Philippe Christe

The impacts of landscape anthropization on mosquito abundance and diversity are already well studied, but the underlying ecological factors behind these effects are still poorly understood. One such underlying ecological factor may be related to the loss of amphibians in human‐modified landscapes, providing ideal habitats for several mosquito species. In this study, we conducted a mosquito and amphibian larvae survey in 77 ponds along a gradient of landscape anthropization in western Switzerland. We used structural equation models to investigate the direct and indirect effects of building footprints and several local pond parameters on mosquito abundance and composition through amphibian abundance. We highlighted that landscape anthropization increases the presence probability of mosquito larvae and the proportion of Culex pipiens in mosquito communities. Our results also suggested that one of the ecological mechanisms underlying these effects is a reduction in amphibian abundance, limiting competition and predation experienced by mosquitoes in human‐modified landscapes. In addition, we showed that several local pond characteristics prevent the presence and abundance of mosquito larvae. Indeed, deep ponds, which promote amphibian abundance, limit the probability of larval mosquito presence, and large and old ponds have a lower larval mosquito abundance. Amphibians appear to be effective control agents of natural mosquito populations. Therefore, the development of measures to protect amphibians in human‐modified landscapes could help to reduce both mosquito‐related nuisances and the risk of emergence of vector‐borne diseases in humans and wildlife.

In recent decades, the emergence and resurgence of vector‐borne diseases have been well documented worldwide, especially in tropical regions where protection and defense tools for human populations are still very limited. In this context, the dynamics of pathogens are influenced by landscape anthropization (i.e., urbanization, deforestation, and agricultural development), and one of the mechanisms through which this occurs is a change in the abundance and/or diversity of the vectors. An increasing number of empirical studies have described heterogeneous effects of landscape anthropization on vector communities; therefore, it is difficult to have an overall picture of these effects on a global scale. Here, we performed a meta‐analysis to quantify the impacts of landscape anthropization on a global scale on the presence/abundance and diversity of mosquitoes, the most important arthropods affecting human health. We obtained 338 effect sizes on 132 mosquito species, compiled from 107 studies in 52 countries that covered almost every part of the world. The results of the meta‐analysis showed an overall decline of mosquito presence/abundance and diversity in response to urbanization, deforestation, and agricultural development, except for a few mosquito species that have been able to exploit landscape anthropization well. Our results highlighted that these few favored mosquito species are those of global concern. They, thus, provide a better understanding of the overall effect of landscape anthropization on vector communities and, more importantly, suggest a greater risk of emergence and transmission of vector‐borne diseases in human‐modified landscapes.

Wildlife conservation and management need accurate methods for population survey and monitoring. Absolute counts of roe deer populations ( Capreolus capreolus ) are not possible, but the rapid advancement of motion‐sensitive camera technologies and new analytical approaches might potentially lead to more precise estimates at lower costs compared to traditional survey methods. We applied spatially explicit photographic capture–recapture models (SCR) in the Lake Geneva basin, Switzerland, from 25 April to 20 September 2018 to estimate roe deer densities in a pilot survey. We investigated the effect of survey duration and camera density on male roe deer density estimates to select the sampling design that produced density estimates with sufficient accuracy and precision at lower costs (i.e., material, fieldwork, data processing, and analyses). Males could be identified based on their antlers, which allowed us to apply SCR to estimate their density. Because females could not be identified individually, we inferred the overall roe deer density (adult and sub‐adult roe deer) based on the sex ratio estimated from motion‐sensitive camera photos. According to the results of sub‐sampling simulations and by taking into account the financial costs associated with fieldwork and analyses, we conclude that 20 motion‐sensitive cameras set over 20 nights (i.e., the 20/20 method) is a good compromise to provide reliable estimates of male roe deer density. Furthermore, studies estimating overall roe deer density using SCR and sex ratio estimates should be conducted from mid‐August to the end of October just after rutting season and the peak of yearling dispersal, when the movement rates of males and females, and hence their detection probabilities, are similar and when males are still carrying their antlers. This approach was successfully applied in 4 selected study areas with contrasting roe deer management regimes, resulting in overall roe deer density estimates ranging from 3.9 ± 1.3 (SE) deer/km 2 forest to 22.5 ± 6.1 deer/km 2 forest. Our study provides a valuable and cost‐effective approach using photographic SCR methodology and sex ratio information to calculate roe deer density estimates that can be used in management measures such as defining hunting quotas.