Comparative Sublethal Toxicity of Nine Pesticides on Olfactory Learning Performances of the Honeybee Apis mellifera

Université Bordeaux 1, Talence, Aquitaine, France
Archives of Environmental Contamination and Toxicology (Impact Factor: 1.9). 03/2005; 48(2):242-50. DOI: 10.1007/s00244-003-0262-7
Source: PubMed


Using a conditioned proboscis extension response (PER) assay, honeybees (Apis mellifera L.) can be trained to associate an odor stimulus with a sucrose reward. Previous studies have shown that observations of conditioned PER were of interest for assessing the behavioral effects of pesticides on the honeybee. In the present study, the effects of sublethal concentrations of nine pesticides on learning performances of worker bees subjected to the PER assay were estimated and compared. Pesticides were tested at three concentrations. The highest concentration of each pesticide corresponded to the median lethal dose value (48-h oral LD50), received per bee and per day, divided by 20. Reduced learning performances were observed for bees surviving treatment with fipronil, deltamethrin, endosulfan, and prochloraz. A lack of behavioral effects after treatment with lambda-cyalothrin, cypermethrin, tau-fluvalinate, triazamate, and dimethoate was recorded. No-observed-effect concentrations (NOECs) for the conditioned PER were derived for the studied pesticides. Our study shows that the PER assay can be used for estimating sublethal effects of pesticides on bees. Furthermore, comparisons of sensitivity as well as the estimation of NOECs, useful for regulatory purposes, are possible.

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    • "Neonicotinoids act on the insect nervous system through agonistic actions on nicotinic acetylcholine receptors (Tan et al., 2007). For European honeybees, the LD50 for oral administration of thiamethoxam over 48 h is 5 ng, and LD50 for contact administration over 24 h is 29 ng (Decourtye et al., 2005). Furthermore, the LD50 of thiamethoxam for newly emerged AHBs is 4.28 ng bee À1 (Oliveira et al., 2014). "
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    ABSTRACT: Multiple stressors, such as chemicals and pathogens, are likely to be detrimental for the health and lifespan of Apis mellifera, a bee species frequently exposed to both factors in the field and inside hives. The main objective of the present study was to evaluate comparatively the health of Carniolan and Africanized honey bees (AHB) co-exposed to thiamethoxam and Nosema ceranae (N. ceranae) spores. Newly-emerged worker honey bees were exposed solely with different sublethal doses of thiamethoxam (2% and 0.2% of LD50 for AHB), which could be consumed by bees under field conditions. Toxicity tests for the Carniolan bees were performed, and the LD50 of thiamethoxam for Carniolan honey bees was 7.86 ng bee−1. Immunohistological analyses were also performed to detect cell death in the midgut of thiamethoxam and/or N. ceranae treated bees. Thiamethoxam exposure had no negative impact on Nosema development in experimental conditions, but it clearly inhibited cell death in the midgut of thiamethoxam and Nosema-exposed bees, as demonstrated by immunohistochemical data. Indeed, thiamethoxam exposure only had a minor synergistic toxic effect on midgut tissue when applied as a low dose simultaneously with N. ceranae to AHB and Carniolan honey bees, in comparison with the effect caused by both stressors separately. Our data provides insights into the effects of the neonicotenoid thiamethoxam on the AHB and Carniolan honey bee life span, as well as the effects of simultaneous application of thiamethoxam and N. ceranae spores to honey bees.
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    • "The maximum value, detected in honey bees from Barxeta apiary, was 223 ng/g, around 74% of LD50 (detailed information in the supplementary information Table S3). These concentrations are above of those considered sublethal and could be responsible of honey bee losses or even acute intoxication of forager honey bees (Decourtye et al., 2005). However, low levels can produce sublethal effects during long periods without presence of dead honey bees at the entrance of the hive. "
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    ABSTRACT: Samples of dead honey bees (Apis mellifera L.) were collected periodically from 4 different locations during citrus and stone fruit trees blooming season to evaluate the potential impact of agrochemicals on honey bee death rate. For the determination of mortality, dead honey bee traps were placed in front of the experimental hives entrance located in areas of intensive agriculture in Valencian Community (Spain). A total of 34 bee samples, obtained along the monitoring period, were analyzed by means of QuEChERS extraction method and screened for 58 pesticides or their degradation products by LC-MS/MS. An average of four pesticides per honey bee sample was detected. Coumaphos, an organophosphate acaricide used against varroosis in the experimental hives, was detected in 94% of the samples. However, this acaricide was unlikely to be responsible for honey bee mortality because its constantly low concentration during all the monitoring period, even before and after acute mortality episodes. The organophosphates chlorpyrifos and dimethoate, as well as the neonicotinoid imidacloprid, were the most frequently detected agrochemicals. Almost 80% of the samples had chlorpyrifos, 68% dimethoate, and 32% imidacloprid. Maximum concentrations for these three compounds were 751, 403, 223ng/g respectively. Influence of these pesticides on acute honey bee mortality was demonstrated by comparing coincidence between death rate and concentrations of chlorpyrifos, dimethoate and imidacloprid.
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    • ") versus other neonicotinoids, and can act synergistically with N. ceranae to kill honey bees in the laboratory (Vidau et al., 2011; Retschnig et al., 2014a). Taufluvalinate has an acute contact toxicity of 0.2 g μg bee −1 , but was reported to have no lethal effect at daily oral doses of 5 or 10 μg bee −1 (Decourtye et al., 2005). "
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    ABSTRACT: Interactions between pesticides and parasites are believed to be responsible for increased mortality of honey bee (Apis mellifera) colonies in the northern hemisphere. Previous efforts have employed experimental approaches using small groups under laboratory conditions to investigate influence of these stressors on honey bee physiology and behaviour, although both the colony level and field conditions play a key role for eusocial honeybees. Here, we challenged honey bee workers under in vivo colony conditions with sub-lethal doses of the neonicotinoid thiacloprid, the miticide tau-fluvalinate, and the endoparasite Nosema ceranae, to investigate potential effects on longevity and behaviour using observation hives. In contrast to previous laboratory studies our results do not suggest interactions among stressors, but rather lone effects of pesticides and the parasite on mortality and behaviour, respectively. These effects appear to be weak due to different outcomes at the two study sites, thereby suggesting that the role of thiacloprid, tau-fluvalinate, and N. ceranae and interactions among them may have been overemphasized. In the future, investigations into the effects of honey bee stressors should prioritize the use of colonies maintained under a variety of environmental conditions in order to obtain more biologically relevant data. This article is protected by copyright. All rights reserved.
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