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In recent years, a number of studies have suggested that visual status signaling operates in social wasps. In the paper wasp Polistes dominula, status is thought to be signaled by a region of black pigmentation on the yellow clypeus. Specifically, studies of the invasive North American population have indicated that the clypeal patterning of P. dominula females conveys information on their agonistic abilities in various natural contexts such as dominance within the nest and competitive interactions. However, studies of native European populations have, so far, failed in demonstrating such a function of the clypeal patterning. The present work investigated the status signaling in an Italian population of this species, eliminating any chemical and behavioral factors of the signaler and controlling for signaler size, therefore, focusing on visual stimulus alone. Using tightly controlled laboratory settings, we performed two bioassays representing two distinct natural contexts: a competitive interaction over food resources and a nest defense scenario. To this end: (1) we offered to future foundresses food patches guarded by two odorless conspecific lures differing only in visual facial cues and (2) we presented odorless wasp lures with a different clypeal patterning to solitary foundresses defending their own nest. We found no evidence for any role of the clypeal patterning in the rival assessment in both contexts. Hence, we conclude that P. dominula foundresses belonging to the Italian population lack visual status signaling on their clypeus. Further studies will elucidate factors and mechanisms underlying the geographical variation and evolution of visual signals in paper wasps. [ABSTRACT FROM AUTHOR]

Detection and identification of fungal cryptic species has been facilitated by DNA sequencing. However, the examination of some phenotypic traits is fundamental for the confirmation of genetic results. MALDI- TOF mass spectrometry has shown remarkable reliability in the recognition of species-specific phenotypic markers and has already been tested in several species of fungi. However, even though there is no direct evidence, the age of the mycelium appears to influence the composition of the metabolites detected. In this study, we demonstrate that MALDI- TOF is a reliable technique to identify suitable metabolites to distinguish three monophyletic species of Diplodia ( D. pinea, D. seriata and D. scrobiculata), thus supporting recent DNA results. Nevertheless, different collections of samples over a period of 3 months after inoculation also revealed that the MALDI- TOF spectra are highly dependent on mycelial age. More importantly, the species-specific markers emerge only after 1 month of mycelial growth. The methodological and biological implications of these findings are discussed. [ABSTRACT FROM AUTHOR]

The social biology of the waspParischnogaster striatulahas been studied in Peninsular Malaysia. This species shows the main characteristics of hover wasps (Vespidae, Stenogastrinae) which set them aside from the other social Vespidae. These include the use of an abdominal secretion in brood rearing, the three-phase egg deposition and the presence of only four larval instars. Colonies are invariably small sized and on average 1.92 females on the nests present developed ovaries. Colony life revolves around a dominant female, which has developed ovaries and spends most of her time on the nest. Since visual cues were recently found in two different species ofLiostenogaster(Stenogastrinae), we also looked for a possible badge of status in these wasps but with negative results. [ABSTRACT FROM AUTHOR]

Both recognition and conventional signals are widespread in the animal kingdom. Chemical communication plays a major role in invertebrates, and especially in social insects. In the last decade, observational and experimental evidence has shown the existence of visual quality signals and individual recognition cues in Polistes paper wasps, meaning that visual communication might also be common in insect societies. Here we show that two species of facultatively eusocial hover wasps (Vespidae, Stenogastrinae) use the visual channel for social communication. By combining morphoanatomical measurements and behavioural assays, we found that the size of the dark facial markings was related to reproductive status and dominance in colonies of Liostenogaster vechti, thus representing a badge of status. By contrast, no correlation between facial coloration and reproductive status was found in Liostenogaster flavolineata, which instead used facial markings as familiar visual recognition cues. Our results reveal that visual communication in social insects might be more widespread than previously thought and has evolved independently in distinct wasp taxa facing similar selection pressures. [Copyright &y& Elsevier]

The predatory behaviour of Vespa crabro hornets on the honeybee Apis mellifera ligustica and the counter strategy of the prey were observed and described in two apiaries of 27 and 41 colonies in Central Italy. Observations were carried out in the second half of October and accompanied by experiments aimed at determining the mechanisms of honeybee defence. We confirmed that V. crabro represents a relatively mild predator for A. mellifera ligustica but it can have a considerable impact on already debilitated colonies. Hornet predatory strategy is to spot then swoop on returning foragers. Honeybee defence centres on forming packed aggregations of individuals near the hive opening, which probably deters the wasps from entering. Coordinated behaviour by the bees, which cling together in groups, can knock the approaching hornets down, which are then totally covered by the bees. This balling behaviour has the effect of over-heating the predator whose lethal thermal limit is about 44 °C, although other factors, such as carbon dioxide emission and the release of venom by the honeybees, may also contribute to the death of the hornet. Comparing the differences and similarities of this behaviour with those observed in other species of Apis and Vespa reveals that these two species are an interesting model for the study of the evolutionary arms race. [ABSTRACT FROM AUTHOR]

The article discusses research done in Malaysia on the hover wasp, whose scientific name is Liostenogaster topographica Turillazi 1999, focusing on its social biology and the architecture of its nest construction. It provides information on the shared social and behavioral features with other hover wasps. Highlighted is the distinct difference in the architecture of its nest and the use of reddish material in its construction for defense against predators.

