Biology subjects

Locatelli, F. F.

Publications and source records attributed to Locatelli, F. F..

6 recordsLinked to original sources

bioRxiv2026

Sequential multimodal sensory integration drives foraging decisions in leaf-cutting ants: Volatiles, contact cues and phytochemistry

Identifying the sensory cues that enable insects to find host plants, and understanding the neurobiology underlying their selection, provide solid foundations for developing state-of-the-art pest management strategies. Our work was aimed at identifying the main sensory cues attracting the leaf-cutting ant Acromyrmex ambiguus to alternative host plants in commercial willow plantations in the Lower Delta of the Parana River (Argentina), with a focus on native plant species. Eight plant species were selected and evaluated as potential hosts under field and laboratory conditions, allowing the establishment of a robust hierarchy of preference based on individual and collective behaviour. As a result, Senna corymbosa emerged as the most preferred species, whereas Blepharocalyx salicifolius was the least preferred. Video analyses of ant foraging in controlled indoor nests revealed a sequential decision-making process underlying plant preference and consumption. This included an initial approach driven by olfactory cues, followed by a second step involving contact-dependent cues that elicited leaf-cutting and carrying the leaf fragments to the nest. Volatile compounds and leaf cuticular components potentially involved in plant preference were identified. In addition, physicochemical analysis of both plant species - including total sugars, organic matter, polyphenols, leaf hardness, total proteins and lignin-revealed differences, particularly in polyphenol content, which may contribute to preference patterns. These findings provide insights into the sensory ecology of host preference and inform management strategies based on the reintroduction of native plants as alternative resources in willow plantations, potentially reducing pesticide use and promoting environmental sustainability. Summary statementThis work shows how leaf-cutting-ants rely on olfactory and contact cues, sequentially, for foraging decision-making of plant species. Thus, revealing how sensory cues shape their foraging decisions.

animal behavior and cognition↗

bioRxiv2026

Developmental Olfactory Experience Dissociates Hedonic Valence from Exploratory Arousal in Drosophila melanogaster

Insects rely on olfactory cues to navigate complex environments, with many innate behaviors governed by evolutionary hardwired neural circuits. However, the extent to which early-life sensory experience can recalibrate these innate responses remains a subject of intense debate. Here, we investigate how chronic exposure to odorants of varying innate valences during development and early adulthood modulates olfactory preference and exploratory drive in Drosophila melanogaster. Using a high-resolution two-choice assay, we demonstrate a fundamental functional dissociation in olfactory plasticity: while the innate hedonic valence of most odorants remains remarkably resilient to developmental environmental manipulation, early-life experience profoundly reprograms exploratory dynamics. Specifically, chronic exposure to propionic acid and benzaldehyde induced sex-specific shifts in locomotor arousal and trap-entry decisions without altering the intrinsic hedonic valuation of the stimuli. Conversely, general exploratory drive toward 1-octanol and isoamyl acetate remained rigidly hardwired, although 1-octanol exhibited subtle, experience-dependent habituation in odor preference. This resilience of innate valence suggests that the olfactory circuit actively prioritizes functional stability to ensure that critical ecological cues remain reliably encoded. Our findings reveal that Drosophila employs a modular adaptive strategy to integrate chronic sensory information: unreinforced early-life experience selectively reconfigures motor reactivity to scale navigational intensity to familiar landscapes, while leaving primary sensory-driven valences largely intact.

neuroscience↗

bioRxiv2026

Subjective rather than absolute reward value determines long-term memory formation in honey bees

How animals evaluate reward quality is a fundamental question in neuroscience and behavioral biology. Here we show that in honey bees (Apis mellifera), the value of a sucrose reward is not processed in absolute terms but relative to prior experience, and that this subjective evaluation strongly influences long-term memory formation. Using appetitive olfactory conditioning of the proboscis extension reflex (PER), we demonstrate that memory performance is determined by the contrast between a previously experienced reward and the reward used during training, rather than by the absolute concentration of sucrose received. This effect operates across multiple timescales, from contrasts between successive trials within a single session to differences between rewards experienced 24 hours apart. We further show that prior exposure to sucrose solutions of different concentrations modulates gustatory responsiveness and alters the sensitivity of antennal gustatory receptor neurons, suggesting that peripheral sensory plasticity contributes to experience-dependent changes in reward evaluation. Dissociating pre- and post-ingestive reward components revealed that the contrast between the sucrose concentration sensed by the antennae and the concentration ingested is sufficient to modulate memory formation. Together, our results indicate that bees form an internal expectation of reward quality based on experience, and that this expectation rescales the perceived value of subsequent rewards, thereby shaping associative memory strength. These findings provide a mechanistic framework for understanding how invertebrates perform relative reward comparisons across multiple temporal scales, with implications for flexible foraging strategies in dynamic environments.

