NDLI: Characterization of overwintering sites (hibernacula) of the West Nile vector Culex pipiens in Central Italy

Content Provider	Springer Nature : BioMed Central
Author	Romiti, Federico Casini, Riccardo Del Lesto, Irene Magliano, Adele Ermenegildi, Arianna Droghei, Sarah Tofani, Silvia Scicluna, Maria Teresa Pichler, Verena Augello, Adriana Censi, Francesco Scaringella, Paolo Luigi Mastrobuoni, Giovanni Bacciotti, Debora Nencetti, Alberto De Liberato, Claudio
Abstract	Background In cool-temperate regions, mosquitoes face winter conditions that hinder their development. To cope with cold temperatures, species like Culex pipiens, a major vector of West Nile virus (WNV), diapause as adult females in overwintering shelters known as hibernacula. This study aimed to identify and characterize the overwintering sites of Cx. pipiens in central Italy, analyzing the environmental factors influencing the abundance of the two biological forms, Cx. pipiens pipiens and Cx. pipiens molestus. Methods Field surveys were conducted in Lazio and Tuscany over two consecutive winters (2022/2023 and 2023/2024). Overwintering mosquitoes were collected from different hibernacula types, including natural caves, artificial cavities and buildings. Environmental variables such as temperature, humidity, light intensity and vapor pressure deficit (VPD) were recorded in the entrance and inner rooms of each hibernaculum. Mosquito species and Cx. pipiens forms were identified through morphological and molecular analyses. A beta regression model was applied to assess the relationship between environmental factors and Cx. pipiens abundance. Redundancy analysis (RDA) was used to explore the impact of small- and landscape-scale variables on biological forms distribution. Results Culex pipiens presence was confirmed in 24 hibernacula and represented the most abundant species, with Anopheles maculipennis s.l., Culiseta annulata and Culex hortensis accounting for 0.4% of the collected individuals. Comparing the entrance and inner rooms, a higher abundance of Cx. pipiens s.s. was observed in the darker environments, characterized by a humidity of 50–75%, a temperature of 10–20 °C and a VPD of 0.3–0.8 kPa. Inside the inner rooms, Cx. pipiens females preferred lower temperatures, light intensity and humidity, combined with higher VPD. The RDA highlighted that Cx. pipiens pipiens was associated with low temperatures and VPD and high humidity levels, preferring semi-natural areas. Culex pipiens molestus was positively associated with artificial areas. Hybrids were observed in several types of hibernacula. Conclusions This study provides insights into the overwintering ecology of Cx. pipiens in southern Europe, highlighting the environmental factors driving its abundance. These results may inform future vector control strategies aimed at reducing mosquito populations and limiting WNV diffusion in temperate regions. Graphical Abstract
Related Links	https://parasitesandvectors.biomedcentral.com/counter/pdf/10.1186/s13071-025-06710-5.pdf
Ending Page	16
Page Count	16
Starting Page	1
File Format	HTM / HTML
ISSN	17563305
DOI	10.1186/s13071-025-06710-5
Journal	Parasites & Vectors
Issue Number	1
Volume Number	18
Language	English
Publisher	BioMed Central
Publisher Date	2025-02-24
Access Restriction	Open
Subject Keyword	Parasitology Entomology Tropical Medicine Infectious Diseases Veterinary Medicine Veterinary Science Virology Culex pipiens Diapause Overwintering Hibernacula West Nile virus Environmental factors Vector control Italy Veterinary Medicine/Veterinary Science
Content Type	Text
Resource Type	Article
Subject	Veterinary Infectious Diseases Parasitology
Journal Impact Factor	3/2023
5-Year Journal Impact Factor	3.3/2023

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