Vector Signals

About Vector Signals

A private, AI-curated podcast delivering 15-20 minute deep dives into the latest Nature articles on mosquito-borne viruses and AI-driven therapeutic breakthroughs. Designed for the researchers of the Saleh Lab at Institut Pasteur, each episode distills cutting-edge science into accessible insights—so you can stay current, even during your busiest bench days.

Publisher

Maddy Chang McDonough

Category

science

Language

en

Explicit

No

First episode

18 Feb 2023

Latest episode

17 Nov 2025

Latest episodes

26 episodes in the feed.

1. 

   17 Nov 2025

   Tiger Mosquito Larvae Exhibit Consistent Individual Personality (November 2025)

   Briefing Document: Personality Traits in the Tiger Mosquito, Aedes albopictus Source: Cordeschi, G., Mastrantonio, V., De Nicola, C. et al. Insect vectors have personality: first evidence with the tiger mosquito Aedes albopictus. Sci Rep 15, 39943 (2025). https://doi.org/10.1038/s41598-025-23665-w (https://doi.org/10.1038/s41598-025-23665-w) Date: Received - 16 June 2025 | Accepted - 08 October 2025 | Published - 14 November 2025 Executive Summary This document synthesizes findings from a foundational study providing the first evidence of animal personality in a mosquito species, the tiger mosquito Aedes albopictus. Researchers investigated personality traits in the larval stage, a critical phase in the mosquito life cycle. The study demonstrates that individual mosquito larvae exhibit consistent, repeatable differences in behavior across time, specifically in the traits of activity, exploration, and boldness. Key findings indicate that these traits are not only stable within individuals but are also significantly correlated, forming a "behavioral syndrome" where more active larvae are also bolder and more exploratory. These individual behavioral variations were observed independent of sex. The discovery of personality in mosquito larvae challenges the traditional view of insects as having purely stereotyped behaviors and introduces a new dimension of intra-specific diversity. The implications of these findings are substantial, impacting both basic mosquito biology and applied public health strategies. Larval personality may influence population dynamics through differential resource acquisition and survival rates. Furthermore, these traits could persist through metamorphosis ("carry-over effects"), affecting adult mosquito characteristics such as dispersal and disease transmission potential. Critically, the study suggests that the effectiveness of current larval control methods—both chemical and biological—may be influenced by the personality composition of a mosquito population. This research lays the groundwork for incorporating behavioral ecology into vector control strategies and the management of mosquito-borne diseases. -------------------------------------------------------------------------------- 1. Introduction: The Concept of Animal Personality in Insects Animal personality is defined as consistent, inter-individual variation in behavioral traits that is stable across time and different contexts. For the past two decades, this has been a central topic in behavioral ecology, primarily focusing on vertebrates. Key personality traits include boldness (risk-taking), exploration, activity, aggressiveness, and sociability. These traits are often correlated, forming what are known as behavioral syndromes. A growing body of research demonstrates that personality significantly influences ecological and evolutionary processes by affecting: Population demography and persistence Local adaptation Dispersal dynamics Species interactions While initial research concentrated on vertebrates, an increasing number of studies have documented personality in invertebrates, including insects. This has challenged the conventional view that insects exhibit purely stereotyped behaviors. It is now evident that personality shapes insect population ecology and evolution. For instance: In the field cricket Gryllus integer, populations exposed to higher predation exhibit reduced boldness. In the firebug Pyrrhocoris apterus, bolder and more exploratory individuals are more likely to disperse and host parasites. Despite this progress, the existence and implications of personality traits in mosquito species remained an unexplored area of research until this study. 