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Patrizia Dettorre - One of the best experts on this subject based on the ideXlab platform.

  • pheromone induced accuracy of nestmate recognition in Carpenter Ants simultaneous decrease in type i and type ii errors
    The American Naturalist, 2019
    Co-Authors: Natacha Rossi, Martin Giurfa, David Baracchi, Patrizia Dettorre
    Abstract:

    AbstractThe ecological and evolutionary success of social insects relies on their ability to efficiently discriminate between group members and aliens. Nestmate recognition occurs by phenotype matc...

  • pheromone induced accuracy of nestmate recognition in Carpenter Ants simultaneous decrease in type i and type ii errors
    The American Naturalist, 2019
    Co-Authors: Natacha Rossi, Martin Giurfa, David Baracchi, Patrizia Dettorre
    Abstract:

    AbstractThe ecological and evolutionary success of social insects relies on their ability to efficiently discriminate between group members and aliens. Nestmate recognition occurs by phenotype matching, the comparison of the referent (colony) phenotype to the one of an encountered individual. Based on the level of dissimilarity between the two, the discriminator accepts or rejects the target. The tolerated degree of mismatch is predicted by the acceptance threshold model, which assumes adaptive threshold shifts depending on the costs of discrimination errors. Inherent in the model is that rejection (type I) and acceptance (type II) errors are reciprocally related: if one type decreases, the other increases. We studied whether alarm pheromones modulate the acceptance threshold. We exposed Camponotus aethiops Ants to formic acid and subsequently measured aggression toward nestmates and nonnestmates. Formic acid induced both more nonnestmate rejection and more nestmate acceptance than a control treatment, th...

  • disentangling environmental and heritable nestmate recognition cues in a Carpenter ant
    Journal of Insect Physiology, 2009
    Co-Authors: Jelle S Van Zweden, Stephanie Dreier, Patrizia Dettorre
    Abstract:

    Discriminating between group members and strangers is a key feature of social life. Nestmate recognition is very effective in social insects and is manifested by aggression and rejection of alien individuals, which are prohibited to enter the nest. Nestmate recognition is based on the quantitative variation in cuticular hydrocarbons, which can include heritable cues from the workers, as well as acquired cues from the environment or queen-derived cues. We tracked the profile of six colonies of the ant Camponotus aethiops for a year under homogeneous laboratory conditions. We performed chemical and behavioral analyses. We show that nestmate recognition was not impaired by constant environment, even though cuticular hydrocarbon profiles changed over time and were slightly converging among colonies. Linear hydrocarbons increased over time, especially in queenless colonies, but appeared to have weak diagnostic power between colonies. The presence of a queen had little influence on nestmate discrimination abilities. Our results suggest that heritable cues of workers are the dominant factor influencing nestmate discrimination in these Carpenter Ants and highlight the importance of colony kin structure for the evolution of eusociality.

Roxana Josens - One of the best experts on this subject based on the ideXlab platform.

  • Individual size as determinant of sugar responsiveness in Ants
    Behavioral Ecology and Sociobiology, 2018
    Co-Authors: Roxana Josens, M. Agustina Lopez, Nélida Jofré, Martin Giurfa
    Abstract:

