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Di Noi A, Caliani I, D'Agostino A, Cai G, Romi M, Campani T, Ferrante F, Baracchi D, Casini S. Assessing the effects of a commercial fungicide and an herbicide, alone and in combination, on Apis mellifera: Insights from biomarkers and cognitive analysis. CHEMOSPHERE 2024; 359:142307. [PMID: 38734252 DOI: 10.1016/j.chemosphere.2024.142307] [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: 06/15/2023] [Revised: 02/20/2024] [Accepted: 05/09/2024] [Indexed: 05/13/2024]
Abstract
Agrochemicals play a vital role in protecting crops and enhancing agricultural production by reducing threats from pests, pathogens and weeds. The toxicological status of honey bees can be influenced by a number of factors, including pesticides. While extensive research has focused on the lethal and sublethal effects of insecticides on individual bees and colonies, it is important to recognise that fungicides and herbicides can also affect bees' health. Unfortunately, in the field, honey bees are exposed to mixtures of compounds rather than single substances. This study aimed to evaluate the effects of a commercial fungicide and a commercial herbicide, both individually and in combination, on honey bees. Mortality assays, biomarkers and learning and memory tests were performed, and the results were integrated to assess the toxicological status of honey bees. Neurotoxicity (acetylcholinesterase and carboxylesterase activities), detoxification and metabolic processes (glutathione S-transferase and alkaline phosphatase activities), immune system function (lysozyme activity and haemocytes count) and genotoxicity biomarkers (Nuclear Abnormalities assay) were assessed. The fungicide Sakura® was found to activate detoxification enzymes and affect alkaline phosphatase activity. The herbicide Elegant 2FD and the combination of both pesticides showed neurotoxic effects and induced detoxification processes. Exposure to the herbicide/fungicide mixture impaired learning and memory in honey bees. This study represents a significant advance in understanding the toxicological effects of commonly used commercial pesticides in agriculture and contributes to the development of effective strategies to mitigate their adverse effects on non-target insects.
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Affiliation(s)
- Agata Di Noi
- Department of Life Sciences, University of Siena, Via Mattioli, 4, Siena, 53100, Italy
| | - Ilaria Caliani
- Department of Physical, Earth and Environmental Sciences, University of Siena, Via Mattioli, 4, Siena, 53100, Italy.
| | - Antonella D'Agostino
- Department of Economics and Statistics, University of Siena, Piazza S. Francesco 7, 53100 Siena, Italy
| | - Giampiero Cai
- Department of Life Sciences, University of Siena, Via Mattioli, 4, Siena, 53100, Italy
| | - Marco Romi
- Department of Life Sciences, University of Siena, Via Mattioli, 4, Siena, 53100, Italy
| | - Tommaso Campani
- Department of Physical, Earth and Environmental Sciences, University of Siena, Via Mattioli, 4, Siena, 53100, Italy
| | - Federico Ferrante
- Department of Ecological and Biological Science, Tuscia University, Largo dell'Università s.n.c., 01100 6, Viterbo, Italy
| | - David Baracchi
- Department of Biology, University of Florence, Via Madonna del Piano, 6, Sesto Fiorentino, 50019, Italy
| | - Silvia Casini
- Department of Physical, Earth and Environmental Sciences, University of Siena, Via Mattioli, 4, Siena, 53100, Italy
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Mogensen AL, Andersen LB, Sørensen JG, Offenberg J. Manipulated ants: inducing loyalty to sugar feeders with an alkaloid. PEST MANAGEMENT SCIENCE 2024; 80:3445-3450. [PMID: 38407544 DOI: 10.1002/ps.8049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Revised: 02/22/2024] [Accepted: 02/26/2024] [Indexed: 02/27/2024]
Abstract
BACKGROUND Wood ants are promising biocontrol agents in fruit plantations because they prey on pest insects and inhibit plant diseases. However, these ants also attend plant-feeding homopterans to harvest their honeydew secretions, thereby increasing their numbers. This problem can be solved by offering ants alternative sugar sources that are more attractive than honeydew. From natural interactions, it is known that some species manipulate mutualistic partners toward loyalty by adding alkaloids to the food they offer their mutualists. Inspired by this, the addition of alkaloids might be used to make ants loyal to artificial sugar feeders and thus used to reduce populations of ant-farmed homopterans in ant-mediated biological control. We aimed to explore whether wood ants (Formica polyctena) would develop a taste preference for morphine-containing sugar solutions in two-choice laboratory tests. RESULTS After having fed on a morphine/sugar solution for 1 week, ants showed a significant preference for morphine solutions compared with equal concentration sugar solutions without morphine. Furthermore, ants lost this preference after 6-9 days on a morphine-free diet. CONCLUSION The results show that wood ants react to morphine in their food, enabling chemical manipulation of their behavior, most likely through a taste preference. Thus, ants are susceptible to manipulation by mutualistic partners in natural interactions and furthermore may be manipulated artificially in biocontrol programs to avoid ant-mediated build-up of homopteran populations. © 2024 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
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Affiliation(s)
- Anders Lander Mogensen
- Department of Biology, Aarhus University, Aarhus, Denmark
- Department of Ecoscience, Aarhus University, Aarhus, Denmark
| | - Laurits Bundgaard Andersen
- Department of Biology, Aarhus University, Aarhus, Denmark
- Department of Ecoscience, Aarhus University, Aarhus, Denmark
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Matsumoto Y, Matsumoto CS, Mizunami M. Critical roles of nicotinic acetylcholine receptors in olfactory memory formation and retrieval in crickets. Front Physiol 2024; 15:1345397. [PMID: 38405118 PMCID: PMC10884312 DOI: 10.3389/fphys.2024.1345397] [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: 11/27/2023] [Accepted: 01/29/2024] [Indexed: 02/27/2024] Open
Abstract
Acetylcholine (ACh) is a major excitatory neurotransmitter in the insect central nervous system, and insect neurons express several types of ACh receptors (AChRs). AChRs are classified into two subgroups, muscarinic AChRs and nicotinic AChRs (nAChRs). nAChRs are also divided into two subgroups by sensitivity to α-bungarotoxin (α-BGT). The cricket Gryllus bimaculatus is one of the useful insects for studying the molecular mechanisms in olfactory learning and memory. However, the roles of nAChRs in olfactory learning and memory of the cricket are still unknown. In the present study, to investigate whether nAChRs are involved in cricket olfactory learning and memory, we tested the effects of two different AChR antagonists on long-term memory (LTM) formation and retrieval in a behavioral assay. The two AChR antagonists that we used are mecamylamine (MEC), an α-BGT-insensitive nAChR antagonist, and methyllycaconitine (MLA), an α-BGT-sensitive nAChR antagonist. In crickets, multiple-trial olfactory conditioning induced 1-day memory (LTM), whereas single-trial olfactory conditioning induced 1-h memory (mid-term memory, MTM) but not 1-day memory. Crickets injected with MEC 20 min before the retention test at 1 day after the multiple-trial conditioning exhibited no memory retrieval. This indicates that α-BGT-insensitive nAChRs participate in memory retrieval. In addition, crickets injected with MLA before the multiple-trial conditioning exhibited MTM but not LTM, indicating that α-BGT-sensitive nAChRs participate in the formation of LTM. Moreover, injection of nicotine (an nAChR agonist) before the single-trial conditioning induced LTM. Finally, the nitric oxide (NO)-cGMP signaling pathway is known to participate in the formation of LTM in crickets, and we conducted co-injection experiments with an agonist or inhibitor of the nAChR and an activator or inhibitor of the NO-cGMP signaling pathway. The results suggest that nAChR works upstream of the NO-cGMP signaling system in the LTM formation process.
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Affiliation(s)
- Yukihisa Matsumoto
- Institute of Education, Liberal Arts and Sciences Division, Tokyo Medical and Dental University, Ichikawa, Chiba, Japan
| | | | - Makoto Mizunami
- Faculty of Science, Hokkaido University, Sapporo, Hokkaido, Japan
- Research Institute for Electronic Science, Hokkaido University, Sapporo, Hokkaido, Japan
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Robert T, Tarapata K, Nityananda V. Learning modifies attention during bumblebee visual search. Behav Ecol Sociobiol 2024; 78:22. [PMID: 38333735 PMCID: PMC10847365 DOI: 10.1007/s00265-024-03432-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Revised: 12/15/2023] [Accepted: 01/12/2024] [Indexed: 02/10/2024]
Abstract
Abstract The role of visual search during bee foraging is relatively understudied compared to the choices made by bees. As bees learn about rewards, we predicted that visual search would be modified to prioritise rewarding flowers. To test this, we ran an experiment testing how bee search differs in the initial and later part of training as they learn about flowers with either higher- or lower-quality rewards. We then ran an experiment to see how this prior training with reward influences their search on a subsequent task with different flowers. We used the time spent inspecting flowers as a measure of attention and found that learning increased attention to rewards and away from unrewarding flowers. Higher quality rewards led to decreased attention to non-flower regions, but lower quality rewards did not. Prior experience of lower rewards also led to more attention to higher rewards compared to unrewarding flowers and non-flower regions. Our results suggest that flowers would elicit differences in bee search behaviour depending on the sugar content of their nectar. They also demonstrate the utility of studying visual search and have important implications for understanding the pollination ecology of flowers with different qualities of reward. Significance statement Studies investigating how foraging bees learn about reward typically focus on the choices made by the bees. How bees deploy attention and visual search during foraging is less well studied. We analysed flight videos to characterise visual search as bees learn which flowers are rewarding. We found that learning increases the focus of bees on flower regions. We also found that the quality of the reward a flower offers influences how much bees search in non-flower areas. This means that a flower with lower reward attracts less focussed foraging compared to one with a higher reward. Since flowers do differ in floral reward, this has important implications for how focussed pollinators will be on different flowers. Our approach of looking at search behaviour and attention thus advances our understanding of the cognitive ecology of pollination. Supplementary Information The online version contains supplementary material available at 10.1007/s00265-024-03432-z.