2. Study Context: The Tiger Mosquito (Aedes albopictus) Mosquitoes (Diptera: Culicidae) comprise approximately 3,500 species and are globally significant vectors for major diseases affecting humans and animals, including malaria, dengue, yellow fever, and chikungunya. The larval stage is a critical part of their life cycle, as it is when they accumulate the necessary food reserves for metamorphosis. Conditions experienced during this stage can have lasting "carry-over effects" on adult traits and, consequently, on their potential to transmit pathogens. The subject of this study, the tiger mosquito Aedes albopictus, is an invasive species native to Asia that has spread to every continent except Antarctica. Its rapid expansion and capacity to vector several arboviruses make it a major global threat to public health. The primary objective of this research was to address the gap in mosquito biology by investigating the presence of personality traits in Ae. albopictus larvae. Specifically, the study aimed to: Characterize the larval personality traits of activity, exploration, and boldness. Assess whether these traits are consistent and repeatable over time. Determine if these traits are correlated, indicating a behavioral syndrome. 3. Methodology The study was conducted under controlled laboratory conditions using 41 Ae. albopictus larvae (16 males, 18 females, 7 unsexed) sourced from a mass colony. Each larva was individually tested for three behavioral traits on two consecutive days. Trait | Definition | Measurement Method Activity | The general level of an individual's movement. | Percentage of time a larva spent performing "thrashing" behavior (energetic lateral body flexions) in its housing tray over a 10-minute period. Exploration | An individual's reaction to a new situation. | The number of unique 2x2 cm cells crossed by a larva in a novel, larger arena over a 10-minute period. Boldness | The propensity for risk-taking behaviors. | The latency (in seconds) for a larva to re-emerge at the water's surface after diving in response to a simulated aerial threat (a standardized shadow stimulus). Statistical analysis was performed using Generalized Linear Mixed-Effect Models (GLMM) to assess the repeatability of each behavior, with individual identity included as a random factor and sex as a fixed effect. Spearman’s rank correlation was used to test for relationships among the traits. 4. Key Findings The study produced three principal findings that collectively provide the first evidence for personality in a mosquito vector. 4.1. High Inter-Individual Behavioral Diversity The larvae displayed a wide range of behaviors across all three measured traits, demonstrating significant diversity among individuals. Activity (Thrashing Time): Ranged from 5.2% to 92.6% in the first trial. Exploration (Cells Crossed): Ranged from 12 to 111 cells in the first trial. Boldness (Re-emergence Latency): Ranged from 24.63s to 370.02s in the first trial. 4.2. Behaviors are Repeatable and Consistent All three behavioral traits showed significant repeatability across the two trials, confirming that the observed inter-individual differences were stable over time. This consistency is the defining characteristic of animal personality. Sex was found to have no significant effect on any of the measured traits. Table 1: Repeatability Estimates for Behavioral Traits Trait | Repeatability (R) | 95% Confidence Interval | P-value