neuroscience↗

bioRxiv2023

Sensory adaptation modulates coding and perceptual quality of odor mixtures

The sensitivity of the sensory systems must be dynamic in order to allow animals to adjust their behavior based on experience to optimize detection of relevant information while ignoring stimuli with no predictive value. In this context, one of the main phenomena that modulate the olfactory system is sensory adaptation. It is usually defined as a decrease in the sensitivity or response to a stimulus after a sustained exposure to it. Adaptation may occur in brief intervals of time and depends on the immediate prior experience. Here, we investigate aspects of the function and neurobiology of sensory adaptation in olfaction using the honeybee Apis mellifera. By means of electroantennograms we set stimulation protocols that induced sensory adaptation. We show that activation patterns that encode mixtures of odorants in the antennal lobe are drastically altered after sensory adaptation, favoring the representation of stimuli that are present at sub-threshold concentrations. We investigate the effects that sensory adaptation has on the perception of odorant mixtures and show that adapting animals to one of the components of a binary mixture, reduces the appetitive learning of the adapted stimulus and enhances the detection and learning of the non-adapted stimulus in cases in which it would stay normally occluded. These results suggest that olfactory sensory adaptation is critical to allow detection of minor components present in complex mixtures, emphasizing its role as a fundamental mechanism to improve sensitivity to discrete stimuli.

neuroscience↗

bioRxiv2021

Honey bees can store and retrieve independent memory traces after complex experiences that combine appetitive and aversive associations

Real-world experiences do often mix appetitive and aversive events. Understanding the ability of animals to extract, store and use this information is an important issue in neurobiology. We used honey bees as model to study learning and memory after a differential conditioning that combines appetitive and aversive training trials. First of all, we describe an aversive conditioning paradigm that constitutes a clear opposite of the well known appetitive olfactory conditioning of the proboscis extension response. A neutral odour is presented paired with the bitter substance quinine. Aversive memory is evidenced later as an odour-specific impairment in appetitive conditioning. Then we tested the effect of mixing appetitive and aversive conditioning trials distributed along the same training session. Differential conditioning protocols like this were used before to study the ability to discriminate odours, however they were not focused on whether appetitive and aversive memories are formed. We found that after a differential conditioning, honey bees establish independent appetitive and aversive memories that do not interfere with each other during acquisition or storage. Finally, we moved the question forward to retrieval and memory expression to evaluate what happens when appetitive and the aversive learned odours are mixed during test. Interestingly, opposite memories compete in a way that they do not cancel each other out. Honey bees showed the ability to switch from expressing appetitive to aversive memory depending on their satiation level.

animal behavior and cognition↗

bioRxiv2019

Gain modulation and odor concentration invariance in early olfactory networks

A conserved principle of the olfactory system, in most, if not all animals, is that each olfactory receptor interacts with different odorant molecules and each odorant molecule interacts with different olfactory receptors. This broad receptive field of the receptors constitutes the basis of a combinatorial code that allows animals to discriminate many more odorants than the actual number of receptor types that they express. A drawback is that high odorant concentrations recruit lower affinity receptors, which can give rise to the perception of qualitatively different odors. Here we addressed the contribution that early signal-processing in the honey bee antennal lobe does to keep odor representation stable across concentrations. We describe the contribution that GABA-A and GABA-B receptors-dependent-inhibition plays in terms of the amplitude and temporal profiles of the signals that convey odor information from the antennal lobes to the mushroom bodies. GABA reduces the amplitude of odor elicited signals and the number of glomeruli that are recruited in a concentration-dependent way. Blocking GABA-A and GABA-B receptors decreases the correlation among glomerular activity patterns elicited by different concentrations of the same odor. Based on the results we built a realistic computational model of the antennal lobe that could be further used to evaluate the signal processing properties of the AL network under conditions that cannot be achieved in physiology experiments. Interestingly, even though based on rather simplistic topology and interactions among cells solely mediated by GABA-A and GABA-B interactions, the AL model reproduced the key features of the AL stable response in relation to different concentrations.

neuroscience↗