Incidence of dengue and chikungunya viruses in mosquitoes and human patients in border provinces of Vietnam

Background: Dengue virus remains a major threat in Vietnam, while chikungunya virus is expected to become one. Surveillance was conducted from 2012 to 2014 in Vietnam to assess the presence of dengue and chikungunya viruses in patients hospitalized with acute fever in five Vietnam provinces neighboring Lao PDR and Cambodia. Surveillance was extended to mosquitoes present in the vicinity of the patients' households. Results: A total 558 human serum samples were collected along with 1104 adult mosquitoes and 12,041 larvae from 2250 households. Dengue virus was found in 17 (3%) human serum samples and in 9 (0.8%) adult mosquitoes. Chikungunya virus was detected in 2 adult mosquitoes (0.18%) while no chikungunya virus was detected in humans. Differing densities of mosquito populations were found, with the highest in the Long An Province border with Cambodia. Long An Province also displayed the lowest rate of infection, despite a very high Breteau Index, high human population density and presence of the main cross border road system. The highest incidence was found in Dac Nong Province, where the Breteau and Container indices were the second lowest. Dengue virus was detected in five Aedes albopictus, three Aedes aegypti and one Culex vishnui. Chikungunya virus was detected in two Ae. aegypti. All infected mosquitoes belonged to haplotypes described in other parts of the world and a number of novel haplotypes were found among uninfected mosquitoes. Conclusions: Dengue is considered to be regularly introduced to Vietnam from Cambodia, mostly through human movement. The data reported here provides a complementary picture. Due to intensive international trade, long-distance transportation of mosquito populations may play a role in the regular importation of dengue in Vietnam through Ho Chi Minh City. It is important to decipher the movement of mosquitoes in Vietnam, not only at the Lao PDR and Cambodia borders but also through international trade routes. Mosquito surveillance programs should address and follow mosquito populations instead of mosquito species

The genetic architecture of chemosensory cues involved in species recognition: a behavioral approach in the house mouse.

International audienceThe genetics of chemical signals is poorly understood. We addressed this issue in two subspecies of mice, Mus musculus musculus and M. m. domesticus, comparing their odor phenotypes with that of their hybrids. Earlier studies indicated that these subspecies could be discriminated on the basis of their urinary odor. We assessed male odor phenotypes from perception of musculus mice acting as olfactometers. Our results point to a complex genetic determinism. Reciprocal F1 hybrids produced a distinct odor phenotype, with shared characteristics distinguishing them from their parents, and stronger similarity to domesticus than to musculus. These results are consistent with implications of genes with partial dominance and a parent of origin effect. Further, similarities between reciprocal F2 allowed us to reject a direct role of the Y-chromosome in shaping the odor phenotype. However we show that the X-chromosome could be involved in explaining domesticus phenotype, while epistasis between genes on the sex chromosomes and the autosomes might influence musculus phenotype

Habituation-Discrimination/Generalisation tests

Behavioural data of discrimination tests between two urinary stimuli placed on two sides of a box, after habituation to an other urinary stimulus. Data are time spent (in seconds) in contact with each stimulus, recorded in laboratory with the Observer 5.0 software. Information about the tested mice and the stimuli are present, as well as references to the sections of the article referring to each test

131120 choice test data

Behavioural data of simultaneous choice tests between two urinary stimuli at the end of the branches of a Y maze. Data are time spent (in seconds) in the neutral part, on each branch, and in contact with each stimulus, recorded in laboratory with the Observer 5.0 software. Information about the tested mice and the stimuli are present, as well as references to the sections of the article referring to each test

Undiscovered diversity of dipteran parasitoids infecting mongolian orthopterans

International audienceDiversity of parasitoids species remains questioning in several ecosystems poorly surveyed. The present study is focused on dipteran parasitoids species infecting orthopteran in forest-steppe ecosystem of Mongolia. Among a total of 420 hosts from four species, 20 were found to be infected and 200 larvae of dipteran parasitoids recovered. Genetic studies on a subset of larvae shows the presence of up to seven taxa whose none is represented in databases (although 13 species were previously reported in Mongolia), indicating a large and unexplored diversity of dipteran parasitoid in Mongolia. Further studies will be focused in establishing of this diversity and the determination of the species

Urinary volatile molecules vary in males of the 2 european subspecies of the house mouse and their hybrids

Mice recognize other mice by identifying chemicals that confer a molecular signature to urinary marks. Such molecules may be involved in species recognition, and previous behavioral studies have related divergence of sexual preference between 2 subspecies of the house mouse (Mus musculus musculus and Mus musculus domesticus) to urinary odors. To characterize the differences between odors of males of the 2 subspecies and their first-generation offspring, the urinary volatile molecules were examined via gas chromatography coupled to mass spectrometry. Seven molecules were present in the samples from mice of at least one group. Their quantity varied among groups: M. m. domesticus showed a quantitatively richer panel of odorants in their urine when compared with M. m. musculus. The hybrids showed a more complex picture that was not directly related to one or the other parental subspecies. These quantitative differences may contribute to the specificity of the odorant bouquet of the 2 subspecies

Sexual selection against natural hybrids may contribute to reinforcement in a house mouse hybrid zone

International audienceSexual selection may hinder gene flow across contact zones when hybrid recognition signals are discriminated against. We tested this hypothesis in a unimodal hybrid zone between Mus musculus musculus and Mus musculus domesticus where a pattern of reinforcement was described and lower hybrid fitness documented. We presented mice from the border of the hybrid zone with a choice between opposite sex urine from the same subspecies versus hybrids sampled in different locations across the zone. While no preference was evidenced in domesticus mice, musculus males discriminated in favour of musculus signals and against hybrid signals. Remarkably, the pattern of hybrid unattractiveness did not vary across the hybrid zone. Moreover, allopatric populations tested in the same conditions did not discriminate against hybrid signals, indicating character displacement for signal perception or preference. Finally, habituation-discrimination tests assessing similarities between signals pointed out that hybrid signals differed from the parental ones. Overall, our results suggest that perception of hybrids as unattractive has evolved in border populations of musculus after the secondary contact with domesticus. We discuss the mechanisms involved in hybrid unattractiveness, and the potential impact of asymmetric sexual selection on the hybrid zone dynamics and gene flow between the two subspecies

Females of two subspecies of mice differ in their urinary volatile profile

Mice recognize other mice by identifying chemicals that confer a molecular signature to urinary marks. Such molecules may be involved in species recognition, and previous behavioral studies have related divergence of sexual preference between 2 subspecies of the house mouse (Mus musculus musculus and Mus musculus domesticus) to urinary odors