Parischnogaster mellyi is a common species of hover wasp which lives in the Oriental Region. In this research we wanted to achieve a deeper understanding of some aspects of its social biology and chemical ecology considering the composition of colonies, the reproductive potential of the female nest-mates, the chemical similarities between the adult cuticular hydrocarbons, the nest paper, the Dufour's gland secretion of the females and the pap placed on the eggs as a support for larval development. We were able to assess with nest exchange experiments that this species is capable of immature brood recognition. Neither the pap placed on eggs, nor the nest odour are used in this recognition process, despite the potential discrimination cues shown by chemical analyses. [ABSTRACT FROM PUBLISHER]

Microplastics (MPs) are growing and ubiquitous environmental pollutants and represent one of the greatest contemporary challenges caused by human activities. Current research has predominantly examined the singular toxicological effects of individual polymers, neglecting the prevailing reality of organisms confronted with complex contaminant mixtures and potential synergistic effects. To fill this research gap, we investigated the lethal and sublethal effects of two common MPs, polystyrene (PS - 4.8-5.8 μm) and poly(methyl methacrylate) (PMMA - 1-40 μm), and their combination (MIX), on the pollinating insect Apis mellifera. For each treatment, we evaluated the oral toxicity of two ecologically relevant and one higher concentration (0.5, 5 and 50 mg/L) and analysed their effects on the immune system and worker survival. As immune activation can alter the cuticular hydrocarbon profile of honey bees, we used gas chromatography-mass spectrometry (GC-MS) to investigate whether MPs lead to changes in the chemical profile of foragers and behavioural assay to test whether such changes affect behavioural patterns of social recognition, undermining overall colony integrity. The results indicate an additive negative effect of PS and PMMA on bee survival and immune response, even at ecologically relevant concentrations. Furthermore, alterations in cuticle profiles were observed with both MPs at the highest and intermediate concentrations, with PMMA being mainly responsible. Both MPs exposure resulted in a reduction in the abundance of several cuticular compounds. Hive entry guards did not show increased inspection or aggressive behaviour towards exposed foragers, allowing them to enter the colony without being treated differently from uncontaminated foragers. These findings raise concerns not only for the health of individual bees, but also for the entire colony, which could be at risk if contaminated nestmates enter the colony undetected, allowing MPs to spread throughout the hive., Competing Interests: Declaration of competing interest All authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Viral infections can be detrimental to the foraging ability of the western honey bee, Apis mellifera. The deformed wing virus (DWV) is the most common honey bee virus and has been proposed as a possible cause of learning and memory impairment. However, evidence for this phenomenon so far has come from artificially infected bees, while less is known about the implications of natural infections with the virus. Using the proboscis extension reflex (PER), we uncovered no significant association between a simple associative learning task and natural DWV load. However, when assessed through a reversal associative learning assay, bees with higher DWV load performed better in the reversal learning phase. DWV is able to replicate in the honey bee mushroom bodies, where the GABAergic signalling pathway has an antagonistic effect on associative learning but is crucial for reversal learning. Hence, we assessed the pattern of expression of several GABA-related genes in bees with different learning responses. Intriguingly, mushroom body expression of selected genes was positively correlated with DWV load, but only for bees with good reversal learning performance. We hypothesise that DWV might improve olfactory learning performance by enhancing the GABAergic inhibition of responses to unrewarded stimuli, which is consistent with the behavioural patterns that we observed. However, at higher disease burdens, which might be induced by an artificial infection or by a severe, natural Varroa infestation, this DWV-associated increase in GABA signalling could impair associative learning as previously reported by other studies., Competing Interests: Competing interests The authors declare no competing or financial interests., (© 2024. Published by The Company of Biologists Ltd.)

Agrochemicals play a vital role in protecting crops and enhancing agricultural production by reducing threats from pests, pathogens and weeds. The toxicological status of honey bees can be influenced by a number of factors, including pesticides. While extensive research has focused on the lethal and sublethal effects of insecticides on individual bees and colonies, it is important to recognise that fungicides and herbicides can also affect bees' health. Unfortunately, in the field, honey bees are exposed to mixtures of compounds rather than single substances. This study aimed to evaluate the effects of a commercial fungicide and a commercial herbicide, both individually and in combination, on honey bees. Mortality assays, biomarkers and learning and memory tests were performed, and the results were integrated to assess the toxicological status of honey bees. Neurotoxicity (acetylcholinesterase and carboxylesterase activities), detoxification and metabolic processes (glutathione S-transferase and alkaline phosphatase activities), immune system function (lysozyme activity and haemocytes count) and genotoxicity biomarkers (Nuclear Abnormalities assay) were assessed. The fungicide Sakura® was found to activate detoxification enzymes and affect alkaline phosphatase activity. The herbicide Elegant 2FD and the combination of both pesticides showed neurotoxic effects and induced detoxification processes. Exposure to the herbicide/fungicide mixture impaired learning and memory in honey bees. This study represents a significant advance in understanding the toxicological effects of commonly used commercial pesticides in agriculture and contributes to the development of effective strategies to mitigate their adverse effects on non-target insects., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Scientific research on the impact of microplastics (MPs) in terrestrial systems is still emerging, but it has confirmed adverse health effects in organisms exposed to plastics. Although recent studies have shown the toxicological effects of individual MPs polymers on honey bees, the effects of different polymer combinations on cognitive and behavioural performance remain unknown. To fill this knowledge gap, we investigated the effects of oral exposure to spherical MPs on cognitive performance and brain accumulation in the honey bee Apis mellifera. We evaluated the acute toxicity, after a two-day exposure, of polystyrene (PS - 4.8-5.8 μm) and plexiglass (Poly(methyl methacrylate), or PMMA - 1-40 μm) MPs, and a combination of the two (MIX), at two environmentally relevant and one higher concentration (0.5, 5 and 50 mg L -1 ) and analysed their effects on sucrose responsiveness and appetitive olfactory learning and memory. We also used fluorescent thermoset amino formaldehyde MPs (1-5 μm) to explore whether microspheres of this diameter could penetrate the insect blood-brain barrier (BBB), using Two-Photon Fluorescence Microscopy (TPFM) in combination with an optimized version of the DISCO clearing technique. The results showed that PS reduced sucrose responsiveness, while PMMA had no significant effect; however, the combination had a marked negative effect on sucrose responsiveness. PMMA, PS, and MIX impaired bee learning and memory in bees, with PS showing the most severe effects. 3D brain imaging analysis using TFPM showed that 1-5 μm MPs penetrated and accumulated in the brain after only three days of oral exposure. These results raise concerns about the potential mechanical, cellular, and biochemical damage that MPs may cause to the central nervous system., Competing Interests: Declaration of competing interest The authors declare no competing interests., (Copyright © 2023 The Author(s). Published by Elsevier B.V. All rights reserved.)