    Social insects commonly exhibit division of labor in non-reproductive tasks. Task allocation may be related to size, form, and ergonomic differences when workers are anatomically variable. Carpenter Ants Camponotus mus collecting nectar exhibit a wide forager size variation, thus raising the question of whether large and minor workers differ in their gustatory responsiveness and specialize, therefore, on different nectar sources. To answer this question, we first established the sucrose concentration at which small and large Ants in the laboratory respond appetitively to a sugar solution (sucrose acceptance threshold, SAT) after experiencing a high or a low starvation regime (4- or 1-day carbohydrate deprivation, respectively). Under high starvation, no differences in SATs were found between larger and smaller Ants. Under low starvation, both sizes increased their SATs but larger Ants had a higher SAT, thus preferring more concentrated solutions while smaller Ants responded mostly to more diluted sucrose solutions. In a field assay in which the distribution of larger and smaller Ants on sugary food sources was analyzed, small and medium Ants were found—in different proportions—at all food sources while larger Ants were only found at nectar sources with a higher sugar flow rate, i.e., providing more sugar per unit time. Both field and laboratory assays supported that sugar-related parameters act as determinAnts of the size distribution of Ants among food sources. In addition, interindividual differences in alternative non-sugar-related variables may contribute to this distribution, leading thereby to a potential nectar foraging specialization. Significance statement Task specialization is crucial for the ecological success of social insects. Carpenter Ants allocate individuals of variable size to foraging, thus raising the question of whether they differ in their food preferences. We determined the sugar concentration at which an appetitive response occurs in small and large Carpenter Ants, and analyzed their distribution on natural and artificial nectar sources in a field assay. Under low starvation, larger Ants responded more than smaller Ants to higher sucrose concentrations. Coincidently, in the field assay, they were mainly present at sources with higher sucrose delivery. This kind of specialization may reflect the fact that larger Ants have larger feeding apparatuses, which may confer a better capacity to deal with the higher viscosity of more concentrated nectars and allow collecting more food at nectaries with higher sugar flow rates. Size specialization may thus increase colony success in the exploitation of variable food sources.

  • sucking pump activity in feeding behaviour regulation in Carpenter Ants
    Journal of Insect Physiology, 2009
    Co-Authors: Agustina Falibene, Alberto De Figueiredo Gontijo, Roxana Josens
    Abstract:

    Modulation of liquid feeding-rate would allow insects to ingest more food in the same time when this was required. Ants can vary nectar intake rate by increasing sucking pump frequency according to colony requirements. We analysed electrical signals generated by sucking pump activity of Ants during drinking solutions of different sucrose concentrations and under different carbohydrate-deprivation levels. Our aim was to define parameters that characterize the recordings and analyse their relationship with feeding behaviour. Signals showed that the initial and final frequencies of sucking pump activity, as well as the difference between them were higher in sugar-deprived Ants. However, these parameters were not influenced by sucrose solution concentration, which affected the number of pump contractions and the volume per contraction. Unexpectedly, we found two different responses in feeding behaviour of starved and non-starved Ants depending on concentration. Starved Ants drank dilute solutions for the same length of time as non-starved Ants but ingested higher volumes. While drinking the concentrated solutions, starved Ants drank the same volume, but did so in a shorter time than the non-starved ones. Despite these differences, for each analysed concentration the total number of pump contractions remained constant independently of sugar-deprivation level. These results are discussed in the frame of feeding regulation and decision making in ant foraging behaviour.

  • nectar intake rate is modulated by changes in sucking pump activity according to colony starvation in Carpenter Ants
    Journal of Comparative Physiology A-neuroethology Sensory Neural and Behavioral Physiology, 2008
    Co-Authors: Agustina Falibene, Roxana Josens
    Abstract:

    Dynamics of fluid feeding has been deeply studied in insects. However, the ability to vary the nectar-intake rate depending only on the carbohydrate deprivation has been clearly demonstrated only in Camponotus mus Ants. When insect morphometry and fluid properties remain constant, changes in intake rate could only be attributed to variations in sucking pump activity. Previous records of the electrical activity generated during feeding in C. mus have revealed two different signal patterns: the regular (RP, frequencies: 2-5 Hz) and the irregular (IP, frequencies: 7-12 Hz). This work studies the mechanism underlying food intake-rate modulation in Ants by analysing whether these patterns are involved. Behaviour and electrical activity generated by Ants at different starvation levels were analysed during feeding on sucrose solutions. Ants were able to modulate the intake rate for a variety of sucrose concentrations (10, 40 and 60%w/w). The IP only occurred for 60% of solutions and its presence did not affect the intake rate. However, during the RP generated under the starved state, we found frequencies up to 7.5 Hz. RP frequencies positively correlated with the intake-rate for all sucrose concentrations. Hence, intake-rate modulation according to sugar deprivation is mainly achieved by the ant's ability to vary the pumping frequency.

Martin Giurfa - One of the best experts on this subject based on the ideXlab platform.

  • pheromone induced accuracy of nestmate recognition in Carpenter Ants simultaneous decrease in type i and type ii errors
    The American Naturalist, 2019
    Co-Authors: Natacha Rossi, Martin Giurfa, David Baracchi, Patrizia Dettorre
    Abstract:

    AbstractThe ecological and evolutionary success of social insects relies on their ability to efficiently discriminate between group members and aliens. Nestmate recognition occurs by phenotype matc...

