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Ferrante F, Pasquini E, Cappa F, Bellocchio L, Baracchi D. Unravelling the microplastic menace: Different polymers additively increase bee vulnerability. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 352:124087. [PMID: 38703977 DOI: 10.1016/j.envpol.2024.124087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2024] [Revised: 04/08/2024] [Accepted: 04/29/2024] [Indexed: 05/06/2024]
Abstract
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.
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Affiliation(s)
- Federico Ferrante
- Department of Biology, University of Florence, Via Madonna del Piano, 6, Sesto Fiorentino, 50019, Italy; Department of Ecological and Biological Sciences, University of Viterbo, Largo dell'Università, 01100, Viterbo, Italy
| | - Elisa Pasquini
- Department of Biology, University of Florence, Via Madonna del Piano, 6, Sesto Fiorentino, 50019, Italy; Center for Mind/Brain Science (CIMeC), University of Trento, Rovereto, Italy
| | - Federico Cappa
- Department of Biology, University of Florence, Via Madonna del Piano, 6, Sesto Fiorentino, 50019, Italy
| | - Lorenzo Bellocchio
- Department of Biology, University of Florence, Via Madonna del Piano, 6, Sesto Fiorentino, 50019, Italy
| | - David Baracchi
- Department of Biology, University of Florence, Via Madonna del Piano, 6, Sesto Fiorentino, 50019, Italy.
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2
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Barou‐Dagues M, Dubois F. Exploring the interplay between natural and intersexual selection on the evolution of a cognitive trait. Ecol Evol 2022; 12:e9066. [PMID: 35813909 PMCID: PMC9251863 DOI: 10.1002/ece3.9066] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 05/25/2022] [Accepted: 06/08/2022] [Indexed: 01/02/2023] Open
Abstract
There has been an increased focus on the role of natural and sexual selection in shaping cognitive abilities, but the importance of the interaction between both forces remains largely unknown. Intersexual selection through female mate choice might be an important driver of the evolution of cognitive traits, especially in monogamous species, where females may obtain direct fitness benefits by choosing mates with better cognitive abilities. However, the importance given by female to male cognitive traits might vary among species and/or populations according to their life-history traits and ecology. To disentangle the effects of natural and sexual selection, here we use an agent-based simulation model and compare the model's predictions when females mate with the first randomly encountered male (i.e., under natural selection) versus when they choose among males based on their cognitive trait values (i.e., under natural and intersexual selection). Males and females are characterized, respectively, by their problem-solving ability and assessment strategy. At each generation, agents go through (1) a choosing phase during which females assess the cognitive abilities of potential mates until eventually finding an acceptable one and (2) a reproductive phase during which all males compete for limited resources that are exploited at a rate, which depends on their cognitive abilities. Because males provide paternal care, the foraging success of mated males determines the breeding success of the pair through its effect on nestling provisioning efficiency. The model predicts that intersexual selection plays a major role in most ecological conditions, by either reinforcing or acting against the effect of natural selection. The latter case occurs under harsh environmental conditions, where intersexual selection contributes to maintaining cognitive diversity. Our findings thus demonstrate the importance of considering the interaction between both selective forces and highlight the need to build a conceptual framework to target relevant cognitive traits.
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Affiliation(s)
| | - Frédérique Dubois
- Département des Sciences BiologiquesUniversité de MontréalMontréalQuebecCanada
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3
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No effect of dual exposure to sulfoxaflor and a trypanosome parasite on bumblebee olfactory learning. Sci Rep 2022; 12:8611. [PMID: 35597818 PMCID: PMC9124203 DOI: 10.1038/s41598-022-12714-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 04/27/2022] [Indexed: 11/18/2022] Open
Abstract
Bees are important pollinators in wild and agricultural ecosystems, and understanding the factors driving their global declines is key to maintaining these pollination services. Learning, which has been a focus of previous ecotoxicological studies in bees, may play a key role in driving colony fitness. Here we move beyond the standard single-stressor approach to ask how multiple stressors, an agrochemical (sulfoxaflor, a relatively new insecticide) and a parasite (Crithidia bombi, a prevalent gut parasite of bumblebees), impact learning in the bumblebee Bombus terrestris. We developed a modified version of the classic proboscis extension reflex assay to assess the combined effects of acute oral sulfoxaflor exposure and infection by C. bombi on olfactory learning of bumblebee workers. We found no evidence that either sulfoxaflor, C. bombi, or their combination had any significant effect on bumblebee olfactory learning, despite their known negative impacts on other aspects of bumblebee health. This suggests that losses in cognitive ability, as measured here, are unlikely to explain the impacts of sulfoxaflor and its interactions with other stressors on bumblebees. Our novel methodology provides a model system within which to test interactive effects of other key stressors on bee health.
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4
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5
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Propolis of stingless bees for the development of novel functional food and nutraceutical ingredients: A systematic scoping review of the experimental evidence. J Funct Foods 2022. [DOI: 10.1016/j.jff.2021.104902] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
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6
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Chen P, Lu YH, Lin YH, Wu CP, Tang CK, Wei SC, Wu YL. Deformed wing virus infection affects the neurological function of Apis mellifera by altering extracellular adenosine signaling. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2021; 139:103674. [PMID: 34737063 DOI: 10.1016/j.ibmb.2021.103674] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 10/04/2021] [Accepted: 10/24/2021] [Indexed: 06/13/2023]
Abstract
Deformed wing virus (DWV) infection is believed to be closely associated with colony losses of honeybee (Apis mellifera) due to reduced learning and memory of infected bees. The adenosine (Ado) pathway is important for maintaining immunity and memory function in animals, and it enhances antivirus responses by regulating carbohydrate metabolism in insects. Nevertheless, its effect on the memory of invertebrates is not yet clear. This study investigated how the Ado pathway regulates energy metabolism and memory in honeybees following DWV infection. Decreased Ado receptor (Ado-R) expression in the brain of infected bees resulted in a carbohydrate imbalance as well as impairments of glutamate-glutamine (Glu-Gln) cycle and long-term memory. Dietary supplementation with Ado not only increased the brain energy metabolism but also rescued long-term memory loss by upregulating the expression of memory-related genes. The present study demonstrated the regulation of the Ado pathway upon DWV infection and provides insights into the mechanisms underlying energy regulation and the neurological function of honeybees.
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Affiliation(s)
- Ping Chen
- Department of Entomology, National Taiwan University, Taipei, 106, Taiwan
| | - Yun-Heng Lu
- Department of Entomology, National Taiwan University, Taipei, 106, Taiwan
| | - Yu-Hsien Lin
- Department of Plant Physiology, Swammerdam Institute for Life Sciences, University of Amsterdam, 1098 XH, Amsterdam, the Netherlands
| | - Carol-P Wu
- Department of Entomology, National Taiwan University, Taipei, 106, Taiwan
| | - Cheng-Kang Tang
- Department of Entomology, National Taiwan University, Taipei, 106, Taiwan
| | - Sung-Chan Wei
- Department of Entomology, National Taiwan University, Taipei, 106, Taiwan
| | - Yueh-Lung Wu
- Department of Entomology, National Taiwan University, Taipei, 106, Taiwan.