Biopesticides are considered eco-friendly alternatives to synthetic agrochemicals. However, their impact on non-target organisms is still poorly understood. Social wasps, in particular, are a largely neglected group when it comes to risk assessment of plant protection products, despite the relevant ecological and economic services provided by these insects. In the present study, we evaluated the impact of a common biopesticide, the entomopathogenic fungus Beauveria bassiana, on the paper wasp Polistes dominula. We adopted a holistic approach in ecotoxicology by focusing not only on the detrimental effects on isolated individuals, but also on the whole colony. Both adult wasps belonging to different castes and immature larvae were topically exposed to a field-realistic concentration of fungal spores from the commercial strain of B. bassiana ATCC 74040 to assess the impact of the biopesticide on their survival, behavior and physiology. Our results showed that the fungus causes a number of adverse effects on P. dominula, that include increased mortality, altered locomotion and feeding rate, selective ejection of exposed larvae from nests, reduced oviposition rate and ovary development in foundresses, and colony failure. Our findings provide new insights on the often-neglected sublethal effects of pollutants that can jeopardize not only individual beneficial insects, but also the delicate social balance of their colonies and their valuable ecosystem services, highlighting that the natural origin of plant-protection products does not always guarantee environmental safety., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

In the last one-hundred years, the exponential expansion of wine making has artificialized the agricultural landscape as well as its microbial diversity, spreading human selected Saccharomyces cerevisiae strains. Evidence showed that social wasps can harbor a significant fraction of the yeast phenotypic diversity of a given area of wine production, allowing different strains to overwinter and mate in their gut. The integrity of the wasp-yeast ecological interaction is of paramount importance to maintain the resilience of microbial populations associated to wine aromatic profiles. In a field experiment, we verified whether Polistes dominula wasps, reared in laboratory and fed with a traceable S. cerevisiae strain, could be a useful tool to drive the controlled yeast dispersion directly on grapes. The demonstration of the biotechnological potential of social insects in organic wine farming lays the foundations for multiple applications including maintenance of microbial biodiversity and rewilding vineyards through the introduction of wasp associated microbiomes., (© 2023. Springer Nature Limited.)

As synthetic pesticides play a major role in pollinator decline worldwide, biopesticides have been gaining increased attention to develop more sustainable methods for pest management in agriculture. These biocontrol agents are usually considered as safe for non-target species, such as pollinators. Unfortunately, when it comes to non-target insects, only the acute or chronic effects on survival following exposure to biopesticides are tested. Although international boards have highlighted the need to include also behavioral and morphophysiological traits when assessing risks of plant protection products on pollinators, no substantial concerns have been raised about the risks associated with sublethal exposure to these substances. Here, we provide a comprehensive review of the studies investigating the potential adverse effects of biopesticides on different taxa of pollinators (bees, butterflies, moths, beetles, flies, and wasps). We highlight the fragmentary knowledge on this topic and the lack of a systematic investigation of these negative effects of biopesticides on insect pollinators. We show that all the major classes of biopesticides, besides their direct toxicity, can also cause a plethora of more subtle detrimental effects in both solitary and social species of pollinators. Although research in this field is growing, the current risk assesment approach does not suffice to properly assess all the potential side-effects that these agents of control may have on pollinating insects. Given the urgent need for a sustainable agriculture and wildlife protection, it appears compelling that these so far neglected detrimental effects should be thoroughly assessed before allegedly safe biopesticides can be used in the field and, in this view, we provide a perspective for future directions., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

