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/

The XI International Conference of the EMCA, held from November 7th to 10th, 2023, in Palma de Mallorca, served as a gathering for vector control specialists to share research and insights. With the theme “Shaping the Future of Vector Control in Europe,” the conference was organized by Dr. Francis Schaffner, president of EMCA, along with Dr. Carlos Barceló and Prof. Miguel A. Miranda from the Universitat de les Illes Balears (UIB). Among the highlights was E4Warning’s presentation on their Mark-Release-Recapture (MRR) experiments with Culex pipiens mosquitoes.

Eva Veronesi from SUPSI discussed the developed protocol for breeding, marking, and recapturing these mosquitoes and shared preliminary results from two pilot studies conducted in Switzerland last September. These studies are vital for understanding mosquito behavior and movement, key factors in vector-borne disease control.

The MRR technique, a fundamental method in ecological studies, involves capturing, marking, and releasing individuals back into their environment, then recapturing them after a period. This technique provides insights into movement patterns, survival rates, and population sizes, crucial for ecological and epidemiological studies.

In the summer of 2024, these methodologies will be applied in Switzerland and Spain to study the dispersal capacity of Culex mosquitoes, especially Culex pipiens and Culex molestus, which are known for transmitting the West Nile Virus (WNV).

These experiments are part of Work Package 5 (WP5) in the E4Warning project, which focuses on quantifying and understanding the movements of both vectors (mosquitoes) and hosts (birds) in WNV transmission. The data obtained will be instrumental in developing strategies to control WNV in Europe.

Additionally, the conference served as a valuable meeting point for various partners involved in the E4Warning project. This opportunity for face-to-face interaction and collaboration among researchers and specialists was crucial for fostering synergy and advancing the project’s objectives. Such gatherings reinforce the importance of collaborative efforts in addressing public health challenges like vector-borne diseases.