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Affiliation(s)
- Théo Robert
- Biosciences Institute, Newcastle University, Henry Wellcome Building, Framlington Place, Newcastle Upon Tyne, NE2 4HH UK
| | - Karolina Tarapata
- Biosciences Institute, Newcastle University, Henry Wellcome Building, Framlington Place, Newcastle Upon Tyne, NE2 4HH UK
| | - Vivek Nityananda
- Biosciences Institute, Newcastle University, Henry Wellcome Building, Framlington Place, Newcastle Upon Tyne, NE2 4HH UK
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Symington HA, Glover BJ. Strawberry varieties differ in pollinator-relevant floral traits. Ecol Evol 2024; 14:e10914. [PMID: 38322008 PMCID: PMC10844710 DOI: 10.1002/ece3.10914] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Revised: 12/22/2023] [Accepted: 01/03/2024] [Indexed: 02/08/2024] Open
Abstract
A rising global population will need more food, increasing demand for insect pollination services. However, general insect declines conflict with this demand. One way to mitigate this conflict is to grow crop flowers that are easier for insects to find and more rewarding to those that visit them. This study quantifies variation in the pollinator-relevant traits of nectar and pollen production, flower size and flower shape in commercial strawberry, finding significant variation between varieties in all traits. Bumblebees could learn to distinguish between the extremes of variation in flower shape, but this learning is very slow, indicating that this variation is at the limit of that which can be detected by bumblebees. Bee preferences for nectar of differing sugar concentrations at field-realistic volumes were consistent with previous observations at larger volumes, suggesting that it is valid to translate lab findings to the field. This study builds on our knowledge of the range of pollinator reward present in a single cultivated species and of the impact of field-realistic levels of variation in floral traits on bumblebee preferences.
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Galante H, Czaczkes TJ. Invasive ant learning is not affected by seven potential neuroactive chemicals. Curr Zool 2024; 70:87-97. [PMID: 38476136 PMCID: PMC10926265 DOI: 10.1093/cz/zoad001] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Accepted: 01/20/2023] [Indexed: 03/14/2024] Open
Abstract
Argentine ants Linepithema humile are one of the most damaging invasive alien species worldwide. Enhancing or disrupting cognitive abilities, such as learning, has the potential to improve management efforts, for example by increasing preference for a bait, or improving ants' ability to learn its characteristics or location. Nectar-feeding insects are often the victims of psychoactive manipulation, with plants lacing their nectar with secondary metabolites such as alkaloids and non-protein amino acids which often alter learning, foraging, or recruitment. However, the effect of neuroactive chemicals has seldomly been explored in ants. Here, we test the effects of seven potential neuroactive chemicals-two alkaloids: caffeine and nicotine; two biogenic amines: dopamine and octopamine, and three nonprotein amino acids: β-alanine, GABA and taurine-on the cognitive abilities of invasive L. humile using bifurcation mazes. Our results confirm that these ants are strong associative learners, requiring as little as one experience to develop an association. However, we show no short-term effect of any of the chemicals tested on spatial learning, and in addition no effect of caffeine on short-term olfactory learning. This lack of effect is surprising, given the extensive reports of the tested chemicals affecting learning and foraging in bees. This mismatch could be due to the heavy bias towards bees in the literature, a positive result publication bias, or differences in methodology.
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Affiliation(s)
- Henrique Galante
- Department of Zoology and Evolutionary Biology, Animal Comparative Economics Laboratory, University of Regensburg, 93053 Regensburg, Germany
| | - Tomer J Czaczkes
- Department of Zoology and Evolutionary Biology, Animal Comparative Economics Laboratory, University of Regensburg, 93053 Regensburg, Germany
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Mustard JA, Dobb R, Wright GA. Chronic nicotine exposure influences learning and memory in the honey bee. JOURNAL OF INSECT PHYSIOLOGY 2023; 151:104582. [PMID: 37918514 DOI: 10.1016/j.jinsphys.2023.104582] [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: 05/23/2023] [Revised: 10/07/2023] [Accepted: 10/30/2023] [Indexed: 11/04/2023]
Abstract
In insects, nicotine activates nicotinic acetylcholine receptors, which are expressed throughout the central nervous system. However, little work has been done to investigate the effects of chronic nicotine treatment on learning or other behaviors in non-herbivorous insects. To examine the effects of long term nicotine consumption on learning and memory, honey bees were fed nicotine containing solutions over four days. Bees were able to detect nicotine at 0.1 mM in sucrose solutions, and in a no choice assay, bees reduced food intake when nicotine was 1 mM or higher. Treatment with a low dose of nicotine decreased the proportion of bees able to form an associative memory when bees were conditioned with either a massed or spaced appetitive olfactory training paradigm. On the other hand, higher doses of nicotine increased memory retention and the proportion of bees responding to the odor during 10 min and 24 h recall tests. The reduction in nicotine containing food consumed may also impact response levels during learning and recall tests. These data suggest that long term exposure to nicotine has complex effects on learning and memory.
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Affiliation(s)
- Julie A Mustard
- School of Integrative Biological and Chemical Sciences, University of Texas Rio Grande Valley, Brownsville, TX 78520, USA.
| | - Rachel Dobb
- Centre for Behaviour and Evolution, Institute of Neuroscience, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE1 7RU, UK
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8
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Waller S, Powell A, Noel R, Schueller MJ, Ferrieri RA. Radiocarbon Flux Measurements Reveal Mechanistic Insight into Heat-Stress Induction of Nicotine Biosynthesis in Nicotiana attenuata. Int J Mol Sci 2023; 24:15509. [PMID: 37958493 PMCID: PMC10650385 DOI: 10.3390/ijms242115509] [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: 09/22/2023] [Revised: 10/19/2023] [Accepted: 10/22/2023] [Indexed: 11/15/2023] Open
Abstract
The effect of high-temperature (HT) stress on nicotine biosynthesis in Nicotiana attenuata was examined. Nicotine content was measured in mature leaves, young sink leaves, and in roots from well-watered plants grown at 25 °C as controls and from plants exposed to 38 °C and 43 °C temperatures applied for 24, 48, 72, and 96 h duration. At 38 °C, all leaf nicotine levels were significantly less than control plants for up to 72 h exposure but rose sharply thereafter to levels significantly greater than controls with 96 h exposure. In contrast, plants exposed to 43 °C never exhibited a reduction in leaf nicotine content and showed an increase in content with just 48 h exposure. Using radioactive 11CO2 and 13NO3-, we found that HT stress reduced both CO2 fixation and nitrate uptake. Furthermore, radiocarbon flux analysis revealed that 'new' carbon partitioning (as 11C) into the 11C-radiolabeled amino acid (AA) pool was significantly reduced with HT stress as were yields of [11C]-aspartic acid, an important AA in nicotine biosynthesis, and its beta-amido counterpart [11C]-asparagine. In contrast, [12C]-aspartic acid levels appeared unaffected at 38 °C but were elevated at 43 °C relative to controls. [12C]-Asparagine levels were noted to be elevated at both stress temperatures. Since HT reductions in carbon input and nitrogen uptake were noted to impede de novo AA biosynthesis, protein degradation at HT was examined as a source of AAs. Here, leaf total soluble protein (TSP) content was reduced 39% with long exposures to both stress temperatures. However, Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) which was 41% TSP appeared unaffected. Altogether, these results support the theory that plant proteins other than Rubisco degrade at elevated temperatures freeing up essential AAs in support of nicotine biosynthesis.
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Affiliation(s)
- Spenser Waller
- Missouri Research Reactor Center, University of Missouri, Columbia, MO 65211, USA; (S.W.); (R.N.); (M.J.S.)
- School of Natural Resources, University of Missouri, Columbia, MO 65211, USA
| | - Avery Powell
- Missouri Research Reactor Center, University of Missouri, Columbia, MO 65211, USA; (S.W.); (R.N.); (M.J.S.)
- School of Natural Resources, University of Missouri, Columbia, MO 65211, USA
| | - Randi Noel
- Missouri Research Reactor Center, University of Missouri, Columbia, MO 65211, USA; (S.W.); (R.N.); (M.J.S.)
