Background Serratia marcescens and Enterobacter cloacae are associated with Anopheles gambiae mosquitoes and have been found to possess anti-plasmodial properties, making them suitable candidates to explore for bacteria-mediated disease/vector control. Their natural growth trends in the mosquito particularly after the host has fed on sugar and blood is required to deepen our understanding of how they can be effectively utilized in vector/disease control. Methods In this study, we employed a time-course experiment to investigate the dynamics of S. marcescens and E. cloacae in An. gambiae s.l mosquitoes over a 48-h period after feeding. Absolute bacterial counts were estimated using quantitative PCR (qPCR) on cDNA obtained from total RNA from mosquitoes and, with standard curves from bacterial isolates. A generalized additive mixed model (GAMM) was employed to investigate the interaction effects of diet and time on the bacteria trends while accounting for non-linear trends and repeated measures (random effects for ID). Results We show that E. cloacae are constitutively ~ 2000-fold more abundant in both sugar and blood fed mosquitoes than S. marcescens. In sugar-fed mosquitoes, both bacterial species are generally in equilibrium except at 2 h after the sugar meal when S. marcescens dips significantly (p = 0.03). E. cloacae remain remarkably stable at ~ 107 CFU/mL over 24–48 h in sugar- and blood-fed mosquitoes, while S. marcescens demonstrate non-linear growth dynamics (p = 0.02) in response to blood meal characterized by a sharp increase from a lower initial baseline (103 CFU/mL) to a peak of 105 CFU/mL at ~ 19 h post–blood meal, representing ~ 100-fold increase in its abundance. Conclusion Contrary to the general perception that members of Enterobacteriaceae increase after the mosquito blood feeds, our results provide evidence that Serratia but not Enterobacter naturally proliferates following a blood meal. This highlights that the choice of microbes for disease/vector biocontrol strategies must be informed by the specific growth kinetics of the candidate species. This work also hints on a multi-species consortium approach as a probable robust strategy for biocontrol.

Serratia marcescens and Enterobacter cloacae exhibit differential population dynamics in Anopheles gambiae s.l after sugar and blood feeding

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2026年4月21日

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Seraphim N. A. Tetteh,
Stephanie N. A. S. Addo,
Jewelna Akorli

摘要

Background

Serratia marcescens and Enterobacter cloacae are associated with Anopheles gambiae mosquitoes and have been found to possess anti-plasmodial properties, making them suitable candidates to explore for bacteria-mediated disease/vector control. Their natural growth trends in the mosquito particularly after the host has fed on sugar and blood is required to deepen our understanding of how they can be effectively utilized in vector/disease control.

Methods

In this study, we employed a time-course experiment to investigate the dynamics of S. marcescens and E. cloacae in An. gambiae s.l mosquitoes over a 48-h period after feeding. Absolute bacterial counts were estimated using quantitative PCR (qPCR) on cDNA obtained from total RNA from mosquitoes and, with standard curves from bacterial isolates. A generalized additive mixed model (GAMM) was employed to investigate the interaction effects of diet and time on the bacteria trends while accounting for non-linear trends and repeated measures (random effects for ID).

Results

We show that E. cloacae are constitutively ~ 2000-fold more abundant in both sugar and blood fed mosquitoes than S. marcescens. In sugar-fed mosquitoes, both bacterial species are generally in equilibrium except at 2 h after the sugar meal when S. marcescens dips significantly (p = 0.03). E. cloacae remain remarkably stable at ~ 10⁷ CFU/mL over 24–48 h in sugar- and blood-fed mosquitoes, while S. marcescens demonstrate non-linear growth dynamics (p = 0.02) in response to blood meal characterized by a sharp increase from a lower initial baseline (10³ CFU/mL) to a peak of 10⁵ CFU/mL at ~ 19 h post–blood meal, representing ~ 100-fold increase in its abundance.

Conclusion

Contrary to the general perception that members of Enterobacteriaceae increase after the mosquito blood feeds, our results provide evidence that Serratia but not Enterobacter naturally proliferates following a blood meal. This highlights that the choice of microbes for disease/vector biocontrol strategies must be informed by the specific growth kinetics of the candidate species. This work also hints on a multi-species consortium approach as a probable robust strategy for biocontrol.