The massive use of plastic has contributed to huge quantities of hazardous refuse at a global scale and represents one of the most prominent issues of the Anthropocene. Microplastics (MPs) have been detected in almost all environments and pose a potential threat to a variety of plant and animal species. Many studies have reported a variety of effects, from negligible to detrimental, of MPs to aquatic organisms. Conversely, much less is known about their effect on terrestrial biota, and particularly on animal behavior and cognition. We assessed the oral toxicity of polyethylene (PE) MPs at three different concentrations (0.5, 5, and 50 mg L -1 ), and at different timescales (1 day and 7 days of exposure) and tested for their effects on survival, food intake, sucrose responsiveness, habituation to sucrose and appetitive olfactory learning and memory in the honey bee Apis mellifera. We found that workers were not completely unaffected by acute and prolonged ingestion of this polymer. A significant effect of PE on bee mortality was found for the highest concentration but not for lower ones. PE affected feeding behavior in a concentration-dependent manner, with bees consuming more food than controls when exposed to low concentration PE. Regarding our behavioral and cognitive experiments, the high concentration PE was found to affect only bees' ability to respond consistently to sucrose but not sucrose sensitivity, habituation to sucrose or learning and memory abilities, even for prolonged exposure to PE. While these last results may look somewhat encouraging, we discussed why caution is warranted before ruling out the possibility that PE particles at environmental concentrations are harmful to honey bees., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

The ability to vary the characteristics of one's voice is a critical feature of human communication. Understanding whether and how animals change their calls will provide insights into the evolution of language. We asked to what extent the vocalizations of penguins, a phylogenetically distant species from those capable of explicit vocal learning, are flexible and responsive to their social environment. Using a principal components (PCs) analysis, we reduced 14 vocal parameters of penguin's contact calls to four PCs, each comprising highly correlated parameters and which can be categorized as fundamental frequency, formant frequency, frequency modulation, and amplitude modulation rate and duration. We compared how these differed between individuals with varying degrees of social interactions: same-colony versus different-colony, same colony over 3 years and partners versus non-partners. Our analyses indicate that the more penguins experience each other's calls, the more similar their calls become over time, that vocal convergence requires a long time and relative stability in colony membership, and that partners' unique social bond may affect vocal convergence differently than non-partners. Our results suggest that this implicit form of vocal plasticity is perhaps more widespread across the animal kingdom than previously thought and may be a fundamental capacity of vertebrate vocalization.

Individuals differing in their cognitive abilities and foraging strategies may confer a valuable benefit to their social groups as variability may help them to respond flexibly in scenarios with different resource availability. Individual learning proficiency may either be absolute or vary with the complexity or the nature of the problem considered. Determining whether learning ability correlates between tasks of different complexity or between sensory modalities is of high interest for research on brain modularity and task-dependent specialization of neural circuits. The honeybee Apis mellifera constitutes an attractive model to address this question because of its capacity to successfully learn a large range of tasks in various sensory domains. Here, we studied whether the performance of individual bees in a simple visual discrimination task (a discrimination between two visual shapes) is stable over time and correlates with their capacity to solve either a higher-order visual task (a conceptual discrimination based on spatial relationships between objects) or an elemental olfactory task (a discrimination between two odorants). We found that individual learning proficiency within a given task was maintained over time and that some individuals performed consistently better than others within the visual modality, thus showing consistent aptitude across visual tasks of different complexity. By contrast, performance in the elemental visual-learning task did not predict performance in the equivalent elemental olfactory task. Overall, our results suggest the existence of cognitive specialization within the hive, which may contribute to ecological social success., Competing Interests: Competing interests The authors declare no competing or financial interests., (© 2021. Published by The Company of Biologists Ltd.)

Decision-making processes face the dilemma of being accurate or faster, a phenomenon that has been described as speed-accuracy trade-off in numerous studies on animal behaviour. In social insects, discriminating between colony members and aliens is subject to this trade-off as rapid and accurate rejection of enemies is of primary importance for the maintenance and ecological success of insect societies. Recognition cues distinguishing aliens from nestmates are embedded in the cuticular hydrocarbon (CHC) layer and vary among colonies. In walking carpenter ants, exposure to formic acid (FA), an alarm pheromone, improves the accuracy of nestmate recognition by decreasing both alien acceptance and nestmate rejection. Here, we studied the effect of FA exposure on the spontaneous aggressive mandible opening response (MOR) of harnessed Camponotus aethiops ants presented with either nestmate or alien CHCs. FA modulated both MOR accuracy and the latency to respond to odours of conspecifics. In particular, FA decreased the MOR towards nestmates but increased it towards aliens. Furthermore, FA decreased MOR latency towards aliens but not towards nestmates. As response latency can be used as a proxy of response speed, we conclude that contrary to the prediction of the speed-accuracy trade-off theory, ants did not trade off speed against accuracy in the process of nestmate recognition., Competing Interests: Competing interests The authors declare no competing or financial interests., (© 2021. Published by The Company of Biologists Ltd.)

Floral nectar is a pivotal element of the intimate relationship between plants and pollinators. Nectars are composed of a plethora of nutritionally valuable compounds but also hundreds of secondary metabolites (SMs) whose function remains elusive. Here we performed a set of behavioural experiments to study whether five ubiquitous nectar non-protein amino acids (NPAAs: β-alanine, GABA, citrulline, ornithine and taurine) interact with gustation, feeding preference, and learning and memory in Apis mellifera. We showed that foragers were unable to discriminate NPAAs from water when only accessing antennal chemo-tactile information and that freely moving bees did not exhibit innate feeding preferences for NPAAs. Also, NPAAs did not alter food consumption or longevity in caged bees over 10 days. Taken together our data suggest that natural concentrations of NPAAs did not alter nectar palatability to bees. Olfactory conditioning assays showed that honey bees were more likely to learn a scent when it signalled a sucrose reward containing either β-alanine or GABA, and that GABA enhanced specific memory retention. Conversely, when ingested two hours prior to conditioning, GABA, β-alanine, and taurine weakened bees' acquisition performances but not specific memory retention, which was enhanced in the case of β-alanine and taurine. Neither citrulline nor ornithine affected learning and memory. NPAAs in nectars may represent a cooperative strategy adopted by plants to attract beneficial pollinators.

