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Yu C, Lin R, Fu M, Zhou Y, Zong F, Jiang H, Lv N, Piao X, Zhang J, Liu Y, Brock TCM. Impact of imidacloprid on life-cycle development of Coccinella septempunctata in laboratory microcosms. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2014; 110:168-173. [PMID: 25240465 DOI: 10.1016/j.ecoenv.2014.08.022] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2014] [Revised: 08/17/2014] [Accepted: 08/19/2014] [Indexed: 06/03/2023]
Abstract
Long-term effects of a single application of imidacloprid on ladybird beetle, Coccinella septempunctata L., were studied in indoor laboratory microcosms, starting with the 2nd instar larvae of C. septempunctata but covering the full life cycle. The microcosms comprised enclosures containing a pot with soil planted with broad bean plants and black bean aphid, Aphis craccivora Koch, as food. Exposure doses (0.85-13.66g a.i. ha(-1)) in the long-term microcosm experiment were based on a preliminary short-term (72h) toxicity test with 2nd instar larvae. The measurement endpoints used to calculate NOERs (No Observed Effect application Rates) included development time, hatching, pupation, adult emergence, survival and number of eggs produced. Furthermore, for these endpoints ER50 (application rate causing 50 percent effect) and LR50 (application rate causing 50 percent mortality) values were calculated when possible. The single imidacloprid application affected survival (lowest LR50 4.07g a.i. ha(-1); NOER 3.42g a.i. ha(-1)), egg production (ER50 26.63g a.i. ha(-1)) and egg hatching (NOER 6.83g a.i. ha(-1)). Statistically significant treatment-related effects on the whole development duration, pupation and adult emergence could not be demonstrated (NOER≥13.66g a.i. ha(-1)). The lowest L(E)R50 values and NOERs derived from the laboratory microcosm test with C. septempunctata are lower than the reported field application rates of imidacloprid (15-60g a.i. ha(-1)) in cotton cultivation in China, suggesting potential risks to beneficial arthropods.
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Affiliation(s)
- Caihong Yu
- College of Chemistry and Environment Engineering, China University of Mining and Technology (Beijing), 100083 Beijing, China
| | - Ronghua Lin
- Institute for the Control of Agrochemicals, Ministry of Agriculture, 100125 Beijing, China.
| | - Maoran Fu
- College of Chemistry and Environment Engineering, China University of Mining and Technology (Beijing), 100083 Beijing, China
| | - Yanming Zhou
- Institute for the Control of Agrochemicals, Ministry of Agriculture, 100125 Beijing, China
| | - Fulin Zong
- Institute for the Control of Agrochemicals, Ministry of Agriculture, 100125 Beijing, China
| | - Hui Jiang
- Institute for the Control of Agrochemicals, Ministry of Agriculture, 100125 Beijing, China
| | - Ning Lv
- Institute for the Control of Agrochemicals, Ministry of Agriculture, 100125 Beijing, China
| | - Xiuying Piao
- Institute for the Control of Agrochemicals, Ministry of Agriculture, 100125 Beijing, China
| | - Jia Zhang
- Institute for the Control of Agrochemicals, Ministry of Agriculture, 100125 Beijing, China
| | - Yongquan Liu
- Institute for the Control of Agrochemicals, Ministry of Agriculture, 100125 Beijing, China
| | - Theo C M Brock
- Alterra, Wageningen University and Research Centre, PO Box 47, 6700 AA, Wageningen, The Netherlands
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Sandrock C, Tanadini M, Tanadini LG, Fauser-Misslin A, Potts SG, Neumann P. Impact of chronic neonicotinoid exposure on honeybee colony performance and queen supersedure. PLoS One 2014; 9:e103592. [PMID: 25084279 PMCID: PMC4118897 DOI: 10.1371/journal.pone.0103592] [Citation(s) in RCA: 133] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Accepted: 07/03/2014] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Honeybees provide economically and ecologically vital pollination services to crops and wild plants. During the last decade elevated colony losses have been documented in Europe and North America. Despite growing consensus on the involvement of multiple causal factors, the underlying interactions impacting on honeybee health and colony failure are not fully resolved. Parasites and pathogens are among the main candidates, but sublethal exposure to widespread agricultural pesticides may also affect bees. METHODOLOGY/PRINCIPAL FINDINGS To investigate effects of sublethal dietary neonicotinoid exposure on honeybee colony performance, a fully crossed experimental design was implemented using 24 colonies, including sister-queens from two different strains, and experimental in-hive pollen feeding with or without environmentally relevant concentrations of thiamethoxam and clothianidin. Honeybee colonies chronically exposed to both neonicotinoids over two brood cycles exhibited decreased performance in the short-term resulting in declining numbers of adult bees (-28%) and brood (-13%), as well as a reduction in honey production (-29%) and pollen collections (-19%), but colonies recovered in the medium-term and overwintered successfully. However, significantly decelerated growth of neonicotinoid-exposed colonies during the following spring was associated with queen failure, revealing previously undocumented long-term impacts of neonicotinoids: queen supersedure was observed for 60% of the neonicotinoid-exposed colonies within a one year period, but not for control colonies. Linked to this, neonicotinoid exposure was significantly associated with a reduced propensity to swarm during the next spring. Both short-term and long-term effects of neonicotinoids on colony performance were significantly influenced by the honeybees' genetic background. CONCLUSIONS/SIGNIFICANCE Sublethal neonicotinoid exposure did not provoke increased winter losses. Yet, significant detrimental short and long-term impacts on colony performance and queen fate suggest that neonicotinoids may contribute to colony weakening in a complex manner. Further, we highlight the importance of the genetic basis of neonicotinoid susceptibility in honeybees which can vary substantially.
