Journal Article•
Potential routes of exposure as a foundation for a risk assessment scheme: a Conceptual Model
TL;DR: The quantitative pollinator conceptual model (QPCM) describes the flow pathways and potential exposure routes for honeybees and other bee pollinators in sufficient detail to support quantitative exposure modelling and risk assessment and shows the importance of measuring the distribution of pesticide residues in the areas that lead to exposure and in the hive.
Abstract: Background: The global interest in improving the regulatory risk assessment of pesticides in honeybees and other pollinator insects has led to new test requirements and a conceptual model has been published in the US. It is of interest for modellers and risk assessors to have a more detailed conceptual model that describes the movement of deleterious substances from the point of initial exposure to the point of impact on the protection goals, such as colony health, or honey production. Results: The flow of pesticide residues from application to distribution in the hive is described in an integrated conceptual model. The significance of this model for assessing the relative contribution of various potential routes of exposure, guiding test requirements and describing the quantitative distribution of residues among the castes and task groups of honeybees in the colony was described using data from studies with chlorpyrifos and several neonicotinoids. Conclusion: The quantitative pollinator conceptual model (QPCM) describes the flow pathways and potential exposure routes for honeybees and other bee pollinators in sufficient detail to support quantitative exposure modelling and risk assessment and shows the importance of measuring the distribution of pesticide residues in the areas that lead to exposure and in the hive.
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213 citations
TL;DR: It is submitted that 2 key processes underlie honey bee pesticide exposure: 1) the acquisition of pesticide by foraging bees, and 2) the in‐hive distribution of pesticide returned by foragers.
Abstract: The role of pesticides in recent honey bee losses is controversial, partly because field studies often fail to detect effects predicted by laboratory studies. This dissonance highlights a critical gap in the field of honey bee toxicology: there exists little mechanistic understanding of the patterns and processes of exposure that link honey bees to pesticides in their environment. The authors submit that 2 key processes underlie honey bee pesticide exposure: 1) the acquisition of pesticide by foraging bees, and 2) the in-hive distribution of pesticide returned by foragers. The acquisition of pesticide by foraging bees must be understood as the spatiotemporal intersection between environmental contamination and honey bee foraging activity. This implies that exposure is distributional, not discrete, and that a subset of foragers may acquire harmful doses of pesticide while the mean colony exposure would appear safe. The in-hive distribution of pesticide is a complex process driven principally by food transfer interactions between colony members, and this process differs importantly between pollen and nectar. High priority should be placed on applying the extensive literature on honey bee biology to the development of more rigorously mechanistic models of honey bee pesticide exposure. In combination with mechanistic effects modeling, mechanistic exposure modeling has the potential to integrate the field of honey bee toxicology, advancing both risk assessment and basic research. Environ Toxicol Chem 2017;36:871-881. © 2016 SETAC.
54 citations
TL;DR: How certain pesticide risks are particularly important under circumstances related to the cavity nesters is highlighted, incorporating the relative importance of environmental contamination due to pesticide chemical behaviors.
Abstract: Abstract Declines of pollinator health and their populations continue to be commercial and ecological concerns. Agricultural practices, such as the use of agrochemicals, are among factors attributed to honey bee (Apis mellifera L. (Hymenoptera: Apidae)) population losses and are also known to have negative effects on populations of managed non-Apis pollinators. Although pesticide registration routinely requires evaluation of impacts on honey bees, studies of this social species may not reveal important pesticide exposure routes where managed, solitary bees are commonly used. Studies of solitary bees offer additional bee models that are practical from the aspect of availability, known rearing protocols, and the ability to assess effects at the individual level without confounding factors associated with colony living. In addition to understanding bees, it is further important to understand how pesticide characteristics determine their environmental whereabouts and persistence. Considering our research expertise in advancing the management of solitary bees for crop pollination, this forum focuses on routes of pesticide exposure experienced by cavity-nesting bees, incorporating the relative importance of environmental contamination due to pesticide chemical behaviors. Exposure routes described are larval ingestion, adult ingestion, contact, and transovarial transmission. Published research reports of effects of several pesticides on solitary bees are reviewed to exemplify each exposure route. We highlight how certain pesticide risks are particularly important under circumstances related to the cavity nesters.
46 citations
Cites background from "Potential routes of exposure as a f..."
...2014, Purdy 2014, USEPA, PMRA, and CDPR 2014, Heard et al....
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TL;DR: It is suggested that the analysis of pesticides in bee bread and in bees from the brood comb is a useful addition to dead bee and suspected crop analysis in poisoning incidents to inform the extent of recent in-hive contamination.
18 citations
TL;DR: In this article , the sub-lethal effects of MEOF-contaminated pollen and queen cell wax on replacement queen development were examined, and the results showed that exposed colonies were largely able to produce replacement queens of similar physiological and reproductive quality as unexposed colonies.