2. 

   24 Oct 2025

   Predicting Dengue Risk with Machine Learning and Microclimate Data (October 2025)

   Briefing: Fine-Scale Predictive Modeling for Dengue Risk in Malaysia Source: Dom, N.C., Abdullah, N.A.M.H., Dapari, R. et al. Fine-scale predictive modeling of Aedes mosquito abundance and dengue risk indicators using machine learning algorithms with microclimatic variables. Sci Rep 15, 37017 (2025). https://doi.org/10.1038/s41598-025-17191-y (https://doi.org/10.1038/s41598-025-17191-y) Date: Received - 01 February 2025 | Accepted - 21 August 2025 | Published - 23 October 2025 Executive Summary This briefing document synthesizes the findings of a study on the use of machine learning (ML) for fine-scale prediction of Aedes mosquito abundance and dengue risk in Kuala Selangor, Malaysia. Faced with a doubling of dengue cases in 2023, the study addresses the limitations of coarse, regional forecasting models by incorporating daily microclimatic data (temperature, relative humidity, rainfall) to improve predictive accuracy at the neighborhood level. Key Takeaways: Variable Model Performance: No single machine learning algorithm—Artificial Neural Network (ANN), Random Forest (RF), or Support Vector Machine (SVM)—was universally superior. Performance was highly dependent on the specific mosquito species (Ae. aegypti vs. Ae. albopictus), the risk indicator being predicted (Aedes Index vs. Dengue Positive Trap Index), and the combination of microclimatic inputs. For instance, ANN excelled at predicting the Ae. aegypti Aedes Index, while SVM was most effective for predicting the Ae. albopictus Dengue Positive Trap Index. Impact of Predictor Complexity: Models incorporating multiple microclimatic variables (dual or triple combinations) generally yielded lower error metrics than single-variable models. However, increasing model complexity did not always improve accuracy and, in some cases, led to overfitting and higher prediction errors, particularly for ANN models. This highlights a critical trade-off between model complexity and predictive power. Moderate and Time-Lagged Climatic Influence: While statistically significant, the correlations between microclimatic variables and mosquito indices were weak to moderate (correlation coefficients ranged from -0.30 to 0.32). This indicates that microclimate alone is insufficient to fully explain mosquito population dynamics and that other unmodeled factors, such as breeding site density, vegetation, and human activity, play a crucial role. The analysis also revealed significant time lags of up to 91 days, suggesting cumulative or delayed environmental effects on mosquito life cycles. Species-Specific Ecological Responses: The study identified distinct ecological sensitivities between the primary dengue vectors. Aedes albopictus demonstrated a quicker response to rainfall for dengue risk (a lag of -28 days) compared to Aedes aegypti (-63 days), which aligns with its known preference for more transient breeding habitats. Conclusion: The research validates the potential of fine-scale, microclimate-driven ML models as a valuable tool for creating proactive and targeted dengue control strategies. However, it underscores that effective implementation requires careful model selection tailored to specific species and local conditions. Future predictive systems would benefit from integrating a broader range of ecological and anthropogenic data to enhance accuracy and operational value. -------------------------------------------------------------------------------- 1. Background and Rationale Dengue fever remains a significant and escalating public health threat in Malaysia. The Ministry of Health reported over 123,000 cases in 2023, a twofold increase from 2021, with the state of Selangor bearing the highest burden. This trend suggests that existing vector control strategies, public awareness campaigns, and regulatory enforcement face significant limitations, particularly in densely populated urban areas. The proliferation of Aedes mosquitoes, the primary vectors for dengue, is heavily influenced by environmental conditions, especially microclimatic variables like temperature, humidity, and rainfall. Previous predictive models have often relied on coarse-resolution data from regional weather stations or satellites. This approach fails to capture the localized microclimatic variations critical to mosquito breeding at the neighborhood or household level, thereby limiting the models' utility for guiding timely and targeted interventions. This study aimed to bridge this gap by developing and evaluating fine-scale predictive models for Aedes mosquito abundance and dengue risk indicators in Kuala Selangor, a known dengue hotspot. The core objective was to leverage machine learning algorithms to analyze daily, localized microclimatic data, thereby improving forecasting accuracy for more effective, data-driven vector control. 2. Methodological Framework The study was conducted over 26 weeks, from February 6 to August 6, 2023, in urban and suburban districts of Kuala Selangor, a region with a tropical climate conducive to mosquito breeding. 2.1. Data Collection and Key Indicators Microclimatic Data: Daily mean, minimum, and maximum temperature, relative humidity, and rainfall were recorded using calibrated weather sensors. Entomological Data: A total of 60 Gravitrap-Outdoor Sentinel (GOS) traps were deployed in shaded, sheltered outdoor locations to capture adult female Aedes mosquitoes. Traps were serviced weekly. Outcome Variables (Risk Indicators): Aedes Index (AI): The proportion of traps containing at least one adult female Aedes mosquito. This serves as an indicator of mosquito abundance. Dengue Positive Trap Index (DPTI): The percentage of traps with at least one female Aedes mosquito testing positive for the dengue virus NS1 antigen, indicating active virus transmission risk. Species Analyzed: Predictions were generated for Aedes aegypti, Aedes albopictus, and the combined "Total Aedes" population. 2.2. Machine Learning Approach Algorithms: Three ML algorithms were selected for their strengths in modeling complex, nonlinear relationships: Artificial Neural Networks (ANN): Adept at capturing subtle patterns in high-dimensional data. Random Forest (RF): Robust in handling feature interactions and noisy data. Support Vector Machines (SVM): Performs well with limited datasets and resists overfitting. Predictor Combinations: Models were trained using single-variable (e.g., temperature alone), dual-variable (e.g., temperature + rainfall), and triple-variable (all three factors) inputs to assess individual and synergistic effects. Data Processing: Time Lags: Cross-correlation analysis was used to identify the most significant time lag (up to 91 days) between each microclimatic variable and the mosquito indices. Data Standardization: Predictor variables were standardized using z-score transformation to ensure uniform scaling. Data Split: The dataset was split chronologically into a 70% training set (first 18 weeks) and a 30% test set (final 8 weeks) to simulate real-world forecasting conditions. Mo...

3. 

   1 Oct 2025

   Medfly Gut Microbiota and Insecticide Resistance (September 2025)

