Biology subjects

Russell, A. L.

Publications and source records attributed to Russell, A. L..

18 recordsLinked to original sources

bioRxiv2026

Salt sweetens the deal: bumble bees prefer sodium-enriched nectar when its sugar concentration is low

Foraging decisions often depend on net energy intake, but the need for specific micronutrients means that foods are not always comparable based on energy content. Although sodium is essential for many physiological functions, many organisms face challenges obtaining it, especially those relying on a plant-based diet. Flowering plants often lure pollinators by manipulating nectar carbohydrate content, but nectar sodium might also influence pollinator choice. We experimentally tested how sodium addition and nectar carbohydrate concentration interact to affect bumble bee foraging decisions by allowing bees to forage on artificial flowers containing either low- or high-sucrose nectar, with or without sodium. We also explored whether sugar and sodium content in floral nectar trade-off across plant species. Bees preferred sodium-enriched nectar and preference nearly doubled when sucrose concentration was low. Furthermore, bees switched more often from flowers without sodium to those with sodium when sucrose concentration was low. Given increased fidelity for artificial flowers with nectar sodium, sodium may enhance plant fitness by increasing conspecific pollen receipt. Yet despite behavioral evidence that sodium enhances the perceived quality of low-sucrose nectar for bees, we found no evidence for a nectar sugar-sodium trade-off across plant species. We discuss implications for plant-pollinator interactions and flower evolution.

animal behavior and cognition↗

bioRxiv2025

Bees attend primarily to costs, not benefits, to avoid exploitation by floral mimics

Animals are expected to weigh costs and benefits when making foraging decisions. Flowering plants often offer floral food rewards to pollinators, but also frequently deceive pollinators into visiting without providing rewards. Although floral mimicry, in which rewardless flowers mimic rewarding (model) flowers is common, it remains unclear whether pollinators evaluate the relative costs and benefits of visiting each. Using a signal detection theory (SDT) framework, we investigated how bumble bee decisions respond to experimental manipulations of costs and benefits within an intersexual floral mimicry system in which unrewarding female flowers imperfectly mimic pollen-rewarding male flowers (models). Using a fully factorial design, we increased the cost of visiting mimics (by adding quinine), increased the benefit of visiting models (by adding pollen), increased both simultaneously, and made no changes (control). As predicted by SDT, increasing mimic costs led to a conservative bias: bees made more correct rejections, but fewer correct detections. Contradicting SDT predictions, enhancing model reward did not elicit a liberal bias and decision performance remained unchanged. Our findings suggest that bees prioritize avoiding costly errors under uncertainty, even when this limits potential gains. Such conservative foraging decisions may help stabilize deceptive systems by allowing mimics to persist despite moderate costs.

animal behavior and cognition↗

bioRxiv2025

Bacteria accumulate more rapidly on shorter lived flowers, but abiotic factors affect flower aging and bacterial accumulation

Outcomes of ecological interactions often depend on the abundance and identity of the organisms involved. Flower-bacteria interactions can strongly affect plant ecology, and the identities of epiphytic flower bacteria are relatively well documented. Yet little is known about how the abundance of epiphytic bacteria on flowers changes over time. In this field study, we quantified how the abundance of culturable epiphytic bacteria on flowers changed as flowers aged and how abiotic factors influenced bacterial abundance and flower longevity. To accomplish this, we sampled flowers from anthesis to senescence of 8 plant species that varied substantially in terms of flower longevity and comprised 8 different genera from 7 different families. As expected, flowers of all plant species accumulated more bacteria with age. However, plant species with longer-lived flowers accumulated bacteria relatively more slowly, suggesting such plant species may have evolved more effective antibacterial defenses. Although elevated temperature is often expected to boost bacterial growth and diminish flower longevity, temperature was negatively associated with both flower longevity and bacterial accumulation, suggesting that changes to flower longevity strongly affect bacterial populations. In contrast, precipitation was positively associated with flower longevity and negatively associated with bacterial accumulation, likely because precipitation reduced plant water stress while also dislodging bacteria from flowers. Finally, we discuss the implications of our results for plant-bacterial-pollinator interactions.

ecology↗

bioRxiv2025

Extracellular spike waveform analysis reveals cell type-specific changes in the superior colliculus of fragile X mice