Abstract: Abstract Honey bees are incidentally exposed to pesticides such as the insect growth regulator methoxyfenozide (MEOF) during crop pollination, exposures that extend into the hive via contaminated stored food. We examined the sublethal effects of MEOF-contaminated pollen and queen cell wax on replacement queen development. MEOF-exposed colonies were largely able to produce replacement queens of similar physiological and reproductive quality as unexposed colonies. Newly established queens did not differ in their body mass, ovariole development, or protein and fatty acid contents in their ovaries and fat bodies. MEOF and control queens had similar glandular contents of queen mandibular pheromone (QMP) and queen retinue pheromone (QRP) compounds. However, MEOF queens stored less sperm in their spermathecae than control queens. Given that queen productivity is ultimately limited by sperm availability, MEOF contamination might shorten the functional lifespan of exposed queens.
1 citations
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TL;DR: The results suggest that sublethal exposure of CPF alone but especially when Pristine® is added reduces queen emergence possibly due to compromised immunity in developing queens.
Abstract: The effects of sublethal pesticide exposure on queen emergence and virus titers were examined. Queen rearing colonies were fed pollen with chlorpyrifos (CPF) alone (pollen-1) and with CPF and the fungicide Pristine® (pollen-2). Fewer queens emerged when larvae from open foraging (i.e., outside) colonies were reared in colonies fed pollen-1 or 2 compared with when those larvae were reared in outside colonies. Larvae grafted from and reared in colonies fed pollen-2 had lower rates of queen emergence than pollen-1 or outside colonies. Deformed wing virus (DWV) and black queen cell virus were found in nurse bees from colonies fed pollen-1 or 2 and in outside colonies. The viruses also were detected in queen larvae. However, we did not detect virus in emerged queens grafted from and reared in outside colonies. In contrast, DWV was found in all emerged queens grafted from colonies fed pollen-1 or 2 either reared in outside hives or those fed pollen-1 or 2. The results suggest that sublethal exposure of CPF alone but especially when Pristine® is added reduces queen emergence possibly due to compromised immunity in developing queens.
92 citations
"Potential routes of exposure as a f..." refers background or methods in this paper
...The work of De Grandi Hoffman et al on chlorpyrifos showed that there was a decline in exposure of more than one thousand fold from the primary exposure of adult foragers to chlorpyrifos in almond pollen through the secondary exposure of hive bees and nurse bees to the royal jelly fed to the queen and young larvae.(5) In work with a series of neonicotinoids (Purdy 2014, published herewith), primary exposure concentrations up to 14....
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...A refined version of the Quantitative Pollinator Conceptual Model (QPCM) was developed based on field studies with chlorpyrifos and neonicotinoids which are described elsewhere, (5) (Purdy 2014, ACS Poster San Francisco)....
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TL;DR: The use of CPY in agriculture in North America does not present an unacceptable risk to honeybees, and compliance with the label precautions and good agricultural practice with the product is the norm in North American agriculture.
Abstract: Pollinators are crucial species of almost all natural and artificial terrestrial ecosystems (Garibaldi et al. 2013; NAS 2007). While most of the world’s food supply, including important crops such as cereals, are mainly wind pollinated, more than three-quarters of angiosperms rely on animals for pollination and approximately 75 % of the leading global fruit-, vegetable-, and seed-crops depend at least partially on animal pollination. Most animal pollination is done by insects, particularly bees. In the United States (US) and Canada, the production of crops that require or benefit from pollination by insects is large. It is estimated that the pollination services of the European honey bee, Apis mellifera L. (Aide), are worth over $15 billion annually to US agriculture, and the value of non-Apis pollinators to production of crops is estimated to be over $11 billion. In addition to helping ensure a diverse supply of food for humans, pollination plays a critical role in providing the basis for essential ecosystem productivity and services
44 citations
"Potential routes of exposure as a f..." refers background in this paper
...(3),(4) _ENREF_2 This work presents a more advanced version of the conceptual model for pollinator risk assessment, which includes both exposure inputs, and depurition over time....
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TL;DR: There is an incorrect text in the original publication of the article and the authors would like to correct the error, and the corrected sentence should read as given below.
Abstract: There is an incorrect text in the original publication of the article. The authors would like to correct the error, and the corrected sentence should read as given below. Within the different insecticide classes, the neonicotinoid insecticides, which include imidacloprid, acetamiprid, clothianidin, thiamethoxam, thiacloprid, dinotefuran and nitenpyram, are an important group of neurotoxins specifically acting as agonists of the insect nicotinic acetylcholine receptors (nAChR) (Matsuda et al. Trends Pharmacol Sci 22:573–580, 2001; Elbert et al. Pest Manag Sci 64:1099–1105, 2008).
26 citations
"Potential routes of exposure as a f..." refers background in this paper
...(9-11) According to Bailey and Ball “Viruses have probably always been prime sources of confusion and error in the diagnosis and management of bee diseases”....
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