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Affiliation(s)
| | | | - Lorenzo G. Tanadini
- Division of Biostatistics, Institute for Social and Preventive Medicine, University of Zurich, Zurich, Switzerland
| | - Aline Fauser-Misslin
- Agroscope, Swiss Bee Research Centre, Berne, Switzerland
- Institute of Bee Health, Vetsuisse Faculty, University of Berne, Berne, Switzerland
| | - Simon G. Potts
- School of Agriculture, Policy and Development, University of Reading, Reading, United Kingdom
| | - Peter Neumann
- Agroscope, Swiss Bee Research Centre, Berne, Switzerland
- Institute of Bee Health, Vetsuisse Faculty, University of Berne, Berne, Switzerland
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53
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Tan K, Chen W, Dong S, Liu X, Wang Y, Nieh JC. Imidacloprid alters foraging and decreases bee avoidance of predators. PLoS One 2014; 9:e102725. [PMID: 25025334 PMCID: PMC4099376 DOI: 10.1371/journal.pone.0102725] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Accepted: 06/20/2014] [Indexed: 11/18/2022] Open
Abstract
Concern is growing over the effects of neonicotinoid pesticides, which can impair honey bee cognition. We provide the first demonstration that sublethal concentrations of imidacloprid can harm honey bee decision-making about danger by significantly increasing the probability of a bee visiting a dangerous food source. Apis cerana is a native bee that is an important pollinator of agricultural crops and native plants in Asia. When foraging on nectar containing 40 µg/L (34 ppb) imidacloprid, honey bees (Apis cerana) showed no aversion to a feeder with a hornet predator, and 1.8 fold more bees chose the dangerous feeder as compared to control bees. Control bees exhibited significant predator avoidance. We also give the first evidence that foraging by A. cerana workers can be inhibited by sublethal concentrations of the pesticide, imidacloprid, which is widely used in Asia. Compared to bees collecting uncontaminated nectar, 23% fewer foragers returned to collect the nectar with 40 µg/L imidacloprid. Bees that did return respectively collected 46% and 63% less nectar containing 20 µg/L and 40 µg/L imidacloprid. These results suggest that the effects of neonicotinoids on honey bee decision-making and other advanced cognitive functions should be explored. Moreover, research should extend beyond the classic model, the European honey bee (A. mellifera), to other important bee species.
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Affiliation(s)
- Ken Tan
- Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Science, Kunming, Yunnan Province, China
- Eastern Bee Research Institute, Yunnan Agricultural University, Heilongtan, Kunming, Yunnan Province, China
- * E-mail:
| | - Weiwen Chen
- Eastern Bee Research Institute, Yunnan Agricultural University, Heilongtan, Kunming, Yunnan Province, China
| | - Shihao Dong
- Eastern Bee Research Institute, Yunnan Agricultural University, Heilongtan, Kunming, Yunnan Province, China
| | - Xiwen Liu
- Eastern Bee Research Institute, Yunnan Agricultural University, Heilongtan, Kunming, Yunnan Province, China
| | - Yuchong Wang
- Eastern Bee Research Institute, Yunnan Agricultural University, Heilongtan, Kunming, Yunnan Province, China
| | - James C. Nieh
- Division of Biological Sciences, Section of Ecology, Behavior, and Evolution, University of California San Diego, La Jolla, California, United States of America
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54
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Environmental fate of soil applied neonicotinoid insecticides in an irrigated potato agroecosystem. PLoS One 2014; 9:e97081. [PMID: 24823765 PMCID: PMC4019649 DOI: 10.1371/journal.pone.0097081] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Accepted: 04/15/2014] [Indexed: 11/19/2022] Open
Abstract
Since 1995, neonicotinoid insecticides have been a critical component of arthropod management in potato, Solanum tuberosum L. Recent detections of neonicotinoids in groundwater have generated questions about the sources of these contaminants and the relative contribution from commodities in U.S. agriculture. Delivery of neonicotinoids to crops typically occurs as a seed or in-furrow treatment to manage early season insect herbivores. Applied in this way, these insecticides become systemically mobile in the plant and provide control of key pest species. An outcome of this project links these soil insecticide application strategies in crop plants with neonicotinoid contamination of water leaching from the application zone. In 2011 and 2012, our objectives were to document the temporal patterns of neonicotinoid leachate below the planting furrow following common insecticide delivery methods in potato. Leaching loss of thiamethoxam from potato was measured using pan lysimeters from three at-plant treatments and one foliar application treatment. Insecticide concentration in leachate was assessed for six consecutive months using liquid chromatography-tandem mass spectrometry. Findings from this study suggest leaching of neonicotinoids from potato may be greater following crop harvest in comparison to other times during the growing season. Furthermore, this study documented recycling of neonicotinoid insecticides from contaminated groundwater back onto the crop via high capacity irrigation wells. These results document interactions between cultivated potato, different neonicotinoid delivery methods, and the potential for subsurface water contamination via leaching.