A long-standing goal of neuroscience has been to elucidate the diverse complement of neurons in the brain, which can be defined by several criteria. Analysis of action potential shape in extracellular recordings has revealed subpopulations in several regions of the brain, allowing for insights into neuronal subtype-specific function in the intact brain. The superior colliculus (SC) is a critical sensorimotor region, integrating visual, somatosensory, auditory, and nociceptive inputs to direct complex behaviors. Recent work suggests that the SC may be adversely impacted in neurodevelopmental disorders (NDDs), underscoring its importance. However, our understanding of cellular diversity in the SC lags in comparison to other regions, limiting our ability to parse circuit changes in NDDs. Here, we utilized semi-automated clustering methods to classify neurons in the mouse SC based on multiple features of extracellularly recorded waveforms to identify five putative cell types. Secondary analysis of firing statistics and visual tuning properties supported the cluster segregation. Interestingly, the proportions of units assigned to each cluster differed in the SC of a mouse model of fragile X syndrome (FXS, Fmr1-/y), with only four of five types identified. Furthermore, we observed changes in waveform properties and firing statistics, but not visual tuning properties, between genotypes in a subtype-specific manner. Taken together, these data add to our understanding of neuronal diversity in the SC and alterations of visual circuit organization and function in NDDs.

neuroscience↗

bioRxiv2025

Take it or leaf it: bees learn leaf shape as a cue when flower color is easily learned

Over a century of research has demonstrated that pollinators, such as bees, associatively learn diverse flower cues, including tactile, visual, and olfactory cues, to find food rewards. However, floral cues are not always reliable, as flowers of different plant species often differ in terms of the qualities of their food rewards, even when flower types resemble each other. At the same time, some non-floral traits, such as leaf shape, differ reliably among plant species and might be associatively learned by bees to improve foraging success. In this laboratory study, we tested whether generalist bees (Bombus impatiens) can (1) associatively learn differences in leaf shape to discriminate rewarding from unrewarding flowers and (2) rely more on differences in leaf shape when a flower color cue is harder to discriminate. We therefore assigned bees to either of two treatments: in one treatment, rewarding and unrewarding artificial targets ( flowers) differed greatly in petal color, and in the other treatment, they differed little; each treatments targets differed in leaf shape in the same way. As expected, bees learned significantly faster when flower petal colors were more dissimilar and thus relatively easier to discriminate. These bees also learned and recalled the correct combination of petal color and leaf shape. Yet when petal colors differed relatively little, bees had a much harder time learning petal color and did not show evidence of having remembered leaf shape. Our results demonstrate that leaf shape is a cue that foraging bees can learn to associate with a pollen food reward. However, leaf shape may be learned secondarily to, or only in combination with floral cues (such as petal color). We discuss evidence of compound learning and overshadowing and implications of our results for pollinator-mediated selection on non-floral plant traits.

animal behavior and cognition↗

bioRxiv2024

One for the road: Bumble bees consume pollen at flowers

Bees are the primary consumers of pollen in many ecosystems, but pollen consumption by adult bees is rarely studied, leaving a gap in our understanding of the nutritional ecology of collective foraging and pollination biology more generally. For example, while eusocial bees feed upon pollen from colony stores, whether they also consume pollen directly from flowers to meet their own needs or to assess its quality for the broader collective is unknown. We therefore captured wild bumble bee colonies (B. bimaculatus and B. griseocollis) and tested whether individual workers consumed pollen directly from flowers in a lab-based foraging assay. After confirming presence of floral pollen in worker crops (i.e., consumption at flowers), in a field setting we tested alternative hypotheses for the function of this behavior using information about the composition, abundance, and diversity of pollen found in the crops vs. pollen baskets of three species of pollen- and nectar-foraging bumble bees (Bombus bimaculatus, B. griseocollis, and B. impatiens). Consistent with the hypothesis that consuming pollen at flowers reflects sampling, total pollen quantity in crops was consistently smaller than in pollen baskets, and basket pollen tended to be a subset of that found in crops. Further, pollen foragers consumed more and different kinds of pollen than nectar foragers. Pollen consumption at flowers is thus unlikely to be purely incidental, or to substantially benefit workers nutritionally. Instead, consuming pollen directly from flowers likely allows foragers to quickly assess pollen quality before collecting it to feed the colony as whole. SIGNIFICANCE STATEMENTWhile nectar-collecting bees are classic models for the study of foraging behavior and plant-pollinator interactions, little is known about how bees assess pollen while foraging. Pollen is a critical source of protein and lipids, offered by many plant species alongside or instead of nectar. Though variation in pollen macronutrient content and secondary chemistry affect bee reproductive performance and health, whether and how foragers evaluate pollen quality is not known. We show that foraging worker bumble bees consume pollen at flowers and suggest this behavior may allow them to sample its nutritional quality. This sheds new light on the nutritional basis of plant-pollinator interactions and adds to our understanding of how bees regulate their collection of this critical resource.

