Residual Longevity of Recaptured Sterile Mosquitoes as a Tool to Understand Field Performance and Reveal Quality

Abstract

Invasive mosquito species, such as Aedes albopictus, pose significant threats to both ecosystems and public health due to their role in transmitting diseases, such as dengue, Zika, and chikungunya. The Sterile Insect Technique (SIT) is a promising vector control strategy aimed at reducing mosquito populations by releasing sterile males to mate with wild females and reduce their reproduction rates. In this study, we employed the captive cohort method, which assesses the remaining longevity of randomly caught released individuals, to assess the longevity and frailty dynamics of sterile and non-sterile Ae. albopictus males. Using a mark-release-recapture approach (MRR), we compared the residual lifespan of sterile and non-sterile released males with that of wild, non-sterile males, aiming to understand the frailty dynamics of released males and, therefore, their quality and field performance. Contrary to expectations, our results revealed that released sterile males showed increased longevity compared to non-sterile males. Further, the marking process did not impact the longevity between lab-kept and marked males, suggesting that the marking process does not adversely affect survival under controlled conditions. These findings underscore the importance of optimizing pre-release and mass-rearing practices to enhance the effectiveness of SIT programs. Our study also demonstrates for the first time the use of the captive cohort method for understanding the biological dynamics of sterile mosquito populations in SIT programs, providing valuable insights for improving vector control strategies.

Keywords: Aedes albopictus; captive cohort method; mosquito longevity; sterile insect technique; vector control.

Figure 1

Kaplan–Meier curves of cumulative survival (a) of males marked vs. not-marked (small-scale production, BPI); (b) sterile vs. not-sterile, transported and kept in the laboratory; (c) released vs. non-released and transported; (d) sterile vs. non-sterile, transported and released. “Transported” males were produced in a mass production facility (CAA, Italy) and transported to Greece (BPI). The p values of the long-rank test are given on each graph.

Figure 2

Kaplan–Meier curves of cumulative survival for wild males captured in the sterile male release area (Vravrona) and the nearby control area (Artemida). The p-value of the long-rank test is provided on the graph.