  • pheromone induced accuracy of nestmate recognition in Carpenter Ants simultaneous decrease in type i and type ii errors
    The American Naturalist, 2019
    Co-Authors: Natacha Rossi, Martin Giurfa, David Baracchi, Patrizia Dettorre
    Abstract:

    AbstractThe ecological and evolutionary success of social insects relies on their ability to efficiently discriminate between group members and aliens. Nestmate recognition occurs by phenotype matching, the comparison of the referent (colony) phenotype to the one of an encountered individual. Based on the level of dissimilarity between the two, the discriminator accepts or rejects the target. The tolerated degree of mismatch is predicted by the acceptance threshold model, which assumes adaptive threshold shifts depending on the costs of discrimination errors. Inherent in the model is that rejection (type I) and acceptance (type II) errors are reciprocally related: if one type decreases, the other increases. We studied whether alarm pheromones modulate the acceptance threshold. We exposed Camponotus aethiops Ants to formic acid and subsequently measured aggression toward nestmates and nonnestmates. Formic acid induced both more nonnestmate rejection and more nestmate acceptance than a control treatment, th...

  • Individual size as determinant of sugar responsiveness in Ants
    Behavioral Ecology and Sociobiology, 2018
    Co-Authors: Roxana Josens, M. Agustina Lopez, Nélida Jofré, Martin Giurfa
    Abstract:

    Social insects commonly exhibit division of labor in non-reproductive tasks. Task allocation may be related to size, form, and ergonomic differences when workers are anatomically variable. Carpenter Ants Camponotus mus collecting nectar exhibit a wide forager size variation, thus raising the question of whether large and minor workers differ in their gustatory responsiveness and specialize, therefore, on different nectar sources. To answer this question, we first established the sucrose concentration at which small and large Ants in the laboratory respond appetitively to a sugar solution (sucrose acceptance threshold, SAT) after experiencing a high or a low starvation regime (4- or 1-day carbohydrate deprivation, respectively). Under high starvation, no differences in SATs were found between larger and smaller Ants. Under low starvation, both sizes increased their SATs but larger Ants had a higher SAT, thus preferring more concentrated solutions while smaller Ants responded mostly to more diluted sucrose solutions. In a field assay in which the distribution of larger and smaller Ants on sugary food sources was analyzed, small and medium Ants were found—in different proportions—at all food sources while larger Ants were only found at nectar sources with a higher sugar flow rate, i.e., providing more sugar per unit time. Both field and laboratory assays supported that sugar-related parameters act as determinAnts of the size distribution of Ants among food sources. In addition, interindividual differences in alternative non-sugar-related variables may contribute to this distribution, leading thereby to a potential nectar foraging specialization. Significance statement Task specialization is crucial for the ecological success of social insects. Carpenter Ants allocate individuals of variable size to foraging, thus raising the question of whether they differ in their food preferences. We determined the sugar concentration at which an appetitive response occurs in small and large Carpenter Ants, and analyzed their distribution on natural and artificial nectar sources in a field assay. Under low starvation, larger Ants responded more than smaller Ants to higher sucrose concentrations. Coincidently, in the field assay, they were mainly present at sources with higher sucrose delivery. This kind of specialization may reflect the fact that larger Ants have larger feeding apparatuses, which may confer a better capacity to deal with the higher viscosity of more concentrated nectars and allow collecting more food at nectaries with higher sugar flow rates. Size specialization may thus increase colony success in the exploitation of variable food sources.