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55
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Cutler GC, Scott-Dupree CD, Drexler DM. Honey bees, neonicotinoids and bee incident reports: the Canadian situation. PEST MANAGEMENT SCIENCE 2014; 70:779-783. [PMID: 23873722 DOI: 10.1002/ps.3613] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Revised: 07/06/2013] [Accepted: 07/19/2013] [Indexed: 06/02/2023]
Abstract
BACKGROUND Neonicotinoid insecticides have been the target of much scrutiny as possible causes of recent declines observed in pollinator populations. Although neonicotinoids have been implicated in honey bee pesticide incidents, there has been little examination of incident report data. Here we summarize honey bee incident report data obtained from the Canadian Pest Management Regulatory Agency (PMRA). RESULTS In Canada, there were very few honey bee incidents reported in 2007-2011 and data were not collected prior to 2007. In 2012, a significant number of incidents were reported in the province of Ontario, where exposure to neonicotinoid dust during planting of corn was suspected to have caused the incident in up to 70% of cases. Most of these incidents were classified as 'minor' by the PMRA, and only six cases were considered 'moderate' or 'major'. In that same year, there were over three times as many moderate or major incidents due to older non-neonicotinoid pesticides, involving numbers of hives or bees far greater than the number of moderate or major incidents suspected to be due to neonicotinoid poisoning. CONCLUSIONS These data emphasize that, while exposure of honey bees to neonicotinoid-contaminated dust during corn planting needs to be mitigated, other pesticides also pose a risk.
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Affiliation(s)
- G Christopher Cutler
- Department of Environmental Sciences, Dalhousie University, Truro, Nova Scotia, Canada
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56
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Becher MA, Grimm V, Thorbek P, Horn J, Kennedy PJ, Osborne JL. BEEHAVE: a systems model of honeybee colony dynamics and foraging to explore multifactorial causes of colony failure. J Appl Ecol 2014; 51:470-482. [PMID: 25598549 PMCID: PMC4283046 DOI: 10.1111/1365-2664.12222] [Citation(s) in RCA: 179] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Accepted: 01/10/2014] [Indexed: 12/03/2022]
Abstract
A notable increase in failure of managed European honeybee Apis mellifera L. colonies has been reported in various regions in recent years. Although the underlying causes remain unclear, it is likely that a combination of stressors act together, particularly varroa mites and other pathogens, forage availability and potentially pesticides. It is experimentally challenging to address causality at the colony scale when multiple factors interact. In silico experiments offer a fast and cost‐effective way to begin to address these challenges and inform experiments. However, none of the published bee models combine colony dynamics with foraging patterns and varroa dynamics. We have developed a honeybee model, BEEHAVE, which integrates colony dynamics, population dynamics of the varroa mite, epidemiology of varroa‐transmitted viruses and allows foragers in an agent‐based foraging model to collect food from a representation of a spatially explicit landscape. We describe the model, which is freely available online (www.beehave-model.net). Extensive sensitivity analyses and tests illustrate the model's robustness and realism. Simulation experiments with various combinations of stressors demonstrate, in simplified landscape settings, the model's potential: predicting colony dynamics and potential losses with and without varroa mites under different foraging conditions and under pesticide application. We also show how mitigation measures can be tested. Synthesis and applications. BEEHAVE offers a valuable tool for researchers to design and focus field experiments, for regulators to explore the relative importance of stressors to devise management and policy advice and for beekeepers to understand and predict varroa dynamics and effects of management interventions. We expect that scientists and stakeholders will find a variety of applications for BEEHAVE, stimulating further model development and the possible inclusion of other stressors of potential importance to honeybee colony dynamics.
