Investigation of Cytoplasmic Incompatibility Patterns in Culex pipiens: From Field Samples to Laboratory Isofemale Lines.

This protocol describes approaches to qualify Wolbachia-induced cytoplasmic incompatibility (CI) patterns (compatible, uni or bidirectional) in crosses between two or more Culex pipiens isofemale lines, hosting different Wolbachia (wPip) strains. Here, we describe how to (1) collect the larvae in the field and grow them to the adult stage in the insectary, (2) set up isofemale lines in the insectary, (3) genetically characterize the wPip group of these lines, and (4) perform reciprocal crosses to qualify CI.

Dynamic of resistance alleles of two major insecticide targets in Anopheles gambiae (s.l.) populations from Benin, West Africa.

Background: Insecticide resistance is a growing concern for malaria control and vector control effectiveness relies on assessing it distribution and understanding its evolution.

Methods: We assessed resistance levels and the frequencies of two major target-site mutations, L1014F-VGSC and G119S-ace-1, conferring resistance to pyrethroids (PYRs) and carbamates/organophosphates (CXs/OPs) insecticides. These data were compared to those acquired between 2006 and 2010 to follow resistance evolutionary trends over ten years.

Stable coexistence of incompatible Wolbachia along a narrow contact zone in mosquito field populations.

In arthropods, the intracellular bacteria Wolbachia often induce cytoplasmic incompatibility (CI) between sperm and egg, which causes conditional embryonic death and promotes the spatial spread of Wolbachia infections into host populations. The ability of Wolbachia to spread in natural populations through CI has attracted attention for using these bacteria in vector-borne disease control. The dynamics of incompatible Wolbachia infections have been deeply investigated theoretically, whereas in natural populations, there are only few examples described, especially among incompatible infected hosts.

GENE-dosage effects on fitness in recent adaptive duplications: ace-1 in the mosquito Culex pipiens.

Gene duplications have long been advocated to contribute to the evolution of new functions. The role of selection in their early spread is more controversial. Unless duplications are favored for a direct benefit of increased expression, they are likely detrimental.

Cytoplasmic incompatibility as a means of controlling Culex pipiens quinquefasciatus mosquito in the islands of the south-western Indian Ocean.

The use of the bacterium Wolbachia is an attractive alternative method to control vector populations. In mosquitoes, as in members of the Culex pipiens complex, Wolbachia induces a form of embryonic lethality called cytoplasmic incompatibility, a sperm-egg incompatibility occurring when infected males mate either with uninfected females or with females infected with incompatible Wolbachia strain(s). Here we explore the feasibility of the Incompatible Insect Technique (IIT), a species-specific control approach in which field females are sterilized by inundative releases of incompatible males.

Fossil rhabdoviral sequences integrated into arthropod genomes: ontogeny, evolution, and potential functionality.

Retroelements represent a considerable fraction of many eukaryotic genomes and are considered major drives for adaptive genetic innovations. Recent discoveries showed that despite not normally using DNA intermediates like retroviruses do, Mononegaviruses (i.e.

Diversification of Wolbachia endosymbiont in the Culex pipiens mosquito.

The α-proteobacteria Wolbachia are among the most common intracellular bacteria and have recently emerged as important drivers of arthropod biology. Wolbachia commonly act as reproductive parasites in arthropods by inducing cytoplasmic incompatibility (CI), a type of conditional sterility between hosts harboring incompatible infections. In this study, we examined the evolutionary histories of Wolbachia infections, known as wPip, in the common house mosquito Culex pipiens, which exhibits the greatest variation in CI crossing patterns observed in any insect.

Multiple Wolbachia determinants control the evolution of cytoplasmic incompatibilities in Culex pipiens mosquito populations.

Wolbachia are maternally inherited endosymbionts that can invade arthropod populations through manipulation of their reproduction. In mosquitoes, Wolbachia induce embryonic death, known as cytoplasmic incompatibility (CI), whenever infected males mate with females either uninfected or infected with an incompatible strain. Although genetic determinants of CI are unknown, a functional model involving the so-called mod and resc factors has been proposed.

High incidence of ace-1 duplicated haplotypes in resistant Culex pipiens mosquitoes from Algeria.

The status of genes conferring resistance to organophosphate and carbamate insecticides has been examined in Culex pipiens pipiens mosquitoes sampled in Algeria. Presence of overproduced esterases was sporadic, but acetylcholinesterase-1 resistant alleles were observed in almost all samples. We focused our study on the AChE1 G119S substitution characterized in almost all samples, mostly at the heterozygous state.

Insecticide resistance in Culex pipiens quinquefasciatus and Aedes albopictus mosquitoes from La Réunion Island.

Resistance to insecticides was monitored on Culex pipiens quinquefasciatus mosquitoes collected in twelve localities of La Réunion, a geographically isolated island of the Indian Ocean. This mosquito is of medical concern in the region as a known vector for filariasis and a potential vector for West Nile and Rift Valley Fever viruses. Our bioassays indicated the presence of resistance to all tested insecticides, i.

Malaria vectors in the Republic of Benin: distribution of species and molecular forms of the Anopheles gambiae complex.

