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ABSTRACT Visual recognition of three-dimensional signals, such as faces, is challenging because the signals appear different from different viewpoints. A flexible but cognitively challenging solution is viewpoint-independent recognition, where receivers identify signals from novel viewing angles. Here, we used same/different concept learning to test viewpoint-independent face recognition in Polistes fuscatus, a wasp that uses facial patterns to individually identify conspecifics. We found that wasps use extrapolation to identify novel views of conspecific faces. For example, wasps identify a pair of pictures of the same wasp as the ‘same’, even if the pictures are taken from different views (e.g. one face 0 deg rotation, one face 60 deg rotation). This result is notable because it provides the first evidence of view-invariant recognition via extrapolation in an invertebrate. The results suggest that viewpoint-independent recognition via extrapolation may be a widespread strategy to facilitate individual face recognition. 

Abstract Although much work has focused on non-social personality traits such as activity, exploration, and neophobia, there is a growing appreciation that social personality traits play an important role in group dynamics, disease transmission, and fitness and that social personality traits may be linked to non-social personality traits. These relationships are important because behavioral syndromes, defined here as correlated behavioral phenotypes, can constrain evolutionary responses. However, the strength and direction of relationships between social and non-social personality traits remain unclear. In this project, we examine social and non-social personality traits, and the relationships between them, in the paper wasp Polistes fuscatus. With a novel assay, we identify 5 personality traits, 2 non-social (exploration and activity), and 3 social (aggression, affiliation, and antennation) personality traits. We also find that social and non-social personality traits are phenotypically linked. We find a positive correlation between aggression and activity and a negative correlation between affiliation and activity. We also find a positive correlation between exploration and activity. Our work is an important step in understanding how phenotypic linkage between social and non-social behaviors may influence behavioral evolution. As a burgeoning model system for the study of genetic and neurobiological mechanisms of social behavior, Polistes fuscatus has the potential to add to this work by exploring the causes and consequences of individual behavioral variation. 

Abstract Signals and receiver responses often vary across a species’ geographic range. Effective communication requires a match between signal and receiver response, so there is much interest in the developmental mechanisms that maintain this link. Two potential mechanisms are genetic covariance between signal and receiver response and plasticity where individuals adjust their phenotype based on their partner’s phenotype. Here, we test how plasticity contributes to geographic variation in individual face recognition in Polistes fuscatus wasps. Previous work has shown that P. fuscatus from Michigan, USA (MI) have variable facial patterns used for individual recognition, while P. fuscatus from central Pennsylvania, USA (PA) lack variable facial patterns and are unable to learn individual conspecifics. We experimentally altered rearing environment, so wasps were either reared with their own population or in a common garden with wasps from both populations. Then, we tested the wasps’ capacity to learn and remember individual conspecific faces. Consistent with previous work, MI wasps reared with MI wasps were adept at learning conspecific faces, while PA wasps reared with PA wasps were unable to learn conspecific faces. However, MI and PA wasps reared in a common garden developed similar, intermediate capacity for individual face learning. These results indicate that individual face learning in Polistes wasps is highly plastic and responsive to the social environment. Plasticity in receiver responses may be a common mechanism mediating geographic differences in non-sexual signaling systems and may play a role in maintaining links between signals and receiver responses in geographically variable communication systems. 

Abstract Vairimorpha (=Nosema) ceranaeis a widespread pollinator parasite that commonly infects honeybees and wild pollinators, including bumblebees. Honeybees are highly competentV. ceranaehosts and previous work in experimental flight cages suggestsV. ceranaecan be transmitted during visitation to shared flowers. However, the relationship between floral visitation in the natural environment and the prevalence ofV. ceranaeamong multiple bee species has not been explored. Here, we analyzed the number and duration of pollinator visits to particular components of squash flowers—including the petals, stamen, and nectary—at six farms in southeastern Michigan, USA. We also determined the prevalence ofV. ceranaein honeybees and bumblebees at each site. Our results showed that more honeybee flower contacts and longer duration of contacts with pollen and nectar were linked with greaterV. ceranaeprevalence in bumblebees. Honeybee visitation patterns appear to have a disproportionately large impact onV. ceranaeprevalence in bumblebees even though honeybees are not the most frequent flower visitors. Floral visitation by squash bees or other pollinators was not linked withV. ceranaeprevalence in bumblebees. Further,V. ceranaeprevalence in honeybees was unaffected by floral visitation behaviors by any pollinator species. These results suggest that honeybee visitation behaviors on shared floral resources may be an important contributor to increasedV. ceranaespillover to bumblebees in the field. Understanding howV. ceranaeprevalence is influenced by pollinator behavior in the shared floral landscape is critical for reducing parasite spillover into declining wild bee populations. 