BEEHAVE offers a valuable tool for researchers to design and focus field experiments, for regulators to explore the relative importance of stressors to devise management and policy advice and for beekeepers to understand and predict varroa dynamics and effects of management interventions. We expect that scientists and stakeholders will find a variety of applications for BEEHAVE, stimulating further model development and the possible inclusion of other stressors of potential importance to honeybee colony dynamics.
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Affiliation(s)
- Matthias A Becher
- Environment & Sustainability Institute, University of Exeter, Penryn Campus Penryn, Cornwall, TR10 9FE, UK ; Rothamsted Research West Common, Harpenden, Hertfordshire, AL5 2JQ, UK
| | - Volker Grimm
- UFZ, Helmholtz Centre for Environmental Research - UFZ Permoserstr. 15, 04318, Leipzig, Germany ; Institute for Biochemistry and Biology, University of Potsdam Maulbeerallee 2, 14469, Potsdam, Germany ; German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig Deutscher Platz 5e, 04103, Leipzig, Germany
| | - Pernille Thorbek
- Environmental Safety, Syngenta, Jealott's Hill International Research Centre Bracknell, Berkshire, RG42 6EY, UK
| | - Juliane Horn
- UFZ, Helmholtz Centre for Environmental Research - UFZ Permoserstr. 15, 04318, Leipzig, Germany
| | - Peter J Kennedy
- Environment & Sustainability Institute, University of Exeter, Penryn Campus Penryn, Cornwall, TR10 9FE, UK ; Rothamsted Research West Common, Harpenden, Hertfordshire, AL5 2JQ, UK
| | - Juliet L Osborne
- Environment & Sustainability Institute, University of Exeter, Penryn Campus Penryn, Cornwall, TR10 9FE, UK ; Rothamsted Research West Common, Harpenden, Hertfordshire, AL5 2JQ, UK
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Staveley JP, Law SA, Fairbrother A, Menzie CA. A Causal Analysis of Observed Declines in Managed Honey Bees ( Apis mellifera). HUMAN AND ECOLOGICAL RISK ASSESSMENT : HERA 2014; 20:566-591. [PMID: 24363549 PMCID: PMC3869053 DOI: 10.1080/10807039.2013.831263] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Accepted: 07/23/2013] [Indexed: 05/11/2023]
Abstract
The European honey bee (Apis mellifera) is a highly valuable, semi-free-ranging managed agricultural species. While the number of managed hives has been increasing, declines in overwinter survival, and the onset of colony collapse disorder in 2006, precipitated a large amount of research on bees' health in an effort to isolate the causative factors. A workshop was convened during which bee experts were introduced to a formal causal analysis approach to compare 39 candidate causes against specified criteria to evaluate their relationship to the reduced overwinter survivability observed since 2006 of commercial bees used in the California almond industry. Candidate causes were categorized as probable, possible, or unlikely; several candidate causes were categorized as indeterminate due to lack of information. Due to time limitations, a full causal analysis was not completed at the workshop. In this article, examples are provided to illustrate the process and provide preliminary findings, using three candidate causes. Varroa mites plus viruses were judged to be a "probable cause" of the reduced survival, while nutrient deficiency was judged to be a "possible cause." Neonicotinoid pesticides were judged to be "unlikely" as the sole cause of this reduced survival, although they could possibly be a contributing factor.
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58
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Fauser-Misslin A, Sadd BM, Neumann P, Sandrock C. Influence of combined pesticide and parasite exposure on bumblebee colony traits in the laboratory. J Appl Ecol 2013. [DOI: 10.1111/1365-2664.12188] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Aline Fauser-Misslin
- Institute of Bee Health; Vetsuisse Faculty and Faculty of Medicine; University of Bern; Länggass-Strasse 109a 3001 Bern Switzerland
| | - Ben M. Sadd
- School of Biological Sciences; Illinois State University; Campus Box 4120 Normal IL 61790 USA
| | - Peter Neumann
- Institute of Bee Health; Vetsuisse Faculty and Faculty of Medicine; University of Bern; Länggass-Strasse 109a 3001 Bern Switzerland
| | - Christoph Sandrock
- Swiss Bee Research Centre; Agroscope Liebefeld-Posieux ALP; Schwarzenburgstrasse 161 3003 Bern Switzerland
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59
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Laycock I, Cresswell JE. Repression and recuperation of brood production in Bombus terrestris bumble bees exposed to a pulse of the neonicotinoid pesticide imidacloprid. PLoS One 2013; 8:e79872. [PMID: 24224015 PMCID: PMC3817108 DOI: 10.1371/journal.pone.0079872] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Accepted: 09/27/2013] [Indexed: 11/19/2022] Open
Abstract
Currently, there is concern about declining bee populations and some blame the residues of neonicotinoid pesticides in the nectar and pollen of treated crops. Bumble bees are important wild pollinators that are widely exposed to dietary neonicotinoids by foraging in agricultural environments. In the laboratory, we tested the effect of a pulsed exposure (14 days 'on dose' followed by 14 days 'off dose') to a common neonicotinoid, imidacloprid, on the amount of brood (number of eggs and larvae) produced by Bombus terrestris L. bumble bees in small, standardised experimental colonies (a queen and four adult workers). During the initial 'on dose' period we observed a dose-dependent repression of brood production in colonies, with productivity decreasing as dosage increased up to 98 µg kg(-1) dietary imidacloprid. During the following 'off dose' period, colonies showed a dose-dependent recuperation such that total brood production during the 28-day pulsed exposure was not correlated with imidacloprid up to 98 µg kg(-1). Our findings raise further concern about the threat to wild bumble bees from neonicotinoids, but they also indicate some resilience to a pulsed exposure, such as that arising from the transient bloom of a treated mass-flowering crop.