Members of the Anopheles gambiae complex are among the best malaria vectors in the world, but their vectorial capacities vary between species and populations. A large-scale sampling of An. gambiae sensu lato was carried out in 2006 and 2007 in various bioclimatic areas of Benin (West Africa).

Multiple duplications of the rare ace-1 mutation F290V in Culex pipiens natural populations.

Two amino acid substitutions in acetylcholinesterase 1 (AChE1), G119S and F290V, are responsible for resistance to organophosphate and carbamate insecticides in Culex pipiens mosquitoes. These mutations generate very different levels of insensitivity to insecticide inhibitors. We described here a biochemical method that rapidly identifies AChE1 variants (susceptible, G119S and F290V, named S, R and V, respectively) present in individual mosquitoes.

Genes conferring resistance to organophosphorus insecticides in Culex pipiens (Diptera: Culicidae) from Tunisia.

In Tunisia, the mosquito Culex pipiens shows various organophosphate resistance alleles at Ester and ace-1 loci. The characterization and the distribution pattern of these alleles were studied among 20 populations sampled from north to center of Tunisia. At the Ester locus, Ester4, Ester5, and Ester(B12) were present.

Ace-1 duplication in Anopheles gambiae: a challenge for malaria control.

Background: Insecticide resistance is a rapid and recent evolutionary phenomenon with serious economic and public health implications. In the mosquito Anopheles gambiae s.s.

Characterization of a novel high-activity esterase in Tunisian populations of the mosquito Culex pipiens.

AIn the mosquito Culex pipiens (L.) (Diptera: Culicidae) esterases contribute to insecticide resistance by their increased activity. These esterases display a heterogeneous geographical distribution, particularly in Tunisia, where they are very diverse.

Evolution of resistance under insecticide selection pressure in Culex pipiens quinquefasciatus (Diptera, Culicidae) from Martinique.

Population surveys of Culex pipiens quinquefasciatus carried out in 1991 and 1999 were compared with data collected in 1990 before the beginning of the control program against this mosquito. Larval samples collected in 1999 displayed resistance to the four tested insecticides: permethrin, propoxur, temephos, and chlorpyrifos. Temephos resistance ratio at LC50 (RR50) ranged between 8.

Genetic differentiation of Anopheles claviger s.s. in Europe.

Two groups of Anopheles claviger sensu stricto Meigen (Diptera: Culicidae) were recently found in France, representing unclear genetic entities. To better understand this situation, sampling was extended to 13 European countries, and 47 samples were analyzed by investigating the polymorphism of 11 autosomal and 1 sex-linked allozyme loci. Genetic differentiation, as measured by F(st), between these two groups was confirmed, with no isolation by distance within each group.

A novel acetylcholinesterase gene in mosquitoes codes for the insecticide target and is non-homologous to the ace gene in Drosophila.

Acetylcholinesterase (AChE) is the target of two major insecticide families, organophosphates (OPs) and carbamates. AChE insensitivity is a frequent resistance mechanism in insects and responsible mutations in the ace gene were identified in two Diptera, Drosophila melanogaster and Musca domestica. However, for other insects, the ace gene cloned by homology with Drosophila does not code for the insensitive AChE in resistant individuals, indicating the existence of a second ace locus.

High resistance to Bacillus sphaericus binary toxin in culex pipiens (Diptera: Culicidae): the complex situation of west Mediterranean countries.

This study was aimed at clarifying the nature of the resistance to Bacillus sphaericus Neide (Bs) that Culex pipiens L. has developed in west Mediterranean countries, France, and Tunisia. Two recessive and sex-linked mutants, sp-1R and sp-2R, were previously detected in southern France.

EVOLUTION OF RESISTANCE IN CULEX PIPIENS: ALLELE REPLACEMENT AND CHANGING ENVIRONMENT.

Fixation of adaptive mutations in populations is often constrained by pleiotropic fitness costs. The evolutionary pathways that compensate such fitness disadvantages are either the occurrence of modifier genes or replacement of the adaptive allele by less costly ones. In this context, 23 years of evolution of insecticide resistance genes in the mosquito Culex pipiens from southern France are analyzed.

POPULATION STRUCTURE AND DYNAMICS OF SELECTED GENES IN THE MOSQUITO CULEX PIPIENS.

To determine the outcome of the combined effects of gene flow, genetic drift, and selection on the evolution of insecticide-resistance genes in the mosquito Culex pipiens, samples were collected along three transects crossing treated and nontreated areas in northern Spain and southern France. Electrophoretic polymorphisms of five presumably neutral genes disclosed that differentiation among samples was low, and that both Wright F-statistics and Slatkin private-alleles methods provided a high estimate for Nm. In contrast, there was a strong differentiation in the distribution of resistance genes closely associated with insecticide treatments.

Developmental studies inDrosophila : V. Alkaline phosphatases, dehydrogenases and oxidases in organs and whole-fly homogenates during development ofD. pseudoobscura.

Alkaline phosphatases and several dehydrogenases and oxidases separated by a microdisc electrophoresis technique have been studied during larval and early pupal development ofD. pseudoobscura salivary glands, fat body, hemolymph, body wall and whole body. Tissue-specific enzymes were observed and the qualitative differences occurring during the development are discussed.