Background: To develop a tool for assessing normalcy of the thoracic aorta (TA) by echocardiography, based on either a linear regression model (Z-score), or a machine learning technique, namely one-class support vector machine (OC-SVM) (Q-score). Methods: TA diameters were measured in 1112 prospectively enrolled healthy subjects, aging 5 to 89 years. Considering sex, age and body surface area we developed two calculators based on the traditional Z-score and the novel Q-score. The calculators were compared in 198 adults with TA > 40 mm, and in 466 patients affected by either Marfan syndrome or bicuspid aortic valve (BAV). Results: Q-score attained a better Area Under the Curve (0.989; 95% CI 0.984-0.993, sensitivity = 97.5%, specificity = 95.4%) than Z-score (0.955; 95% CI 0.942-0.967, sensitivity = 81.3%, specificity = 93.3%; p < 0.0001) in patients with TA > 40 mm. The prevalence of TA dilatation in Marfan and BAV patients was higher as Z-score > 2 than as Q-score < 4% (73.4% vs. 50.09%, p < 0.00001). Conclusions: Q-score is a novel tool for assessing TA normalcy based on a model requiring less assumptions about the distribution of the relevant variables. Notably, diameters do not need to depend linearly on anthropometric measurements. Additionally, Q-score can capture the joint distribution of these variables with all four diameters simultaneously, thus accounting for the overall aortic shape. This approach results in a lower rate of predicted TA abnormalcy in patients at risk of TA aneurysm. Further prognostic studies will be necessary for assessing the relative effectiveness of Q-score versus Z-score.

The entomopathogenic fungus Beauveria bassiana is a widely used biopesticide that is considered as an effective alternative to classical agrochemicals. B. bassiana is thought to be safe for pollinators although little is known about its side-effects on pollinators' behaviour and cognition. Here, we focused on honey bees and used the proboscis extension response (PER) protocol to assess whether B. bassiana affects individual sucrose responsiveness, non-associative and associative olfactory learning and memory. Fungus-treated bees displayed an enhanced sucrose responsiveness, which could not be explained by metabolic alterations. Strikingly, exposed bees were twice as inconsistent as controls in response to sucrose, showing PER to lower but not to higher sucrose concentrations. Exposed bees habituated less to sucrose and had a better acquisition performance in the conditioning phase than controls. Further, neither mid- nor long-term memory were affected by the fungus. As sucrose responsiveness is the main determinant of division of foraging labour, these changes might unsettle the numerical ratio between the sub-castes of foragers leading to suboptimal foraging. Although the use of biocontrol strategies should be preferred over chemical pesticides, careful assessment of their side-effects is crucial before claiming that they are safe for pollinators.

Since their discovery in insects, pheromones are considered as ubiquitous and stereotyped chemical messengers acting in intraspecific animal communication. Here we studied the effect of pheromones in a different context as we investigated their capacity to induce persistent modulations of associative learning and memory. We used honey bees, Apis mellifera, and combined olfactory conditioning and pheromone preexposure with disruption of neural activity and two-photon imaging of olfactory brain circuits, to characterize the effect of pheromones on olfactory learning and memory. Geraniol, an attractive pheromone component, and 2-heptanone, an aversive pheromone, improved and impaired, respectively, olfactory learning and memory via a durable modulation of appetitive motivation, which left odor processing unaffected. Consistently, interfering with aminergic circuits mediating appetitive motivation rescued or diminished the cognitive effects induced by pheromone components. We thus show that these chemical messengers act as important modulators of motivational processes and influence thereby animal cognition.

Image source forensics is widely considered as one of the most effective ways to verify in a blind way digital image authenticity and integrity. In the last few years, many researchers have applied data-driven approaches to this task, inspired by the excellent performance obtained by those techniques on computer vision problems. In this survey, we present the most important data-driven algorithms that deal with the problem of image source forensics. To make order in this vast field, we have divided the area in five sub-topics: source camera identification, recaptured image forensic, computer graphics (CG) image forensic, GAN-generated image detection, and source social network identification. Moreover, we have included the works on anti-forensics and counter anti-forensics. For each of these tasks, we have highlighted advantages and limitations of the methods currently proposed in this promising and rich research field.

The 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, thus uncovering an unexpected effect of an alarm pheromone on responses to nestmates. Nestmate discrimination accuracy was improved via a decrease in both types of errors, a result that cannot be explained by a shift in the acceptance threshold. We propose that formic acid increases the amount of information available to the ants, thus decreasing the perceived phenotypic overlap between nestmate and nonnestmate recognition cues. This mechanism for improved discrimination reveals a novel function of alarm pheromones in recognition processes and may have far-reaching implications in our understanding of the modus operandi of recognition systems in general.