- Division of Plant Science & Technology, University of Missouri, Columbia, MO 65211, USA
| | - Michael J. Schueller
- Missouri Research Reactor Center, University of Missouri, Columbia, MO 65211, USA; (S.W.); (R.N.); (M.J.S.)
- Chemistry Department, University of Missouri, Columbia, MO 65211, USA
| | - Richard A. Ferrieri
- Missouri Research Reactor Center, University of Missouri, Columbia, MO 65211, USA; (S.W.); (R.N.); (M.J.S.)
- Division of Plant Science & Technology, University of Missouri, Columbia, MO 65211, USA
- Chemistry Department, University of Missouri, Columbia, MO 65211, USA
- Interdisciplinary Plant Group, University of Missouri, Columbia, MO 65211, USA
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Balduino HDK, Tunes P, Giordano E, Guarnieri M, Machado SR, Nepi M, Guimarães E. To each their own! Nectar plasticity within a flower mediates distinct ecological interactions. AOB PLANTS 2023; 15:plac067. [PMID: 36751365 PMCID: PMC9893873 DOI: 10.1093/aobpla/plac067] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Accepted: 12/29/2022] [Indexed: 06/18/2023]
Abstract
Nuptial and extranuptial nectaries are involved in interactions with different animal functional groups. Nectar traits involved in pollination mutualisms are well known. However, we know little about those traits involved in other mutualisms, such as ant-plant interactions, especially when both types of nectaries are in the same plant organ, the flower. Here we investigated if when two types of nectaries are exploited by distinct functional groups of floral visitors, even being within the same plant organ, the nectar secreted presents distinct features that fit animal requirements. We compared nectar secretion dynamics, floral visitors and nectar chemical composition of both nuptial and extranuptial nectaries in natural populations of the liana Amphilophium mansoanum (Bignoniaceae). For that we characterized nectar sugar, amino acid and specialized metabolite composition by high-performance liquid chromatography. Nuptial nectaries were visited by three medium- and large-sized bee species and extranuptial nectaries were visited mainly by ants, but also by cockroaches, wasps and flies. Nuptial and extranuptial nectar differed regarding volume, concentration, milligrams of sugars per flower and secretion dynamics. Nuptial nectar was sucrose-dominated, with high amounts of γ-aminobutyric acid and β-aminobutyric acid and with theophylline-like alkaloid, which were all exclusive of nuptial nectar. Whereas extranuptial nectar was hexose-rich, had a richer and less variable amino acid chemical profile, with high amounts of serine and alanine amino acids and with higher amounts of the specialized metabolite tyramine. The nectar traits from nuptial and extranuptial nectaries differ in energy amount and nutritional value, as well as in neuroactive specialized metabolites. These differences seem to match floral visitors' requirements, since they exclusively consume one of the two nectar types and may be exerting selective pressures on the composition of the respective resources of interest.
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Affiliation(s)
- Hannelise de Kassia Balduino
- Graduate Course in Plant Biology, São Paulo State University, 18618-689 Botucatu, Brazil
- Laboratory of Ecology and Evolution of Plant-Animal Interactions, Institute of Biosciences, São Paulo State University, 18618-689 Botucatu, Brazil
| | - Priscila Tunes
- Laboratory of Ecology and Evolution of Plant-Animal Interactions, Institute of Biosciences, São Paulo State University, 18618-689 Botucatu, Brazil
| | - Emanuele Giordano
- Laboratory of Analytical Methods for Chemical Ecology - Plant Reproductive Biology, Department of Life Sciences, University of Siena, 53100 Siena, Italy
| | - Massimo Guarnieri
- Laboratory of Analytical Methods for Chemical Ecology - Plant Reproductive Biology, Department of Life Sciences, University of Siena, 53100 Siena, Italy
| | - Silvia Rodrigues Machado
- Laboratory of Plant Anatomy, Institute of Biosciences, São Paulo State University, 18618-689 Botucatu, Brazil
| | - Massimo Nepi
- Laboratory of Analytical Methods for Chemical Ecology - Plant Reproductive Biology, Department of Life Sciences, University of Siena, 53100 Siena, Italy
- National Biodiversity Future Center (NBFC), 90133 Palermo, Italy
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Barberis M, Calabrese D, Galloni M, Nepi M. Secondary Metabolites in Nectar-Mediated Plant-Pollinator Relationships. PLANTS (BASEL, SWITZERLAND) 2023; 12:plants12030550. [PMID: 36771634 PMCID: PMC9920422 DOI: 10.3390/plants12030550] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 01/17/2023] [Accepted: 01/19/2023] [Indexed: 06/01/2023]
Abstract
In recent years, our understanding of the complex chemistry of floral nectar and its ecological implications for plant-pollinator relationships has certainly increased. Nectar is no longer considered merely a reward for pollinators but rather a plant interface for complex interactions with insects and other organisms. A particular class of compounds, i.e., nectar secondary compounds (NSCs), has contributed to this new perspective, framing nectar in a more comprehensive ecological context. The aim of this review is to draft an overview of our current knowledge of NSCs, including emerging aspects such as non-protein amino acids and biogenic amines, whose presence in nectar was highlighted quite recently. After considering the implications of the different classes of NSCs in the pollination scenario, we discuss hypotheses regarding the evolution of such complex nectar profiles and provide cues for future research on plant-pollinator relationships.
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Affiliation(s)
- Marta Barberis
- Department of Biological, Geological and Environmental Sciences, University of Bologna, Via Irnerio 42, 40126 Bologna, Italy
| | - Daniele Calabrese
- Department of Life Sciences, University of Siena, Via P.A. Mattioli 4, 53100 Siena, Italy
| | - Marta Galloni
- Department of Biological, Geological and Environmental Sciences, University of Bologna, Via Irnerio 42, 40126 Bologna, Italy
| | - Massimo Nepi
- Department of Life Sciences, University of Siena, Via P.A. Mattioli 4, 53100 Siena, Italy
- National Biodiversity Future Centre (NBFC), 90123 Palermo, Italy
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Hojo MK. Evolution of chemical interactions between ants and their mutualist partners. CURRENT OPINION IN INSECT SCIENCE 2022; 52:100943. [PMID: 35691585 DOI: 10.1016/j.cois.2022.100943] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Revised: 05/31/2022] [Accepted: 06/02/2022] [Indexed: 06/15/2023]
Abstract
Mutualism is the reciprocal exploitation of interacting participants and is vulnerable to nonrewarding cheating. Ants are dominant insects in most terrestrial ecosystems, and some aphids and lycaenid butterfly species provide them with nutritional nectar rewards and employ ants as bodyguards. In this review, I discuss how chemical communication based on condition-dependent signaling and recognition plasticity regulate the payoff of interacting participants. I argue that the selfishness of both participants explains the signaling and communication among participants and contributes to the stability of these mutualisms. Uncovering the origin and maintenance of mutualistic association of ants will come from future research on ant collective behavior, the genetic and neural basis of cooperation, and a deeper understanding of the costs and benefits of these interactions.
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Affiliation(s)
- Masaru K Hojo
- Department of Biosciences, School of Biological and Environmental Sciences, Kwansei Gakuin University, 1 Gakuen-Uegahara, Sanda, Hyogo 669-1330, Japan.
