The dose makes the poison: have “field realistic” rates of exposure of bees to neonicotinoid insecticides been overestimated in laboratory studies?

Carreck, Norman; Ratnieks, Francis L. W.

doi:10.3896/ibra.1.53.5.08

Cited by 129 publications

(128 citation statements)

References 29 publications

(4 reference statements)

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“…Even the highest dose we used (7.20 ng/bee) is within the range of exposures found in agricultural settings and prior studies of the effects of imidacloprid on foragers (Colin et al 2004;Rortais et al 2005;Bonmatin et al 2005;Feltham et al 2014;Stoner and Eitzer 2012;Blacquiere et al 2012;Carreck and Ratnieks 2014;Laycock et al 2014;Fischer et al 2014). Imidacloprid adversely affected two components of foraging in our study: the number of returning bees and the number of foraging trips.…”

Section: Discussionmentioning

confidence: 67%

“…The SLS Model also predicts variation in colony persistence, whether a colony survives or goes extinct because of stress, depends on initial conditions and can explain contrasting results observed in previous studies (Desneux et al 2007;Gill et al 2012;Goulson 2013;Lu et al 2014). Pesticide studies sometimes yield inconsistent results because studies have used different methods (see Cresswell 2011;Carreck and Ratnieks 2014 for reviews). Such inconsistencies, combined with difficulties in understanding responses to multiple stressors, could be why the discovery of the underlying causes of CCD has remained so elusive.…”

Section: Introductionmentioning

confidence: 98%

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Sublethal imidacloprid effects on honey bee flower choices when foraging

et al. 2015

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Neonicotinoids, systemic neuro-active pesticides similar to nicotine, are widely used in agriculture and are being investigated for a role in honey bee colony losses. We examined one neonicotinoid pesticide, imidacloprid, for its effects on the foraging behavior of free-flying honey bees (Apis mellifera anatoliaca) visiting artificial blue and white flowers. Imidacloprid doses, ranging from 1/5 to 1/50 of the reported LD50, were fed to bees orally. The study consisted of three experimental parts performed sequentially without interruption. In Part 1, both flower colors contained a 4 μL 1 M sucrose solution reward. Part 2 offered bees 4 μL of 1.5 M sucrose solution in blue flowers and a 4 μL 0.5 M sucrose solution reward in white flowers. In Part 3 we reversed the sugar solution rewards, while keeping the flower color consistent. Each experiment began 30 min after administration of the pesticide. We recorded the percentage of experimental bees that returned to forage after treatment. We also recorded the visitation rate, number of flowers visited, and floral reward choices of the bees that foraged after treatment. The forager return rate declined linearly with increasing imidacloprid dose. The number of foraging trips by returning bees was also affected adversely. However, flower fidelity was not affected by imidacloprid dose. Foragers visited both blue and white flowers extensively in Part 1, and showed greater fidelity for the flower color offering the higher sugar solution reward in Parts 2 and 3. Although larger samples sizes are needed, our study suggests that imidacloprid may not affect the ability to select the higher nectar reward when rewards were reversed. We observed acute, mild effects on foraging by honey bees, so mild that storage of imidacloprid tainted-honey is very plausible and likely to be found in honey bee colonies.

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Section: Discussionmentioning

confidence: 67%

Section: Introductionmentioning

confidence: 98%

Sublethal imidacloprid effects on honey bee flower choices when foraging

et al. 2015

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“…There is a real potential for bumblebees to be exposed to widespread neonicotinoid pesticides under field conditions at the doses used, with concentrations in nectar and pollen measured in flowers and in storage within honeybee and bumblebee colonies around these levels or higher (Krupke et al, 2012;Stoner & Eitzer, 2012;Sanchez-Bayo & Goka, 2014;David et al, 2016). Although some authors have argued that neonicotinoid exposures will occur in very short pulses (Carreck & Ratnieks, 2014), studies of field levels suggest that bees may be chronically exposed throughout their lives (Sanchez-Bayo & Goka, 2014), with exposure being a season-long threat (Long & Krupke, 2016). Queen bumblebees developing within colonies in agricultural areas are likely to be minimally exposed for periods consistent with the exposure in this study due to late-season seed-dressing applications leading to drift of neonicotinoids (David et al, 2016), systemic neonicotinoids in certain late-flowering crop plants (e.g.…”

Section: Discussionmentioning

confidence: 99%

Neonicotinoids override a parasite exposure impact on hibernation success of a key bumblebee pollinator

Fauser

Sandrock

Neumann

et al. 2017

Ecological Entomology

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Abstract. 1. Seasonal adaptations enabling the bridging of periodic challenging abiotic conditions are taxonomically widespread. However, sensitivity to other environmental stresses can be heightened during these periods.2. Several temperate insects with over-wintering strategies play key ecosystem and economic roles, including wild bee pollinators. For example, hibernation survival in temperate bumblebees is crucial, as only new queens of future social colonies over-winter. These bees are also faced with other abiotic and biotic stressors, some of which have been linked to recent pollinator declines, such as exposure to pesticides and parasites.3. Using a fully crossed experiment, the influence of dietary exposure to neonicotinoid insecticides (thiamethoxam and clothianidin) and/or the prevalent bumblebee parasite Crithidia bombi on hibernation survival and hibernation weight change of Bombus terrestris bumblebee queens was investigated.4. Both neonicotinoid and C. bombi exposures reduced hibernation success individually, but no additive or synergistic effects between the stressors were found. Further, effects were asynchronous, with early neonicotinoid effects on hibernation mortality overriding later parasite effects under combined exposures. Neonicotinoid exposure also increased hibernation weight loss of surviving queens.5. Diapause periods, employed by numerous temperate organisms, are likely to be especially vulnerable to environmental stresses, besides the seasonal challenge for which these periods are an adaptation. Thus, diapause requires inclusion during the consideration of the impacts of such stresses. Accordingly, it is demonstrated here that naturally relevant exposures of pesticides and parasites have important detrimental effects on bumblebees during a critical hibernation period, with potential consequences for populations of these key wild pollinators.

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“…Most recent key studies investigating colony-level effects in social bees were done under laboratory or semi-field conditions. One challenge in these studies is to choose doses that are relevant to field exposure, including the concentration, duration of exposure, and choice (reviewed in Carreck and Ratnieks, 2014). For example, Henry et al (2012) administered 1.34 ng of thiamethoxam in a single feeding to individual honey bees -an amount that a bee would consume during a whole week of foraging (Carreck and Ratnieks, 2014).…”

Section: Introductionmentioning

confidence: 99%