1
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Yadav P, Borges RM. Oviposition decisions under environment-induced physiological stress in parasitoids. CURRENT OPINION IN INSECT SCIENCE 2024; 65:101240. [PMID: 39084490 DOI: 10.1016/j.cois.2024.101240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2024] [Revised: 07/17/2024] [Accepted: 07/21/2024] [Indexed: 08/02/2024]
Abstract
Parasitoids constantly evaluate their environment to optimise oviposition host utilisation based on their life history parameters and host characteristics, including density. Any factors impairing chemosensory perception, learning and memory of oviposition decisions negatively impact fitness. In the Anthropocene, stressors, for example, elevated temperatures, Wolbachia infection (likely modulated by temperature), pesticides, light pollution and water deficits in plants that provide resources for parasitoid hosts, impact parasitoid oviposition. Such physiological stressors often induce superparasitism since parasitoids are unable to remember prior oviposition on hosts or cause impaired offspring sex ratio. While the effect of these stressors on parasitoid oviposition has been examined individually, their combined effects remain unexplored. Since parasitoids are exposed to these stressors simultaneously, future work must examine their cumulative impact.
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Affiliation(s)
| | - Renee M Borges
- Centre for Ecological Sciences, Indian Institute of Sciences, Bengaluru 560012, India.
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2
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Erratt KJ, Freeman EC. Cyanobacteria in the Anthropocene: Synanthropism forged in an era of global change. WATER ENVIRONMENT RESEARCH : A RESEARCH PUBLICATION OF THE WATER ENVIRONMENT FEDERATION 2024; 96:e11066. [PMID: 39031717 DOI: 10.1002/wer.11066] [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: 03/19/2024] [Revised: 05/14/2024] [Accepted: 05/31/2024] [Indexed: 07/22/2024]
Abstract
The Anthropocene has driven a transformative era where human activities exert unprecedented influence on Earth's biosphere. Consequently, synanthropic organisms, adept at thriving in human-modified environments, have emerged. While well studied in terrestrial ecosystems, the presence and ecological importance of synanthropic species in aquatic ecosystems, specifically among cyanobacteria, are less understood. Cyanobacteria blooms, notorious for their detrimental effects on ecosystems and human health, are increasing in frequency and intensity globally. In this perspective, we explore the evidence supporting this rise of cyanobacteria blooms, emphasizing the roles of human-induced eutrophication and climate change on select cyanobacteria genera. Cyanobacteria are not a monolith, with certain genera showing an observable increase within anthropogenically modified environments. We propose the establishment of a new sub-branch of phycology that explicitly investigates the ecology and physiology of synanthropic cyanobacteria. Understanding the intricate interactions between synanthropic species and human populations is imperative for managing human-altered ecosystems and conserving freshwater resources, particularly in the face of increasing global water insecurity. PRACTITIONER POINTS: The rise in cyanobacteria blooms is driven by a small subset of human-adapted genera-synanthropic cyanobacteria. Research is needed to characterize synanthropic cyanobacteria, which will aid in developing tailored management approaches. A paradigm shift from domesticating to "rewilding" landscapes and modifying behaviors to facilitate cohabitation are solutions to reducing risks.