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7
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Zulhendri F, Felitti R, Fearnley J, Ravalia M. The use of propolis in dentistry, oral health, and medicine: A review. J Oral Biosci 2021; 63:23-34. [PMID: 33465498 DOI: 10.1016/j.job.2021.01.001] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 01/07/2021] [Accepted: 01/08/2021] [Indexed: 02/06/2023]
Abstract
BACKGROUND Propolis is a resinous product that is collected from plants by bees to cover holes and crevices in their hives. Propolis has potent antibacterial, antiviral, anti-inflammatory, wound healing, and anticancer properties. Propolis has been used therapeutically by humans for centuries, including the treatment of dental caries and mouth infections. HIGHLIGHT This review article attempts to analyze the potential use of propolis in general dentistry and oral health management. CONCLUSION Propolis is potentially useful in dentistry and oral health management based on available in vitro, in vivo, and ex vivo studies, as well as human clinical trials.
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Affiliation(s)
| | - Rafael Felitti
- Oral Rehabilitation and Prosthodontics, Private Practice, Montevideo, Uruguay.
| | - James Fearnley
- Apiceutical Research Centre, NorthYorkshire, United Kingdom.
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8
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Carlesso D, Smargiassi S, Sassoli L, Cappa F, Cervo R, Baracchi D. Exposure to a biopesticide interferes with sucrose responsiveness and learning in honey bees. Sci Rep 2020; 10:19929. [PMID: 33199794 PMCID: PMC7670424 DOI: 10.1038/s41598-020-76852-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Accepted: 10/28/2020] [Indexed: 02/07/2023] Open
Abstract
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.
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Affiliation(s)
- Daniele Carlesso
- Department of Biology, University of Florence, Via Madonna del Piano, 6, 50019, Sesto Fiorentino, Italy.,Department of Biological Sciences, Macquarie University, Sydney, NSW, 2109, Australia
| | - Stefania Smargiassi
- Department of Life Sciences and Systems Biology, University of Turin, Via Accademia Albertina 13, 10123, Turin, Italy
| | - Lara Sassoli
- Department of Biology, University of Florence, Via Madonna del Piano, 6, 50019, Sesto Fiorentino, Italy
| | - Federico Cappa
- Department of Biology, University of Florence, Via Madonna del Piano, 6, 50019, Sesto Fiorentino, Italy
| | - Rita Cervo
- Department of Biology, University of Florence, Via Madonna del Piano, 6, 50019, Sesto Fiorentino, Italy
| | - David Baracchi
- Department of Biology, University of Florence, Via Madonna del Piano, 6, 50019, Sesto Fiorentino, Italy.
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9
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The Effect of Foraging on Bumble Bees, Bombus terrestris, Reared under Laboratory Conditions. INSECTS 2020; 11:insects11050321. [PMID: 32456127 PMCID: PMC7290516 DOI: 10.3390/insects11050321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/07/2020] [Revised: 04/06/2020] [Accepted: 05/21/2020] [Indexed: 11/16/2022]
Abstract
Bumble bees are important pollinators broadly used by farmers in greenhouses and under conditions in which honeybee pollination is limited. As such, bumble bees are increasingly being reared for commercial purposes, which brings into question whether individuals reared under laboratory conditions are fully capable of physiological adaptation to field conditions. To understand the changes in bumble bee organism caused by foraging, we compared the fundamental physiological and immunological parameters of Bombus terrestris workers reared under constant optimal laboratory conditions with workers from sister colonies that were allowed to forage for two weeks in the field. Nutritional status and immune response were further determined in wild foragers of B.terrestris that lived under the constant influence of natural stressors. Both wild and laboratory-reared workers subjected to the field conditions had a lower protein concentration in the hemolymph and increased antimicrobial activity, the detection of which was limited in the non-foragers. However, in most of the tested parameters, specifically the level of carbohydrates, antioxidants, total hemocyte concentration in the hemolymph and melanization response, we did not observe any significant differences between bumble bee workers produced in the laboratory and wild animals, nor between foragers and non-foragers. Our results show that bumble bees reared under laboratory conditions can mount a sufficient immune response to potential pathogens and cope with differential food availability in the field, similarly to the wild bumble bee workers.
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10
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Fouks B, Robb EG, Lattorff HMG. Role of conspecifics and personal experience on behavioral avoidance of contaminated flowers by bumblebees. Curr Zool 2019; 65:447-455. [PMID: 31413717 PMCID: PMC6688574 DOI: 10.1093/cz/zoy099] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Accepted: 12/11/2018] [Indexed: 11/14/2022] Open
Abstract
Pollinators use multiple cues whilst foraging including direct cues from flowers and indirect cues from other pollinators. The use of indirect social cues is common in social insects, such as honeybees and bumblebees, where a social environment facilitates the ability to use such cues. Bumblebees use cues to forage on flowers according to previous foraging experiences. Flowers are an essential food source for pollinators but also pose a high risk of parasite infection through the shared use of flowers leading to parasite spillover. Nevertheless, bumblebees have evolved behavioral defense mechanisms to limit parasite infection by avoiding contaminated flowers. Mechanisms underlying the avoidance of contaminated flowers by bumblebees are poorly understood. Bumblebees were recorded having the choice to forage on non-contaminated flowers and flowers contaminated by a trypan osome gut parasite, Crithidia bombi. The use of different treatments with presence or absence of conspecifics on both contaminated and non-contaminated flowers allowed to investigate the role of social visual cues on their pathogen avoidance behavior. Bumblebees are expected to use social visual cues to avoid contaminated flowers. Our study reveals that the presence of a conspecific on flowers either contaminated or not does not help bumblebee foragers avoiding contaminated flowers. Nevertheless, bumblebees whereas gaining experience tend to avoid their conspecific when placed on contaminated flower and copy it when on the non-contaminated flower. Our experiment suggests a detrimental impact of floral scent on disease avoidance behavior.
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Affiliation(s)
- Bertrand Fouks
- Institut für Biologie, Molekulare Ökologie, Martin-Luther-Universität Halle-Wittenberg Hoher Weg, Halle (Saale), Germany.,Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, Oslo, Norway
| | - Emily G Robb
- Institut für Biologie, Molekulare Ökologie, Martin-Luther-Universität Halle-Wittenberg Hoher Weg, Halle (Saale), Germany.,Microbes and Pathogens Biology, The Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, United Kingdom
| | - H Michael G Lattorff
- Institut für Biologie, Molekulare Ökologie, Martin-Luther-Universität Halle-Wittenberg Hoher Weg, Halle (Saale), Germany.,International Centre of Insect Physiology and Ecology (ICIPE), Nairobi, Kenya.,German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Deutscher Platz, Leipzig, Germany
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11
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Muth F, Francis JS, Leonard AS. Modality-specific impairment of learning by a neonicotinoid pesticide. Biol Lett 2019; 15:20190359. [PMID: 31362607 DOI: 10.1098/rsbl.2019.0359] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Neonicotinoid pesticides can impair bees' ability to learn and remember information about flowers, critical for effective foraging. Although these effects on cognition may contribute to broader effects on health and performance, to date they have largely been assayed in simplified protocols that consider learning in a single sensory modality, usually olfaction. Given that real flowers display a variety of potentially useful signals, we assessed the effects of acute neonicotinoid exposure on multimodal learning in free-flying bumblebees. We found that neonicotinoid consumption differentially impacted learning of floral stimuli, impairing scent, but not colour, learning. These findings raise questions about the mechanisms by which pesticides might differentially impair sensory systems, with implications for how neonicotinoids affect multiple aspects of bee ecology.