The expertise of humans for recognizing faces is largely based on holistic processing mechanism, a sophisticated cognitive process that develops with visual experience. The various visual features of a face are thus glued together and treated by the brain as a unique stimulus, facilitating robust recognition. Holistic processing is known to facilitate fine discrimination of highly similar visual stimuli, and involves specialized brain areas in humans and other primates. Although holistic processing is most typically employed with face stimuli, subjects can also learn to apply similar image analysis mechanisms when gaining expertise in discriminating novel visual objects, like becoming experts in recognizing birds or cars. Here, we ask if holistic processing with expertise might be a mechanism employed by the comparatively miniature brains of insects. We thus test whether honeybees ( Apis mellifera ) and/or wasps ( Vespula vulgaris ) can use holistic-like processing with experience to recognize images of human faces, or Navon-like parameterized-stimuli. These insect species are excellent visual learners and have previously shown ability to discriminate human face stimuli using configural type processing. Freely flying bees and wasps were consequently confronted with classical tests for holistic processing, the part-whole effect and the composite-face effect. Both species could learn similar faces from a standard face recognition test used for humans, and their performance in transfer tests was consistent with holistic processing as defined for studies on humans. Tests with parameterized stimuli also revealed a capacity of honeybees, but not wasps, to process complex visual information in a holistic way, suggesting that such sophisticated visual processing may be far more spread within the animal kingdom than previously thought, although may depend on ecological constraints.

We introduce an architecture based on deep hierarchical decompositions to learn effective representations of large graphs. Our framework extends classic R-decompositions used in kernel methods, enabling nested part-of-part relations. Unlike recursive neural networks, which unroll a template on input graphs directly, we unroll a neural network template over the decomposition hierarchy, allowing us to deal with the high degree variability that typically characterize social network graphs. Deep hierarchical decompositions are also amenable to domain compression, a technique that reduces both space and time complexity by exploiting symmetries. We show empirically that our approach is able to outperform current state-of-the-art graph classification methods on large social network datasets, while at the same time being competitive on small chemobiological benchmark datasets., (Copyright © 2018 Orsini, Baracchi and Frasconi.)

Lateralization is a fundamental property of the human brain that affects perceptual, motor, and cognitive processes. It is now acknowledged that left-right laterality is widespread across vertebrates and even some invertebrates such as fruit flies and bees. Honeybees, which learn to associate an odorant (the conditioned stimulus, CS) with sucrose solution (the unconditioned stimulus, US), recall this association better when trained using their right antenna than they do when using their left antenna. Correspondingly, olfactory sensilla are more abundant on the right antenna and odor encoding by projection neurons of the right antennal lobe results in better odor differentiation than those of the left one. Thus, lateralization arises from asymmetries both in the peripheral and central olfactory system, responsible for detecting the CS. Here, we focused on the US component and studied if lateralization exists in the gustatory system of Apis mellifera . We investigated whether sucrose sensitivity is lateralized both at the level of the antennae and the fore-tarsi in two independent groups of bees. Sucrose sensitivity was assessed by presenting bees with a series of increasing concentrations of sucrose solution delivered either to the left or the right antenna/tarsus and measuring the proboscis extension response to these stimuli. Bees experienced two series of stimulations, one on the left and the other on the right antenna/tarsus. We found that tarsal responsiveness was similar on both sides and that the order of testing affects sucrose responsiveness. On the contrary, antennal responsiveness to sucrose was higher on the right than on the left side, and this effect was independent of the order of antennal stimulation. Given this asymmetry, we also investigated antennal lateralization of habituation to sucrose. We found that the right antenna was more resistant to habituation, which is consistent with its higher sucrose sensitivity. Our results reveal that the gustatory system presents a peripheral lateralization that affects stimulus detection and non-associative learning. Contrary to the olfactory system, which is organized in two distinct brain hemispheres, gustatory receptor neurons converge into a single central region termed the subesophagic zone (SEZ). Whether the SEZ presents lateralized gustatory processing remains to be determined.

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 because of their high sensitivity. We then studied the ability of ants to learn and remember odor-heat associations using 75°C as the 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 a 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., Competing Interests: Competing interestsThe authors declare no competing or financial interests., (© 2017. Published by The Company of Biologists Ltd.)

Pheromones are chemical messengers that trigger stereotyped behaviors and/or physiological processes in individuals of the same species. Recent reports suggest that pheromones can modulate behaviors not directly related to the pheromonal message itself and contribute, in this way, to behavioral plasticity. We tested this hypothesis by studying the effect of pheromones on sucrose responsiveness and habituation in honey bees. We exposed workers to three pheromone components: geraniol, which in nature is used in an appetitive context, and isopentyl acetate (IPA) and 2-heptanone (2H), which signal aversive situations. Pheromones associated with an aversive context induced a significant decrease of sucrose responsiveness as 40% and 60% of bees exposed to IPA and 2H, respectively, did not respond to any sucrose concentration. In bees that responded to sucrose, geraniol enhanced sucrose responsiveness while 2H, but not IPA, had the opposite effect. Geraniol and IPA had no effect on habituation while 2H induced faster habituation than controls. Overall, our results demonstrate that pheromones modulate reward responsiveness and to a lower degree habituation. Through their effect on sucrose responsiveness they could also affect appetitive associative learning. Thus, besides conveying stereotyped messages, pheromones may contribute to individual and colony-level plasticity by modulating motivational state and learning performances.