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Affiliation(s)
- Kevin J Erratt
- Department of Physical and Environmental Sciences, University of Toronto, Toronto, Ontario, Canada
| | - Erika C Freeman
- Ecosystems and Global Change Group, Department of Plant Sciences, University of Cambridge, Cambridge, UK
- Department of Aquatic Ecology, Eawag: Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland
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3
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Sepúlveda-Rodríguez G, Roberts KT, Araújo P, Lehmann P, Baird E. Bumblebee thermoregulation at increasing temperatures is affected by behavioral state. J Therm Biol 2024; 121:103830. [PMID: 38604117 DOI: 10.1016/j.jtherbio.2024.103830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 02/07/2024] [Accepted: 02/28/2024] [Indexed: 04/13/2024]
Abstract
Over the past decades, increasing environmental temperatures have been identified as one of the causes of major insect population declines and biodiversity loss. However, it is unclear how these rising temperatures affect endoheterothermic insects, like bumblebees, that have evolved thermoregulatory capacities to exploit cold and temperate habitats. To investigate this, we measured head, thoracic, and abdominal temperature of bumblebee (Bombus terrestris) workers across a range of temperatures (24 °C-32 °C) during three distinct behaviors. In resting bumblebees, the head, abdomen, and thorax conformed to the environmental temperature. In pre-flight bumblebees, the head and abdominal temperatures were elevated with respect to the environmental temperature, while the thoracic temperature was maintained, indicating a pre-flight muscle warming stage. In post-flight bumblebees, abdominal temperature increased at the same rate as environmental temperature, but the head and the thoracic temperature did not. By calculating the excess temperature ratio, we show that thermoregulation in bumblebees during flight is partially achieved by the active transfer of heat produced in the thorax to the abdomen, where it can more easily be dissipated. These results provide the first indication that the thermoregulatory abilities of bumblebees are plastic and behavior dependent. We also show that the flight speed and number of workers foraging increase with increasing temperature, suggesting that bees do not avoid flying at these temperatures despite its impact on behavioral performance.
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Affiliation(s)
| | - Kevin T Roberts
- Department of Zoology, Stockholm University, Stockholm, 11418, Sweden.
| | - Priscila Araújo
- Department of Zoology, Stockholm University, Stockholm, 11418, Sweden.
| | - Philipp Lehmann
- Department of Zoology, Stockholm University, Stockholm, 11418, Sweden; Department of Animal Physiology, Zoological Institute and Museum, University of Greifswald, D-17489, Greifswald, Germany.
| | - Emily Baird
- Department of Zoology, Stockholm University, Stockholm, 11418, Sweden.
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4
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Ghisbain G, Thiery W, Massonnet F, Erazo D, Rasmont P, Michez D, Dellicour S. Projected decline in European bumblebee populations in the twenty-first century. Nature 2024; 628:337-341. [PMID: 37704726 DOI: 10.1038/s41586-023-06471-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Accepted: 07/21/2023] [Indexed: 09/15/2023]
Abstract
Habitat degradation and climate change are globally acting as pivotal drivers of wildlife collapse, with mounting evidence that this erosion of biodiversity will accelerate in the following decades1-3. Here, we quantify the past, present and future ecological suitability of Europe for bumblebees, a threatened group of pollinators ranked among the highest contributors to crop production value in the northern hemisphere4-8. We demonstrate coherent declines of bumblebee populations since 1900 over most of Europe and identify future large-scale range contractions and species extirpations under all future climate and land use change scenarios. Around 38-76% of studied European bumblebee species currently classified as 'Least Concern' are projected to undergo losses of at least 30% of ecologically suitable territory by 2061-2080 compared to 2000-2014. All scenarios highlight that parts of Scandinavia will become potential refugia for European bumblebees; it is however uncertain whether these areas will remain clear of additional anthropogenic stressors not accounted for in present models. Our results underline the critical role of global change mitigation policies as effective levers to protect bumblebees from manmade transformation of the biosphere.
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Affiliation(s)
- Guillaume Ghisbain
- Spatial Epidemiology Lab (SpELL), Université Libre de Bruxelles, Brussels, Belgium.
- Laboratory of Zoology, Research Institute for Biosciences, Université de Mons, Mons, Belgium.
| | - Wim Thiery
- Department of Hydrology and Hydraulic Engineering, Vrije Universiteit Brussel, Brussels, Belgium
| | - François Massonnet
- Earth and Climate Research Center, Earth and Life Institute, Université catholique de Louvain, Louvain-la-Neuve, Belgium
| | - Diana Erazo
- Spatial Epidemiology Lab (SpELL), Université Libre de Bruxelles, Brussels, Belgium
| | - Pierre Rasmont
- Laboratory of Zoology, Research Institute for Biosciences, Université de Mons, Mons, Belgium
| | - Denis Michez
- Laboratory of Zoology, Research Institute for Biosciences, Université de Mons, Mons, Belgium
| | - Simon Dellicour
- Spatial Epidemiology Lab (SpELL), Université Libre de Bruxelles, Brussels, Belgium.