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Affiliation(s)
- Felicity Muth
- Department of Integrative Biology, University of Texas at Austin, 2415 Speedway, Austin, TX 78712, USA
| | - Jacob S Francis
- Department of Biology, University of Nevada, Reno, NV 89557, USA
| | - Anne S Leonard
- Department of Biology, University of Nevada, Reno, NV 89557, USA
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12
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Figueroa LL, Blinder M, Grincavitch C, Jelinek A, Mann EK, Merva LA, Metz LE, Zhao AY, Irwin RE, McArt SH, Adler LS. Bee pathogen transmission dynamics: deposition, persistence and acquisition on flowers. Proc Biol Sci 2019; 286:20190603. [PMID: 31138075 PMCID: PMC6545085 DOI: 10.1098/rspb.2019.0603] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Accepted: 05/03/2019] [Indexed: 12/24/2022] Open
Abstract
Infectious diseases are a primary driver of bee decline worldwide, but limited understanding of how pathogens are transmitted hampers effective management. Flowers have been implicated as hubs of bee disease transmission, but we know little about how interspecific floral variation affects transmission dynamics. Using bumblebees ( Bombus impatiens), a trypanosomatid pathogen ( Crithidia bombi) and three plant species varying in floral morphology, we assessed how host infection and plant species affect pathogen deposition on flowers, and plant species and flower parts impact pathogen survival and acquisition at flowers. We found that host infection with Crithidia increased defaecation rates on flowers, and that bees deposited faeces onto bracts of Lobelia siphilitica and Lythrum salicaria more frequently than onto Monarda didyma bracts . Among flower parts, bracts were associated with the lowest pathogen survival but highest resulting infection intensity in bee hosts. Additionally, we found that Crithidia survival across flower parts was reduced with sun exposure. These results suggest that efficiency of pathogen transmission depends on where deposition occurs and the timing and place of acquisition, which varies among plant species and environmental conditions. This information could be used for development of wildflower mixes that maximize forage while minimizing disease spread.
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Affiliation(s)
| | - Malcolm Blinder
- Department of Biology, University of Massachusetts, Amherst, MA 01003, USA
| | - Cali Grincavitch
- Department of Biology, University of Massachusetts, Amherst, MA 01003, USA
| | - Angus Jelinek
- Department of Biology, University of Massachusetts, Amherst, MA 01003, USA
| | - Emilia K. Mann
- Department of Biology, University of Massachusetts, Amherst, MA 01003, USA
| | - Liam A. Merva
- Department of Biology, University of Massachusetts, Amherst, MA 01003, USA
| | - Lucy E. Metz
- Department of Biology, University of Massachusetts, Amherst, MA 01003, USA
| | - Amy Y. Zhao
- Department of Biology, University of Massachusetts, Amherst, MA 01003, USA
| | - Rebecca E. Irwin
- Department of Applied Ecology, North Carolina State University, 127 David Clark Laboratories, Raleigh, NC 27695, USA
| | - Scott H. McArt
- Department of Entomology, Cornell University, Ithaca, NY 14853, USA
| | - Lynn S. Adler
- Department of Biology, University of Massachusetts, Amherst, MA 01003, USA
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13
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Binning SA, Roche DG, Grutter AS, Colosio S, Sun D, Miest J, Bshary R. Cleaner wrasse indirectly affect the cognitive performance of a damselfish through ectoparasite removal. Proc Biol Sci 2019. [PMID: 29514969 DOI: 10.1098/rspb.2017.2447] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Cleaning organisms play a fundamental ecological role by removing ectoparasites and infected tissue from client surfaces. We used the well-studied cleaning mutualisms involving the cleaner wrasse, Labroides dimidiatus, to test how client cognition is affected by ectoparasites and whether these effects are mitigated by cleaners. Ambon damselfish (Pomacentrus amboinensis) collected from experimental reef patches without cleaner wrasse performed worse in a visual discrimination test than conspecifics from patches with cleaners. Endoparasite abundance also negatively influenced success in this test. Visual discrimination performance was also impaired in damselfish experimentally infected with gnathiid (Crustacea: Isopoda) ectoparasites. Neither cleaner absence nor gnathiid infection affected performance in spatial recognition or reversal learning tests. Injection with immune-stimulating lipopolysaccharide did not affect visual discrimination performance relative to saline-injected controls, suggesting that cognitive impairments are not due to an innate immune response. Our results highlight the complex, indirect role of cleaning organisms in promoting the health of their clients via ectoparasite removal and emphasize the negative impact of parasites on host's cognitive abilities.
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Affiliation(s)
- Sandra A Binning
- Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland .,School of Biological Sciences, The University of Queensland, St-Lucia, Australia.,Département de sciences biologiques, Université de Montréal, Montréal, QC, Canada
| | - Dominique G Roche
- Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland.,School of Biological Sciences, The University of Queensland, St-Lucia, Australia
| | - Alexandra S Grutter
- School of Biological Sciences, The University of Queensland, St-Lucia, Australia
| | - Simona Colosio
- Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
| | - Derek Sun
- School of Biological Sciences, The University of Queensland, St-Lucia, Australia
| | - Joanna Miest
- Department of Life and Sports Sciences, University of Greenwich, Kent, UK
| | - Redouan Bshary
- Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
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14
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Dunlap AS, Austin MW, Figueiredo A. Components of change and the evolution of learning in theory and experiment. Anim Behav 2019. [DOI: 10.1016/j.anbehav.2018.05.024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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15
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Immune-cognitive system connectivity reduces bumblebee foraging success in complex multisensory floral environments. Sci Rep 2018; 8:5953. [PMID: 29654316 PMCID: PMC5899130 DOI: 10.1038/s41598-018-24372-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Accepted: 04/03/2018] [Indexed: 02/07/2023] Open
Abstract
Bumblebees are declining at alarming rate worldwide, posing a significant threat to the function and diversity of temperate ecosystems. These declines have been attributed, in part, to the direct effect of specific pathogens on bumblebee survival. However, pathogens may also have a negative impact on host populations indirectly through immune-induced cognitive deficits in infected individuals. To gain greater insight into mechanisms and potential conservation implications of such 'immune-brain crosstalk' in bumblebees, we non-pathogenetically activated humoral and cellular immune pathways in individuals and then tested for long-term reductions in cognitive performance and foraging proficiency. We show that chronic activation of humoral, but not a cellular, immune pathways and effectors in foragers significantly reduces their ability to flexibly and efficiently harvest resources in multi-sensory floral environments for at least 7 days post-treatment. Humoral defense responses thus have the potential to confer significant foraging costs to bumblebee foragers over timeframes that would negatively impact colony growth and reproductive output under natural conditions. Our findings indicate that fitness effects of immune-brain crosstalk should be considered before attributing wild bumblebee decline to a particular pathogen species.
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16
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Martin CD, Fountain MT, Brown MJF. Bumblebee olfactory learning affected by task allocation but not by a trypanosome parasite. Sci Rep 2018; 8:5809. [PMID: 29643344 PMCID: PMC5895637 DOI: 10.1038/s41598-018-24007-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Accepted: 03/26/2018] [Indexed: 01/20/2023] Open
Abstract
Parasites can induce behavioural changes in their host organisms. Several parasite species are known to infect bumblebees, an important group of pollinators. Task allocation within bumblebee colonies can also cause differences in behaviour. Thus, task allocation may lead to context-dependent impacts of parasites on host behaviour. This study uses Bombus terrestris and its gut trypanosome Crithidia bombi, to investigate the effects of parasitism, task allocation (foraging or nest-work) and their interactions, on olfactory learning. Prior to undergoing the olfactory learning task, bees were orally infected with a field-realistic dose of C. bombi, and observed to determine task allocation. Parasitism did not significantly affect olfactory learning, but task allocation did, with foragers being significantly more likely to learn than nest bees. There was no significant interaction between parasitism and task. These results suggest that C. bombi is unlikely to affect pollination services via changes in olfactory learning of its host if bees are under no environmental or nutritional stress. However, wild and commercial colonies are likely to face such stressors. Future studies in the field are needed to extrapolate our results to real world effects.
