A recent study, published in Insects with E4Warning participation, explores the residual longevity of sterile male mosquitoes and its significance for understanding their field performance in Sterile Insect Technique (SIT) programs: an eco-friendly vector control method where sterile male mosquitoes are released to mate with wild females, reducing mosquito populations over time.

The study aimed to assess the longevity and quality of sterile and non-sterile male Aedes albopictus mosquitoes by using the “mark-release-recapture” (MRR) method. The findings revealed several important insights:

1. Sterile Males’ Longevity: Contrary to expectations, the study found that sterile male mosquitoes had a longer lifespan than their non-sterile counterparts when released into the wild. This extended longevity is a significant advantage for SIT programs, as it increases the likelihood of sterile males mating with wild females, thereby enhancing the effectiveness of population suppression efforts.

2. Effect of Wild Exposure: Sterile males that had been released into the wild lived longer when recaptured and monitored in a laboratory setting. This suggests that exposure to the wild, including factors like fluctuating environmental conditions and access to richer food sources, may improve the performance of sterile males.

3. No Negative Effect of Marking or Sterilization: The process of marking the mosquitoes with fluorescent dyes (following IAEA protocols) and sterilization via gamma radiation did not negatively affect their longevity. This supports the continued use of these practices in SIT programs.

4. Transport and Mass Rearing: Males reared and transported from large-scale production facilities exhibited slightly shorter lifespans compared to those reared locally under small-scale conditions. This suggests that optimizing transportation and rearing conditions can further improve the performance of sterile mosquitoes in the field.

Understanding the longevity and quality of sterile mosquitoes is crucial for optimizing SIT programs, particularly in areas where mosquito populations pose a significant public health threat. The study underscores the importance of refining rearing, sterilization, and transportation techniques to maximize the success of SIT in controlling vector populations and reducing the risk of mosquito-borne diseases.

This research advances our understanding of how sterile males perform in the field, providing valuable insights that can be applied to ongoing and future SIT initiatives and vector dispersal capacity estimation within the E4Warning project.

The study was a collaborative effort involving several institutions and experts across Europe. Key contributors included researchers from the following institutions: Benaki Phytopathological Institute (BPI) in Greece, Centre d’Estudis Avançats de Blanes (CEAB-CSIC), CREAF, and ICREA in Spain, Centro Agricoltura Ambiente “G. Nicoli” in Crevalcore, Italy, Centre for Vectors and Infectious Diseases Research Doutor Francisco Cambournac (CEVDI) at the National Institute of Health Doutor Ricardo Jorge (INSA) in Palmela, Portugal, and the Faculty of Medicine, Environmental Health Institute (ISAMB) at the University of Lisbon, and ASTRE, CIRAD, INRAE, based in La Réunion, France.

Link to the paper: Balatsos, G., Blanco-Sierra, L., Karras, V., Puggioli, A., Costa Osório, H., Bellini, R., Papachristos, D.P., Bouyer, J., Bartumeus, F., Papadopoulos, N.T., & Michaelakis, A. 2024. Residual Longevity of Recaptured Sterile Mosquitoes as a Tool to Understand Field Performance and Reveal Quality. Insects 15, no. 11: 826. https://doi.org/10.3390/insects15110826

You can find other scientific papers produced by E4Warning in our “Publication website”: https://www.e4warning.eu/outputs/publications/

During the summer of 2024, project partners in Spain and Germany have been actively tagging birds with bio-loggers at key study sites to monitor their local and regional movements. Understanding bird movements and space usage during mosquito season is essential, as birds are the primary reservoirs for West Nile Virus (WNV). This project focuses on quantifying the mobility of key reservoir species, filling a crucial gap in current research by examining the local movement and dispersal patterns of resident bird species. Unlike the more extensively studied migratory birds, resident birds’ space usage near human settlements has been less explored. By gathering empirical data on these local movements, we aim to enhance our understanding of how resident bird populations contribute to virus transmission in areas close to human activity.

Fieldwork involves capturing and tagging various bird species with bio-loggers provided by the Max Planck Institute (MPI). For smaller bird species, such as blackbirds (Turdus merula) and starlings (Sturnus vulgaris), we are using bio-logging devices developed by MPI that operate with SigFox technology. Although the SigFox IoT network offers lower spatial accuracy compared to satellite navigation, it supports the creation of particularly small devices thanks to the network’s low power demands requiring fewer electronic components. This allows tracking of smaller species with minimal impact on their natural behaviour.  This innovative technology also allows for near real-time tracking and data transmission to the MovBank platform, making it ideal for monitoring the movements of these smaller species across different environments.

The data collected from these birds will be compared with similar data from other study sites within the project during the next years, allowing us to gain a deeper understanding of the potential WNV transmission dynamics across various landscapes. In addition to blackbirds and starlings, other species being tagged include mallards (Anas platyrhynchos), pigeons (Columba livia), and either western marsh harriers (Circus aeruginosus) or northern goshawks (Accipiter gentilis). The capture and tagging process began in June 2024 and will continue until September 2024, providing valuable insights into how these birds move through different landscapes and potentially contribute to the spread of WNV.

• Read more about the SigFox technology for animal tracking here: A multi-species evaluation of digital wildlife monitoring using the Sigfox IoT network.