animal behavior and cognition↗

bioRxiv2024

Learning to handle flowers increases pollen collection benefits for bees but does not affect pollination success for plants

Behavior frequently affects cooperation as well as conflict in plant-pollinator interactions. Pollinators such as bees often modify how they handle flowers with experience and such learning is generally assumed to increase collection of floral food rewards. The complexity of flower morphology also affects how quickly pollinators learn and recall how to access floral rewards from a given flower type. Because learning to handle a flower can increase extraction of food rewards (such as pollen) and often involves the pollinator altering how it interacts with the flowers reproductive organs, pollinator learning could affect pollination success. Yet how pollinator cognition and flower morphology interact to affect pollination success is unknown. We therefore asked how learning and memory of flower handling by pollen-foraging generalist bumble bees (Bombus impatiens) varied among four morphologically distinct flower types (Phacelia campanularia, Exacum affine, Solanum elaeagnifolium, and Erythranthe guttata) and affected pollen collection and pollen deposition on these flowers. We found that bees learned and remembered how to handle some flower types more quickly than others. Learning typically involved development of motor routines unique to each flower type. While bees invariably learned to improve pollen collection, how quickly bees learned and remembered each flower type did not affect pollen collection. Surprisingly, pollen deposition on flowers was not affected by bee foraging experience. Thus, even though learning benefits the bee, it does not alter female (and potentially male) fitness benefits for the plant. We discuss potential reasons for these patterns and consequences for bee behavior and flower evolution.

animal behavior and cognition↗

bioRxiv2024

Supplier-origin gut microbiomes affect host body weight and select autism-related behaviors

Autism spectrum disorders (ASD) are complex human neurodiversities increasing in prevalence within the human population. In search of therapeutics to improve quality-of-life for ASD patients, the gut microbiome (GM) has become a promising target as a growing body of work supports roles for the complex community of microorganisms in influencing host behavior via the gut-brain-axis. However, whether naturally-occurring microbial diversity within the host GM affects these behaviors is often overlooked. Here we applied a model of population-level differences in the GM to a classic ASD model - the BTBR T+ Itpr3tf/J mouse - to assess how complex GMs affect host behavior. Leveraging the naturally occurring differences between supplier-origin GMs, our data demonstrate that differing, complex GMs selectively effect host ASD-related behavior - especially neonatal ultrasonic communication - and reveal a male-specific effect on behavior not typically observed in this strain. We then identified that the body weight of BTBR mice is influenced by the postnatal GM which was potentially mediated by microbiome-dependent effects on energy harvest in the gut. These data provide insight into how variability within the GM affects host behavior and growth, thereby emphasizing the need to incorporate naturally occurring diversity within the host GM as an experimental factor in biomedical research.

microbiology↗

bioRxiv2024

Buzz-world: Global patterns and drivers of buzzing bees and poricidal plants

Foraging behavior frequently plays a major role in driving the geographic distribution of animals. Buzzing to extract protein-rich pollen from flowers is a key foraging behavior used by bee species across at least 83 genera (these genera comprise [~]58% of all bee species). Although buzzing is widely recognized to affect the ecology and evolution of bees and flowering plants (e.g., buzz-pollinated flowers), global patterns and drivers of buzzing bee biogeography remain unexplored. Here, we investigate the global species distribution patterns within each bee family and how patterns and drivers differ with respect to buzzing bee species. We found that both distributional patterns and drivers of richness typically differed for buzzing species compared to hotspots for all bee species and when grouped by family. A major predictor of the distribution, but not species richness overall for buzzing members of four of the five major bee families included in analyses (Andrenidae, Halictidae, Colletidae and to a lesser extent, Apidae) was the richness of poricidal flowering plant species, which depend on buzzing bees for pollination. As poricidal plant richness was highest in areas with low wind and high aridity, we discuss how global hotspots of buzzing bee biodiversity are likely driven by both biogeographic factors and plant host availability. Whilst we explored global patterns with State-level data, higher resolution work is needed to explore local level drivers of patterns, but from a global perspective, buzz-pollinated plants clearly play a greater role in the ecology and evolution of buzzing bees than previously predicted.

ecology↗

bioRxiv2024

Widespread evolution of poricidal flowers: A striking example of morphological convergence across flowering plants

