Biology subjects

Harrap, M. J. M.

Publications and source records attributed to Harrap, M. J. M..

4 recordsLinked to original sources

bioRxiv2026

Low-latency multicamera 3D tracking of insects with Braid

Advances in camera technology and computer vision techniques have allowed researchers to track animals in 3D in ways which previously were difficult or impossible. Many such 3D tracking tools make use of multiple cameras, but unfamiliarity with the principles and technology involved can make it difficult to employ such techniques. In this protocol, we describe Braid, open-source software for live, multi-camera 3D tracking of insects. Using background-subtraction, Braid performs detection of objects without requiring the use of physical markers affixed to the insect. Braid constructs low-latency 3D position estimates using Kalman filtering and nearest neighbor data association. We document in detail the process of tracking freely flying bees within a flight arena using Braid. This protocol includes instructions on installation, configuration of cameras, setup, calibration, and operation. Within the system described here, we demonstrate that Braid can achieve position estimates accurate to <1 millimeter (within a 0.3 cubic meter volume). These factors make Braid suitable for tracking small, fast-flying animals like insects. Braid's low latency allows live tracking, removing the necessity to collect large video files and making it suitable for integration in closed loop systems such as virtual reality. Code is available at https://github.com/strawlab/strand-braid

animal behavior and cognition↗

bioRxiv2025

Bumblebees learn to use peripheral taste to predict the presence of nectar in flowers

Learning cues such as tastes associated with palatable food is an important mechanism animals have for foraging optimally. Insects can use gustatory receptor neurons (GRNs) in their mouthparts to detect nutrients and toxins, but they also taste compounds using sensilla on peripheral organs such as their antennae. Bees are adept at learning to associate floral traits with the presence of nectar rewards, but few studies have examined how they incorporate gustatory information from their antennae with rewards. Here, we characterize the ability of adult worker bumblebees (Bombus terrestris) to taste sugar, salt, and bitter compounds using their antennae and then tested whether they could use this sensory information to associate it with food. We show that bumblebees have antennal GRNs sensitive to sugars, salts, and bitter compounds and that they can use surface chemistry differences detected by their periphery to learn about the presence or absence of flower rewards in a free-flight assay. Naive bumblebees showed no instinctual preferences toward or against any surface chemistry tested. Bumblebees performed best when sucrose surface cues were associated with sucrose reward, but they could learn to associate any cue with the presence or absence of sucrose solution. Interestingly, the bees found it more difficult to associate quinine surface chemistry with the presence of reward than its absence. These results indicate that bees have the potential to learn to associate another floral trait - chemicals on the surfaces of petals - with the quality of floral rewards. Summary statementBehavioural experiments and electrophysiological recordings show bumblebees can detect peripheral taste cues on surfaces of artificial flowers, including bitter toxins, and learn to use these to predict rewards.

animal behavior and cognition↗

bioRxiv2024

Variations of floral temperature in changing weather conditions

O_LIFloral temperature is a flower characteristic that has the potential to impact the fitness of flowering plants and their pollinators. Likewise, the presence of floral temperature patterns, areas of contrasting temperature across the flower, can have similar impacts on the fitness of both mutualists. C_LIO_LIIt is currently poorly understood how floral temperature changes under the influence of different weather conditions, and how floral traits may moderate these changes. Such weather dependency will impact how stable floral temperatures are over time and their utility to plant and pollinator. The stability of floral temperature cues is likely to facilitate effective plant-pollinator interactions and play a role in the plants reproductive success. C_LIO_LIWe use thermal imaging to monitor how floral temperatures and temperature patterns of four plant species (Cistus snow fire and snow white, Coreopsis verticillata and Geranium psilostemon) change with several weather variables (illumination, temperature; windspeed; cloud cover; humidity and pressure) during times that pollinators are active. C_LIO_LIAll weather variables influenced floral temperature in one or more species. The directionality of these relationships were similar across species. In all species light conditions (illumination) had the greatest influence on floral temperature overall, and in generation of contrasting temperatures between parts of the flower, temperature patterns. The effect sizes of other weather variables were lower and more varied across the four species. Most likely, floral traits such as pigmentation and structure influence these relationships between weather conditions and generation of floral temperature. C_LIO_LISynthesis: Floral temperature and the extent to which flowers showed contrasting temperature patterns were influenced predominantly by light conditions. However, several weather variables had additional, lesser, influences. Furthermore, differences in floral traits, pigmentation and structure, likely resulted in differences in temperature responses to given conditions between species and different parts of the same flower. However, floral temperatures and contrasting temperature patterns that are sufficiently elevated for detection by pollinators were maintained across most conditions if flowers received moderate illumination. This suggests the presence of elevated floral temperature and contrasting temperature patterns are fairly constant and may have potential to influence plant-pollinator interactions across weather conditions. C_LI

plant biology↗

bioRxiv2021

The role of petal transpiration in floral humidity generation

Floral humidity, an area of elevated humidity in the headspace of flowers, has been detected across angiosperms and may function as a pollinator cue for insect pollinators. It is believed floral humidity is produced predominantly through a combination of evaporation of both liquid nectar and transpirational water loss from the flower. However, the role of transpiration in floral humidity generation has not been tested and is largely inferred by continued humidity production when nectar is removed from flowers. Understanding the extent that transpiration contributes to floral humidity has important implications for understanding the function of floral humidity. We test whether transpiration contributes to the floral humidity generation of two species previously identified to produce elevated floral humidity, Calystegia silvatica and Eschscholzia californica. Floral humidity production of flowers that underwent an antitranspirant treatment, petrolatum gel which blocks transpiration from treated tissues, is compared to flowers that did not receive such treatments. Gel treatments reduced floral humidity production to approximately a third of that produced by untreated flowers in C. silvatica, and half of that in E. californica. This confirms, the previously untested, inferences that transpiration has a large contribution to floral humidity generation and that this contribution may vary between species. HIGHLIGHTWe confirm, the previously untested, inferences that transpiration has a large contribution to floral humidity generation and show that this contribution may vary between species.

plant biology↗