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Affiliation(s)
- Ian Laycock
- College of Life & Environmental Sciences, Biosciences, University of Exeter, Exeter, United Kingdom
| | - James E. Cresswell
- College of Life & Environmental Sciences, Biosciences, University of Exeter, Exeter, United Kingdom
- Centre for Pollination Studies, University of Calcutta, Kolkata, India
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60
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A four-year field program investigating long-term effects of repeated exposure of honey bee colonies to flowering crops treated with thiamethoxam. PLoS One 2013; 8:e77193. [PMID: 24194871 PMCID: PMC3806756 DOI: 10.1371/journal.pone.0077193] [Citation(s) in RCA: 137] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Accepted: 09/08/2013] [Indexed: 11/19/2022] Open
Abstract
Neonicotinoid residues in nectar and pollen from crop plants have been implicated as one of the potential factors causing the declines of honey bee populations. Median residues of thiamethoxam in pollen collected from honey bees after foraging on flowering seed treated maize were found to be between 1 and 7 µg/kg, median residues of the metabolite CGA322704 (clothianidin) in the pollen were between 1 and 4 µg/kg. In oilseed rape, median residues of thiamethoxam found in pollen collected from bees were between <1 and 3.5 µg/kg and in nectar from foraging bees were between 0.65 and 2.4 µg/kg. Median residues of CGA322704 in pollen and nectar in the oilseed rape trials were all below the limit of quantification (1 µg/kg). Residues in the hive were even lower in both the maize and oilseed rape trials, being at or below the level of detection of 1 µg/kg for bee bread in the hive and at or below the level of detection of 0.5 µg/kg for hive nectar, honey and royal jelly samples. The long-term risk to honey bee colonies in the field was also investigated, including the sensitive overwintering stage, from four years consecutive single treatment crop exposures to flowering maize and oilseed rape grown from thiamethoxam treated seeds at rates recommended for insect control. Throughout the study, mortality, foraging behavior, colony strength, colony weight, brood development and food storage levels were similar between treatment and control colonies. Detailed examination of brood development throughout the year demonstrated that colonies exposed to the treated crop were able to successfully overwinter and had a similar health status to the control colonies in the following spring. We conclude that these data demonstrate there is a low risk to honey bees from systemic residues in nectar and pollen following the use of thiamethoxam as a seed treatment on oilseed rape and maize.
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61
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Neonicotinoid clothianidin adversely affects insect immunity and promotes replication of a viral pathogen in honey bees. Proc Natl Acad Sci U S A 2013; 110:18466-71. [PMID: 24145453 DOI: 10.1073/pnas.1314923110] [Citation(s) in RCA: 390] [Impact Index Per Article: 35.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Large-scale losses of honey bee colonies represent a poorly understood problem of global importance. Both biotic and abiotic factors are involved in this phenomenon that is often associated with high loads of parasites and pathogens. A stronger impact of pathogens in honey bees exposed to neonicotinoid insecticides has been reported, but the causal link between insecticide exposure and the possible immune alteration of honey bees remains elusive. Here, we demonstrate that the neonicotinoid insecticide clothianidin negatively modulates NF-κB immune signaling in insects and adversely affects honey bee antiviral defenses controlled by this transcription factor. We have identified in insects a negative modulator of NF-κB activation, which is a leucine-rich repeat protein. Exposure to clothianidin, by enhancing the transcription of the gene encoding this inhibitor, reduces immune defenses and promotes the replication of the deformed wing virus in honey bees bearing covert infections. This honey bee immunosuppression is similarly induced by a different neonicotinoid, imidacloprid, but not by the organophosphate chlorpyriphos, which does not affect NF-κB signaling. The occurrence at sublethal doses of this insecticide-induced viral proliferation suggests that the studied neonicotinoids might have a negative effect at the field level. Our experiments uncover a further level of regulation of the immune response in insects and set the stage for studies on neural modulation of immunity in animals. Furthermore, this study has implications for the conservation of bees, as it will contribute to the definition of more appropriate guidelines for testing chronic or sublethal effects of pesticides used in agriculture.