The evolution of tube-like floral morphologies that control pollen release via small openings (functionally poricidal flowers) represents a taxonomically and geographically widespread instance of repeated and independent evolution of a functionally similar morphology. Poricidal flowers are also often closely associated with buzz pollination by bees. Yet we lack an updated angiosperm-wide survey of their phylogenetic distribution. We identify all known angiosperm genera containing poricidal flowers via a literature survey. We determined their phylogenetic distribution and minimum number of independent gains and losses via a species-level angiosperm-wide phylogeny. We estimated if evolution of poricidal flowers is associated with changes in speciation/extinction via diversification rate analyses. Poricidal flowers occur across 87 angiosperm families and 639 genera containing >28,000 species. At the species level, an average of 205 independent gains and 215 losses of poricidal flowers occurred. Angiosperm-wide analyses suggest an early burst in poricidal evolution, but no differences in net diversification (origination-extinction) between non-poricidal and poricidal taxa. Analyses for two focal families however indicate strong context-dependent effects of poricidal flowers on diversification. Poricidal evolution thus represents a large-scale example of convergent evolution in floral form, but effects on diversification appear to be strongly contingent on phylogenetic and ecological background.

evolutionary biology↗

bioRxiv2023

The Relationship Between Preference and Switching in Flower Foraging by Bees

It seems self-evident that generalist foragers switch more between resources than specialists but despite diverse ecological and evolutionary implications, how variation in switching relates to variation in preference warrants additional study. Here we tested predictions based on a simple probability model, using flower-foraging bees as a model system. In laboratory assays, we presented bumble bee (Bombus impatiens) workers with flowers of two species, Tecoma stans and T. alata, from which they could collect nectar and/or pollen. We quantified landing preference and occurrence of switching between species in successive visits. Bees varied greatly in floral preference. Almost half showed statistically significant preferences for one or the other species, while the rest were generalists. As expected, generalists using both flower species switched more in successive visits than bees that were more specialized, a pattern fit to a quadratic function. However, generalist individuals switched more than expected based on null expectation. A Modified Jacobs Index (MJI) of switching was significantly positively correlated with degree of preference: generalist bees had more negative MJIs than specialist bees, indicating that even after the expected statistical effect of preference on switching was accounted for, they switched more than specialists. A simulation ruled out the possibility that the pattern was due to bias in MJI. Generalist-specialist differences in which food was collected (nectar versus pollen) were also ruled out. We discuss possible explanations for our observed pattern and outline possible ways in which preference and switching frequency will interact to shape pollinator behavior and the floral resource. Significance statementBehavioral preference is the subject of a large literature in areas such as foraging, mating and communication. However, a preference measure alone does not necessarily tell us if choices for one alternative are made in runs or intermingled with choices for another alternative. The distinction between preference and the sequential pattern of choices is relevant in many contexts in behavioral ecology but has been a particular focus of study in flower foraging by pollinators. Even in that literature, the relationship between preference and sequential pattern in switching warrants further examination. In our study, bees were shown to vary in preference for flowers of two species. Some were generalists; some were specialists on one or the other species. Generalist bees switched more than specialist bees, even after controlling for statistical effects of preference on switching frequency. The report of this generalist-specialist pattern in switching may be novel and has far-reaching implications throughout the field of behavioral ecology.

animal behavior and cognition↗

bioRxiv2023

Effect size of delayed freezing, diurnal variation, and hindgut location on the mouse fecal microbiome relative to a standardized biological variable

BackgroundWhile murine fecal collection is central to microbiome research, there are a number of practical considerations that may vary during fecal sample collection, including time to sample storage, time of day the sample is collected, and position within the colon during terminal collections. While the need to control these factors is recognized, the relative effect on microbial community of duration at room temperature, time of day, and hindgut position, in the context of a known biological variable, is unclear. To answer these questions, and assess reproducibility of results across different microbiome compositions, parallel experiments were performed to investigate the effect of those factors on the microbiome of age- and sex-matched isogenic mice colonized with two different vendor-origin microbiomes. Results16S rRNA amplicon sequencing data from flash-frozen fecal samples showed no statistical difference in alpha or beta diversity compared to samples incubated for 1, 2, 3, 4, 6, and 9 hours at room temperature. Overall, samples collected in the AM period showed greater richness and alpha-diversity compared to samples collected in the PM period. While a significant effect of time was detected in all hindgut regions, the effect increased from cecum to distal colon. When using two vendor-origin microbiomes as a biological variable, its effect size vastly outweighed the effect size of the time samples spent at room temperature, the time of day samples were collected, and the position within the colon from which samples were collected. ConclusionsThis study has highlighted multiple scenarios encountered in microbiome research that may affect outcome measures of microbial diversity and composition. Unexpectedly, delayed time to sample cold storage up to nine hours did not affect the alpha or global beta diversity of fecal sample. We then presented evidence of location- and time-dependent effects within the hindgut on microbial richness, diversity, and composition. We finally demonstrated a relatively low effect size of these technical factors when compared to a primary experimental factor with large intergroup variability.