While our conceptual understanding of emotions is largely based on human subjective experiences, research in comparative cognition has shown growing interest in the existence and identification of "emotion-like" states in non-human animals. There is still ongoing debate about the nature of emotions in animals (especially invertebrates), and certainly their existence and the existence of certain expressive behaviors displaying internal emotional states raise a number of exciting and challenging questions. Interestingly, at least superficially, insects (bees and flies) seem to fulfill the basic requirements of emotional behavior. Yet, recent works go a step further by adopting terminologies and interpretational frameworks that could have been considered as crude anthropocentrism and that now seem acceptable in the scientific literature on invertebrate behavior and cognition. This change in paradigm requires, therefore, that the question of emotions in invertebrates is reconsidered from a cautious perspective and with parsimonious explanations. Here we review and discuss this controversial topic based on the recent finding that bumblebees experience positive emotions while experiencing unexpected sucrose rewards, but also incorporating a broader survey of recent literature in which similar claims have been done for other invertebrates. We maintain that caution is warranted before attributing emotion-like states to honey bees and bumble bees as some experimental caveats may undermine definitive conclusions. We suggest that interpreting many of these findings in terms of motivational drives may be less anthropocentrically biased and more cautious, at least until more careful experiments warrant the use of an emotion-related terminology.

Many plants defend themselves against herbivores by chemical deterrents in their tissues and the presence of such substances in floral nectar means that pollinators often encounter them when foraging. The effect of such substances on the foraging behaviour of pollinators is poorly understood. Using artificial flowers in tightly-controlled laboratory settings, we examined the effects of the alkaloid nicotine on bumblebee foraging performance. We found that bumblebees confronted simultaneously with two equally rewarded nicotine-containing and nicotine-free flower types are deterred only by unnaturally high nicotine concentrations. This deterrence disappears or even turns into attraction at lower nectar-relevant concentrations. The alkaloid has profound effects on learning in a dose-dependent manner. At a high natural dose, bees learn the colour of a nicotine-containing flower type more swiftly than a flower type with the same caloric value but without nicotine. Furthermore, after experiencing flowers containing nicotine in any tested concentration, increasing numbers of bumblebees stay more faithful to these flowers, even if they become a suboptimal choice in terms of reward. These results demonstrate that alkaloids enhance pollinator flower constancy, opening new perspectives in co-evolutionary process between plants and pollinators.

Social insects excel in discriminating nestmates from intruders, typically relying on colony odours. Remarkably, some wasp species achieve such discrimination using visual information. However, while it is universally accepted that odours mediate a group level recognition, the ability to recognise colony members visually has been considered possible only via individual recognition by which wasps discriminate 'friends' and 'foes'. Using geometric morphometric analysis, which is a technique based on a rigorous statistical theory of shape allowing quantitative multivariate analyses on structure shapes, we first quantified facial marking variation of Liostenogaster flavolineata wasps. We then compared this facial variation with that of chemical profiles (generated by cuticular hydrocarbons) within and between colonies. Principal component analysis and discriminant analysis applied to sets of variables containing pure shape information showed that despite appreciable intra-colony variation, the faces of females belonging to the same colony resemble one another more than those of outsiders. This colony-specific variation in facial patterns was on a par with that observed for odours. While the occurrence of face discrimination at the colony level remains to be tested by behavioural experiments, overall our results suggest that, in this species, wasp faces display adequate information that might be potentially perceived and used by wasps for colony level recognition.

The presence of antimicrobial secondary metabolites in nectar suggests that pollinators, which are threatened globally by emergent disease, may benefit from the consumption of nectars rich in these metabolites. We tested whether nicotine, a nectar secondary metabolite common in Solanaceae and Tilia species, is used by parasitized bumblebees as a source of self-medication , using a series of toxicological, microbiological and behavioural experiments. Caged bees infected with Crithidia bombi had a slight preference for sucrose solution laced with the alkaloid and behavioural tests showed that the parasite infection induced an increased consumption of nicotine during foraging activity, though nicotine had an appetite-reducing effect overall. When ingested, nicotine delayed the progression of a gut infection in bumblebees by a few days, but dietary nicotine did not clear the infection, and after 10 days the parasite load approached that of control bees. Moreover, when pathogens were exposed to the alkaloid prior to host ingestion, the protozoan's viability was not directly affected, suggesting that anti-parasite effects were relatively weak. Nicotine consumption in a single dose did not impose any cost even in starved bees but the alkaloid had detrimental effects on healthy bees if consistently consumed for weeks. These toxic effects disappeared in infected bees, suggesting that detoxification costs might have been counterbalanced by the advantages in slowing the progression of the infection. Nicotine consumption did not affect bee lifespan but the reduction in the parasite load may have other likely unexplored subtle benefits both for individual bees and their colony.  Potential evidence for self-medication is discussed. The contention that secondary metabolites in nectar may be under selection from pollinators, or used by plants to enhance their own reproductive success, remains to be confirmed.