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62
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Martin W. Making valid causal inferences from observational data. Prev Vet Med 2013; 113:281-97. [PMID: 24113257 DOI: 10.1016/j.prevetmed.2013.09.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2013] [Revised: 08/29/2013] [Accepted: 09/13/2013] [Indexed: 11/26/2022]
Abstract
The ability to make strong causal inferences, based on data derived from outside of the laboratory, is largely restricted to data arising from well-designed randomized control trials. Nonetheless, a number of methods have been developed to improve our ability to make valid causal inferences from data arising from observational studies. In this paper, I review concepts of causation as a background to counterfactual causal ideas; the latter ideas are central to much of current causal theory. Confounding greatly constrains causal inferences in all observational studies. Confounding is a biased measure of effect that results when one or more variables, that are both antecedent to the exposure and associated with the outcome, are differentially distributed between the exposed and non-exposed groups. Historically, the most common approach to control confounding has been multivariable modeling; however, the limitations of this approach are discussed. My suggestions for improving causal inferences include asking better questions (relates to counterfactual ideas and "thought" trials); improving study design through the use of forward projection; and using propensity scores to identify potential confounders and enhance exchangeability, prior to seeing the outcome data. If time-dependent confounders are present (as they are in many longitudinal studies), more-advanced methods such as marginal structural models need to be implemented. Tutorials and examples are cited where possible.
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Affiliation(s)
- Wayne Martin
- Professor Emeritus, University of Guelph, Guelph, Ontario, Canada N1G 2W1.
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63
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Derecka K, Blythe MJ, Malla S, Genereux DP, Guffanti A, Pavan P, Moles A, Snart C, Ryder T, Ortori CA, Barrett DA, Schuster E, Stöger R. Transient exposure to low levels of insecticide affects metabolic networks of honeybee larvae. PLoS One 2013; 8:e68191. [PMID: 23844170 PMCID: PMC3699529 DOI: 10.1371/journal.pone.0068191] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Accepted: 05/27/2013] [Indexed: 01/21/2023] Open
Abstract
The survival of a species depends on its capacity to adjust to changing environmental conditions, and new stressors. Such new, anthropogenic stressors include the neonicotinoid class of crop-protecting agents, which have been implicated in the population declines of pollinating insects, including honeybees (Apis mellifera). The low-dose effects of these compounds on larval development and physiological responses have remained largely unknown. Over a period of 15 days, we provided syrup tainted with low levels (2 µg/L(-1)) of the neonicotinoid insecticide imidacloprid to beehives located in the field. We measured transcript levels by RNA sequencing and established lipid profiles using liquid chromatography coupled with mass spectrometry from worker-bee larvae of imidacloprid-exposed (IE) and unexposed, control (C) hives. Within a catalogue of 300 differentially expressed transcripts in larvae from IE hives, we detect significant enrichment of genes functioning in lipid-carbohydrate-mitochondrial metabolic networks. Myc-involved transcriptional response to exposure of this neonicotinoid is indicated by overrepresentation of E-box elements in the promoter regions of genes with altered expression. RNA levels for a cluster of genes encoding detoxifying P450 enzymes are elevated, with coordinated downregulation of genes in glycolytic and sugar-metabolising pathways. Expression of the environmentally responsive Hsp90 gene is also reduced, suggesting diminished buffering and stability of the developmental program. The multifaceted, physiological response described here may be of importance to our general understanding of pollinator health. Muscles, for instance, work at high glycolytic rates and flight performance could be impacted should low levels of this evolutionarily novel stressor likewise induce downregulation of energy metabolising genes in adult pollinators.
