Biology subjects

Houle, J.

Publications and source records attributed to Houle, J..

6 recordsLinked to original sources

bioRxiv2026

Olfactory Search Behavior Across Flow Regimes Supports a Unifying Framework

How animals perform odor-guided search across the broad range of dynamic flow conditions they encounter in nature is not well understood. Prior work treats established strategies such as circling and zigzagging as discrete, context-dependent behaviors. Here, we propose a parsimonious mathematical framework that unites these motifs into a continuum. We show that free flying Drosophila exhibit this continuum by smoothly reshaping search behavior between circling and zigzagging across unsteady flow, still air, and a range of wind speeds. Strikingly, a flow-invariant rhythmic course progression underlies this behavioral spectrum. Available data from moths and sharks across different flow regimes suggest a similarly preserved rhythm, while the rate of this rhythm varies across taxa. Together, these results support a common conceptual basis for olfactory search behavior and explain how search geometry can adapt automatically to local flow.

animal behavior and cognition↗

bioRxiv2026

Wind history shapes olfactory search response in free flying Drosophila melanogaster

The ability of flying insects to locate distant food and mates by tracking odor plumes through turbulent and unsteady flow represents a remarkable feat of sensorimotor integration. Successful navigation requires not only extracting a reliable directional estimate from an intermittent olfactory signal, but also contending with the challenging dynamics of variable winds. While prior work has established that insects integrate the history of odor encounters to shape search decisions, whether they also retain a working memory of recently experienced wind conditions has remained unknown. Here, we use optogenetics combined with controlled wind perturbations in a free-flight wind tunnel to investigate how wind history modulates the olfactory search behavior of Drosophila melanogaster. By introducing lateral "gust" flow via auxiliary fans and independently delivering olfactory stimuli, we show that the wind experienced during an olfactory stimulus shapes both the immediate surge response and the subsequent spatial search. Flies that received an olfactory stimulus while being displaced by a crosswind gust were significantly more likely to return to the gust zone during the post-stimulus search phase compared to flies that received the same odor cue in steady laminar flow. Meanwhile, surge responses and course directions exhibited during search indicate that moment-to-moment flight kinematics may be driven more by instantaneous flow. These results reveal that wind experience is tracked in addition to olfactory experience, and provide evidence that Drosophila maintain a short-term working memory of ambient wind conditions to guide olfactory navigation.

animal behavior and cognition↗

bioRxiv2025

Vespula pensylvanica locate odor sources across diverse natural wind conditions

Many organisms across ecosystems track odor plumes to locate mates and food. In flying insects, the task of localizing an odor source is particularly challenging due to the complicated dynamics associated with wind flow and odor plume dispersion through spatially complex environments. Although wind tunnel experiments have been instrumental for answering many questions related to olfactory search, such experiments cannot replicate the complexity of natural wind conditions. Thus, our knowledge of how real-world wind characteristics influence insects success and strategies to locate odor sources remains an open area of investigation. Here, we tested whether certain wind conditions were more favorable for foraging insects by comparing yellowjacket arrival times and corresponding wind conditions across three distinct natural environments. Our results indicate that Vespula pensylvanica are capable of locating odor sources across the full range of observed wind conditions, without any clear preferences. This suggests that insects have adapted strategies to perform odor localization tasks across the full spectrum of natural wind that they may encounter. Our field-based approach provides insight into key considerations for future wind tunnel experiments which seek to better resolve insect plume tracking in understudied flow regimes.

animal behavior and cognition↗

bioRxiv2024

Pooled nanoparticle screening using a chemical barcoding approach

We report the development of a small molecule-based barcoding platform for pooled screening of nanoparticle delivery. Using aryl halide-based tags (halocodes), we achieve high-sensitivity detection via gas chromatography coupled with mass spectrometry or electron capture. This enables barcoding and tracking of nanoparticles with minimal halocode concentrations and without altering their physicochemical properties. To demonstrate the utility of our platform for pooled screening, we synthesized a halocoded library of polylactide-co-glycolide (PLGA) nanoparticles and quantified uptake in ovarian cancer cells in a pooled manner. Our findings correlate with conventional fluorescence-based assays. Additionally, we demonstrate the potential of halocodes for spatial mapping of nanoparticles using mass spectrometry imaging (MSI). Halocoding presents an accessible and modular nanoparticle screening platform capable of quantifying delivery of pooled nanocarrier libraries in a range of biological settings.

bioengineering↗

bioRxiv2023

Near-surface wind variability over spatiotemporal scales relevant to plume tracking insects

Odor plume tracking is an important biological process for many organisms, and flying insects have served as popular model systems for studying these behaviors both in the field and in lab settings. The shape and statistics of the airborne odor plumes that insects follow are largely governed by the wind that advects them. Prior atmospheric studies have investigated aspects of microscale wind patterns with an emphasis on characterizing pollution dispersion, enhancing weather prediction models, and for assessing wind energy potential. Here, we aim to characterize microscale wind dynamics through the lens of short-term ecological functions by focusing on spatial and temporal scales most relevant to an insect actively searching for an odor source. We collected and compared near-surface wind data across three distinct environments (sage steppe, forest, and urban) in locations across Northern Nevada. Our findings show that near-surface wind direction variability decreases with increasing wind speeds and increases in environments with greater surface complexity. Across environments, there is a strong correlation between the variability in wind speed (i.e. turbulence intensity) and wind direction (i.e. the standard deviation in wind direction). In some environments, the standard deviation in wind direction varied as much as 15{degrees} to 75{degrees} on time scales of 1-10 minutes. We draw insights between our findings and previous plume tracking experiments to provide a general intuition for future field research and guidance for wind tunnel experimental design. From our analyses, we hypothesize that there may be an ideal range of wind speeds and environment complexity in which insects will be most successful when tracking an odor plume to its source.

ecology↗

bioRxiv2022

Active Anemosensing Hypothesis: How Flying Insects Could Estimate Ambient Wind Direction Through Sensory Integration & Active Movement

Estimating the direction of ambient fluid flow is a crucial step during chemical plume tracking for flying and swimming animals. How animals accomplish this remains an open area of investigation. Recent calcium imaging with tethered flying Drosophila has shown that flies encode the angular direction of multiple sensory modalities in their central complex: orientation, apparent wind (or airspeed) direction, and direction of motion. Here we describe a general framework for how these three sensory modalities can be integrated over time to provide a continuous estimate of ambient wind direction. After validating our framework using a flying drone, we use simulations to show that ambient wind direction can be most accurately estimated with trajectories characterized by frequent, large magnitude turns. Furthermore, sensory measurements and estimates of their derivatives must be integrated over a period of time that incorporates at least one of these turns. Finally, we discuss approaches that insects might use to simplify the required computations, and present a list of testable predictions. Together, our results suggest that ambient flow estimation may be an important driver underlying the zigzagging maneuvers characteristic of plume tracking animals trajectories.

animal behavior and cognition↗