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Muth F, Philbin CS, Jeffrey CS, Leonard AS. Discovery of octopamine and tyramine in nectar and their effects on bumblebee behavior. iScience 2022; 25:104765. [PMID: 35942103 PMCID: PMC9356080 DOI: 10.1016/j.isci.2022.104765] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2022] [Revised: 05/30/2022] [Accepted: 07/10/2022] [Indexed: 11/17/2022] Open
Abstract
Nectar chemistry can influence the behavior of pollinators in ways that affect pollen transfer, yet basic questions about how nectar chemical diversity impacts plant-pollinator relationships remain unexplored. For example, plants’ capacity to produce neurotransmitters and endocrine disruptors may offer a means to manipulate pollinator behavior. We surveyed 15 plant species and discovered that two insect neurotransmitters, octopamine and tyramine, were widely distributed in floral nectar. We detected the highest concentration of these chemicals in Citrus, alongside the well-studied alkaloid caffeine. We explored the separate and interactive effects of these chemicals on insect pollinators in a series of behavioral experiments on bumblebees (Bombus impatiens). We found that octopamine and tyramine interacted with caffeine to alter key aspects of bee behavior relevant to plant fitness (sucrose responsiveness, long-term memory, and floral preferences). These results provide evidence for a means by which synergistic or antagonistic nectar chemistry might influence pollinators. We found octopamine and tyramine in the floral nectar of 15 plant species These neurotransmitters orchestrate insect foraging and influence bee cognition In Citrus, these chemicals occur with caffeine, well known for its effects on bees Nectar neurotransmitters interact with caffeine to alter pollinator behavior
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Affiliation(s)
- Felicity Muth
- Department of Integrative Biology, University of Texas at Austin; Austin, TX 78712, USA
- Corresponding author
| | - Casey S. Philbin
- Hitchcock Center for Chemical Ecology, University of Nevada, Reno; Reno, NV 89557, USA
- Corresponding author
| | | | - Anne S. Leonard
- Department of Biology, University of Nevada, Reno; Reno, NV 89557, USA
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Sestari I, Campos ML. Into a dilemma of plants: the antagonism between chemical defenses and growth. PLANT MOLECULAR BIOLOGY 2022; 109:469-482. [PMID: 34843032 DOI: 10.1007/s11103-021-01213-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Accepted: 10/28/2021] [Indexed: 05/21/2023]
Abstract
Chemical defenses are imperative for plant survival, but their production is often associated with growth restrictions. Here we review the most recent theories to explain this complex dilemma of plants. Plants are a nutritional source for a myriad of pests and pathogens that depend on green tissues to complete their life cycle. Rather than remaining passive victims, plants utilize an arsenal of chemical defenses to fend off biotic attack. While the deployment of such barriers is imperative for survival, the production of these chemical defenses is typically associated with negative impacts on plant growth. Here we discuss the most recent theories which explain this highly dynamic growth versus defense dilemma. Firstly, we discuss the hypothesis that the antagonism between the accumulation of chemical defenses and growth is rooted in the evolutionary history of plants and may be a consequence of terrestrialization. Then, we revise the different paradigms available to explain the growth versus chemical defense antagonism, including recent findings that update these into more comprehensive and plausible theories. Finally, we highlight state-of-the-art strategies that are now allowing the activation of growth and the concomitant production of chemical barriers in plants. Growth versus chemical defense antagonism imposes large ecological and economic costs, including increased crop susceptibility to pests and pathogens. In a world where these plant enemies are the main problem to increase food production, we believe that this review will summarize valuable information for future studies aiming to breed highly defensive plants without the typical accompanying penalties to growth.
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Affiliation(s)
- Ivan Sestari
- Coordenadoria Especial de Ciências Biológicas e Agronômicas, Universidade Federal de Santa Catarina, Curitibanos, SC, Brazil
| | - Marcelo Lattarulo Campos
- Integrative Plant Research Laboratory, Departamento de Botânica e Ecologia, Instituto de Biociências, Universidade Federal de Mato Grosso, Cuiabá, MT, Brazil.
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14
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Nicolson SW. Sweet solutions: nectar chemistry and quality. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210163. [PMID: 35491604 PMCID: PMC9058545 DOI: 10.1098/rstb.2021.0163] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Accepted: 11/07/2021] [Indexed: 12/22/2022] Open
Abstract
Nectar, the main floral reward for pollinators, varies greatly in composition and concentration. The assumption that nectar quality is equivalent to its sugar (energy) concentration is too simple. Diverse non-sugar components, especially amino acids and secondary metabolites, play various roles in nutrition and health of pollinators. Many nectar compounds have indirect effects by altering the foraging behaviour of pollinators or protecting them from disease. This review also emphasizes the water component of nectar, often ignored because of evaporative losses and difficulties in sampling small nectar volumes. Nectar properties vary with environmental factors, pollinator visits and microbial contamination. Pollination mutualisms depend on the ability of insect and vertebrate pollinators to cope with and benefit from the variation and diversity in nectar chemistry. This article is part of the theme issue 'Natural processes influencing pollinator health: from chemistry to landscapes'.
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Affiliation(s)
- Susan W. Nicolson
- Department of Zoology and Entomology, University of Pretoria, Pretoria 0002, South Africa
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15
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Shell WA, Rehan SM. Comparative metagenomics reveals expanded insights into intra- and interspecific variation among wild bee microbiomes. Commun Biol 2022; 5:603. [PMID: 35715496 PMCID: PMC9205906 DOI: 10.1038/s42003-022-03535-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Accepted: 05/26/2022] [Indexed: 11/17/2022] Open
Abstract
The holobiont approach proposes that species are most fully understood within the context of their associated microbiomes, and that both host and microbial community are locked in a mutual circuit of co-evolutionary selection. Bees are an ideal group for this approach, as they comprise a critical group of pollinators that contribute to both ecological and agricultural health worldwide. Metagenomic analyses offer comprehensive insights into an organism’s microbiome, diet, and viral load, but remain largely unapplied to wild bees. Here, we present metagenomic data from three species of carpenter bees sampled from around the globe, representative of the first ever carpenter bee core microbiome. Machine learning, co-occurrence, and network analyses reveal that wild bee metagenomes are unique to host species. Further, we find that microbiomes are likely strongly affected by features of their local environment, and feature evidence of plant pathogens previously known only in honey bees. Performing the most comprehensive comparative analysis of bee microbiomes to date we discover that microbiome diversity is inversely proportional to host species social complexity. Our study helps to establish some of the first wild bee hologenomic data while offering powerful empirical insights into the biology and health of vital pollinators. Global wild bee metagenomes provide insights into microbiome, sociality and pollinator health.
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Affiliation(s)
- Wyatt A Shell
- Department of Biology, York University, Toronto, ON, Canada
| | - Sandra M Rehan
- Department of Biology, York University, Toronto, ON, Canada.
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16
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Zhou Y, Yin M, Abbas F, Sun Y, Gao T, Yan F, Li X, Yu Y, Yue Y, Yu R, Fan Y. Classification and Association Analysis of Gerbera ( Gerbera hybrida) Flower Color Traits. FRONTIERS IN PLANT SCIENCE 2022; 12:779288. [PMID: 35145530 PMCID: PMC8824200 DOI: 10.3389/fpls.2021.779288] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Accepted: 12/31/2021] [Indexed: 05/17/2023]
Abstract
Floral color plays a crucial role in plant life such as plant-pollinator interactions and modifying the abiotic environment of reproductive structures. In the current study, 123 gerbera accessions were divided into six color groups (white, yellow, orange, pink, red, and purple), based on Royal Horticultural Society Color Chart calibration and colorimeter measurement. Partial least squares discriminant analysis showed that the white group was mainly affected by L* value, a* value, C value, and total anthocyanin contents, while the yellow group was positively correlated with L* value, b* value, and total anthocyanin contents. Similarly, the orange group was mainly affected by b* value and total carotenoid contents, whereas the pink group was positively correlated with L* and h values. Furthermore, the red group was affected by L* value, a* value, C value, and total anthocyanin contents, whilst the purple group was mainly distributed by L* value, a* value, b* value, and total anthocyanin contents. Based on 'Jin Xiang' transcriptome data, 14,106 expressed sequence tag (EST)-SSR markers were identified and 48 pairs of primers (19 newly developed primers) were screened. Population genetic structure, neighbor-joining clustering, and principal coordinate analysis showed that 123 gerbera accessions could be divided into two groups. EST-SSR-based association analysis showed that 1, 1, 2, 1, 1, 2, and 1 significant loci were related to L*, a*, b*, C, and h, total carotenoid, and total anthocyanin contents, respectively. These results provide an important reference for flower color classification and genetic improvement of gerbera.
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Affiliation(s)
- Yiwei Zhou
- The Research Center for Ornamental Plants, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, China
| | - Mao Yin
- The Research Center for Ornamental Plants, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, China
| | - Farhat Abbas
- The Research Center for Ornamental Plants, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, China
| | - Yue Sun
- The Research Center for Ornamental Plants, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, China
| | - Ting Gao
- The Research Center for Ornamental Plants, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, China
| | - Fulong Yan
- The Research Center for Ornamental Plants, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, China
| | - Xinyue Li
- The Research Center for Ornamental Plants, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, China
| | - Yunyi Yu
- The Research Center for Ornamental Plants, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, China
| | - Yuechong Yue
- The Research Center for Ornamental Plants, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, China
- Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, South China Agricultural University, Guangzhou, China
| | - Rangcai Yu
- College of Life Sciences, South China Agricultural University, Guangzhou, China
| | - Yanping Fan
- The Research Center for Ornamental Plants, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, China
- Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, South China Agricultural University, Guangzhou, China
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17
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Dieng H, Satho T, Mohd Radzi NHSB, Abang F, A. Kassim NF, Zuharah WF, Hashim NA, Morales Vargas RE, Morales NP. Flower Mimics Roll Out Multicolored Carpets to Lure and Kill the House Fly. INSECTS 2021; 12:1097. [PMID: 34940185 PMCID: PMC8706000 DOI: 10.3390/insects12121097] [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: 09/18/2021] [Revised: 11/15/2021] [Accepted: 11/23/2021] [Indexed: 11/16/2022]
Abstract
Flowers and their spatial clustering are important parameters that mediate the foraging behavior and visitation rate of pollinating insects. Visual stimuli are crucial for triggering behavioral changes in the house fly, Musca domestica, which regularly visits plants for feeding and reproduction. The success of bait technology, which is the principal means of combatting flies, is adversely affected by reduced attractiveness and ineffective application techniques. Despite evidence that house flies have color vision capacity, respond to flowers, and exhibit color and pattern preference, the potential of artificial flowers as attractive factors has not been explored. The present study was performed to investigate whether artificial floral designs can lure and kill house flies. Starved wild house flies were presented with equal opportunities to acquire sugar meals, to which boric acid had been added as a toxin, from one flower arrangement (blue-dominated design, BDD; yellow-dominated design, YDD; or pink-dominated design, PDD), and a non-toxic white design (WDD). We also allowed house flies to forage within an enclosure containing two non-toxic floral designs (WDDs). The differences in mortality between the two environments with and without toxicant were examined. The survival rate of Musca domestica was extremely high when WDDs containing non-toxic sugar sources were the only feeding sites available. When given an option to forage in an environment containing a BDD and a WDD, house flies showed a high mortality rate (76%) compared to their counterparts maintained in the WDD environment (2%). When kept in an enclosure containing one YDD and a WDD, flies showed a mortality rate of 88%; however, no mortality occurred among flies confined to a compound with a WDD pair. When provided an even chance of foraging in an enclosure containing a mixed pair of floral arrangements (PDD and WDD) and another with two WDDs, flies showed a higher mortality rate (78%) in the first environment. However, the maximum survival rate (100%) was seen in the WDD environment. Exposure to YDD tended to result in a greater mortality rate than with the two other floral designs. Mortality gradually increased with time among flies exposed to tested artificial floral designs. The results presented here clearly indicated that artificial flower arrangements with a toxic sugar reward were strikingly attractive for house flies when their preferred color (white) was present. These observations offer novel possibilities for future development of flower mimic-based house fly control.
