Impact of Mosquito Feeding Behavior on Wolbachia-Based Dengue Control

Date: Received - 17 February 2025 | Accepted - 18 July 2025 | Published - 29 July 2025

Source: Johnson, R.M., Breban, M.I., Nolan, B.L. et al. Implications of successive blood feeding on Wolbachia-mediated dengue virus inhibition in Aedes aegypti mosquitoes. Nat Commun 16, 6971 (2025). https://doi.org/10.1038/s41467-025-62352-2

Executive Summary

This document synthesizes findings from a study on the interplay between mosquito feeding behavior and the effectiveness of Wolbachia bacteria in inhibiting the dengue virus (DENV-2). The central conclusion is that successive blood feeding by Aedes aegypti mosquitoes, a natural behavior often overlooked in laboratory settings, enhances the relative efficacy of the wAlbB Wolbachia strain. While frequent feeding accelerates virus dissemination in both Wolbachia-infected and uninfected (wildtype, WT) mosquitoes, the effect is significantly more pronounced in the WT population.

This leads to a critical insight: traditional single-feed laboratory experiments likely underestimate the real-world impact of Wolbachia-based control strategies. The modeling of epidemiologically relevant factors shows that the protective advantage of wAlbB over WT is magnified under conditions that mimic natural feeding patterns. These findings provide robust support for the ongoing deployment of Wolbachia-transinfected mosquitoes for dengue transmission control, suggesting their functional inhibition of DENV-2 may be even stronger than previously demonstrated.

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Introduction and Study Context

The release of Aedes aegypti mosquitoes transinfected with the Wolbachia pipientis bacterium is a promising novel strategy to combat the significant public health threat of dengue virus (DENV). Wolbachia inhibits virus transmission, but the mechanisms are not fully understood, and the effectiveness can be incomplete.

A critical factor often unaccounted for in laboratory assessments is the natural feeding behavior of Ae. aegypti, which frequently take multiple blood meals. Previous work has shown that this "successive feeding" can accelerate virus dissemination from the mosquito's midgut, thereby shortening the extrinsic incubation period (EIP)—the time required for a mosquito to become infectious.

This study investigated the hypothesis that successive blood feeding decreases the effectiveness of Wolbachia by facilitating more efficient DENV-2 dissemination in mosquitoes carrying the wMelM and wAlbB strains.

Key Findings

I. Successive Feeding Accelerates DENV-2 Dissemination

The study compared mosquitoes given a single infectious blood meal (single-fed, SF) to those given an additional non-infectious blood meal four days later (double-fed, DF).

• Increased Dissemination: At 7 days post-infection, a second blood meal significantly increased the rate of DENV-2 dissemination in both wildtype (WT) and wAlbB-infected mosquitoes.

• Higher Viral Titers: Correspondingly, double-fed WT and wAlbBmosquitoes exhibited higher DENV-2 genome equivalents (viral load) in their bodies compared to their single-fed counterparts.

• Temporal Shift: Time course experiments confirmed that successive feeding leads to earlier dissemination, effectively shortening the EIP in both WT and wAlbB mosquitoes. For example, at day 5 post-infection, dissemination in the double-fed WT group was significantly higher than in the single-fed group. A similar, though less pronounced, acceleration was observed in wAlbB mosquitoes at days 6 and 7.

II. Wolbachia Strain Performance and Density

The study reaffirmed the virus-inhibiting properties of Wolbachia and explored the role of bacterial density.

• Strong Virus Inhibition: Consistent with previous research, both Wolbachiastrains strongly inhibited DENV-2. Mosquitoes with wMelM showed stronger inhibition (fewer infections and disseminations) than those with wAlbB. Due to the extremely low infection rates in wMelM mosquitoes, many subsequent analyses focused on the wAlbB strain.

• Wolbachia Density: While a second blood meal slightly increased wAlbBdensity, there was no significant correlation between Wolbachia levels and DENV-2 levels in individual mosquitoes. Instead, higher DENV-2 titers were strongly associated with whether the infection had disseminated, suggesting that midgut escape allows for increased viral replication in other tissues.

III. Modeling the Extrinsic Incubation Period (EIP)

By modeling the time course data, the study quantified the impact of successive feeding on the EIP, defined as the time until 50% of mosquitoes develop a disseminated infection (EIP50).

• EIP50 Reduction in wAlbB Mosquitoes: Successive feeding significantly shortened the time to 50% dissemination in wAlbB mosquitoes.

wAlbB Mosquito Group | Estimated EIP50 (Days Post-Infection) | 95% Credible Interval
Single-Fed (SF) | 8.38 days | 7.72–9.01 days
Double-Fed (DF) | 6.86 days | 6.03–7.62 days

• High Dissemination in WT Mosquitoes: In WT mosquitoes, dissemination rates exceeded 50% at all examined time points for both single- and double-fed groups. This prevented the calculation of a precise EIP50 but highlighted their high susceptibility compared to Wolbachia-infected mosquitoes.

Core Conclusion: Enhanced Relative Efficacy of Wolbachia

The study's most significant contribution comes from modeling the epidemiological consequences of a shortened EIP. Researchers calculated the probability of a mosquito surviving beyond its EIP—a key factor for transmission potential.

• Survival Past EIP:

    ◦ Double-fed mosquitoes (both WT and wAlbB) were consistently more likely to survive beyond the EIP than single-fed mosquitoes.

    ◦ WT mosquitoes were always more likely to survive beyond the EIP than their wAlbB counterparts, regardless of feeding status or assumed lifespan (4, 7, or 10 days).

• The Critical Insight (Odds Ratio Analysis): The study calculated the odds ratio of a mosquito surviving past the EIP for wAlbB relative to WT. This comparison revealed that while successive feeding helps the virus in both groups, it helps the virus more in the WT group.

    ◦ The odds ratios for double-fed mosquitoes were much smaller than for single-fed mosquitoes. This indicates that the protective effect of wAlbB is magnified under successive feeding conditions.

    ◦ In the study's words: "although successive feeding did reduce EIP for wAlbB mosquitoes, successive feeding has a larger impact on EIP in WT mosquitoes. This suggests that wAlbB remains effective in inhibiting DENV-2 when considering successive feeding."

Implications and Study Limi...