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Affiliation(s)
- Callum D Martin
- School of Biological Sciences, Royal Holloway University of London, Egham, Surrey, United Kingdom.
| | | | - Mark J F Brown
- School of Biological Sciences, Royal Holloway University of London, Egham, Surrey, United Kingdom
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17
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Klein S, Cabirol A, Devaud JM, Barron AB, Lihoreau M. Why Bees Are So Vulnerable to Environmental Stressors. Trends Ecol Evol 2017; 32:268-278. [PMID: 28111032 DOI: 10.1016/j.tree.2016.12.009] [Citation(s) in RCA: 112] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Revised: 12/21/2016] [Accepted: 12/22/2016] [Indexed: 12/25/2022]
Abstract
Bee populations are declining in the industrialized world, raising concerns for the sustainable pollination of crops. Pesticides, pollutants, parasites, diseases, and malnutrition have all been linked to this problem. We consider here neurobiological, ecological, and evolutionary reasons why bees are particularly vulnerable to these environmental stressors. Central-place foraging on flowers demands advanced capacities of learning, memory, and navigation. However, even at low intensity levels, many stressors damage the bee brain, disrupting key cognitive functions needed for effective foraging, with dramatic consequences for brood development and colony survival. We discuss how understanding the relationships between the actions of stressors on the nervous system, individual cognitive impairments, and colony decline can inform constructive interventions to sustain bee populations.
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Affiliation(s)
- Simon Klein
- Research Center on Animal Cognition, Center for Integrative Biology, National Center for Scientific Research(CNRS), University Paul Sabatier(UPS), Toulouse, France; Department of Biological Sciences, Macquarie University, Sydney, NSW, Australia
| | - Amélie Cabirol
- Research Center on Animal Cognition, Center for Integrative Biology, National Center for Scientific Research(CNRS), University Paul Sabatier(UPS), Toulouse, France; Department of Biological Sciences, Macquarie University, Sydney, NSW, Australia
| | - Jean-Marc Devaud
- Research Center on Animal Cognition, Center for Integrative Biology, National Center for Scientific Research(CNRS), University Paul Sabatier(UPS), Toulouse, France
| | - Andrew B Barron
- Department of Biological Sciences, Macquarie University, Sydney, NSW, Australia
| | - Mathieu Lihoreau
- Research Center on Animal Cognition, Center for Integrative Biology, National Center for Scientific Research(CNRS), University Paul Sabatier(UPS), Toulouse, France.
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Piiroinen S, Goulson D. Chronic neonicotinoid pesticide exposure and parasite stress differentially affects learning in honeybees and bumblebees. Proc Biol Sci 2016; 283:rspb.2016.0246. [PMID: 27053744 DOI: 10.1098/rspb.2016.0246] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Accepted: 03/14/2016] [Indexed: 12/17/2022] Open
Abstract
Learning and memory are crucial functions which enable insect pollinators to efficiently locate and extract floral rewards. Exposure to pesticides or infection by parasites may cause subtle but ecologically important changes in cognitive functions of pollinators. The potential interactive effects of these stressors on learning and memory have not yet been explored. Furthermore, sensitivity to stressors may differ between species, but few studies have compared responses in different species. Here, we show that chronic exposure to field-realistic levels of the neonicotinoid clothianidin impaired olfactory learning acquisition in honeybees, leading to potential impacts on colony fitness, but not in bumblebees. Infection by the microsporidian parasite Nosema ceranae slightly impaired learning in honeybees, but no interactive effects were observed. Nosema did not infect bumblebees (3% infection success). Nevertheless, Nosema-treated bumblebees had a slightly lower rate of learning than controls, but faster learning in combination with neonicotinoid exposure. This highlights the potential for complex interactive effects of stressors on learning. Our results underline that one cannot readily extrapolate findings from one bee species to others. This has important implications for regulatory risk assessments which generally use honeybees as a model for all bees.
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Affiliation(s)
- Saija Piiroinen
- School of Life Sciences, University of Sussex, Brighton BN1 9QG, UK
| | - Dave Goulson
- School of Life Sciences, University of Sussex, Brighton BN1 9QG, UK
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19
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20
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von Wyschetzki K, Lowack H, Heinze J. Transcriptomic response to injury sheds light on the physiological costs of reproduction in ant queens. Mol Ecol 2016; 25:1972-85. [PMID: 26880273 DOI: 10.1111/mec.13588] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Revised: 01/27/2016] [Accepted: 02/08/2016] [Indexed: 01/04/2023]
Abstract
The trade-off between reproduction and longevity is widespread among multicellular organisms. As an important exception, the reproductive females of perennial social insects (ants, honeybees, termites) are simultaneously highly fertile and very long-lived relative to their nonreproductive nestmates. The observation that increased fecundity is not coupled with decreased lifespan suggests that social insect queens do not have to reallocate resources between reproduction and self-maintenance. If queens have to compensate for the costs of reproduction on the level of the individual, the activation of other energy-demanding physiological processes might force them to reduce the production of eggs. To test this hypothesis in ant queens, we increased immunity costs by injury and measured the effect of this treatment on egg-laying rates and genomewide gene expression. Amputation of both middle legs led to a temporary decrease in egg-laying rates and affected the expression of 947 genes corresponding to 9% of the transcriptome. The changes comprised the upregulation of the immune and wound healing response on the one hand, and the downregulation of germ cell development, central nervous system development and learning ability on the other hand. Injury strongly influenced metabolism by inducing catabolism and repressing amino acid and nitrogen compound metabolism. By comparing our results to similar transcriptomic studies in insects, we found a highly consistent upregulation of immune genes due to sterile and septic wounding. The gene expression changes, complemented by the temporary decline of egg-laying rates, clearly reveal a trade-off between reproduction and the immune response in social insect queens.
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Affiliation(s)
- Katharina von Wyschetzki
- LS Zoologie/Evolutionsbiologie, Universität Regensburg, Universitätsstraße 31, D-93053, Regensburg, Germany
| | - Helena Lowack
- LS Zoologie/Evolutionsbiologie, Universität Regensburg, Universitätsstraße 31, D-93053, Regensburg, Germany
| | - Jürgen Heinze
- LS Zoologie/Evolutionsbiologie, Universität Regensburg, Universitätsstraße 31, D-93053, Regensburg, Germany
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Piiroinen S, Botías C, Nicholls E, Goulson D. No effect of low-level chronic neonicotinoid exposure on bumblebee learning and fecundity. PeerJ 2016; 4:e1808. [PMID: 27014515 PMCID: PMC4806594 DOI: 10.7717/peerj.1808] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 02/23/2016] [Indexed: 11/22/2022] Open
Abstract
In recent years, many pollinators have declined in abundance and diversity worldwide, presenting a potential threat to agricultural productivity, biodiversity and the functioning of natural ecosystems. One of the most debated factors proposed to be contributing to pollinator declines is exposure to pesticides, particularly neonicotinoids, a widely used class of systemic insecticide. Also, newly emerging parasites and diseases, thought to be spread via contact with managed honeybees, may pose threats to other pollinators such as bumblebees. Compared to honeybees, bumblebees could be particularly vulnerable to the effects of stressors due to their smaller and more short-lived colonies. Here, we studied the effect of field-realistic, chronic clothianidin exposure and inoculation with the parasite Nosema ceranae on survival, fecundity, sugar water collection and learning using queenless Bombus terrestris audax microcolonies in the laboratory. Chronic exposure to 1 ppb clothianidin had no significant effects on the traits studied. Interestingly, pesticide exposure in combination with additional stress caused by harnessing bees for Proboscis Extension Response (PER) learning assays, led to an increase in mortality. In contrast to previous findings, the bees did not become infected by N. ceranae after experimental inoculation with the parasite spores, suggesting variability in host resistance or parasite virulence. However, this treatment induced a slight, short-term reduction in sugar water collection, potentially through stimulation of the immune system of the bees. Our results suggest that chronic exposure to 1 ppb clothianidin does not have adverse effects on bumblebee fecundity or learning ability.