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Affiliation(s)
- Hamady Dieng
- Mosquito Research and Control Unit (MRCU), George Town KY1-1106, Cayman Islands
- Institute of Biodiversity and Environmental Conservation, Universiti Malaysia Sarawak, Kota Samarahan 94300, Malaysia
| | - Tomomitsu Satho
- Faculty of Pharmaceutical Sciences, Fukuoka University, Nanakuma Jonan-Ku, Fukuoka 814-0180, Japan;
| | | | - Fatimah Abang
- Faculty of Resource Science and Technology, Universiti Malaysia Sarawak, Kota Samarahan 94300, Malaysia; (N.H.S.B.M.R.); (F.A.)
| | - Nur Faeza A. Kassim
- School of Biological Sciences, Universiti Sains Malaysia, Gelugor 11800, Malaysia; (N.F.A.K.); (W.F.Z.)
| | - Wan Fatma Zuharah
- School of Biological Sciences, Universiti Sains Malaysia, Gelugor 11800, Malaysia; (N.F.A.K.); (W.F.Z.)
| | - Nur Aida Hashim
- School of Food Science and Technology, Universiti Malaysia Terengganu, Kuala Terengganu 21300, Malaysia;
| | | | - Noppawan P. Morales
- Faculty of Science, Mahidol University, Krung Thep Maha Nakhon 10400, Thailand;
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18
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Nectar non-protein amino acids (NPAAs) do not change nectar palatability but enhance learning and memory in honey bees. Sci Rep 2021; 11:11721. [PMID: 34083559 PMCID: PMC8175726 DOI: 10.1038/s41598-021-90895-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Accepted: 05/17/2021] [Indexed: 02/04/2023] Open
Abstract
Floral nectar is a pivotal element of the intimate relationship between plants and pollinators. Nectars are composed of a plethora of nutritionally valuable compounds but also hundreds of secondary metabolites (SMs) whose function remains elusive. Here we performed a set of behavioural experiments to study whether five ubiquitous nectar non-protein amino acids (NPAAs: β-alanine, GABA, citrulline, ornithine and taurine) interact with gustation, feeding preference, and learning and memory in Apis mellifera. We showed that foragers were unable to discriminate NPAAs from water when only accessing antennal chemo-tactile information and that freely moving bees did not exhibit innate feeding preferences for NPAAs. Also, NPAAs did not alter food consumption or longevity in caged bees over 10 days. Taken together our data suggest that natural concentrations of NPAAs did not alter nectar palatability to bees. Olfactory conditioning assays showed that honey bees were more likely to learn a scent when it signalled a sucrose reward containing either β-alanine or GABA, and that GABA enhanced specific memory retention. Conversely, when ingested two hours prior to conditioning, GABA, β-alanine, and taurine weakened bees' acquisition performances but not specific memory retention, which was enhanced in the case of β-alanine and taurine. Neither citrulline nor ornithine affected learning and memory. NPAAs in nectars may represent a cooperative strategy adopted by plants to attract beneficial pollinators.
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19
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Njoroge TM, Calla B, Berenbaum MR, Stone CM. Specific phytochemicals in floral nectar up-regulate genes involved in longevity regulation and xenobiotic metabolism, extending mosquito life span. Ecol Evol 2021; 11:8363-8380. [PMID: 34188892 PMCID: PMC8216986 DOI: 10.1002/ece3.7665] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 04/12/2021] [Accepted: 04/14/2021] [Indexed: 11/06/2022] Open
Abstract
During nectar feeding, mosquitoes ingest a plethora of phytochemicals present in nectar. The ecological and physiological impacts of these ingested phytochemicals on the disease vectors are poorly understood. In this study, we evaluated the effects of three nectar phytochemicals-- caffeine, p-coumaric acid, and quercetin--on longevity, fecundity, and sugar-feeding behavior of the Asian tiger mosquito (Aedes albopictus). Adult females of Ae. albopictus were provided continuous access to 10% sucrose supplemented with one of the three phytochemicals and their fecundity, longevity, and the amount of sucrose consumed determined. Transcriptome response of Ae. albopictus females to p-coumaric acid and quercetin was also evaluated. Dietary quercetin and p-coumaric acid enhanced the longevity of female Ae. albopictus, while caffeine resulted in reduced sugar consumption and enhanced fecundity of gravid females. RNA-seq analyses identified 237 genes that were differentially expressed (DE) in mosquitoes consuming p-coumaric acid or quercetin relative to mosquitoes consuming an unamended sucrose solution diet. Among the DE genes, several encoding antioxidant enzymes, cytochrome P450s, and heat shock proteins were upregulated, whereas histones were downregulated. Overall, our findings show that consuming certain nectar phytochemicals can enhance adult longevity of female Asian tiger mosquitoes, apparently by differentially regulating the expression level of genes involved in longevity and xenobiotic metabolism; this has potential impacts not only on life span but also on vectorial capacity and insecticide resistance.
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Affiliation(s)
- Teresia M. Njoroge
- Department of EntomologyUniversity of Illinois at Urbana‐ChampaignUrbanaILUSA
| | - Bernarda Calla
- Department of EntomologyUniversity of Illinois at Urbana‐ChampaignUrbanaILUSA
| | - May R. Berenbaum
- Department of EntomologyUniversity of Illinois at Urbana‐ChampaignUrbanaILUSA
| | - Christopher M. Stone
- Department of EntomologyUniversity of Illinois at Urbana‐ChampaignUrbanaILUSA
- Illinois Natural History SurveyUniversity of Illinois at Urbana‐ChampaignChampaignILUSA
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20
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Francis JS, Tatarko AR, Richman SK, Vaudo AD, Leonard AS. Microbes and pollinator behavior in the floral marketplace. CURRENT OPINION IN INSECT SCIENCE 2021; 44:16-22. [PMID: 33075580 DOI: 10.1016/j.cois.2020.10.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 10/07/2020] [Accepted: 10/08/2020] [Indexed: 06/11/2023]
Abstract
Pollinator foraging decisions shape microbial dispersal, and microbes change floral phenotypes in ways perceivable by pollinators. Yet, the role microbes play in the cognitive ecology of pollination is relatively unexplored. Reviewing recent literature on floral microbial ecology and pollinator behavior, we advocate for further integration between these two fields. Insights into pollinator learning, memory, and decision-making can help explain their responses to microbially-altered floral phenotypes. Specifically, considering how pollinators forage for multiple nutrients, cope with uncertainty, structure foraging bouts, and move through their environment could inform predictions about microbial dispersal within plant communities. We highlight how behavior connects microbial changes in floral phenotype to downstream effects on both microbial dispersal and plant fitness.
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Affiliation(s)
- Jacob S Francis
- Ecology, Evolution and Conservation Biology Graduate Program, University of Nevada, Reno, 1664 N. Virginia St., Reno, NV 89557, United States
| | - Anna R Tatarko
- Ecology, Evolution and Conservation Biology Graduate Program, University of Nevada, Reno, 1664 N. Virginia St., Reno, NV 89557, United States
| | - Sarah K Richman
- Department of Biology, MS-314, University of Nevada, Reno, 1664 N. Virginia St., Reno, NV 89557, United States
| | - Anthony D Vaudo
- Department of Biology, MS-314, University of Nevada, Reno, 1664 N. Virginia St., Reno, NV 89557, United States
| | - Anne S Leonard
- Department of Biology, MS-314, University of Nevada, Reno, 1664 N. Virginia St., Reno, NV 89557, United States.
