BackgroundVector control through indoor residual spraying (IRS) has been employed on Bioko Island, Equatorial Guinea, under the Bioko Island Malaria Control Project (BIMCP) since 2004. This study analyses the change in mosquito abundance, species composition and outdoor host-seeking proportions from 2009 to 2014, after 11 years of vector control on Bioko Island.MethodsAll-night indoor and outdoor human landing catches were performed monthly in the Bioko Island villages of Mongola, Arena Blanca, Biabia and Balboa from 2009 to 2014. Collected mosquitoes were morphologically identified and a subset of Anopheles gambiae sensu lato (s.l.) were later identified molecularly to their sibling species. Mosquito collection rates, species composition and indoor/outdoor host-seeking sites were analysed using generalized linear mixed models to assess changes in mosquito abundance and behaviour.ResultsThe overall mosquito collection rate declined in each of the four Bioko Island villages. Anopheles coluzzii and Anopheles melas comprised the An. gambiae s.l. mosquito vector population, with a range of species proportions across the four villages. The proportion of outdoor host-seeking An. gambiae s.l. mosquitoes increased significantly in all four villages with an average increase of 58.8 % [57.9, 59.64 %] in 2009 to 70.0 % [67.8, 72.0 %] in 2014. Outdoor host-seeking rates did not increase in the month after an IRS spray round compared to the month before, suggesting that insecticide repellency has little impact on host-seeking behaviour.ConclusionWhile vector control on Bioko Island has succeeded in substantial reduction in overall vector biting rates, populations of An. coluzzii and An. melas persist. Host-seeking behaviour has changed in these An. gambiae s.l. populations, with a shift towards outdoor host-seeking. During this study period, the proportion of host-seeking An. gambiae s.l. caught outdoors observed on Bioko Island increased to high levels, exceeding 80 % in some locations. It is possible that there may be a genetic basis underlying this large shift in host-seeking behaviour, in which case outdoor feeding could pose a serious threat to current vector control programmes. Currently, the BIMCP is preparing for this potential challenge by testing source reduction as a complementary control effort that also targets outdoor transmission.Electronic supplementary materialThe online version of this article (doi:10.1186/s12936-016-1286-6) contains supplementary material, which is available to authorized users.

Background Anopheles (An.) coluzzii, one of Africa’s primary malaria vectors, is highly anthropophilic. This human host preference contributes greatly to its ability to transmit malaria. In contrast, the closely related An. quadriannulatus prefers to feed on bovids and is not thought to contribute to malaria transmission. The diverged preference for host odor profiles between these sibling species is likely reflected in chemosensory gene expression levels in the olfactory organs. Therefore, we compared the transcriptomes of the antennae and maxillary palps between An. coluzzii and An. quadriannulatus, focusing on the major chemosensory gene families.ResultsWhile chemosensory gene expression is strongly correlated between the two species, various chemosensory genes show significantly enhanced expression in one of the species. In the antennae of An. coluzzii the expression of six olfactory receptors (Ors) and seven ionotropic receptors (Irs) is considerably enhanced, whereas 11 Ors and 3 Irs are upregulated in An. quadriannulatus. In the maxillary palps, leaving aside Irs with very low level of expression, one Ir is strongly enhanced in each species. In addition, we find divergence in odorant binding protein (Obp) gene expression, with several highly expressed Obps being enhanced in the antennae and palps of An. coluzzii. Finally, the expression of several gustatory receptors (Grs) in the palps appears to be species-specific, including a homolog of a sugar-sensing Drosophila Gr. ConclusionsA considerable number of Ors and Irs are differentially expressed between these two closely related species with diverging host preference. These chemosensory genes could play a role in the human host preference of the malaria vector An. coluzzii. Additionally, divergence in Obp expression between the two species suggests a possible role of these odor carrier proteins in determining host preference. Finally, divergence in chemosensory expression in the palps may point towards a possible role for the maxillary palps in host differentiation.Electronic supplementary materialThe online version of this article (10.1186/s12864-017-4122-7) contains supplementary material, which is available to authorized users.

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Summary1. Plant functional traits are important determinants of survival and fitness, and wood density (WD) is a key trait linked to mechanical stability, growth rates and drought-and shade-tolerance strategies. Thus, rigorous WD estimates are necessary to identify factors affecting tree performance. 2. We obtained 1766 records of WD from the literature for 141 tree species in the United States. We implemented a hierarchical Bayesian (HB) meta-analysis that incorporated sample size, variance, covariate (e.g. moisture content and latewood proportion) and methodological information to obtain standardized estimates of WD for 305 U.S. tree species. The HB framework allowed 'borrowing of strength' between species such that WD estimates for data-poor species were informed by data-rich species via taxonomic or phylogenetic relationships. 3. After accounting for important covariates and sampling effects, evaluation of the residual variation revealed the potential importance of environmental factors and evolutionary history. Differential variation in WD between species within genera and between genera within orders suggested that WD is relatively conserved in some genera and orders, but not in others. WD also varied between studies (or sites) indicating the potential influence of edaphic, topographic, or population factors on intraspecific variation in WD. 4. Synthesis. Our hierarchical Bayesian approach overcomes many of the limitations of traditional meta-analyses, and the incorporation of phylogenetic or taxonomic information facilitates estimates of trait values for data-poor species. We provide relatively well-constrained WD estimates for 305 tree species, which may be useful for tree growth and forest models, and the uncertainties associated with the estimates may inform future sampling campaigns.

• Premise of the study: Saltwater intrusion is one of the most widespread environmental threats to freshwater wetlands. Iris species worldwide are important members of these plant communities. Wetland irises reproduce clonally and sexually, which permits populations to spread and disperse in benign and stressful conditions. The ability of iris populations to tolerate and adapt to elevated salinity can play an important role in determining the long‐term health of wetland ecosystems.• Methods: We used microsatellite markers to evaluate population structure and genetic diversity, and we performed a common garden experiment to examine the effect of salinity on the growth and reproduction of wild Iris hexagona collected from freshwater and brackish wetlands.• Key results: Colonies were genetically distinct, with average to high heterozygosity (0.55–0.66) for a clonal species. Salinity had negative linear effects on leaf mass (g), clonal growth (g), root mass (g), and flower numbers, and it had nonlinear effects on seed numbers and seed mass (mg). The greatest sexual reproduction occurred in the intermediate‐salinity (4 parts per thousand) treatment. Flowering phenology was delayed for 5 days in the highest‐salinity treatment.• Conclusions: We hypothesized that irises from brackish habitats would tolerate salinity better than freshwater irises would, but no difference in iris performance existed between the two habitats. The observed salinity tolerance and genetic diversity of I. hexagona indicate that populations will persist despite moderate increases in environmental salinity.