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Affiliation(s)
- Saija Piiroinen
- School of Life Sciences, University of Sussex, Brighton, United Kingdom
| | - Cristina Botías
- School of Life Sciences, University of Sussex, Brighton, United Kingdom
| | | | - Dave Goulson
- School of Life Sciences, University of Sussex, Brighton, United Kingdom
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Graystock P, Goulson D, Hughes WOH. Parasites in bloom: flowers aid dispersal and transmission of pollinator parasites within and between bee species. Proc Biol Sci 2015; 282:20151371. [PMID: 26246556 PMCID: PMC4632632 DOI: 10.1098/rspb.2015.1371] [Citation(s) in RCA: 171] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Accepted: 07/15/2015] [Indexed: 01/02/2023] Open
Abstract
The dispersal of parasites is critical for epidemiology, and the interspecific vectoring of parasites when species share resources may play an underappreciated role in parasite dispersal. One of the best examples of such a situation is the shared use of flowers by pollinators, but the importance of flowers and interspecific vectoring in the dispersal of pollinator parasites is poorly understood and frequently overlooked. Here, we use an experimental approach to show that during even short foraging periods of 3 h, three bumblebee parasites and two honeybee parasites were dispersed effectively onto flowers by their hosts, and then vectored readily between flowers by non-host pollinator species. The results suggest that flowers are likely to be hotspots for the transmission of pollinator parasites and that considering potential vector, as well as host, species will be of general importance for understanding the distribution and transmission of parasites in the environment and between pollinators.
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Affiliation(s)
| | - Dave Goulson
- School of Life Sciences, University of Sussex, Brighton BN1 9QG, UK
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Baracchi D, Brown MJF, Chittka L. Weak and contradictory effects of self-medication with nectar nicotine by parasitized bumblebees. F1000Res 2015; 4:73. [PMID: 25949807 PMCID: PMC4406194 DOI: 10.12688/f1000research.6262.1] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 03/17/2015] [Indexed: 11/20/2022] Open
Abstract
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.
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Affiliation(s)
- David Baracchi
- Department of Biological and Experimental Psychology, School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
| | - Mark J. F. Brown
- School of Biological Sciences, Royal Holloway University of London, Egham, Surrey, TW20 0EX, UK
| | - Lars Chittka
- Department of Biological and Experimental Psychology, School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
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24
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Abstract
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.
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Affiliation(s)
- David Baracchi
- Department of Biological and Experimental Psychology, School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
| | - Mark J. F. Brown
- School of Biological Sciences, Royal Holloway University of London, Egham, Surrey, TW20 0EX, UK
| | - Lars Chittka
- Department of Biological and Experimental Psychology, School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
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25
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Abstract
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.
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Affiliation(s)
- David Baracchi
- Department of Biological and Experimental Psychology, School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
| | - Mark J. F. Brown
- School of Biological Sciences, Royal Holloway University of London, Egham, Surrey, TW20 0EX, UK
| | - Lars Chittka
- Department of Biological and Experimental Psychology, School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
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26
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Goulson D, Nicholls E, Botías C, Rotheray EL. Bee declines driven by combined stress from parasites, pesticides, and lack of flowers. Science 2015; 347:1255957. [PMID: 25721506 DOI: 10.1126/science.1255957] [Citation(s) in RCA: 1633] [Impact Index Per Article: 181.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Bees are subject to numerous pressures in the modern world. The abundance and diversity of flowers has declined; bees are chronically exposed to cocktails of agrochemicals, and they are simultaneously exposed to novel parasites accidentally spread by humans. Climate change is likely to exacerbate these problems in the future. Stressors do not act in isolation; for example, pesticide exposure can impair both detoxification mechanisms and immune responses, rendering bees more susceptible to parasites. It seems certain that chronic exposure to multiple interacting stressors is driving honey bee colony losses and declines of wild pollinators, but such interactions are not addressed by current regulatory procedures, and studying these interactions experimentally poses a major challenge. In the meantime, taking steps to reduce stress on bees would seem prudent; incorporating flower-rich habitat into farmland, reducing pesticide use through adopting more sustainable farming methods, and enforcing effective quarantine measures on bee movements are all practical measures that should be adopted. Effective monitoring of wild pollinator populations is urgently needed to inform management strategies into the future.
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Affiliation(s)
- Dave Goulson
- School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QG, UK.
| | - Elizabeth Nicholls
- School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QG, UK
| | - Cristina Botías
- School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QG, UK
| | - Ellen L Rotheray
- School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QG, UK
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27
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Riessberger-Gallé U, Hernández López J, Schuehly W, Crockett S, Krainer S, Crailsheim K. Immune responses of honeybees and their fitness costs as compared to bumblebees. APIDOLOGIE 2014; 46:238-249. [PMID: 26412907 PMCID: PMC4579911 DOI: 10.1007/s13592-014-0318-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Revised: 08/19/2014] [Accepted: 09/16/2014] [Indexed: 06/01/2023]
Abstract
Immune responses of invertebrates imply more than developing a merely unspecific response to an infection. Great interest has been raised to unveil whether this investment into immunity also involves fitness costs associated to the individual or the group. Focusing on the immune responses of honeybees, we use the well-studied insect bumblebee for comparison. Bumblebees are capable of producing specific immune responses to infections whereas this has not been assessed for honeybees so far. We investigated whether a prior bacterial encounter provides protection against a later exposure to the same or a different bacterium in honeybees. Additionally, we studied whether the foraging activities of honeybees and bumblebees are affected upon immune stimulation by assessing the flight performance. Finally, the acceptance behavior of nestmates toward immune-challenged honeybees was determined. Results show that despite stimulating the immune system of honeybees, no protective effects to infections were found. Further, honeybees were not affected by an immune challenge in their flight performance whereas bumblebees showed significant flight impairment. Immune-challenged honeybees showed lower survival rates than naive individuals when introduced into a regular colony. Here, we reveal different immune response-cost scenarios in honeybees and bumblebees for the first time.
