Background: Aedes aegypti is a potential vector for several arboviruses including dengue and Zika viruses. The species seems to be restricted to subtropical/tropical habitats and has difficulties in establishing permanent populations in southern Europe, probably due to constraints during the winter season. The aim of this study was to systematically analyze the cold tolerance (CT) of Ae. aegypti in its most cold-resistant life stage, the eggs. Methods: The CT of Ae. aegypti eggs was compared with that of Ae. albopictus which is well established in large parts of Europe. By systematically studying the literature (meta-analysis), we recognized that CT has been rarely tested in Ae. aegypti eggs, but eggs can survive at zero and sub-zero temperatures for certain exposure periods. To overcome potential bias from experimental differences between studies, we then conducted species comparisons using a harmonized high-resolution CT measuring method. From subtropical populations of the same origin, the survival (hatching in %) and emergence of adults of both species were measured after zero and sub-zero temperature exposures for up to 9 days (3 °C, 0 °C and − 2 °C: ≤ 9 days; − 6 °C: ≤ 2 days). Results: Our data show that Ae. aegypti eggs can survive low and sub-zero temperatures for a short time period similar to or even better than those of Ae. albopictus. Moreover, after short sub-zero exposures of eggs of both species, individuals still developed into viable adults (Ae. aegypti: 3 adults emerged after 6 days at − 2 °C, Ae. albopictus: 1 adult emerged after 1 day at − 6 °C). Conclusions: Thus, both the literature and the present experimental data indicate that a cold winter may not be the preventing factor for the re-establishment of the dengue vector Ae. aegypti in southern Europe.

Background: The common house mosquito Culex pipiens is known to be a major vector for West Nile virus. In order to decrease risks of West Nile virus outbreaks in Europe, insecticides and the bio-larvicide Bacillus thuringiensis israelensis (Bti) are commonly used for vector control. Alarmingly, insecticide resistance has been reported in Cx. pipiens populations from Southern Europe and several countries neighbouring Europe. For Central and Northern Europe, however, the phenotypic insecticide resistance status of Cx. pipiens has not yet been investigated. Methods: A literature review was performed to assess the geographical distribution of insecticide resistance in Cx. pipiens. To fill the gap of knowledge for Central and Northern Europe, WHO susceptibility tests with permethrin, deltamethrin, malathion, bendiocarb and DDT and a larval toxicity test with Bti were performed with a Cx. pipiens population from Belgium, a country in Central Europe. Results: This research provides the first evidence of widespread phenotypic insecticide resistance in Cx. pipiens. In general, Cx. pipiens developed resistance against multiple insecticides in several countries. Another Cx. pipiens population from Belgium was tested and showed insecticide resistance against deltamethrin, permethrin, DDT and possibly against bendiocarb. The bio-larvicide Bti caused lower mortality than reported for other Cx. pipiens populations in the literature. Conclusions: These results indicate the urgent need for insecticide resistance monitoring against commonly used adulticides and larvicides in Europe, for the translation of knowledge gained regarding the limited efficiency and availability of insecticide into EU legislation and the need for innovative non-chemical vector control tools in order to counter the widespread insecticide resistance in Culex populations. Graphical

The risk of increasing dengue (DEN) and chikungunya (CHIK) epidemics impacts 240 million people, health systems, and the economy in the Hindu Kush Himalayan (HKH) region. The aim of this systematic review is to monitor trends in the distribution and spread of DEN/CHIK over time and geographically for future reliable vector and disease control in the HKH region. We conducted a systematic review of the literature on the spatiotemporal distribution of DEN/CHIK in HKH published up to 23 January 2020, following Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. In total, we found 61 articles that focused on the spatial and temporal distribution of 72,715 DEN and 2334 CHIK cases in the HKH region from 1951 to 2020. DEN incidence occurs in seven HKH countries, i.e., India, Nepal, Bhutan, Pakistan, Bangladesh, Afghanistan, and Myanmar, and CHIK occurs in four HKH countries, i.e., India, Nepal, Bhutan, and Myanmar, out of eight HKH countries. DEN is highly seasonal and starts with the onset of the monsoon (July in India and June in Nepal) and with the onset of spring (May in Bhutan) and peaks in the postmonsoon season (September to November). This current trend of increasing numbers of both diseases in many countries of the HKH region requires coordination of response efforts to prevent and control the future expansion of those vector-borne diseases to nonendemic areas, across national borders.

Driven by globalization, urbanization and climate change, the distribution range of invasive vector species has expanded to previously colder ecoregions. To reduce health‐threatening impacts on humans, insect vectors are extensively studied. Population genomics can reveal the genomic basis of adaptation and help to identify emerging trends of vector expansion. By applying whole genome analyses and genotype‐environment associations to populations of the main dengue vector Aedes aegypti, sampled along an altitudinal gradient in Nepal (200–1300 m), we identify putatively adaptive traits and describe the species' genomic footprint of climate adaptation to colder ecoregions. We found two differentiated clusters with significantly different allele frequencies in genes associated to climate adaptation between the highland population (1300 m) and all other lowland populations (≤800 m). We revealed nonsynonymous mutations in 13 of the candidate genes associated to either altitude, precipitation or cold tolerance and identified an isolation‐by‐environment differentiation pattern. Other than the expected gradual differentiation along the altitudinal gradient, our results reveal a distinct genomic differentiation of the highland population. Local high‐altitude adaptation could be one explanation of the population's phenotypic cold tolerance. Carrying alleles relevant for survival under colder climate increases the likelihood of this highland population to a worldwide expansion into other colder ecoregions.

The Hindu Kush Himalayan region is a global hotspot for climate change and highly vulnerable to its direct and indirect impacts. Understanding people’s perception of climate change is crucial for effective adaptation strategies. We conducted a study by using quantitative (Household survey, n = 660) and qualitative data collection tools (Focus group discussion, n = 12; In-depth interviews, n = 27) in central Nepal encompassing three altitudinal regions: Lowland (<1000 m amsl; Terai region), Midland (1000–1500 m amsl; hilly region) and Highland (1500–2100 m amsl; mountainous region). We analyzed 37 years (1981–2017) of climatic data from respective districts (Lowland: Chitwan, Dhading; Midland: Kathmandu, Lalitpur; Highland: Nuwakot, Rasuwa). People’s perception was compared with climate extreme indices measured along these regions and evaluated if they accurately recognized the impacts on the environment and human health. Our findings show significant climate changes, including rising summer temperature, region-specific winter temperatures and extended monsoon seasons in Nepal. Participants in our study accurately perceived these trends but misperceived heavy precipitation patterns. Reported impacts are rise in crop diseases, human diseases, vector expansion and climate induced disasters like floods, landslides, and water resource depletion, with perception accuracy varying by region. These insights highlight the importance of understanding regional and cross-regional perceptions in relation to climate data in order to develop tailored climate adaptation strategies. Policymakers can use this information to establish region-specific educational and communication initiatives, addressing communities’ distinctive vulnerabilities and needs across diverse landscapes. Such approaches can enhance equitable and effective climate resilience in subtropical to alpine regions.