- Laboratory of Clinical and Epidemiological Virology, Department of Microbiology, Immunology and Transplantation, Rega Institute, KU Leuven, Leuven, Belgium.
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5
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Soravia C, Ashton BJ, Thornton A, Bourne AR, Ridley AR. High temperatures during early development reduce adult cognitive performance and reproductive success in a wild animal population. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 912:169111. [PMID: 38070557 DOI: 10.1016/j.scitotenv.2023.169111] [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: 07/17/2023] [Revised: 10/31/2023] [Accepted: 12/02/2023] [Indexed: 12/19/2023]
Abstract
Global warming is rapidly changing the phenology, distribution, behaviour and demography of wild animal populations. Recent studies in wild animals have shown that high temperatures can induce short-term cognitive impairment, and captive studies have demonstrated that heat exposure during early development can lead to long-term cognitive impairment. Given that cognition underpins behavioural flexibility and can be directly linked to fitness, understanding how high temperatures during early life might impact adult cognitive performance in wild animals is a critical next step to predict wildlife responses to climate change. Here, we investigated the relationship between temperatures experienced during development, adult cognitive performance, and reproductive success in wild southern pied babblers (Turdoides bicolor). We found that higher mean daily maximum temperatures during nestling development led to long-term cognitive impairment in associative learning performance, but not reversal learning performance. Additionally, a higher number of hot days (exceeding 35.5 °C, temperature threshold at which foraging efficiency and offspring provisioning decline) during post-fledging care led to reduced reproductive success in adulthood. We did not find evidence that low reproductive success was linked to impaired associative learning performance: associative learning performance was not related to reproductive success. In contrast, reversal learning performance was negatively related to reproductive success in breeding adults. This suggests that reproduction can carry a cost in terms of reduced performance in cognitively demanding tasks, confirming previous evidence in this species. Taken together, these findings indicate that naturally occurring high temperatures during early development have long-term negative effects on cognition and reproductive success in wild animals. Compounding effects of high temperatures on current nestling mortality and on the long-term cognitive and reproductive performance of survivors are highly concerning given ongoing global warming.
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Affiliation(s)
- Camilla Soravia
- Centre for Evolutionary Biology, School of Biological Sciences, University of Western Australia, Perth, WA, Australia.
| | - Benjamin J Ashton
- Centre for Evolutionary Biology, School of Biological Sciences, University of Western Australia, Perth, WA, Australia; School of Natural Sciences, Macquarie University, Sydney, NSW, Australia; FitzPatrick Institute of African Ornithology, University of Cape Town, Cape Town, South Africa.
| | - Alex Thornton
- Centre for Ecology and Conservation, University of Exeter, Penryn, UK.
| | - Amanda R Bourne
- FitzPatrick Institute of African Ornithology, University of Cape Town, Cape Town, South Africa; Australian Wildlife Conservancy, 322 Hay Street, Subiaco, WA, Australia.
| | - Amanda R Ridley
- Centre for Evolutionary Biology, School of Biological Sciences, University of Western Australia, Perth, WA, Australia; FitzPatrick Institute of African Ornithology, University of Cape Town, Cape Town, South Africa.