microbiology↗

bioRxiv2022

The contribution of maternal oral, vaginal, and gut microbiota to the developing offspring gut

There is limited understanding of how the microbiota colonizing various maternal tissues contribute to the development of the neonatal gut microbiota (GM). To determine the contribution of various maternal microbiotic sites to the offspring microbiota in the upper and lower gastrointestinal tract (GIT) during early life, litters of mice were sacrificed at 7, 9, 10, 11, 12, 14, and 21 days of age, and fecal and ileal samples were collected. Dams were euthanized alongside their pups, and oral, vaginal, ileal, and fecal samples were collected. This was done in parallel using mice with either a low-richness or high-richness microbiota to assess the consistency of findings across multiple microbial compositions. Sample were analyzed using 16S rRNA amplicon sequencing. The similarities between matched pup and dam samples were used to determine the contribution of each maternal source to the pup fecal and ileal composition at each timepoint. As expected, similarity between pup and maternal feces increased significantly over time. During earlier time-points however, the offspring fecal and ileal microbiotas were closer in composition to the maternal oral microbiota than other maternal sites. Prominent taxa contributed by the maternal oral microbiota to the neonatal gut microbiota were supplier-dependent and included Lactobacillus spp., Streptococcus spp., and a member of the Pasteurellaceae family. These findings align with the microbial taxa reported in infant microbiotas, highlighting the translatability of mouse models in this regard, as well as the dynamic nature of the gut microbiota during early life.

developmental biology↗

bioRxiv2021

Structural Dynamics of Real and Modeled Solanum Stamens: Implications for Pollen Ejection by Buzzing Bees

An estimated 10% of flowering plant species conceal their pollen within tube-like anthers that dehisce through small apical pores (poricidal anthers). Bees extract pollen from poricidal anthers through a complex motor routine called floral buzzing, whereby the bee applies vibratory forces to the flower stamen by rapidly contracting its flight muscles. The resulting deformation depend on the stamens natural frequencies and vibration mode shapes, yet for most poricidal species these properties have not been sufficiently characterized. We performed experimental modal analysis on Solanum elaeagnifolium stamens to quantify their natural frequencies and vibration modes. Based on morphometric and dynamic measurements, we developed a finite element model of the stamen to identify how variable material properties, geometry and bee weight could affect its dynamics. In general, stamen natural frequencies fell outside the reported floral buzzing range, and variations in stamen geometry and material properties were unlikely to bring natural frequencies within this range. However, inclusion of bee mass reduced natural frequencies to within the floral buzzing frequency range and gave rise to an axial-bending vibration mode. We hypothesize that floral buzzing bees exploit the large vibration amplification factor of this mode to increase anther deformation, which may facilitate pollen ejection.

biophysics↗

bioRxiv2021

Anther cones increase pollen release in buzz-pollinated Solanum flowers

The widespread evolution of tube-like anthers releasing pollen from apical pores is associated with buzz pollination, in which bees vibrate flowers to remove pollen. The mechanical connection among anthers in buzz-pollinated species varies from loosely held conformations, to anthers tightly held together with trichomes or bio-adhesives forming a functionally joined conical structure (anther cone). Joined anther cones in buzz-pollinated species have evolved independently across plant families and via different genetic mechanisms, yet their functional significance remains mostly untested. We used experimental manipulations to compare vibrational and functional (pollen release) consequences of joined anther cones in three buzz-pollinated species of Solanum (Solanaceae). We applied bee-like vibrations to focal anthers in flowers with ("joined") and without ("free") experimentally created joined anther cones, and characterised vibrations transmitted to other anthers and the amount of pollen released. We found that joined anther architectures cause non-focal anthers to vibrate at higher amplitudes than free architectures. Moreover, in the two species with naturally loosely held anthers, anther fusion increases pollen release, while in the species with a free but naturally compact architecture it does not. We discuss hypotheses for the adaptive significance of the convergent evolution of joined anther cones.