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21
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Evolutionary and Ecological Considerations on Nectar-Mediated Tripartite Interactions in Angiosperms and Their Relevance in the Mediterranean Basin. PLANTS 2021; 10:plants10030507. [PMID: 33803275 PMCID: PMC7999006 DOI: 10.3390/plants10030507] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 02/22/2021] [Accepted: 03/03/2021] [Indexed: 11/16/2022]
Abstract
The Mediterranean basin hosts a high diversity of plants and bees, and it is considered one of the world's biodiversity hotspots. Insect pollination, i.e., pollen transfer from male reproductive structures to conspecific female ones, was classically thought to be a mutualistic relationship that links these two groups of organisms, giving rise to an admirable and complex network of interactions. Although nectar is often involved in mediating these interactions, relatively little is known about modifications in its chemical traits during the evolution of plants. Here, we examine how the current sucrose-dominated floral nectar of most Mediterranean plants could have arisen in the course of evolution of angiosperms. The transition from hexose-rich to sucrose-rich nectar secretion was probably triggered by increasing temperature and aridity during the Cretaceous period, when most angiosperms were radiating. This transition may have opened new ecological niches for new groups of insects that were co-diversifying with angiosperms and for specific nectar-dwelling yeasts that originated later (i.e., Metschnikowiaceae). Our hypothesis embeds recent discoveries in nectar biology, such as the involvement of nectar microbiota and nectar secondary metabolites in shaping interactions with pollinators, and it suggests a complex, multifaceted ecological and evolutionary scenario that we are just beginning to discover.
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22
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Di Ilio V, Birkett MA, Pickett JA. Effects of Nicotine and Tobacco-Related Products on the Feeding Behavior of the German Cockroach (Blattodea: Blattellidae). JOURNAL OF INSECT SCIENCE (ONLINE) 2021; 21:3. [PMID: 33686433 PMCID: PMC7940502 DOI: 10.1093/jisesa/ieaa147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Indexed: 06/12/2023]
Abstract
Animals use olfaction to detect developmentally significant volatile organic compounds (VOCs) in their local environment. As part of a wider study aiming to demonstrate that the olfactory responses of animals to VOCs can be modified through the creation of a drug-addicted status and association with a selected VOC, we investigated nicotine and tobacco smoke particulate (TSP) extract as possible addictive compounds for male German cockroaches, Blattella germanica (Linnaeus). In feeding experiments using an artificial food stimulus, food treated with TSP extract was preferred over untreated food. Surprisingly, nicotine, which was expected to be the most important addictive tobacco component, did not induce noticeable effects on cockroach behavior. Both TSP extract and nicotine were shown to be phagostimulants. Olfactometry assays that measured odor-mediated insect behavior demonstrated that male B. germanica did not choose TSP-extract-treated food even when attempts were made specifically to train them via this modality. These results support a hypothesis that B. germanica needs to consume TSP-containing food to show a clear preference for this stimulus and that gustatory mechanisms are involved due to compounds present in the TSP extract.
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Affiliation(s)
- Vincenzo Di Ilio
- Biointeractions and Crop Protection Department, Rothamsted Research, Harpenden, Hertfordshire, UK
- BBCA Onlus, Rome, Italy
| | - Michael A Birkett
- Biointeractions and Crop Protection Department, Rothamsted Research, Harpenden, Hertfordshire, UK
| | - John A Pickett
- Biointeractions and Crop Protection Department, Rothamsted Research, Harpenden, Hertfordshire, UK
- School of Chemistry, Cardiff University, Cardiff, Wales, UK
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23
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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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24
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Muth F, Gaxiola RL, Leonard AS. No evidence for neonicotinoid preferences in the bumblebee Bombus impatiens. ROYAL SOCIETY OPEN SCIENCE 2020; 7:191883. [PMID: 32537195 PMCID: PMC7277277 DOI: 10.1098/rsos.191883] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2019] [Accepted: 04/14/2020] [Indexed: 05/19/2023]
Abstract
Neonicotinoid pesticides can have a multitude of negative sublethal effects on bees. Understanding their impact on wild populations requires accurately estimating the dosages bees encounter under natural conditions. This is complicated by the possibility that bees might influence their own exposure: two recent studies found that bumblebees (Bombus terrestris) preferentially consumed neonicotinoid-contaminated nectar, even though these chemicals are thought to be tasteless and odourless. Here, we used Bombus impatiens to explore two elements of these reported preferences, with the aim of understanding their ecological implication and underlying mechanism. First, we asked whether preferences persisted across a range of realistic nectar sugar concentrations, when measured at a series of time points up until 24 h. Second, we tested whether bees' neonicotinoid preferences were driven by an ability to associate their post-ingestive consequences with floral stimuli such as colour, location or scent. We found no evidence that foragers preferred to consume neonicotinoid-containing solutions, despite finding effects on feeding motivation and locomotor activity in line with previous work. Bees also did not preferentially visit floral stimuli previously paired with a neonicotinoid-containing solution. These results highlight the need for further research into the mechanisms underlying bees' responses to these pesticides, critical for determining how neonicotinoid-driven foraging preferences might operate in the real world for different bee species.
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Affiliation(s)
- Felicity Muth
- Department of Integrative Biology, University of Texas at Austin, TX 78712, USA
- Author for correspondence: Felicity Muth e-mail:
| | - Rebekah L. Gaxiola
- School of Biological Sciences, Washington State University, Vancouver, WA 99164, USA
| | - Anne S. Leonard
- Department of Biology, University of Nevada, Reno, NV 89557, USA
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25
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Jacquemart AL, Buyens C, Hérent MF, Quetin-Leclercq J, Lognay G, Hance T, Quinet M. Male flowers of Aconitum compensate for toxic pollen with increased floral signals and rewards for pollinators. Sci Rep 2019; 9:16498. [PMID: 31712605 PMCID: PMC6848206 DOI: 10.1038/s41598-019-53355-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Accepted: 10/26/2019] [Indexed: 01/25/2023] Open
Abstract
Many plants require animal pollinators for successful reproduction; these plants provide pollinator resources in pollen and nectar (rewards) and attract pollinators by specific cues (signals). In a seeming contradiction, some plants produce toxins such as alkaloids in their pollen and nectar, protecting their resources from ineffective pollinators. We investigated signals and rewards in the toxic, protandrous bee-pollinated plant Aconitum napellus, hypothesizing that male-phase flower reproductive success is pollinator-limited, which should favour higher levels of signals (odours) and rewards (nectar and pollen) compared with female-phase flowers. Furthermore, we expected insect visitors to forage only for nectar, due to the toxicity of pollen. We demonstrated that male-phase flowers emitted more volatile molecules and produced higher volumes of nectar than female-phase flowers. Alkaloids in pollen functioned as chemical defences, and were more diverse and more concentrated compared to the alkaloids in nectar. Visitors actively collected little pollen for larval food but consumed more of the less-toxic nectar. Toxic pollen remaining on the bee bodies promoted pollen transfer efficiency, facilitating pollination.
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Affiliation(s)
- A-L Jacquemart
- Earth and Life Institute- Agronomy - Université catholique de Louvain, Croix du Sud 2, Box L7.05.14, B-1348, Louvain-la-Neuve, Belgium.
| | - C Buyens
- Earth and Life Institute- Agronomy - Université catholique de Louvain, Croix du Sud 2, Box L7.05.14, B-1348, Louvain-la-Neuve, Belgium
| | - M-F Hérent
- Louvain Drug Research Institute, Pharmacognosy Research Group - Université catholique de Louvain, Avenue E. Mounier, 72, B-1200, Brussels, Belgium
| | - J Quetin-Leclercq
- Louvain Drug Research Institute, Pharmacognosy Research Group - Université catholique de Louvain, Avenue E. Mounier, 72, B-1200, Brussels, Belgium
| | - G Lognay
- Analytical Chemistry, Gembloux Agro-Bio Tech, Université de Liège, Passage des Déportés 2, B-5030, Gembloux, Belgium
| | - T Hance
- Earth and Life Institute - Biodiversity - Université catholique de Louvain, Croix du Sud 4, Box L7.07.04, B-1348, Louvain-la-Neuve, Belgium
| | - M Quinet
- Earth and Life Institute- Agronomy - Université catholique de Louvain, Croix du Sud 2, Box L7.05.14, B-1348, Louvain-la-Neuve, Belgium
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Baracchi D. Cognitive ecology of pollinators and the main determinants of foraging plasticity. Curr Zool 2019; 65:421-424. [PMID: 31423133 PMCID: PMC6688568 DOI: 10.1093/cz/zoz036] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Affiliation(s)
- David Baracchi
- Dipartimento di Biologia, Università degli Studi di Firenze, Via Madonna del Piano, 6, Sesto Fiorentino, Firenze, 50019, Italy
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Lande C, Rao S, Morré JT, Galindo G, Kirby J, Reardon PN, Bobe G, Stevens JF. Linden (Tilia cordata) associated bumble bee mortality: Metabolomic analysis of nectar and bee muscle. PLoS One 2019; 14:e0218406. [PMID: 31291287 PMCID: PMC6619659 DOI: 10.1371/journal.pone.0218406] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Accepted: 05/31/2019] [Indexed: 11/19/2022] Open
Abstract
Linden (Tilia spp.), a profusely flowering temperate tree that provides bees with vital pollen and nectar, has been associated with bumble bee (Bombus spp.) mortality in Europe and North America. Bee deaths have been attributed, with inadequate evidence, to toxicity from mannose in nectar or starvation due to low nectar in late blooming linden. Here, we investigated both factors via untargeted metabolomic analyses of nectar from five T. cordata trees beneath which crawling/dead bumble bees (B. vosnesenskii) were observed, and of thoracic muscle of 28 healthy foraging and 29 crawling bees collected from linden trees on cool mornings (< 30°C). Nectar contained the pyridine alkaloid trigonelline, a weak acetylcholinesterase inhibitor, but no mannose. Principal component analysis of muscle metabolites produced distinct clustering of healthy and crawling bees, with significant differences (P<0.05) in 34 of 123 identified metabolites. Of these, TCA (Krebs) cycle intermediates were strongly represented (pathway analysis; P<0.01), suggesting that the central metabolism is affected in crawling bees. Hence, we propose the following explanation: when ambient temperature is low, bees with energy deficit are unable to maintain the thoracic temperature required for flight, and consequently fall, crawl, and ultimately, die. Energy deficit could occur when bees continue to forage on linden despite limited nectar availability either due to loyalty to a previously energy-rich source or trigonelline-triggered memory/learning impairment, documented earlier with other alkaloids. Thus, the combination of low temperature and nectar volume, resource fidelity, and alkaloids in nectar could explain the unique phenomenon of bumble bee mortality associated with linden.
