Cross-tissue and generation predictability of relative Wolbachia densities in the mosquito Aedes aegypti
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Updated: Sep 27, 2025
Maintaining Aedes aegypti Mosquitoes Infected with Wolbachia
Published on: August 14, 2017
Austin J Mejia1,2, H L C Dutra2,3, M J Jones2,3
1Department of Entomology, The Pennsylvania State University, University Park, PA, 16802, USA.
Background:
The insect endosymbiotic bacterium Wolbachia is being deployed in field populations of the mosquito Aedes aegypti for biological control. This microbe prevents the replication of human disease-causing viruses inside the vector, including dengue, Zika and chikungunya. Relative Wolbachia densities may in part predict the strength of this 'viral blocking' effect. Additionally, Wolbachia densities may affect the strength of the reproductive manipulations it induces, including cytoplasmic incompatibility (CI), maternal inheritance rates or induced fitness effects in the insect host. High rates of CI and maternal inheritance and low rates of fitness effects are also key to the successful spreading of Wolbachia through vector populations and its successful use in biocontrol. The factors that control Wolbachia densities are not completely understood.
Methods:
We used quantitative PCR-based methods to estimate relative density of the Wolbachia wAlbB strain in both the somatic and reproductive tissues of adult male and female mosquitoes, as well as in eggs. Using correlation analyses, we assessed whether densities in one tissue predict those in others within the same individual, but also across generations.
Results:
We found little relationship among the relative Wolbachia densities of different tissues in the same host. The results also show that there was very little relationship between Wolbachia densities in parents and those in offspring, both in the same and different tissues. The one exception was with ovary-egg relationships, where there was a strong positive association. Relative Wolbachia densities in reproductive tissues were always greater than those in the somatic tissues. Additionally, the densities were consistent in females over their lifetime regardless of tissue, whereas they were generally higher and more variable in males, particularly in the testes.
Conclusions:
Our results indicate that either stochastic processes or local tissue-based physiologies are more likely factors dictating Wolbachia densities in Ae. aegypti individuals, rather than shared embryonic environments or heritable genetic effects of the mosquito genome. These findings have implications for understanding how relative Wolbachia densities may evolve and/or be maintained over the long term in Ae. aegypti.
Insights
Wolbachia densities in Aedes aegypti mosquitoes vary by tissue and are not strongly inherited. Local factors, not genetics, likely control bacterial levels crucial for biocontrol.
Area of Science:
- Vector-borne disease control
- Microbial ecology
- Insect-microbe interactions
Background:
- Wolbachia bacteria are deployed in Aedes aegypti mosquitoes for biological control of diseases like dengue and Zika.
- Wolbachia density influences viral blocking and reproductive manipulations (e.g., CI) critical for biocontrol success.
- Understanding factors controlling Wolbachia density is essential for effective vector control strategies.
Purpose of the Study:
- To investigate the factors influencing Wolbachia wAlbB strain densities within Aedes aegypti.
- To determine relationships between Wolbachia densities across different tissues and generations.
- To inform biocontrol strategies by clarifying Wolbachia density regulation.
Main Methods:
- Quantitative PCR was used to measure relative Wolbachia wAlbB strain densities.
- Somatic and reproductive tissues of adult male and female mosquitoes, and eggs were analyzed.
- Correlation analyses assessed tissue-specific and intergenerational density relationships.
Main Results:
- Little correlation was found between Wolbachia densities in different tissues within the same mosquito.
- Parental Wolbachia densities showed minimal relationship with offspring densities, except for ovary-egg transmission.
- Reproductive tissues had higher Wolbachia densities than somatic tissues; densities were consistent in females but variable in males.
Conclusions:
- Wolbachia densities in Aedes aegypti are likely dictated by local tissue physiology or stochastic processes, not shared embryonic environments or host genetics.
- These findings impact the understanding of Wolbachia density evolution and long-term maintenance in mosquito populations.
- Results provide insights into optimizing Wolbachia-based vector control programs.