evolutionary biology↗

bioRxiv2021

A cell-ECM mechanism for connecting the ipsilateral eye to the brain

Information about features in the visual world are parsed by circuits in the retina and are then transmitted to the brain by distinct subtypes of retinal ganglion cells (RGCs). Axons from RGC subtypes are stratified in retinorecipient brain nuclei, such as the superior colliculus (SC), to provide a segregated relay of parallel and feature-specific visual streams. Here, we sought to identify the molecular mechanisms that direct the stereotyped laminar targeting of these axons. We focused on ipsilateral-projecting subtypes of RGCs (ipsiRGCs) whose axons target a deep SC sublamina. We identified an extracellular glycoprotein, Nephronectin (NPNT), whose expression is restricted to this ipsiRGC-targeted sublamina. SC-derived NPNT and integrin receptors generated by ipsiRGCs are both required for the targeting of ipsiRGC axons to the deep sublamina of SC. Thus, a cell-extracellular matrix (ECM) recognition mechanism specifies precise laminar targeting of ipsiRGC axons and the assembly of eye-specific parallel visual pathways. Significance StatementDistinct features of the visual world are transmitted from the retina to the brain through anatomically segregated circuits. Despite this being an organizing principle of visual pathways in mammals, we lack an understanding of the signaling mechanisms guiding axons of different types of retinal neurons into segregated layers of brain regions. We explore this question by identifying how axons from the ipsilateral retina innervate a specific lamina of the superior colliculus. Our studies reveal a unique cell-extracellular matrix (ECM) recognition mechanism that specifies precise targeting of these axons to the superior colliculus. Loss of this mechanism not only resulted in the absence of this eye-specific visual circuit, but it led to an impairment of innate predatory visual behavior as well.

neuroscience↗

bioRxiv2020

Prevalence of multiple subtypes of binocularly-modulated visual neurons in the mouse superior colliculus

The superior colliculus (SC) integrates visual and other sensory information to regulate critical reflexive and innate behaviors, such as prey capture. In the mouse, the vast majority of retinal ganglion cells (RGCs) innervate the SC, including inputs from both the contralateral (contra-RGCs) and ipsilateral (ipsi-RGCs) eye. Despite this, previous studies revealed minimal neuronal responses to ipsilateral stimulation and few binocular interactions in the mouse SC. More recent work suggests that ipsi-RGC function and innervation of the SC are critical for efficient prey capture, raising the possibility that binocular interactions in the mouse SC may be more prevalent than previously thought. To explore this possibility, we investigated eye-specific and binocular influences on visual responses and tuning of SC neurons, focusing on the anteromedial region. While the majority of SC neurons were primarily driven by contralateral eye stimulation, we observed that a substantial proportion of units were influenced or driven by ipsilateral stimulation. Clustering based on differential responses to eye-specific stimulus presentation revealed five distinct putative subpopulations and multiple modes of binocular interaction, including facilitation, summation, and suppression. Each of the putative subpopulations exhibited selectivity for orientation, and differences in spatial frequency tuning and spatial summation properties were observed between subpopulations. Further analysis of orientation tuning under different ocular conditions supported differential modes of binocular interaction between putative subtypes. Taken together, these data suggest that binocular interactions in the mouse SC may be more prevalent and diverse than previously understood.

neuroscience↗

bioRxiv2020

Pollinators mediate floral microbial diversity and network under agrochemical disturbance

How pollinators mediate microbiome assembly in the anthosphere is a major unresolved question of theoretical and applied importance in the face of anthropogenic disturbance. We addressed this question by linking visitation of diverse pollinator functional groups (bees, wasps, flies, butterflies, beetles, true bugs and other taxa) to the key properties of floral microbiome (microbial - and {beta}-diversity and microbial network) under agrochemical disturbance, using a field experiment of bactericide and fungicide treatments on cultivated strawberries that differ in flower abundance. Structural equation modeling was used to link agrochemical disturbance and flower abundance to pollinator visitation to floral microbiome properties. Our results revealed that (1) pollinator visitation influenced the - and {beta}-diversity and network centrality of floral microbiome, with different pollinator functional groups affecting different microbiome properties; (2) flower abundance influenced floral microbiome both directly by governing the source pool of microbes and indirectly by enhancing pollinator visitation; and (3) agrochemical disturbance affected floral microbiome primarily directly by fungicide, and less so indirectly via pollinator visitation. These findings improve the mechanistic understanding of floral microbiome assembly, and may be generalizable to many other plants that are visited by diverse insect pollinators in natural and managed ecosystems.

ecology↗