The presence of antimicrobial secondary metabolites in nectar suggests that pollinators, which are threatened globally by emergent disease, may benefit from the consumption of nectars rich in these metabolites. We tested whether nicotine, a nectar secondary metabolite common in Solenaceae and Tilia species, is used by parasitized bumblebees as a source of self-medication , using a series of toxicological, microbiological and behavioural experiments. Caged bees infected with Crithidia bombi [TI1] had a slight preference for sucrose solution laced with the alkaloid and behavioural tests showed that the parasite infection induced an increased consumption of nicotine during foraging activity. When ingested, nicotine delayed the progression of a gut infection in bumblebees by a few days, but dietary nicotine did not clear the infection, and after 10 days the parasite load approached that of control bees. Moreover, when pathogens were exposed to the alkaloid prior to host ingestion the protozoan's viability was not directly affected, suggesting that anti-parasite effects were relatively weak. Nicotine consumption in a single dose did not impose any cost even in food-stressed bees (starved) but the alkaloid had detrimental effects on healthy bees if consistently consumed for weeks. These toxic effects disappeared in infected bees suggesting that detoxification costs might have been counterbalanced by the advantages in slowing the progression of the infection. Nonetheless we did not find a benefit of nicotine consumption in terms of life expectancy of infected bees, making these findings difficult to interpret. Our results indicate that caution is warranted in interpreting impacts of plant metabolites on insect parasites and suggest that the conditions under which nicotine consumption provides benefits to either bees or plants remain to be identified. The contention that secondary metabolites in nectar may be under selection from pollinators, or used by plants to enhance their own reproductive success, remains to be confirmed.

Chemical compounds covering the insect cuticle have several functions ranging from protection against water loss to inter- and intra-specific communication. Their composition is determined by several intrinsic and extrinsic factors. Among these factors, laboratory rearing has been poorly investigated even though it has a strong potential for biasing behavioral experiments. We selected an invasive species with unknown cuticular mixtures as a model. Our aim was to describe its mixtures and to determine if highly simplified laboratory rearing conditions interact with sexual signatures. We analyzed the cuticle by means of two different techniques - gas chromatography/mass spectrometry (GC/MS) and matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) - to obtain data on a wide range of compounds with different molecular weight. We found that both sets of chemicals showed correlations with gender but also that cuticular waxes detected by GC/MS were highly dependent on rearing conditions, with a strong bias in sexual dimorphism. Conversely, the heavier signatures detected by MALDI-TOF showed a less clear diversification between sexes, although the discrimination power was unaffected by rearing conditions. The biological and practical implications of our findings are discussed., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Social life is generally associated with an increased risk of disease transmission, but at the same time it allows behavioural defence at both the individual and collective level. Bees infected with deformed-wing virus were introduced into observation hives; through behavioural observations and chemical analysis of cuticular hydrocarbons from healthy and infected bees, we offer the first evidence that honeybee colonies can detect and remove infected adult bees, probably by recognising the cuticular hydrocarbon profiles of sick individuals. We also found that health-compromised colonies were less efficient at defending themselves against infected bees, thus facing an ever increasing risk of epidemics. This work reveals a new antiseptic behaviour that can only be interpreted as an adaptation at colony level and one which should be considered an element of the social immunity system of the beehive, re-enforcing the view of a colony as an integrated organism., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Sociality is associated with an increased risk of disease transmission and one of the first defense of the insect colonies is represented by antimicrobial secretions. In many eusocial hymenopteran species venom glands represent one of the most important source of antimicrobial substances. It is known that in highly eusocial species the venom is spread on both the cuticle of insects and the comb, thus becoming a component of the so called "social immunity". So far, it is never been ascertained whether this phenomenon is also present in more primitively eusocial and incipiently eusocial groups. Using incipiently eusocial hover wasps as model, we demonstrate that venom is present on insect cuticles and that it strongly acts against microorganisms. By contrast, the nest, regardless of materials, does not represent a ''medium" where the venom is deposited by wasps in order to act as a social antiseptic weapon. Our findings discussed in an evolutionary perspective indicate that a certain degree of sociality or a sufficient number of individuals in an insect society are thresholds to be reached for the rise of complex and efficient forms of collective and social immunity as mechanisms of resistance to diseases., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

The honey bee colonies, with the relevant number of immature brood and adults, and stable, high levels of humidity and temperatures of their nests, result in suitable environments for the development of microorganisms including pathogens. In response, honey bees evolved several adaptations to face the increased risks of epidemic diseases. As the antimicrobial venom peptides of Apis mellifera are present both on the cuticle of adult bees and on the nest wax it has been recently suggested that these substances act as a social antiseptic device. Since the use of venom by honey bees in the context of social immunity needs to be more deeply investigated, we extended the study of this potential role of the venom to different species of the genus Apis (A. mellifera, Apis dorsata, Apis cerana and Apis andreniformis) using MALDI-TOF mass spectrometry techniques. In particular we investigated whether (similarly to A. mellifera) the venom is spread over the body cuticle and on the comb wax of these three Asian species. Our results confirm the idea that the venom functions are well beyond the classical stereotype of defence against predators, and suggest that the different nesting biology of these species may be related to the use of the venom in a social immunity context. The presence of antimicrobial peptides on the comb wax of the cavity-dwelling species and on the cuticle of workers of all the studied species represents a good example of "collective immunity" and a component of the "social immunity " respectively., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

The fraction between 950 and 4000Da of the venom of Apis mellifera has been analyzed with MALDI-TOF mass spectrometry and statistical facilities of the ClinProTools software. Consistent differences in the composition of this venom fraction were observed between queens and workers while younger and older workers (nurses and guards as well as foragers) differ for the relative percentages of two well known cytolytic peptides, namely Melittin and Apamin. Total in situ body methanol extracts and methanol micro-extractions on the cuticle of various parts of the body of drones and females confirmed that venom peptides are smeared on the body surface of females in a not yet clarified way. The observation that venom peptides have been found also on comb wax rises the hypothesis that the use of venom as antimicrobial agent makes part of the social immunity system of A. mellifera., (Copyright (c) 2009 Elsevier Ltd. All rights reserved.)