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6
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Zhou W, Wang Q, Li R, Zhang Z, Wang W, Zhou F, Ling L. The effects of heatwave on cognitive impairment among older adults: Exploring the combined effects of air pollution and green space. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 904:166534. [PMID: 37647952 DOI: 10.1016/j.scitotenv.2023.166534] [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: 04/25/2023] [Revised: 07/23/2023] [Accepted: 08/22/2023] [Indexed: 09/01/2023]
Abstract
The association between heatwaves and cognitive impairment in older adults, especially the joint effect of air pollution and green space on this association, remains unknown. The present cohort study used data from waves of the Chinese Longitudinal Healthy Longevity Survey (CLHLS) from 2008 to 2018. Heatwaves were defined as having daily maximum temperature ≥ 92.5th, 95th and 97.5th percentile that continued at least two, three and four days, measured as the one-year heatwave days prior to the participants' incident cognitive impairment. Data on the annual average air pollutant concentrations of fine particulate matter (PM2.5) and ozone (O3) as well as green space exposure (according to the Normalized Difference Vegetation Index (NDVI)) were collected. Time-varying Cox proportional hazards models were constructed to examine the independent effect of heatwaves on cognitive impairment and the combined effect of heatwaves, air pollution, and green space on cognitive impairment. Potential multiplicative interactions were examined by adding a product term of air pollutants and NDVI with heatwaves in the models. The relative excess risk due to interaction (RERI) was calculated to reflect additive interactions. We found that heatwave exposure was associated with higher risks of cognitive impairment, with hazard ratios (HRs) and 95 % confidence intervals (CIs) ranging from 1.035 (95 % CI: 1.016-1.055) to 1.058 (95 % CI: 1.040-1.075). We observed a positive interaction of PM2.5 concentrations, O3 concentrations, lack of green space, and heatwave exposure on a multiplicative scale (HRs for product terms >1). Furthermore, we found a synergistic interaction of PM2.5 concentrations, O3, lack of green space, and heatwave exposure on an additive scale, with RERIs >0. These results suggest that extreme heat exposure may be a potential risk factor for cognitive impairment in older adults. Additionally, coexposure to air pollution and lack of green space exacerbated the adverse effects of heatwaves on cognitive function.
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Affiliation(s)
- Wensu Zhou
- Department of Medical Statistics, School of Public Health, Sun Yat-sen University, Guangzhou, China
| | - Qiong Wang
- Department of Epidemiology, School of Public Health, Sun Yat-sen University, Guangzhou, China
| | - Rui Li
- Department of Medical Statistics, School of Public Health, Sun Yat-sen University, Guangzhou, China
| | - Zhirong Zhang
- School of Mathematics, Sun Yat-Sen University, Sun Yat-sen University, Guangzhou, China
| | - Wenjuan Wang
- Department of Medical Statistics, School of Public Health, Sun Yat-sen University, Guangzhou, China
| | - Fenfen Zhou
- Department of Medical Statistics, School of Public Health, Sun Yat-sen University, Guangzhou, China
| | - Li Ling
- Department of Medical Statistics, School of Public Health, Sun Yat-sen University, Guangzhou, China; Clinical Research Design Division, Clinical Research Center, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China.
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7
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Soravia C, Ashton BJ, Thornton A, Ridley AR. High temperatures are associated with reduced cognitive performance in wild southern pied babblers. Proc Biol Sci 2023; 290:20231077. [PMID: 37989242 PMCID: PMC10688443 DOI: 10.1098/rspb.2023.1077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 10/20/2023] [Indexed: 11/23/2023] Open
Abstract
Global temperatures are increasing rapidly. While considerable research is accumulating regarding the lethal and sublethal effects of heat on wildlife, its potential impact on animal cognition has received limited attention. Here, we tested wild southern pied babblers (Turdoides bicolor) on three cognitive tasks (associative learning, reversal learning and inhibitory control) under naturally occurring heat stress and non-heat stress conditions. We determined whether cognitive performance was explained by temperature, heat dissipation behaviours, individual and social attributes, or proxies of motivation. We found that temperature, but not heat dissipation behaviours, predicted variation in associative learning performance. Individuals required on average twice as many trials to learn an association when the maximum temperature during testing exceeded 38°C compared with moderate temperatures. Higher temperatures during testing were also associated with reduced inhibitory control performance, but only in females. By contrast, we found no temperature-related decline in performance in the reversal learning task, albeit individuals reached learning criterion in only 14 reversal learning tests. Our findings provide novel evidence of temperature-mediated cognitive impairment in a wild animal and indicate that its occurrence depends on the cognitive trait examined and individual sex.
