, given those currently in the sample. As noted by Li and Stephens, the product of these conditional probabilities for a sequence of draws that gives the frequency of allelic types in a sample is an approximation to the likelihood, and can be used directly in inference.

Migration and recovery of the genetic diversity during the increasing density phase in cyclic vole populations.

In cyclic populations, high genetic diversity is currently reported despite the periodic low numbers experienced by the populations during the low phases. Here, we report spatio-temporal monitoring at a very fine scale of cyclic populations of the fossorial water vole (Arvicola terrestris) during the increasing density phase. This phase marks the transition from a patchy structure (demes) during low density to a continuous population in high density.

A new nematode (Nematoda: Cosmocercidae) from the lizard, Chamaeleo inturensis (Squamata: Chamaeleonidae) from the Democratic Republic of Congo.

Maracaya africana n. sp. (Nematoda: Cosmocercidae) from the large intestine of the lizard Chamaeleo inturensis collected in Democratic Republic of Congo is described and illustrated.

Resistance evolution to Bt crops: predispersal mating of European corn borers.

Over the past decade, the high-dose refuge (HDR) strategy, aimed at delaying the evolution of pest resistance to Bacillus thuringiensis (Bt) toxins produced by transgenic crops, became mandatory in the United States and is being discussed for Europe. However, precopulatory dispersal and the mating rate between resident and immigrant individuals, two features influencing the efficiency of this strategy, have seldom been quantified in pests targeted by these toxins. We combined mark-recapture and biogeochemical marking over three breeding seasons to quantify these features directly in natural populations of Ostrinia nubilalis, a major lepidopteran corn pest.

Influence of geographical scale on the detection of density dependence in the host-parasite system, Arvicola terrestris and Taenia taeniaeformis.

Infection by the cestode Taenia taeniaeformis was investigated within numerous cyclic populations of the fossorial water vole Arvicola terrestris sampled during 4 years in Franche-Comté (France). The relative influence of different rodent demographic parameters on the presence of this cestode was assessed by considering (1) the demographic phase of the cycle; (2) density at the local geographical scale (<0.1 km2); (3) mean density at a larger scale (>10 km2).

Inference on microsatellite mutation processes in the invasive mite, Varroa destructor, using reversible jump Markov chain Monte Carlo.

Varroa destructor is a parasitic mite of the Eastern honeybee Apis cerana. Fifty years ago, two distinct evolutionary lineages (Korean and Japanese) invaded the Western honeybee Apis mellifera. This haplo-diploid parasite species reproduces mainly through brother-sister matings, a system which largely favors the fixation of new mutations.

Introgression in natural populations of bioindicators: a case study of Carabus splendens and Carabus punctatoauratus.

The evolutionary importance of hybridization in wild plants and animals has become increasingly widely recognized in the last decade. In practical terms, hybridization provides an exceptionally tough set of problems for conservation biologists. We illustrate this in a case study of two Carabidae species widely used to evaluate the impact of human activities on biodiversity.

A long-term genetic survey of an ungulate population reveals balancing selection acting on MHC through spatial and temporal fluctuations in selection.

We explored a 13-year genetic survey of the major histocompatibility complex (MHC) and neutral loci of the Soay sheep population of St Kilda to test the existence and causes of balancing selection at the MHC. The sheep population experiences demographic fluctuations, partly driven by the nematode Teladorsagia circumcincta. The spatial differentiation detected at the MHC was comparable to that at neutral loci between 1988 and 1996, but significantly lower between 1996 and 2000.

Genetic structure of the cyclic fossorial water vole (Arvicola terrestris): landscape and demographic influences.

Genetic structure can be strongly affected by landscape features and variation through time and space of demographic parameters such as population size and migration rate. The fossorial water vole (Arvicola terrestris) is a cyclic species characterized by large demographic fluctuations over short periods of time. The outbreaks do not occur everywhere at the same time but spread as a wave at a regional scale.

Clonal reproduction by males and females in the little fire ant.

Sexual reproduction can lead to major conflicts between sexes and within genomes. Here we report an extreme case of such conflicts in the little fire ant Wasmannia auropunctata. We found that sterile workers are produced by normal sexual reproduction, whereas daughter queens are invariably clonally produced.

Regulating insect resistance management: the case of non-Bt corn refuges in the US.

In this paper, we analyze the insect resistance management (IRM) plan put in place by the US Environmental Protection Agency (EPA) to delay the evolution of resistance to Bt corn in natural populations of the European corn borer, Ostrinia nubilalis Hübner. This IRM plan is the most impressive mandatory IRM system ever developed. It forms a coherent whole and includes mandatory refuges, actions to increase growers' compliance and a program for monitoring the evolution of resistance.

Genome size is not related to life-history traits in primates.

Genome size (C value, the haploid DNA content of the nucleus) varies widely among eukaryotes, increasing through duplication or insertion of transposable elements and decreasing through deletions. Here, we investigate relationships between genome size and life-history attributes potentially related to fitness, including body mass, brain mass, gestation time, age at sexual maturity, and longevity, in 42 species of primates. Using multivariate and phylogenetically informed analyses, we show that genome size is unrelated to any of these traits.

When morphometry meets genetics: inferring the phylogeography of Carabus solieri using Fourier analyses of pronotum and male genitalia.

Population differentiation is a crucial step in the speciation process and is therefore a central subject in studies of microevolution. Assessing divergence and inferring its dynamics in space and time generally require a wide array of markers. Until now however, most studies of population structure are based on molecular markers and those concerning morphological traits are more scarce.

Bayesian analysis of an admixture model with mutations and arbitrarily linked markers.

We introduce here a Bayesian analysis of a classical admixture model in which all parameters are simultaneously estimated. Our approach follows the approximate Bayesian computation (ABC) framework, relying on massive simulations and a rejection-regression algorithm. Although computationally intensive, this approach can easily deal with complex mutation models and partially linked loci, and it can be thoroughly validated without much additional computation cost.

A parasite reveals cryptic phylogeographic history of its host.

This study compares the continental phylogeographic patterns of two wild European species linked by a host-parasite relationship: the field mouse Apodemus sylvaticus and one of its specific parasites, the nematode Heligmosomoides polygyrus. A total of 740 base pairs (bp) of the mitochondrial cytochrome b (cyt b) gene were sequenced in 122 specimens of H. polygyrus and compared with 94 cyt b gene sequences (974 bp) previously acquired for A.

The Acrolepiopsis assectella silk cocoon: kairomonal function and chemical characterisation.

Two soluble sericin-like polypeptides, B1 and B2, from leek moth (Acrolepiopsis assectella) cocoons trigger host-acceptance behaviour in the parasitoid, Diadromus pulchellus (Proc. Roy. Soc.