Mosquito Population Control Shows Promise with Wolbachia Release, Long-Term Monitoring Reveals
Dadaosha and Shazai Islands, China – A long-term study published in Infectious Diseases of Poverty details the ecological impact of releasing Wolbachia-infected mosquitoes to suppress populations of Culex quinquefasciatus, a key vector of disease. Researchers found sustained suppression following initial releases, with evidence suggesting potential population replacement on Dadaosha Island years after the intervention ceased.
The study, conducted between 2017 and 2020, focused on releasing male C. quinquefasciatus mosquitoes carrying w*Pip,a *Wolbachia strain that causes cytoplasmic incompatibility – effectively sterilizing females when they mate with infected males. Ovitraps were used to monitor mosquito populations on Dadaosha Island, with egg-positive traps analyzed weekly for w*Pip presence during the release period (ending in late 2017).
Following the cessation of releases,monitoring continued. Starting in July 2019, larval samples from Dadaosha Island ovitraps were analyzed via PCR to assess whether *wpip had spread within the wild population, indicating population replacement. Adult female mosquitoes were also collected on Shazai Island in 2020 through human-landing catch activities – conducted between 9:00-11:00 and 16:00-18:00 near houses in shaded areas – to monitor w*Pip infection rates.Collection involved staff remaining at each location for 15-30 minutes, using a mosquito aspirator to capture females for subsequent PCR analysis. The PCR assays used to detect *wPip in both larvae and adults were consistent with previously established methods [Zheng X,Zhang D,Li Y,Yang C,Wu Y,Liang X,et al. Incompatible and sterile insect techniques combined eliminate mosquitoes. Nature. 2019;572(7767):56-61.].
Data analysis, performed using SPSS 13.0 and graphpad Prism 6.0, employed a range of statistical tests including Mann Whitney U tests, t*-tests, ANOVA, the log-rank test, Pearson correlation, and Fisher’s exact test. Meaning was determined at a *P-value of ≤ 0.05. These analyses will be crucial for understanding the long-term viability and ecological consequences of Wolbachia-based mosquito control strategies, offering valuable insights for future public health interventions aimed at reducing vector-borne disease transmission.