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Affiliation(s)
- Camilla Soravia
- Centre for Evolutionary Biology, School of Biological Sciences, University of Western Australia, Perth, Western Australia, Australia 6009
| | - Benjamin J. Ashton
- Centre for Evolutionary Biology, School of Biological Sciences, University of Western Australia, Perth, Western Australia, Australia 6009
- School of Natural Sciences, Macquarie University, Sydney, New South Wales, Australia 2109
- FitzPatrick Institute of African Ornithology, University of Cape Town, Cape Town, South Africa, 7701
| | - Alex Thornton
- Centre for Ecology and Conservation, University of Exeter, Penryn, TR10 9FE, UK
| | - Amanda R. Ridley
- Centre for Evolutionary Biology, School of Biological Sciences, University of Western Australia, Perth, Western Australia, Australia 6009
- FitzPatrick Institute of African Ornithology, University of Cape Town, Cape Town, South Africa, 7701
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8
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White SA, Dillon ME. Climate warming and bumble bee declines: the need to consider sub-lethal heat, carry-over effects, and colony compensation. Front Physiol 2023; 14:1251235. [PMID: 38028807 PMCID: PMC10644220 DOI: 10.3389/fphys.2023.1251235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2023] [Accepted: 10/17/2023] [Indexed: 12/01/2023] Open
Abstract
Global declines in abundance and diversity of insects are now well-documented and increasingly concerning given the critical and diverse roles insects play in all ecosystems. Habitat loss, invasive species, and anthropogenic chemicals are all clearly detrimental to insect populations, but mounting evidence implicates climate change as a key driver of insect declines globally. Warming temperatures combined with increased variability may expose organisms to extreme heat that exceeds tolerance, potentially driving local extirpations. In this context, heat tolerance limits (e.g., critical thermal maximum, CTmax) have been measured for many invertebrates and are often closely linked to climate regions where animals are found. However, temperatures well below CTmax may also have pronounced effects on insects, but have been relatively less studied. Additionally, many insects with out-sized ecological and economic footprints are colonial (e.g., ants, social bees, termites) such that effects of heat on individuals may propagate through or be compensated by the colony. For colonial organisms, measuring direct effects on individuals may therefore reveal little about population-level impacts of changing climates. Here, we use bumble bees (genus Bombus) as a case study to highlight how a limited understanding of heat effects below CTmax and of colonial impacts and responses both likely hinder our ability to explain past and predict future climate change impacts. Insights from bumble bees suggest that, for diverse invertebrates, predicting climate change impacts will require a more nuanced understanding of the effects of heat exposure and additional studies of carry-over effects and compensatory responses by colonies.
