Biology subjects

Hempel de Ibarra, N.

Publications and source records attributed to Hempel de Ibarra, N..

5 recordsLinked to original sources

bioRxiv2025

A spatially explicit model of pollinator-plant-pathogen interactions

Flowers have long been suggested to be infection hotspots for pollinator diseases, as, during their brief lifespan, they are visited and handled by many individuals from a diverse range of species. Evidence that floral hotspots are an important point of contagion is building, but few models currently allow us to characterise these novel plant-pathogen-pollinator systems where horizontal infections occur from concentrated, short-lived sites of contagion. Infection success is going to depend heavily upon the behaviour of individual pollinators, alongside the structure of the floral landscape that they are foraging within. Here, we describe an individual-based model that considers the impact of environmental heterogeneity and individual differences in movement on the spread of a disease that is spread via floral hotspots, considering a centrally nesting social pollinator (such as a social bee). The biggest effects we saw were associated with the likelihoods of leaving and staying in the nest and the distances travelled by the pollinators, and so it is likely that social pollinators, most of which are constrained to return to a central nest, could be strongly impacted by the schedules they use for allocating foraging behaviour. We also considered the impact of the pollinators being able to deposit and detect temporary scent-marks, which could inform an uninfected pollinator of a potentially infected site. Scent marks have a negative impact on pathogen transmission, and their effect may be dependent on both the longevity of the scent mark, the turnover of flowers in the environment, and the factors affecting pathogen viability and infectivity. Overall, although the structure of the landscape may have limited impact on pathogen spread, the behaviour of the pollinators is important, and needs further consideration within models of this pathogen system. AUTHOR SUMMARYFlowers have long been suggested to be infection hotspots for pollinator diseases, as, during their brief lifespan, they are visited and handled by many individuals from a diverse range of species. Evidence that floral hotspots are an important point of contagion is building, but we currently know little about the environmental biology of these infections. We describe a model that considers how pathogens caught at floral infection hotspots might spread in populations of social pollinators (such as a bumblebee or honeybee), and show that both pollinator behaviour and how flowers are distributed through the landscape can have a big impact on the spread of the pathogen. Pollinators can leave temporary detectable scent marks on the surfaces of the flowers that they visit: our model demonstrates that being able to detect these marks reduces the spread of the pathogen, as the pollinator is better able to avoid potential hotspots.

ecology↗

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↗

bioRxiv2022

How bumblebees coordinate path integration and body orientation at the start of their first learning flight

The start of a bumblebees first learning flight from its nest provides an opportunity to examine the bees learning behaviour on its initial view of the nests unfamiliar surroundings. Bumblebees like many other ants, bees and wasps learn views of their nest surroundings while facing their nest. A bumblebees first fixation of the nest is a coordinated manoeuvre in which the insect faces the nest with its body oriented towards a particular visual feature within its surroundings. The manoeuvres utility is that during return flights after foraging bees, when close to the nest, adopt the same preferred body-orientation (Hempel de Ibarra et al., 2009; Robert et al., 2018). A translational scan oriented orthogonally to the bees body-orientation helps the bee reach the preferred conjunction of nest-fixation and body-orientation. How does a bee, unacquainted with its surroundings, know when it is facing its nest? The details of nest-fixation argue that, like desert ants (Fleischmann et al., 2018), the bee relies on path integration. Path integration gives bees continuously updated information about the current direction of their nest and enables them to fixate the nest when the body points in the appropriate direction. We relate the three components of the coordinated manoeuvre to events in the central complex, noting that nest fixation is in egocentric coordinates, whereas body orientation and flight direction within the visual surroundings of the nest are in geocentric coordinates.

animal behavior and cognition↗

bioRxiv2021

Bumblebees can detect floral humidity

Floral humidity, a region of elevated humidity proximal to the flower, occurs in many plant species and may add to their multimodal floral displays. So far, the ability to detect and respond to floral humidity cues has been only established for hawkmoths when they locate and extract nectar while hovering in front of some moth-pollinated flowers. To test whether floral humidity can be used by other more widespread generalist pollinators, we designed artificial flowers that presented biologically-relevant levels of humidity similar to those shown by flowering plants. Bumblebees showed a spontaneous preference for flowers which produced higher floral humidity. Furthermore, learning experiments showed that bumblebees are able to use differences in floral humidity to distinguish between rewarding and nonrewarding flowers. Our results indicate that bumblebees are sensitive to different levels of floral humidity. In this way floral humidity can add to the information provided by flowers and could impact pollinator behaviour more significantly than previously thought. Summary statementWe demonstrate for the first time that bumblebees show a preference to elevated floral humidity and can learn to distinguish flowers that differ in floral humidity levels.

animal behavior and cognition↗

bioRxiv2018

Approach direction prior to landing explains patterns of colour learning in bees

Gaze direction is closely coupled with body movement in insects and other animals. If movement patterns interfere with the acquisition of visual information, insects can actively adjust them to seek relevant cues. Alternatively, where multiple visual cues are available, an insects movements may influence how it perceives a scene. We show that the way a foraging bumblebee approaches a floral pattern could determine what it learns about the pattern. When trained to vertical bicoloured patterns, bumblebees consistently approached from below centre in order to land in the centre of the target where the reward was located. In subsequent tests, the bees preferred the colour of the lower half of the pattern that they predominantly faced during the approach and landing sequence. A predicted change of learning outcomes occurred when the contrast line was moved up or down off-centre: learned preferences again reflected relative frontal exposure to each colour during the approach, independent of the overall ratio of colours. This mechanism may underpin learning strategies in both simple and complex visual discriminations, highlighting that morphology and action patterns determines how animals solve sensory learning tasks. The deterministic effect of movement on visual learning may have substantially influenced the evolution of floral signals, particularly where plants depend on fine-scaled movements of pollinators on flowers.

animal behavior and cognition↗