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Affiliation(s)
- Ulrike Riessberger-Gallé
- Department of Zoology, Universitätsplatz 2, Karl-Franzens University of Graz, A-8010 Graz, Austria
| | - Javier Hernández López
- Department of Zoology, Universitätsplatz 2, Karl-Franzens University of Graz, A-8010 Graz, Austria
| | - Wolfgang Schuehly
- Department of Zoology, Universitätsplatz 2, Karl-Franzens University of Graz, A-8010 Graz, Austria
| | - Sara Crockett
- Department of Zoology, Universitätsplatz 2, Karl-Franzens University of Graz, A-8010 Graz, Austria
| | - Sophie Krainer
- Department of Zoology, Universitätsplatz 2, Karl-Franzens University of Graz, A-8010 Graz, Austria
| | - Karl Crailsheim
- Department of Zoology, Universitätsplatz 2, Karl-Franzens University of Graz, A-8010 Graz, Austria
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Babin A, Kolly S, Kawecki TJ. Virulent bacterial infection improves aversive learning performance in Drosophila melanogaster. Brain Behav Immun 2014; 41:152-61. [PMID: 24863366 DOI: 10.1016/j.bbi.2014.05.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2014] [Revised: 05/02/2014] [Accepted: 05/15/2014] [Indexed: 10/25/2022] Open
Abstract
Virulent infections are expected to impair learning ability, either as a direct consequence of stressed physiological state or as an adaptive response that minimizes diversion of energy from immune defense. This prediction has been well supported for mammals and bees. Here, we report an opposite result in Drosophila melanogaster. Using an odor-mechanical shock conditioning paradigm, we found that intestinal infection with bacterial pathogens Pseudomonas entomophila or Erwinia c. carotovora improved flies' learning performance after a 1h retention interval. Infection with P. entomophila (but not E. c. carotovora) also improved learning performance after 5 min retention. No effect on learning performance was detected for intestinal infections with an avirulent GacA mutant of P. entomophila or for virulent systemic (hemocoel) infection with E. c. carotovora. Assays of unconditioned responses to odorants and shock do not support a major role for changes in general responsiveness to stimuli in explaining the changes in learning performance, although differences in their specific salience for learning cannot be excluded. Our results demonstrate that the effects of pathogens on learning performance in insects are less predictable than suggested by previous studies, and support the notion that immune stress can sometimes boost cognitive abilities.
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Affiliation(s)
- Aurélie Babin
- Department of Ecology and Evolution, University of Lausanne, Biophore, CH-1015 Lausanne, Switzerland
| | - Sylvain Kolly
- Department of Ecology and Evolution, University of Lausanne, Biophore, CH-1015 Lausanne, Switzerland
| | - Tadeusz J Kawecki
- Department of Ecology and Evolution, University of Lausanne, Biophore, CH-1015 Lausanne, Switzerland.
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29
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Harpur BA, Chernyshova A, Soltani A, Tsvetkov N, Mahjoorighasrodashti M, Xu Z, Zayed A. No genetic tradeoffs between hygienic behaviour and individual innate immunity in the honey bee, Apis mellifera. PLoS One 2014; 9:e104214. [PMID: 25162411 PMCID: PMC4146461 DOI: 10.1371/journal.pone.0104214] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Accepted: 07/11/2014] [Indexed: 12/05/2022] Open
Abstract
Many animals have individual and social mechanisms for combating pathogens. Animals may exhibit short-term physiological tradeoffs between social and individual immunity because the latter is often energetically costly. Genetic tradeoffs between these two traits can also occur if mutations that enhance social immunity diminish individual immunity, or vice versa. Physiological tradeoffs between individual and social immunity have been previously documented in insects, but there has been no study of genetic tradeoffs involving these traits. There is strong evidence that some genes influence both innate immunity and behaviour in social insects – a prerequisite for genetic tradeoffs. Quantifying genetic tradeoffs is critical for understanding the evolution of immunity in social insects and for devising effective strategies for breeding disease-resistant pollinator populations. We conducted two experiments to test the hypothesis of a genetic tradeoff between social and individual immunity in the honey bee, Apis mellifera. First, we estimated the relative contribution of genetics to individual variation in innate immunity of honey bee workers, as only heritable traits can experience genetic tradeoffs. Second, we examined if worker bees with hygienic sisters have reduced individual innate immune response. We genotyped several hundred workers from two colonies and found that patriline genotype does not significantly influence the antimicrobial activity of a worker’s hemolymph. Further, we did not find a negative correlation between hygienic behaviour and the average antimicrobial activity of a worker’s hemolymph across 30 honey bee colonies. Taken together, our work indicates no genetic tradeoffs between hygienic behaviour and innate immunity in honey bees. Our work suggests that using artificial selection to increase hygienic behaviour of honey bee colonies is not expected to concurrently compromise individual innate immunity of worker bees.
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Affiliation(s)
- Brock A. Harpur
- Department of Biology, York University, Toronto, Ontario, Canada
| | - Anna Chernyshova
- Department of Biology, York University, Toronto, Ontario, Canada
| | - Arash Soltani
- Department of Biology, York University, Toronto, Ontario, Canada
| | - Nadejda Tsvetkov
- Department of Biology, York University, Toronto, Ontario, Canada
| | | | - Zhixing Xu
- Department of Biology, York University, Toronto, Ontario, Canada
| | - Amro Zayed
- Department of Biology, York University, Toronto, Ontario, Canada
- * E-mail:
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30
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Alaux C, Crauser D, Pioz M, Saulnier C, Le Conte Y. Parasitic and immune modulation of flight activity in honey bees tracked with optical counters. ACTA ACUST UNITED AC 2014; 217:3416-24. [PMID: 25063861 DOI: 10.1242/jeb.105783] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Host-parasite interactions are often characterized by changes in the host behaviour, which are beneficial to either the parasite or the host, or are a non-adaptive byproduct of parasitism. These interactions are further complicated in animal society because individual fitness is associated with group performance. However, a better understanding of host-parasite interaction in animal society first requires the identification of individual host behavioural modification. Therefore, we challenged honey bee (Apis mellifera) workers with the parasite Nosema ceranae or an immune stimulation and tracked their flight activity over their lifetime with an optic counter. We found that bees responded differently to each stress: both Nosema-infected and immune-challenged bees performed a lower number of daily flights compared with control bees, but the duration of their flights increased and decreased over time, respectively. Overall, parasitized bees spent more time in the field each day than control bees, and the inverse was true for immune-challenged bees. Despite the stress of immune challenge, bees had a survival similar to that of control bees likely because of their restricted activity. We discuss how those different behavioural modifications could be adaptive phenotypes. This study provides new insights into how biological stress can affect the behaviour of individuals living in society and how host responses have evolved.