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Affiliation(s)
- Kamila Derecka
- School of Biosciences, University of Nottingham, Sutton Bonington Campus, Leicestershire, United Kingdom
| | - Martin J. Blythe
- Deep Seq, Centre for Genetics and Genomics, University of Nottingham, Nottingham, United Kingdom
| | - Sunir Malla
- Deep Seq, Centre for Genetics and Genomics, University of Nottingham, Nottingham, United Kingdom
| | - Diane P. Genereux
- Biology Department, Westfield State University, Westfield, Massachusetts, United States of America
| | | | | | | | - Charles Snart
- School of Biosciences, University of Nottingham, Sutton Bonington Campus, Leicestershire, United Kingdom
| | | | - Catharine A. Ortori
- Centre for Analytical Bioscience, School of Pharmacy, University of Nottingham, Nottingham, United Kingdom
| | - David A. Barrett
- Centre for Analytical Bioscience, School of Pharmacy, University of Nottingham, Nottingham, United Kingdom
| | - Eugene Schuster
- Institute of Healthy Ageing, Department of Genetics, Evolution and Environment, University College London, London, United Kingdom
| | - Reinhard Stöger
- School of Biosciences, University of Nottingham, Sutton Bonington Campus, Leicestershire, United Kingdom
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64
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Harpur BA, Minaei S, Kent CF, Zayed A. Admixture increases diversity in managed honey bees: reply to De la Rúa et al. (2013). Mol Ecol 2013; 22:3211-5. [PMID: 24433573 DOI: 10.1111/mec.12332] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Revised: 03/26/2013] [Accepted: 03/29/2013] [Indexed: 11/30/2022]
Abstract
De la Rúa et al. (2013) express some concerns about the conclusions of our recent study showing that management increases genetic diversity of honey bees (Apis mellifera) by promoting admixture (Harpur et al. 2012). We provide a brief review of the literature on the population genetics of A. mellifera and show that we utilized appropriate sampling methods to estimate genetic diversity in the focal populations. Our finding of higher genetic diversity in two managed A. mellifera populations on two different continents is expected to be the norm given the large number of studies documenting admixture in honey bees. Our study focused on elucidating how management affects genetic diversity in honey bees, not on how to best manage bee colonies. We do not endorse the intentional admixture of honey bee populations, and we agree with De la Rúa et al. (2013) that native honey bee subspecies should be conserved.
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Affiliation(s)
- Brock A Harpur
- Department of Biology, York University, 4700 Keele Street, Toronto, M3J 1P3, Ontario, Canada
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65
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Van Dijk TC, Van Staalduinen MA, Van der Sluijs JP. Macro-invertebrate decline in surface water polluted with imidacloprid. PLoS One 2013; 8:e62374. [PMID: 23650513 PMCID: PMC3641074 DOI: 10.1371/journal.pone.0062374] [Citation(s) in RCA: 244] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Accepted: 03/20/2013] [Indexed: 11/18/2022] Open
Abstract
Imidacloprid is one of the most widely used insecticides in the world. Its concentration in surface water exceeds the water quality norms in many parts of the Netherlands. Several studies have demonstrated harmful effects of this neonicotinoid to a wide range of non-target species. Therefore we expected that surface water pollution with imidacloprid would negatively impact aquatic ecosystems. Availability of extensive monitoring data on the abundance of aquatic macro-invertebrate species, and on imidacloprid concentrations in surface water in the Netherlands enabled us to test this hypothesis. Our regression analysis showed a significant negative relationship (P<0.001) between macro-invertebrate abundance and imidacloprid concentration for all species pooled. A significant negative relationship was also found for the orders Amphipoda, Basommatophora, Diptera, Ephemeroptera and Isopoda, and for several species separately. The order Odonata had a negative relationship very close to the significance threshold of 0.05 (P = 0.051). However, in accordance with previous research, a positive relationship was found for the order Actinedida. We used the monitoring field data to test whether the existing three water quality norms for imidacloprid in the Netherlands are protective in real conditions. Our data show that macrofauna abundance drops sharply between 13 and 67 ng l(-1). For aquatic ecosystem protection, two of the norms are not protective at all while the strictest norm of 13 ng l(-1) (MTR) seems somewhat protective. In addition to the existing experimental evidence on the negative effects of imidacloprid on invertebrate life, our study, based on data from large-scale field monitoring during multiple years, shows that serious concern about the far-reaching consequences of the abundant use of imidacloprid for aquatic ecosystems is justified.
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Affiliation(s)
- Tessa C. Van Dijk
- Environmental Sciences, Utrecht University, Utrecht, The Netherlands
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66
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Abstract
Varroa mites and viruses are the currently the high-profile suspects in collapsing bee colonies. Therefore, seasonal variation in varroa load and viruses (Acute-Kashmir-Israeli complex (AKI) and Deformed Wing Virus (DWV)) were monitored in a year-long study. We investigated the viral titres in honey bees and varroa mites from 23 colonies (15 apiaries) under three treatment conditions: Organic acids (11 colonies), pyrethroid (9 colonies) and untreated (3 colonies). Approximately 200 bees were sampled every month from April 2011 to October 2011, and April 2012. The 200 bees were split to 10 subsamples of 20 bees and analysed separately, which allows us to determine the prevalence of virus-infected bees. The treatment efficacy was often low for both treatments. In colonies where varroa treatment reduced the mite load, colonies overwintered successfully, allowing the mites and viruses to be carried over with the bees into the next season. In general, AKI and DWV titres did not show any notable response to the treatment and steadily increased over the season from April to October. In the untreated control group, titres increased most dramatically. Viral copies were correlated to number of varroa mites. Most colonies that collapsed over the winter had significantly higher AKI and DWV titres in October compared to survivors. Only treated colonies survived the winter. We discuss our results in relation to the varroa-virus model developed by Stephen Martin.