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Affiliation(s)
- Claire Lande
- Department of Crop and Soil Science, Oregon State University, Corvallis, Oregon, United States of America
| | - Sujaya Rao
- Department of Crop and Soil Science, Oregon State University, Corvallis, Oregon, United States of America
| | - Jeffrey T. Morré
- Department of Chemistry, Oregon State University, Corvallis, Oregon, United States of America
| | - Gracie Galindo
- Department of Crop and Soil Science, Oregon State University, Corvallis, Oregon, United States of America
| | - Julie Kirby
- Department of Crop and Soil Science, Oregon State University, Corvallis, Oregon, United States of America
| | - Patrick N. Reardon
- NMR Facility, Oregon State University, Corvallis, Oregon, United States of America
| | - Gerd Bobe
- Linus Pauling Institute, Oregon State University, Corvallis, Oregon, United States of America
- Department of Animal and Rangeland Sciences, Oregon State University, Corvallis, Oregon, United States of America
| | - Jan Frederik Stevens
- Linus Pauling Institute, Oregon State University, Corvallis, Oregon, United States of America
- Department of Pharmaceutical Sciences, Oregon State University, Corvallis, Oregon, United States of America
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Brzosko E, Bajguz A. Nectar composition in moth-pollinated Platanthera bifolia and P. chlorantha and its importance for reproductive success. PLANTA 2019; 250:263-279. [PMID: 31020407 DOI: 10.1007/s00425-019-03168-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2019] [Accepted: 04/12/2019] [Indexed: 05/26/2023]
Abstract
Sugars (glucose, fructose and sucrose), as well as proteogenic and non-proteogenic amino acids, are present in the nectar of Platanthera bifolia and P. chlorantha. Nectar quantity and quality are floral traits that are subjected to pollinator-mediated selection. Nectar sugar and amino acid (AA) composition in two sister species, P. bifolia and P. chlorantha, was analysed and the interspecies differences in nectar and the importance of these nectar characteristics for reproductive success were investigated. Nectar was collected from four P. bifolia and three P. chlorantha populations that exist in different habitats in three regions of NE Poland. Nectar from about 30 flowers (from each population) was sampled and analysed using high-performance liquid chromatography. We found the same primary sugars and AA components in the nectar of both species, although their content varied between the populations according to habitat properties. The nectar of P. bifolia and P. chlorantha both had low sugar concentrations (9.04-20.68%) and were dominated by hexoses, with sucrose:hexoses ratios between 0.03 and 0.31 across the different populations (the average for the P. bifolia populations was 0.17 and the average for the P. chlorantha populations was - 0.05). Total sugar content did not influence reproductive success and we found positive selection on fructose content. In general, 23 different AAs were detected in both Platanthera species. Cysteine and γ-aminobutyric acid were present in only one population of P. chlorantha. Sarcosine dominated among the non-proteogenic AAs. To our knowledge, this is the first report that characterizes the sugar and AA profiles in the nectar of P. bifolia and P. chlorantha in natural populations in the context of effectiveness of reproduction. Total AAs negatively influenced male reproductive success (r = - 0.79). Pollinators of the investigated species were found to be sensitive to the AAs' taste, from taste classes I and IV. Correlation between male reproductive success and the content of AAs from these groups was 0.79 in both cases. In this manuscript, we investigated the characteristics of P. bifolia and P. chlorantha nectar, and compared these characteristics to the available data in the context of their adaptations to the requirements of pollinators and with regard to the importance of nectar quality for reproductive success of the studied species.
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Affiliation(s)
- Emilia Brzosko
- Faculty of Biology and Chemistry, Institute of Biology, University of Bialystok, Konstantego Ciolkowskiego 1J, 15-245, Białystok, Poland
| | - Andrzej Bajguz
- Faculty of Biology and Chemistry, Institute of Biology, University of Bialystok, Konstantego Ciolkowskiego 1J, 15-245, Białystok, Poland.
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Ramawat KG, Goyal S. Co-evolution of Secondary Metabolites During Biological Competition for Survival and Advantage: An Overview. ACTA ACUST UNITED AC 2019. [DOI: 10.1007/978-3-319-76887-8_45-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
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30
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Colgan TJ, Fletcher IK, Arce AN, Gill RJ, Ramos Rodrigues A, Stolle E, Chittka L, Wurm Y. Caste- and pesticide-specific effects of neonicotinoid pesticide exposure on gene expression in bumblebees. Mol Ecol 2019; 28:1964-1974. [PMID: 30843300 PMCID: PMC6563198 DOI: 10.1111/mec.15047] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 01/31/2019] [Accepted: 02/05/2019] [Indexed: 01/10/2023]
Abstract
Social bees are important insect pollinators of wildflowers and agricultural crops, making their reported declines a global concern. A major factor implicated in these declines is the widespread use of neonicotinoid pesticides. Indeed, recent research has demonstrated that exposure to low doses of these neurotoxic pesticides impairs bee behaviours important for colony function and survival. However, our understanding of the molecular-genetic pathways that lead to such effects is limited, as is our knowledge of how effects may differ between colony members. To understand what genes and pathways are affected by exposure of bumblebee workers and queens to neonicotinoid pesticides, we implemented a transcriptome-wide gene expression study. We chronically exposed Bombus terrestriscolonies to either clothianidin or imidacloprid at field-realistic concentrations while controlling for factors including colony social environment and worker age. We reveal that genes involved in important biological processes including mitochondrial function are differentially expressed in response to neonicotinoid exposure. Additionally, clothianidin exposure had stronger effects on gene expression amplitude and alternative splicing than imidacloprid. Finally, exposure affected workers more strongly than queens. Our work demonstrates how RNA-Seq transcriptome profiling can provide detailed novel insight on the mechanisms mediating pesticide toxicity to a key insect pollinator.