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Affiliation(s)
- Cédric Alaux
- INRA, Institut National de la Recherche Agronomique, UR 406 Abeilles et Environnement, Domaine Saint-Paul, CS 40509, 84914 Avignon, France
| | - Didier Crauser
- INRA, Institut National de la Recherche Agronomique, UR 406 Abeilles et Environnement, Domaine Saint-Paul, CS 40509, 84914 Avignon, France
| | - Maryline Pioz
- INRA, Institut National de la Recherche Agronomique, UR 406 Abeilles et Environnement, Domaine Saint-Paul, CS 40509, 84914 Avignon, France
| | - Cyril Saulnier
- INRA, Institut National de la Recherche Agronomique, UR 406 Abeilles et Environnement, Domaine Saint-Paul, CS 40509, 84914 Avignon, France
| | - Yves Le Conte
- INRA, Institut National de la Recherche Agronomique, UR 406 Abeilles et Environnement, Domaine Saint-Paul, CS 40509, 84914 Avignon, France
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31
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Mallon EB, Alghamdi A, Holdbrook RTK, Rosato E. Immune stimulation reduces sleep and memory ability in Drosophila melanogaster. PeerJ 2014; 2:e434. [PMID: 24949247 PMCID: PMC4060034 DOI: 10.7717/peerj.434] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Accepted: 05/29/2014] [Indexed: 11/20/2022] Open
Abstract
Psychoneuroimmunology studies the increasing number of connections between neurobiology, immunology and behaviour. We demonstrate the effects of the immune response on two fundamental behaviours: sleep and memory ability in Drosophila melanogaster. We used the Geneswitch system to upregulate peptidoglycan receptor protein (PGRP) expression, thereby stimulating the immune system in the absence of infection. Geneswitch was activated by feeding the steroid RU486, to the flies. We used an aversive classical conditioning paradigm to quantify memory and measures of activity to infer sleep. Immune stimulated flies exhibited reduced levels of sleep, which could not be explained by a generalised increase in waking activity. Immune stimulated flies also showed a reduction in memory abilities. These results lend support to Drosophila as a model for immune–neural interactions and provide a possible role for sleep in the interplay between the immune response and memory.
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Affiliation(s)
- Eamonn B Mallon
- Department of Biology, University of Leicester , Leicester , United Kingdom
| | | | | | - Ezio Rosato
- Department of Genetics, University of Leicester , Leicester , United Kingdom
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Jaumann S, Scudelari R, Naug D. Energetic cost of learning and memory can cause cognitive impairment in honeybees. Biol Lett 2013; 9:20130149. [PMID: 23784929 DOI: 10.1098/rsbl.2013.0149] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The energetic cost of cognitive functions can lead to either impairments in learning and memory, or to trade-offs with other functions, when the amount of available energy is limited. However, it has been suggested that, under such conditions, social groups such as honeybees might be able to ward off cognitive impairments in individual bees by adjusting resource allocation at the colony level. Using two complementary experiments, one that tests the effect of learning on subsequent energetic state and survival, and another that tests the effect of energetic state on learning and retention, we show that individual bees pay a significant energetic cost for learning and therefore suffer from significant cognitive deficits under energetic stress. We discuss the implications of such cognitive impairments for the recent observations of bees disappearing from their colonies as well as for social life in general.
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Affiliation(s)
- Sarah Jaumann
- Department of Biology, Colorado State University, Fort Collins, CO 80523, USA
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33
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Fouks B, Lattorff HMG. Social scent marks do not improve avoidance of parasites in foraging bumblebees. J Exp Biol 2013; 216:285-91. [PMID: 23038725 DOI: 10.1242/jeb.075374] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Foraging is a result of innate and acquired mechanisms, and is optimized in order to increase fitness. During foraging, an animal faces many threats, such as predation and infection. The uptake of parasites and diseases while foraging is common and an individual should be adapted to detect and avoid such threats, using cues from either the abiotic environment or the parasite. Social animals possess an additional cue to detect such contaminated food sources: information provided by conspecifics. Bumblebees avoid contaminated flowers, but the cues used by the bees to distinguish contamination remain unknown. Under controlled laboratory conditions, we tested the use of scent marks derived from other foragers in choosing between a contaminated (by Crithidia bombi) and an uncontaminated flower. As a positive control we tested the bee's choice between two flowers, one scented with geraniol and containing a highly rewarding sugar solution, and the other not scented and containing a poorer reward. The bees mainly chose the uncontaminated and the rewarding scented flowers. Scent marks did not increase the efficiency of the bumblebees in choosing the better flower. The bees from both experiments behaved similarly, showing that the main and most relevant cue used to choose the uncontaminated flower is the odour from the parasite itself. The adaptation of bumblebees to avoid flowers contaminated by C. bombi arose from the long-term host-parasite interaction between these species. This strong adaptation results in an innate behaviour of bees and a detection and aversion of the odour of contaminated flower nectar.
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Affiliation(s)
- Bertrand Fouks
- Institut für Biologie, Molekulare Ökologie, Martin-Luther-Universität Halle-Wittenberg Hoher Weg 4, 06099 Halle (Saale), Germany.
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34
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Raine NE, Chittka L. No trade-off between learning speed and associative flexibility in bumblebees: a reversal learning test with multiple colonies. PLoS One 2012; 7:e45096. [PMID: 23028779 PMCID: PMC3447877 DOI: 10.1371/journal.pone.0045096] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2012] [Accepted: 08/15/2012] [Indexed: 11/27/2022] Open
Abstract
Potential trade-offs between learning speed and memory-related performance could be important factors in the evolution of learning. Here, we test whether rapid learning interferes with the acquisition of new information using a reversal learning paradigm. Bumblebees (Bombus terrestris) were trained to associate yellow with a floral reward. Subsequently the association between colour and reward was reversed, meaning bees then had to learn to visit blue flowers. We demonstrate that individuals that were fast to learn yellow as a predictor of reward were also quick to reverse this association. Furthermore, overnight memory retention tests suggest that faster learning individuals are also better at retaining previously learned information. There is also an effect of relatedness: colonies whose workers were fast to learn the association between yellow and reward also reversed this association rapidly. These results are inconsistent with a trade-off between learning speed and the reversal of a previously made association. On the contrary, they suggest that differences in learning performance and cognitive (behavioural) flexibility could reflect more general differences in colony learning ability. Hence, this study provides additional evidence to support the idea that rapid learning and behavioural flexibility have adaptive value.
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Affiliation(s)
- Nigel E Raine
- Biological and Experimental Psychology Group, School of Biological and Chemical Sciences, Queen Mary, University of London, London, United Kingdom.
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35
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36
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Cloutier CJ, Rodowa MS, Cross-Mellor SK, Chan MYT, Kavaliers M, Ossenkopp KP. Inhibition of LiCl-induced conditioning of anticipatory nausea in rats following immune system stimulation: comparing the immunogens lipopolysaccharide, muramyl dipeptide, and polyinosinic: polycytidylic acid. Physiol Behav 2012; 106:243-51. [PMID: 22342813 DOI: 10.1016/j.physbeh.2012.02.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2011] [Revised: 01/18/2012] [Accepted: 02/05/2012] [Indexed: 11/25/2022]
Abstract
The effects of the bacterial endotoxins, lipopolysaccharide (LPS) and muramyl dipeptide (MDP; Experiment 1), and the viral mimetic, polyinosinic: polycytidylic acid (poly I:C; Experiment 2), on the acquisition of "conditioned gaping" behavior in the rodent model of LiCl-induced anticipatory nausea were examined. Experimentally naïve adult male Long-Evans rats were injected (intraperitoneal, i.p.) with either 200 μg/kg LPS, 1.6 mg/kg MDP, or 0.9% saline (Experiment 1), or 4.0 mg/kg poly I:C or 0.9% saline (Experiment 2), 90 min prior to treatment with 127 mg/kg LiCl or saline control and immediately placed into a distinctive context for 30 min (repeated over 4 conditioning days, spaced 72 h apart). On a drug-free test day (72 h following conditioning day 4), each animal was re-exposed to the context for 10 min, and orofacial and aversive behavioral responses were video recorded and analyzed. The results showed that pre-treatment with LPS, MDP (Experiment 1), or poly I:C (Experiment 2) prior to LiCl+context conditioning significantly impaired the establishment of conditioned gaping behavior, thus blocking the acquisition of anticipatory nausea. Results varied in regards to peripheral acute-phase response sickness behaviors, with significantly reduced weight loss in LPS-treated animals, less robust weight loss in poly I:C-treated animals, and no significant reductions in body weight in MDP-treated animals. The learning impairments observed in the current study suggest that endotoxin treatment with bacterial and viral endotoxin may have stronger central effects on learning and memory behavior, relative to peripheral effects on body weight and other sickness-related responses.