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Affiliation(s)
- Sabrina A. White
- Department of Zoology and Physiology and Program in Ecology, University of Wyoming, Laramie, WY, United States
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9
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Straw EA, Cini E, Gold H, Linguadoca A, Mayne C, Rockx J, Brown MJF, Garratt MPD, Potts SG, Senapathi D. Neither sulfoxaflor, Crithidia bombi, nor their combination impact bumble bee colony development or field bean pollination. Sci Rep 2023; 13:16462. [PMID: 37777537 PMCID: PMC10542809 DOI: 10.1038/s41598-023-43215-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Accepted: 09/21/2023] [Indexed: 10/02/2023] Open
Abstract
Many pollinators, including bumble bees, are in decline. Such declines are known to be driven by a number of interacting factors. Decreases in bee populations may also negatively impact the key ecosystem service, pollination, that they provide. Pesticides and parasites are often cited as two of the drivers of bee declines, particularly as they have previously been found to interact with one another to the detriment of bee health. Here we test the effects of an insecticide, sulfoxaflor, and a highly prevalent bumble bee parasite, Crithidia bombi, on the bumble bee Bombus terrestris. After exposing colonies to realistic doses of either sulfoxaflor and/or Crithidia bombi in a fully crossed experiment, colonies were allowed to forage on field beans in outdoor exclusion cages. Foraging performance was monitored, and the impacts on fruit set were recorded. We found no effect of either stressor, or their interaction, on the pollination services they provide to field beans, either at an individual level or a whole colony level. Further, there was no impact of any treatment, in any metric, on colony development. Our results contrast with prior findings that similar insecticides (neonicotinoids) impact pollination services, and that sulfoxaflor impacts colony development, potentially suggesting that sulfoxaflor is a less harmful compound to bee health than neonicotinoids insecticides.
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Affiliation(s)
- Edward A Straw
- Department of Botany, Trinity College Dublin, Dublin, D02 PN40, Ireland
- Department of Biological Sciences, Centre for Ecology, Evolution and Behaviour, School of Life Sciences and the Environment, Royal Holloway University of London, Egham, Surrey, TW20 0EX, UK
| | - Elena Cini
- Centre for Agri-Environmental Research, School of Agriculture, Policy and Development, University of Reading, Reading, RG6 6AR, UK.
| | - Harriet Gold
- The School of Archaeology, Geography and Environmental Sciences, University of Reading, Reading, RG6 6AB, UK
| | - Alberto Linguadoca
- Department of Biological Sciences, Centre for Ecology, Evolution and Behaviour, School of Life Sciences and the Environment, Royal Holloway University of London, Egham, Surrey, TW20 0EX, UK
- Pesticides Peer Review Unit, European Food Safety Authority (EFSA), Via Carlo Magno 1A, 43126, Parma, Italy
| | - Chloe Mayne
- School of Biological Sciences, University of Reading, Reading, RG6 6AS, UK
| | - Joris Rockx
- Centre for Agri-Environmental Research, School of Agriculture, Policy and Development, University of Reading, Reading, RG6 6AR, UK
| | - Mark J F Brown
- Department of Biological Sciences, Centre for Ecology, Evolution and Behaviour, School of Life Sciences and the Environment, Royal Holloway University of London, Egham, Surrey, TW20 0EX, UK
| | - Michael P D Garratt
- Centre for Agri-Environmental Research, School of Agriculture, Policy and Development, University of Reading, Reading, RG6 6AR, UK
| | - Simon G Potts
- Centre for Agri-Environmental Research, School of Agriculture, Policy and Development, University of Reading, Reading, RG6 6AR, UK
| | - Deepa Senapathi
- Centre for Agri-Environmental Research, School of Agriculture, Policy and Development, University of Reading, Reading, RG6 6AR, UK.
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10
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Hill L, Gérard M, Hildebrandt F, Baird E. Bumblebee cognitive abilities are robust to changes in colony size. Behav Ecol Sociobiol 2023. [DOI: 10.1007/s00265-023-03299-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Abstract
Abstract
Eusocial insect colonies act as a superorganism, which can improve their ability to buffer the negative impact of some anthropogenic stressors. However, this buffering effect can be affected by anthropogenic factors that reduce their colony size. A reduction in colony size is known to negatively affect several parameters like brood maintenance or thermoregulation, but the effects on behaviour and cognition have been largely overlooked. It remains unclear how a sudden change in group size, such as that which might be caused by anthropogenic stressors, affects individual behaviour within a colony. In this study, the bumblebee Bombus terrestris was used to study the effect of social group size on behaviour by comparing the associative learning capabilities of individuals from colonies that were unmanipulated, reduced to a normal size (a colony of 100 workers) or reduced to a critically low but functional size (a colony of 20 workers). The results demonstrated that workers from the different treatments performed equally well in associative learning tasks, which also included no significant differences in the learning capacity of workers that had fully developed after the colony size manipulation. Furthermore, we found that the size of workers had no impact on associative learning ability. The learning abilities of bumblebee workers were thus resilient to the colony reduction they encountered. Our study is a first step towards understanding how eusocial insect cognition can be impacted by drastic reductions in colony size.