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Affiliation(s)
- Thomas J Colgan
- School of Biological and Chemical Sciences, Queen Mary University of London, London, UK.,School of Biological, Earth and Environmental Sciences, University College Cork, Cork, Ireland
| | - Isabel K Fletcher
- School of Biological and Chemical Sciences, Queen Mary University of London, London, UK
| | - Andres N Arce
- Department of Life Sciences, Imperial College London, Ascot, UK
| | - Richard J Gill
- Department of Life Sciences, Imperial College London, Ascot, UK
| | | | - Eckart Stolle
- School of Biological and Chemical Sciences, Queen Mary University of London, London, UK
| | - Lars Chittka
- School of Biological and Chemical Sciences, Queen Mary University of London, London, UK
| | - Yannick Wurm
- School of Biological and Chemical Sciences, Queen Mary University of London, London, UK
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31
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Fossen T, Holmelid B, Øvstedal DO. Bumblebee death associated with Tilia x europaea L. BIOCHEM SYST ECOL 2019. [DOI: 10.1016/j.bse.2018.11.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Palmer-Young EC, Farrell IW, Adler LS, Milano NJ, Egan PA, Junker RR, Irwin RE, Stevenson PC. Chemistry of floral rewards: intra- and interspecific variability of nectar and pollen secondary metabolites across taxa. ECOL MONOGR 2018. [DOI: 10.1002/ecm.1335] [Citation(s) in RCA: 80] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Evan C. Palmer-Young
- Department of Biology; University of Massachusetts at Amherst; Amherst Massachusetts 01003 USA
| | - Iain W. Farrell
- Royal Botanic Gardens, Kew; Richmond Surrey TW9 3AB United Kingdom
| | - Lynn S. Adler
- Department of Biology; University of Massachusetts at Amherst; Amherst Massachusetts 01003 USA
| | - Nelson J. Milano
- Department of Biology; University of Massachusetts at Amherst; Amherst Massachusetts 01003 USA
| | - Paul A. Egan
- Department of Plant Protection Biology; Swedish University of Agricultural Sciences; SE-23053 Alnarp Sweden
| | - Robert R. Junker
- Department of Bioscience; University of Salzburg; Hellbrunnerstrasse 34 5020 Salzburg Austria
| | - Rebecca E. Irwin
- Department of Applied Ecology; North Carolina State University; Raleigh North Carolina 27695 USA
| | - Philip C. Stevenson
- Royal Botanic Gardens, Kew; Richmond Surrey TW9 3AB United Kingdom
- University of Greenwich; Medway ME4 4 TB United Kingdom
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Arce AN, Ramos Rodrigues A, Yu J, Colgan TJ, Wurm Y, Gill RJ. Foraging bumblebees acquire a preference for neonicotinoid-treated food with prolonged exposure. Proc Biol Sci 2018; 285:rspb.2018.0655. [PMID: 30158303 PMCID: PMC6125916 DOI: 10.1098/rspb.2018.0655] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Accepted: 08/07/2018] [Indexed: 12/23/2022] Open
Abstract
Social bees represent an important group of pollinating insects that can be exposed to potentially harmful pesticides when foraging on treated or contaminated flowering plants. To investigate if such exposure is detrimental to bees, many studies have exclusively fed individuals with pesticide-spiked food, informing us about the hazard but not necessarily the risk of exposure. While such studies are important to establish the physiological and behavioural effects on individuals, they do not consider the possibility that the risk of exposure may change over time. For example, many pesticide assays exclude potential behavioural adaptations to novel toxins, such as rejection of harmful compounds by choosing to feed on an uncontaminated food source, thus behaviourally lowering the risk of exposure. In this paper, we conducted an experiment over 10 days in which bumblebees could forage on an array of sucrose feeders containing 0, 2 and 11 parts per billion of the neonicotinoid pesticide thiamethoxam. This more closely mimics pesticide exposure in the wild by allowing foraging bees to (i) experience a field realistic range of pesticide concentrations across a chronic exposure period, (ii) have repeated interactions with the pesticide in their environment, and (iii) retain the social cues associated with foraging by using whole colonies. We found that the proportion of visits to pesticide-laced feeders increased over time, resulting in greater consumption of pesticide-laced sucrose relative to untreated sucrose. After changing the spatial position of each feeder, foragers continued to preferentially visit the pesticide-laced feeders which indicates that workers can detect thiamethoxam and alter their behaviour to continue feeding on it. The increasing preference for consuming the neonicotinoid-treated food therefore increases the risk of exposure for the colony during prolonged pesticide exposure. Our results highlight the need to incorporate attractiveness of pesticides to foraging bees (and potentially other insect pollinators) in addition to simply considering the proportion of pesticide-contaminated floral resources within the foraging landscape.
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Affiliation(s)
- Andres N Arce
- Department of Life Sciences, Imperial College London, Silwood Park Campus, Buckhurst Road, Ascot SL5 7PY, UK
| | - Ana Ramos Rodrigues
- Department of Life Sciences, Imperial College London, Silwood Park Campus, Buckhurst Road, Ascot SL5 7PY, UK
| | - Jiajun Yu
- Department of Life Sciences, Imperial College London, Silwood Park Campus, Buckhurst Road, Ascot SL5 7PY, UK
| | - Thomas J Colgan
- Department of Organismal Biology, Queen Mary University of London, Mile End Road, London E1 4NS, UK
| | - Yannick Wurm
- Department of Organismal Biology, Queen Mary University of London, Mile End Road, London E1 4NS, UK
| | - Richard J Gill
- Department of Life Sciences, Imperial College London, Silwood Park Campus, Buckhurst Road, Ascot SL5 7PY, UK
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Nepi M, Grasso DA, Mancuso S. Nectar in Plant-Insect Mutualistic Relationships: From Food Reward to Partner Manipulation. FRONTIERS IN PLANT SCIENCE 2018; 9:1063. [PMID: 30073014 PMCID: PMC6060274 DOI: 10.3389/fpls.2018.01063] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Accepted: 06/29/2018] [Indexed: 05/27/2023]
Abstract
It has been known for centuries that floral and extra-floral nectar secreted by plants attracts and rewards animals. Extra-floral nectar is involved in so-called indirect defense by attracting animals (generally ants) that prey on herbivores, or by discouraging herbivores from feeding on the plant. Floral nectar is presented inside the flower close to the reproductive organs and rewards animals that perform pollination while visiting the flower. In both cases nectar is a source of carbon and nitrogen compounds that feed animals, the most abundant solutes being sugars and amino acids. Plant-animal relationships involving the two types of nectar have therefore been used for a long time as text-book examples of symmetric mutualism: services provided by animals to plants in exchange for food provided by plants to animals. Cheating (or deception or exploitation), namely obtaining the reward/service without returning any counterpart, is however, well-known in mutualistic relationships, since the interacting partners have conflicting interests and selection may favor cheating strategies. A more subtle way of exploiting mutualism was recently highlighted. It implies the evolution of strategies to maximize the benefits obtained by one partner while still providing the reward/service to the other partner. Several substances other than sugars and amino acids have been found in nectar and some affect the foraging behavior of insects and potentially increase the benefits to the plant. Such substances can be considered plant cues to exploit mutualism. Recent evidence motivated some authors to use the term "manipulation" of animals by plants in nectar-mediated mutualistic relationships. This review highlights the recent background of the "manipulation" hypothesis, discussing it in the framework of new ecological and evolutionary scenarios in plant-animal interactions, as a stimulus for future research.
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Affiliation(s)
- Massimo Nepi
- Department of Life Sciences, University of Siena, Siena, Italy
| | - Donato A. Grasso
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parma, Italy
| | - Stefano Mancuso
- Department of Agrifood Production and Environmental Sciences, University of Florence, Florence, Italy
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Wink M. Plant Secondary Metabolites Modulate Insect Behavior-Steps Toward Addiction? Front Physiol 2018; 9:364. [PMID: 29695974 PMCID: PMC5904355 DOI: 10.3389/fphys.2018.00364] [Citation(s) in RCA: 79] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Accepted: 03/26/2018] [Indexed: 12/11/2022] Open
Abstract
Plants produce a diversity of secondary metabolites (PSMs) that serve as defense compounds against herbivores and microorganisms. In addition, some PSMs attract animals for pollination and seed dispersal. In case of pollinating insects, PSMs with colors or terpenoids with fragrant odors attract pollinators in the first place, but when they arrive at a flower, they are rewarded with nectar, so that the pollinators do not feed on flowers. In order to be effective as defense chemicals, PSMs evolved as bioactive substances, that can interfere with a large number of molecular targets in cells, tissues and organs of animals or of microbes. The known functions of PSMs are summarized in this review. A number of PSMs evolved as agonists or antagonists of neuronal signal transduction. Many of these PSMs are alkaloids. Several of them share structural similarities to neurotransmitters. Evidence for neuroactive and psychoactive PSMs in animals will be reviewed. Some of the neuroactive PSMs can cause addiction in humans and other vertrebrates. Why should a defense compound be addictive and thus attract more herbivores? Some insects are food specialists that can feed on plants that are normally toxic to other herbivores. These specialists can tolerate the toxins and many are stored in the insect body as acquired defense chemicals against predators. A special case are pyrrolizidine alkaloids (PAs) that are neurotoxic and mutagenic in vertebrates. PAs are actively sequestered by moths of the family Arctiidae and a few other groups of arthropods. In arctiids, PAs are not only used for defense, but also serve as morphogens for the induction of male coremata and as precursors for male pheromones. Caterpillars even feed on filter paper impregnated with pure PAs (that modulate serotonin receptors in vertebrates and maybe even in insects) and thus show of behavior with has similarities to addiction in vertebrates. Not only PA specialists, but also many monophagous herbivores select their host plants according to chemical cues i.e., PSMs) and crave for plants with a particular PSMs, again a similarity to addiction in vertebrates.
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Affiliation(s)
- Michael Wink
- Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, Heidelberg, Germany
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36
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Haverkamp A, Hansson BS, Baldwin IT, Knaden M, Yon F. Floral Trait Variations Among Wild Tobacco Populations Influence the Foraging Behavior of Hawkmoth Pollinators. Front Ecol Evol 2018. [DOI: 10.3389/fevo.2018.00019] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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37
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Baluška F, Mancuso S. Plant Cognition and Behavior: From Environmental Awareness to Synaptic Circuits Navigating Root Apices. MEMORY AND LEARNING IN PLANTS 2018. [DOI: 10.1007/978-3-319-75596-0_4] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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