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Affiliation(s)
- Caylen J Cloutier
- Department of Psychology, University of Western Ontario, London, Ontario, Canada N6A5C2.
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37
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Fouks B, Lattorff HMG. Recognition and avoidance of contaminated flowers by foraging bumblebees (Bombus terrestris). PLoS One 2011; 6:e26328. [PMID: 22039462 PMCID: PMC3200320 DOI: 10.1371/journal.pone.0026328] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2011] [Accepted: 09/24/2011] [Indexed: 11/18/2022] Open
Abstract
Bumblebee colonies are founded by a single-mated queen. Due to this life history trait, bumblebees are more susceptible to parasites and diseases than polyandrous and/or polygynous social insects. A greater resistance towards parasites is shown when the genetic variability within a colony is increased. The parasite resistance may be divided into different levels regarding the step of the parasite infection (e.g. parasite uptake, parasite intake, parasite's establishment in the nest, parasite transmission).We investigate the prophylactic behaviour of bumblebees. Bumblebees were observed during their foraging flights on two artificial flowers; one of these was contaminated by Crithidia bombi, a naturally occurring gut parasite of bumblebees (in a control experiment the non-specific pathogen Escherichia coli was used). For C. bombi, bumblebees were preferentially observed feeding on the non-contaminated flower. Whereas for E. coli, the number of visits between flowers was the same, bumblebees spent more time feeding on the non-contaminated flower.These results demonstrate the ability of bumblebees to recognise the contamination of food sources. In addition, bumblebees have a stronger preference for the non-contaminated flower when C. bombi is present in the other flower than with E. coli which might be explained as an adaptive behaviour of bumblebees towards this specific gut parasite. It seems that the more specific the parasite is, the more it reduces the reward of the flower.
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Affiliation(s)
- Bertrand Fouks
- Institute of Biology, Molecular Ecology, Martin-Luther University Halle-Wittenberg, Halle, Germany.
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Park Y, Kim Y, Stanley D. Cellular immunosenescence in adult male crickets, Gryllus assimilis. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2011; 76:185-194. [PMID: 21254201 DOI: 10.1002/arch.20394] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2010] [Accepted: 09/23/2010] [Indexed: 05/30/2023]
Abstract
Ecological immunity studies in invertebrates, particularly insects, have generated new insights into trade-offs between immune functions and other physiological parameters. These studies document physiologically directed reallocations of immune costs to other high-cost areas of physiology. Immunosenescence, recognized as the age-related deterioration of immune functions, is another mechanism of radically altering immune systems. We investigated the hypothesis that aging brings on immunosenescence in adult males of the cricket, Gryllus assimilis. Our data show that the intensity of melanotic nodule formation decreased with adult age from after 3-week post-adult emergence. Circulating hemocyte populations similarly decreased from about 5,000 hemocytes/µl hemolymph to about 1,000 hemocytes/µl hemolymph. The numbers of damaged hemocytes in circulation increased from less than 10% at 1-week post-adult emergence to approximately 60% by 3-week post-adult emergence. The composition of hemocyte types changed with age, with increasing proportions of granulocytes and decreasing proportions of plasmatocytes. The declines in nodule formation were not linked to the adult age of sexual behaviors, which begin shortly after entering adulthood in this species. We infer that age-related senescence, rather than cost reallocations, may account for observed declines in various parameters of immune functions in insects, as seen in other animals.
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Affiliation(s)
- Youngjin Park
- Department of Entomology, University of Georgia, Athens, GA, USA
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Cresswell JE. A meta-analysis of experiments testing the effects of a neonicotinoid insecticide (imidacloprid) on honey bees. ECOTOXICOLOGY (LONDON, ENGLAND) 2011; 20:149-57. [PMID: 21080222 DOI: 10.1007/s10646-010-0566-0] [Citation(s) in RCA: 122] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 10/30/2010] [Indexed: 05/21/2023]
Abstract
Honey bees provide important pollination services to crops and wild plants. The agricultural use of systemic insecticides, such as neonicotinoids, may harm bees through their presence in pollen and nectar, which bees consume. Many studies have tested the effects on honey bees of imidacloprid, a neonicotinoid, but a clear picture of the risk it poses to bees has not previously emerged, because investigations are methodologically varied and inconsistent in outcome. In a meta-analysis of fourteen published studies of the effects of imidacloprid on honey bees under laboratory and semi-field conditions that comprised measurements on 7073 adult individuals and 36 colonies, fitted dose-response relationships estimate that trace dietary imidacloprid at field-realistic levels in nectar will have no lethal effects, but will reduce expected performance in honey bees by between 6 and 20%. Statistical power analysis showed that published field trials that have reported no effects on honey bees from neonicotinoids were incapable of detecting these predicted sublethal effects with conventionally accepted levels of certainty. These findings raise renewed concern about the impact on honey bees of dietary imidacloprid, but because questions remain over the environmental relevance of predominantly laboratory-based results, I identify targets for research and provide procedural recommendations for future studies.
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Affiliation(s)
- James E Cresswell
- School of Biosciences, University of Exeter, Hatherly Laboratories, Prince of Wales Road, Exeter, EX4 4PS, UK.
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Abstract
Diverse animals have evolved an ability to collect antimicrobial compounds from the environment as a means of reducing infection risk. Honey bees battle an extensive assemblage of pathogens with both individual and "social" defenses. We determined if the collection of resins, complex plant secretions with diverse antimicrobial properties, acts as a colony-level immune defense by honey bees. Exposure to extracts from two sources of honey bee propolis (a mixture of resins and wax) led to a significantly lowered expression of two honey bee immune-related genes (hymenoptaecin and AmEater in Brazilian and Minnesota propolis, respectively) and to lowered bacterial loads in the Minnesota (MN) propolis treated colonies. Differences in immune expression were also found across age groups (third-instar larvae, 1-day-old and 7-day-old adults) irrespective of resin treatment. The finding that resins within the nest decrease investment in immune function of 7-day-old bees may have implications for colony health and productivity. This is the first direct evidence that the honey bee nest environment affects immune-gene expression.
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Affiliation(s)
- Michael Simone
- Department of Ecology, Evolution and Behavior, University of Minnesota, Twin Cities, St. Paul, Minnesota 55108, USA.
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Alghamdi A, Raine NE, Rosato E, Mallon EB. No evidence for an evolutionary trade-off between learning and immunity in a social insect. Biol Lett 2009; 5:55-7. [PMID: 18957358 DOI: 10.1098/rsbl.2008.0514] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The immune response affects learning and memory in insects. Given this and the known fitness costs of both the immune system and learning, does an evolutionary trade-off exist between these two systems? We tested this by measuring the learning ability of 12 bumble-bee (Bombus terrestris) colonies in a free-flying paradigm. We then tested their immune response using the zone of inhibition assay. We found a positive relationship between colony learning performance and immune response, that is, fast-learning colonies also show high levels of antimicrobial activity. We conclude that there is no a priori reason to demand an evolutionary relationship between two traits that are linked physiologically.
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Affiliation(s)
- A Alghamdi
- Biology Department, University of Leicester, Leicester LE1 7RH, UK
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