   Gut Microbiota and Insecticide Resistance in the Mediterranean Fruit Fly (Ceratitis capitata) Source: Charaabi, K., Hamdene, H., Djobbi, W. et al. Assessing gut microbiota diversity and functional potential in resistant and susceptible strains of the mediterranean fruit fly. Sci Rep 15, 33456 (2025). https://doi.org/10.1038/s41598-025-01534-w (https://doi.org/10.1038/s41598-025-01534-w) Dates: Received - 06 November 2024 | Accepted - 06 May 2025 | Published - 29 September 2025 Executive Summary This briefing document synthesizes findings from a study investigating the link between gut microbiota and insecticide resistance in the Mediterranean fruit fly (Ceratitis capitata), a destructive agricultural pest. The research reveals a strong correlation between resistance to common insecticides (malathion, dimethoate, and spinosad) and significant alterations in the composition and functional potential of the fly's gut bacterial community. Resistant strains of the medfly, developed over 36 generations of insecticide exposure, exhibit significantly lower microbial diversity compared to their susceptible counterparts. This reduction in diversity is accompanied by a profound shift in the gut's bacterial landscape. Specifically, the phylum Bacillota and the genera Enterococcus and Klebsiella are substantially enriched in resistant flies. Conversely, the dominant phylum Pseudomonadota and the genera Serratia and Buttiauxella are sharply reduced. Functional analysis predicts that the gut microbiota of resistant flies possess enhanced metabolic capabilities for xenobiotic biodegradation. These enriched pathways are associated with the breakdown of various toxic environmental chemicals, suggesting a direct or indirect role in insecticide detoxification. The findings indicate that symbiont-mediated resistance is likely a key mechanism in the medfly, driven by the synergistic effect of multiple bacterial species rather than a single microbe. This research opens new avenues for pest management strategies that could target the gut microbiome to mitigate insecticide resistance. Background and Research Objectives The Mediterranean fruit fly (Ceratitis capitata), or medfly, is a highly polyphagous pest that infests over 300 plant species, causing billions of dollars in annual economic losses worldwide. These losses stem from reduced agricultural production, costly control measures, and restricted market access. While methods like the Sterile Insect Technique (SIT) are used, the predominant control practice remains the application of chemical insecticides. The widespread and excessive use of insecticides has led to the development of significant resistance in medfly populations, undermining control efforts. While resistance is often linked to genetic traits in the insect, such as increased enzyme activity, recent evidence from other species suggests that symbiotic gut microorganisms can play a crucial role. These bacteria may contribute to resistance by directly metabolizing toxic substances or by modulating the host's detoxification gene expression. Despite extensive research on the medfly's gut microbiota in relation to its fitness and SIT applications, the connection to insecticide resistance has remained largely unexplored. This study aimed to address this gap by investigating the potential association between the medfly gut microbiota and insecticide resistance. The primary objectives were to: Characterize and compare the gut microbiota community structure between insecticide-susceptible (IS) and insecticide-resistant (IR) strains of the medfly. Identify specific bacterial taxa that correlate with resistance phenotypes. Predict the functional differences between the microbiomes of susceptible and resistant strains. Experimental Design and Methodology To achieve its objectives, the study employed a controlled laboratory selection process and advanced sequencing techniques. Strain Development: Three insecticide-resistant (IR) strains were developed from a susceptible parent strain (IS) originally from Egypt (Egypt II). For 36 successive generations, populations were exposed to increasing concentrations of one of three insecticides: malathion (ML-SEL strain), dimethoate (Dm-SEL strain), or spinosad (Sp-SEL strain). The selection pressure was calibrated to achieve 50-70% mortality in each generation. Resistance Confirmation: Toxicological bioassays were conducted on the 36th generation of each IR strain and the IS strain. The lethal concentration required to kill 50% of the population (LC50) was calculated to quantify the level of resistance. The results confirmed a significant increase in tolerance in the selected strains. | Strain | Insecticide | LC50 (ppm) | Resistance Ratio (RR) vs. IS Strain | IS | Malathion | 18.8 | - | ML-SEL (G36) | Malathion | 1872.2 | 99.23-fold | IS | Dimethoate | 0.85 | - | Dm-SEL (G36) | Dimethoate | 215.79 | 252.68-fold | IS | Spinosad | 0.55 | - | Sp-SEL (G36) | Spinosad | 133.79 | 241.49-fold Microbiota Analysis: Gut tissues were dissected from adult flies of all four strains. Genomic DNA was extracted, and the V3-V4 region of the 16S rRNA gene was amplified and sequenced. Bioinformatic analyses, including Principal Coordinate Analysis (PCoA), Non-metric Multidimensional Scaling (NMDS), and Linear discriminant analysis Effect Size (LEfSe), were used to analyze microbial diversity, structure, and to identify potential biomarkers. Functional potential was predicted using the Kyoto Encyclopedia of Genes and Genomes (KEGG) database. Key Findings: Shifts in Gut Microbiota Composition The study revealed dramatic and statistically significant differences between the gut microbiomes of insecticide-susceptible and resistant medflies. Reduced Microbial Diversity in Resistant Strains A primary finding was that all three IR strains exhibited significantly lower bacterial richness and diversity compared to the IS parent strain (p < 0.05). This suggests that insecticide exposure acts as a strong selective pressure, favoring the growth of a specialized subset of bacteria that can tolerate or metabolize the toxic compounds. This "selection-cumulation effect" leads to an enrichment of resistance-associated bacteria at the expense of overall diversity. Altered Bacterial Abundance at Phylum and Genus Levels The composition of the gut microbiota was fundamentally altered in the resistant strains. Phylum-Level Shifts: While the phylum Pseudomonadota was dominant in all strains, its relative abundance decreased significantly in the IR strains (from 91.03% in IS to 70.85-75.27% in IR). Conversely, the abundance of the phylum Bacillota increased dramatically (from 8.94% in IS to 24.70-28.90% in IR). Genus-Level Shifts: The most pronounced changes occurred at the genus level, pointing to specific bacteria potentially involved in resistance. | Bacterial Genus | Relative Abundance in IS Strain | Change in IR Strains | Specific Details | ...

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