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67
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Balancing Control and Complexity in Field Studies of Neonicotinoids and Honey Bee Health. INSECTS 2013; 4:153-67. [PMID: 26466800 PMCID: PMC4553434 DOI: 10.3390/insects4010153] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Revised: 01/29/2013] [Accepted: 02/16/2013] [Indexed: 11/17/2022]
Abstract
Amidst ongoing declines in honey bee health, the contributory role of the newer systemic insecticides continues to be intensely debated. Scores of toxicological field experiments, which bee scientists and regulators in the United States have looked to for definitive causal evidence, indicate a lack of support. This paper analyzes the methodological norms that shape the design and interpretation of field toxicological studies. I argue that contemporary field studies of honey bees and pesticides are underpinned by a "control-oriented" approach, which precludes a serious investigation of the indirect and multifactorial ways in which pesticides could drive declines in honey bee health. I trace the historical rise to prominence of this approach in honey bee toxicology to the development of entomology as a science of insecticide development in the United States. Drawing on "complexity-oriented" knowledge practices in ecology, epidemiology, beekeeping and sociology, I suggest an alternative socio-ecological systems approach, which would entail in situ studies that are less concerned with isolating individual factors and more attentive to the interactive and place-based mix of factors affecting honey bee health.
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68
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Easton AH, Goulson D. The neonicotinoid insecticide imidacloprid repels pollinating flies and beetles at field-realistic concentrations. PLoS One 2013; 8:e54819. [PMID: 23382980 PMCID: PMC3557293 DOI: 10.1371/journal.pone.0054819] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Accepted: 12/17/2012] [Indexed: 12/02/2022] Open
Abstract
Neonicotinoids are widely used systemic insecticides which, when applied to flowering crops, are translocated to the nectar and pollen where they may impact upon pollinators. Given global concerns over pollinator declines, this potential impact has recently received much attention. Field exposure of pollinators to neonicotinoids depends on the concentrations present in flowering crops and the degree to which pollinators choose to feed upon them. Here we describe a simple experiment using paired yellow pan traps with or without insecticide to assess whether the commonly used neonicotinoid imidacloprid repels or attracts flying insects. Both Diptera and Coleoptera exhibited marked avoidance of traps containing imidacloprid at a field-realistic dose of 1 µg L(-1), with Diptera avoiding concentrations as low as 0.01 µg L(-1). This is to our knowledge the first evidence for any biological activity at such low concentrations, which are below the limits of laboratory detection using most commonly available techniques. Catch of spiders in pan traps was also slightly reduced by the highest concentrations of imidacloprid used (1 µg L(-1)), but catch was increased by lower concentrations. It remains to be seen if the repellent effect on insects occurs when neonicotinoids are present in real flowers, but if so then this could have implications for exposure of pollinators to neonicotinoids and for crop pollination.
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Affiliation(s)
- Amy H. Easton
- Biological and Environmental Sciences, School of Natural Sciences, University of Stirling, Stirling, Scotland
| | - Dave Goulson
- Biological and Environmental Sciences, School of Natural Sciences, University of Stirling, Stirling, Scotland
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69
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Duke S. Our goals is to publish high-quality front matter articles. PEST MANAGEMENT SCIENCE 2013; 69:1-2. [PMID: 23239644 DOI: 10.1002/ps.3466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
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70
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Cresswell JE, Page CJ, Uygun MB, Holmbergh M, Li Y, Wheeler JG, Laycock I, Pook CJ, de Ibarra NH, Smirnoff N, Tyler CR. Differential sensitivity of honey bees and bumble bees to a dietary insecticide (imidacloprid). ZOOLOGY 2012; 115:365-71. [DOI: 10.1016/j.zool.2012.05.003] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2011] [Revised: 03/27/2012] [Accepted: 05/14/2012] [Indexed: 10/27/2022]
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71
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UHPLC-DAD method for the determination of neonicotinoid insecticides in single bees and its relevance in honeybee colony loss investigations. Anal Bioanal Chem 2012; 405:1007-14. [DOI: 10.1007/s00216-012-6338-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2012] [Revised: 08/03/2012] [Accepted: 08/06/2012] [Indexed: 10/27/2022]
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