  • Aversive learning of odor–heat associations in Ants
    Journal of Experimental Biology, 2017
    Co-Authors: Lucie Desmedt, David Baracchi, Martin Giurfa, Jean-marc Devaud, Patrizia D'ettorre
    Abstract:

    Ants have recently emerged as useful models for the study of olfactory learning. In this framework, the development of a protocol for the appetitive conditioning of the maxilla-labium extension response (MaLER) provided the possibility of studying Pavlovian odor-food learning in a controlled environment. Here we extend these studies by introducing the first Pavlovian aversive learning protocol for harnessed Ants in the laboratory. We worked with Carpenter Ants Camponotus aethiops and first determined the capacity of different temperatures applied to the body surface to elicit the typical aversive mandible opening response (MOR). We determined that 75°C is the optimal temperature to induce MOR and chose the hind legs as the stimulated body region due to their high sensitivity. We then studied the ability of Ants to learn and remember odor-heat associations using 75°C as unconditioned stimulus. We studied learning and short-term retention after absolute (one odor paired with heat) and differential conditioning (a punished odor versus an unpunished odor). Our results show that Ants successfully learn the odor-heat association under a differential-conditioning regime and thus exhibit conditioned MOR to the punished odor. Yet, their performance under an absolute-conditioning regime is poor. These results demonstrate that Ants are capable of aversive learning and confirm previous findings about the different attentional resources solicited by differential and absolute conditioning in general.

David P. Hughes - One of the best experts on this subject based on the ideXlab platform.

  • A Dynamic Individual-Based Model for High-Resolution Ant Interactions
    Journal of Agricultural Biological and Environmental Statistics, 2019
    Co-Authors: Nathan B. Wikle, Ephraim M. Hanks, David P. Hughes
    Abstract:

    Ant feeding interactions (i.e., trophallaxis events) are thought to regulate the flow of nutrients and disease within a colony. Consequently, there is great interest in learning which environmental and behavioral factors drive ant trophallaxis. In this paper, we analyze ant trophallaxis behavior in a colony of 73 Carpenter Ants, observed at 1-s intervals over a period of 4 h. The data represent repeated observations from a dynamic contact network; however, traditional statistical analyses of network models are ill-suited for data observed at such high temporal resolution. We present a model for high-resolution longitudinal network data, where the network is assumed to be a time inhomogeneous, continuous-time Markov chain, with transition rates modeled as a function of time-varying individual and pairwise biological covariates. In particular, the high temporal resolution of the data leads to a tractable likelihood function, and likelihood-based inference procedures are utilized to explain which biological factors drive contact. Our results reveal how differences in ant social castes and individual behaviors, such as ant speed and activity levels, influence patterns of ant trophallaxis in the colony. Supplementary materials accompanying this paper appear online.

  • social spatial and temporal organization in a complex insect society
    Scientific Reports, 2015
    Co-Authors: Lauren E Quevillon, Ephraim M. Hanks, Shweta Bansal, David P. Hughes
    Abstract:

    High-density living is often associated with high disease risk due to density-dependent epidemic spread. Despite being paragons of high-density living, the social insects have largely decoupled the association with density-dependent epidemics. It is hypothesized that this is accomplished through prophylactic and inducible defenses termed ‘collective immunity’. Here we characterise segregation of Carpenter Ants that would be most likely to encounter infectious agents (i.e. foragers) using integrated social, spatial, and temporal analyses. Importantly, we do this in the absence of disease to establish baseline colony organization. Behavioural and social network analyses show that active foragers engage in more trophallaxis interactions than their nest worker and queen counterparts and occupy greater area within the nest. When the temporal ordering of social interactions is taken into account, active foragers and inactive foragers are not observed to interact with the queen in ways that could lead to the meaningful transfer of disease. Furthermore, theoretical resource spread analyses show that such temporal segregation does not appear to impact the colony-wide flow of food. This study provides an understanding of a complex society’s organization in the absence of disease that will serve as a null model for future studies in which disease is explicitly introduced.

  • Gene expression during zombie ant biting behavior reflects the complexity underlying fungal parasitic behavioral manipulation
    BMC Genomics, 2015
    Co-Authors: Charissa De Bekker, Raquel G. Loreto, Robin A. Ohm, Aswathy Sebastian, Istvan Albert, Martha Merrow, Andreas Brachmann, David P. Hughes
    Abstract:

    Background Adaptive manipulation of animal behavior by parasites functions to increase parasite transmission through changes in host behavior. These changes can range from slight alterations in existing behaviors of the host to the establishment of wholly novel behaviors. The biting behavior observed in Carpenter Ants infected by the specialized fungus Ophiocordyceps unilateralis s.l. is an example of the latter. Though parasitic manipulation of host behavior is generally assumed to be due to the parasite’s gene expression, few studies have set out to test this. Results We experimentally infected Carpenter Ants to collect tissue from both parasite and host during the time period when manipulated biting behavior is experienced. Upon observation of synchronized biting, samples were collected and subjected to mixed RNA-Seq analysis. We also sequenced and annotated the O. unilateralis s.l. genome as a reference for the fungal sequencing reads. Conclusions Our mixed transcriptomics approach, together with a comparative genomics study, shows that the majority of the fungal genes that are up-regulated during manipulated biting behavior are unique to the O. unilateralis s.l. genome. This study furthermore reveals that the fungal parasite might be regulating immune- and neuronal stress responses in the host during manipulated biting, as well as impairing its chemosensory communication and causing apoptosis. Moreover, we found genes up-regulated during manipulation that putatively encode for proteins with reported effects on behavioral outputs, proteins involved in various neuropathologies and proteins involved in the biosynthesis of secondary metabolites such as alkaloids.

  • Foraging Ants trade off further for faster: use of natural bridges and trunk trail permanency in Carpenter Ants.
    Die Naturwissenschaften, 2013
    Co-Authors: Raquel G. Loreto, David P. Hughes, Adam G. Hart, Thairine M. Pereira, Mayara L. R. Freitas, Simon L. Elliot
    Abstract:

    Trail-making Ants lay pheromones on the substrate to define paths between foraging areas and the nest. Combined with the chemistry of these pheromone trails and the physics of evaporation, trail-laying and trail-following behaviours provide ant colonies with the quickest routes to food. In relatively uniform environments, such as that provided in many laboratory studies of trail-making Ants, the quickest route is also often the shortest route. Here, we show that Carpenter Ants (Camponotus rufipes), in natural conditions, are able to make use of apparent obstacles in their environment to assist in finding the fastest routes to food. These Ants make extensive use of fallen branches, twigs and lianas as bridges to build their trails. These bridges make trails significantly longer than their straight line equivalents across the forest floor, but we estimate that Ants spend less than half the time to reach the same point, due to increased carriage speed across the bridges. We also found that these trails, mainly composed of bridges, are maintained for months, so they can be characterized as trunk trails. We suggest that pheromone-based foraging trail networks in field conditions are likely to be structured by a range of potentially complex factors but that even then, speed remains the most important consideration.

  • Hidden Diversity Behind the Zombie-Ant Fungus Ophiocordyceps unilateralis: Four New Species Described from Carpenter Ants in Minas Gerais, Brazil
    PLOS ONE, 2011
    Co-Authors: Harry C. Evans, Simon L. Elliot, David P. Hughes
    Abstract:

    BACKGROUND: Ophiocordyceps unilateralis (Clavicipitaceae: Hypocreales) is a fungal pathogen specific to Ants of the tribe Camponotini (Formicinae: Formicidae) with a pantropical distribution. This so-called zombie or brain-manipulating fungus alters the behaviour of the ant host, causing it to die in an exposed position, typically clinging onto and biting into the adaxial surface of shrub leaves. We (HCE and DPH) are currently undertaking a worldwide survey to assess the taxonomy and ecology of this highly variable species. METHODS: We formally describe and name four new species belonging to the O. unilateralis species complex collected from remnant Atlantic rainforest in the south-eastern region (Zona da Mata) of the State of Minas Gerais, Brazil. Fully illustrated descriptions of both the asexual (anamorph) and sexual (teleomorph) stages are provided for each species. The new names are registered in Index Fungorum (registration.indexfungorum.org) and have received IF numbers. This paper is also a test case for the electronic publication of new names in mycology. CONCLUSIONS: We are only just beginning to understand the taxonomy and ecology of the Ophiocordyceps unilateralis species complex associated with Carpenter Ants; macroscopically characterised by a single stalk arising from the dorsal neck region of the ant host on which the anamorph occupies the terminal region and the teleomorph occurs as lateral cushions or plates. Each of the four ant species collected--Camponotus rufipes, C. balzani, C. melanoticus and C. novogranadensis--is attacked by a distinct species of Ophiocordyceps readily separated using traditional micromorphology. The new taxa are named according to their ant host.

Natacha Rossi - One of the best experts on this subject based on the ideXlab platform.