Abstract The dilution effect hypothesis posits that increasing biodiversity reduces infectious disease transmission. Here, we propose that habitat quality might modulate this negative biodiversity–disease relationship. Habitat may influence pathogen prevalence directly by affecting host traits like nutrition and immune response (we coined the term “habitat–disease relationship” to describe this phenomenon) or indirectly by changing host biodiversity (biodiversity–disease relationship). We used a path model to test the relative strength of links between habitat, biodiversity, and pathogen prevalence in a pollinator–virus system. High‐quality habitat metrics were directly associated with viral prevalence, providing evidence for a habitat–disease relationship. However, the strength and direction of specific habitat effects on viral prevalence varied based on the characteristics of the habitat, host, and pathogen. In general, more natural area and richness of land‐cover types were directly associated with increased viral prevalence, whereas greater floral density was associated with reduced viral prevalence. More natural habitat was also indirectly associated with reduced prevalence of two key viruses (black queen cell virus and deformed wing virus) via increased pollinator species richness, providing evidence for a habitat‐mediated dilution effect on viral prevalence. Biodiversity–disease relationships varied across viruses, with the prevalence of sacbrood virus not being associated with any habitat quality or pollinator community metrics. Across all viruses and hosts, habitat–disease and biodiversity–disease paths had effects of similar magnitude on viral prevalence. Therefore, habitat quality is a key driver of variation in pathogen prevalence among communities via both direct habitat–disease and indirect biodiversity–disease pathways, though the specific patterns varied among different viruses and host species. Critically, habitat–disease relationships could either contribute to or obscure dilution effects in natural systems depending on the relative strength and direction of the habitat–disease and biodiversity–disease pathways in that host–pathogen system. Therefore, habitat may be an important driver in the complex interactions between hosts and pathogens. 

Animals live in visually complex environments. As a result, visual systems have evolved mechanisms that simplify visual processing and allow animals to focus on the information that is most relevant to adaptive decision making. This review explores two key mechanisms that animals use to efficiently process visual information: categorization and specialization. Categorization occurs when an animal's perceptual system sorts continuously varying stimuli into a set of discrete categories. Specialization occurs when particular classes of stimuli are processed using distinct cognitive operations that are not used for other classes of stimuli. We also describe a nonadaptive consequence of simplifying heuristics: visual illusions, where visual perception consistently misleads the viewer about the state of the external world or objects within it. We take an explicitly comparative approach by exploring similarities and differences in visual cognition across human and nonhuman taxa. Considering areas of convergence and divergence across taxa provides insight into the evolution and function of visual systems and associated perceptual strategies. 

Exposure to insecticides may contribute to global insect declines due to sublethal insecticide effects on non-target species. Thus far, much research on non-target insecticide effects has focused on neonicotinoids in a few bee species. Much less is known about effects on other insect taxa or newer insecticides, such as sulfoxaflor. Here, we studied the effects of an acute insecticide exposure on both olfactory and visual learning in free-moving Polistes fuscatus paper wasps. Wasps were exposed to a single, field realistic oral dose of either low dose imidacloprid, high dose imidacloprid, or sulfoxaflor. Then, visual and olfactory learning and short-term memory were assessed. We found that acute insecticide exposure influenced performance, as sulfoxaflor and high dose imidacloprid exposed wasps made fewer correct choices than control wasps. Notably, both visual and olfactory performance were similarly impaired. Wasps treated with high dose imidacloprid were also less likely to complete the learning assay than wasps from other treatment groups. Instead, wasps remained stationary and unmoving in the testing area, consistent with imidacloprid interfering with motor control. Finally, wasps treated with sulfoxaflor were more likely to die in the week after treatment than wasps in the other treatment groups. Our findings demonstrate that sublethal, field-realistic dosages of both neonicotinoid and sulfoximine-based insecticides impair wasp learning and short-term memory may have additional effects on survival and motor functioning. Insecticides have broadly detrimental effects on diverse non-target insects that may influence foraging effectiveness, pollination services, and ecosystem function.