Significance statement
While anthropogenic stressors can reduce the colony size of eusocial insects, the impact of this reduction is poorly studied, particularly among bumblebees. We hypothesised that colony size reduction would affect the cognitive capacity of worker bumblebees as a result of fewer social interactions or potential undernourishment. Using differential conditioning, we showed that drastic reductions in colony size have no effect on the associative learning capabilities of the bumblebee Bombus terrestris and that this was the same for individuals that were tested just after the colony reduction and individuals that fully developed under the colony size reduction. We also showed that body size did not affect learning capabilities. This resilience could be an efficient buffer against the ongoing impacts of global change.
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11
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Gérard M, Cariou B, Henrion M, Descamps C, Baird E. Exposure to elevated temperature during development affects bumblebee foraging behavior. Behav Ecol 2022; 33:816-824. [PMID: 35812365 PMCID: PMC9262166 DOI: 10.1093/beheco/arac045] [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: 12/15/2021] [Revised: 04/13/2022] [Accepted: 04/23/2022] [Indexed: 11/14/2022] Open
Abstract
Bee foraging behavior provides a pollination service that has both ecological and economic benefits. However, bee population decline could directly affect the efficiency of this interaction. Among the drivers of this decline, global warming has been implicated as an emerging threat but exactly how increasing temperatures affect bee foraging behavior remains unexplored. Here, we assessed how exposure to elevated temperatures during development affects the foraging behavior and morphology of workers from commercial and wild Bombus terrestris colonies. Workers reared at 33 °C had a higher visiting rate and shorter visiting time than those reared at 27°C. In addition, far fewer workers reared at 33 °C engaged in foraging activities and this is potentially related to the drastic reduction in the number of individuals produced in colonies exposed to 33 °C. The impact of elevated developmental temperature on wild colonies was even stronger as none of the workers from these colonies performed any foraging trips. We also found that rearing temperature affected wing size and shape. Our results provide the first evidence that colony temperature can have striking effects on bumblebee foraging behavior. Of particular importance is the drastic reduction in the number of workers performing foraging trips, and the total number of foraging trips made by workers reared in high temperatures. Further studies should explore if, ultimately, these observed effects of exposure to elevated temperature during development lead to a reduction in pollination efficiency.
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Affiliation(s)
- Maxence Gérard
- INSECT Lab, Division of Functional Morphology, Department of Zoology, Stockholm University, Svante Arrhenius väg 18b, 11418 Stockholm, Sweden
| | - Bérénice Cariou
- INSECT Lab, Division of Functional Morphology, Department of Zoology, Stockholm University, Svante Arrhenius väg 18b, 11418 Stockholm, Sweden
- Sorbonne Université, Faculté des Sciences et Ingénierie, 5 place Jussieu, 75005 Paris, France
| | - Maxime Henrion
- INSECT Lab, Division of Functional Morphology, Department of Zoology, Stockholm University, Svante Arrhenius väg 18b, 11418 Stockholm, Sweden
- Ecole Normale Supérieure de Lyon, 15 parvis René Descartes, Lyon, France, and
| | - Charlotte Descamps
- Earth and Life Institute-Agrotnomy, UCLouvain, Croix du Sud 2, box L7.05.14, 1348 Louvain-la-Neuve, Belgium
| | - Emily Baird
- INSECT Lab, Division of Functional Morphology, Department of Zoology, Stockholm University, Svante Arrhenius väg 18b, 11418 Stockholm, Sweden
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