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Chronic toxicity and physiological changes induced in the honey bee by the exposure to fipronil and Bacillus thuringiensis spores alone or combined
... TAS, which stands for total antioxidant status, is a crucial indicator of the nutritional status of honey bees, similar to glucose, TP, and TG levels [32,36]. These markers were specifically chosen because the honey bee hemolymph contains significant enzymes originating from the fat body, which include aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, and gamma-glutamyl transpeptidase [37]. These ...
... TAS, which stands for total antioxidant status, is a crucial indicator of the nutritional status of honey bees, similar to glucose, TP, and TG levels [32,36]. These markers were specifically chosen because the honey bee hemolymph contains significant enzymes originating from the fat body, which include aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, and gamma-glutamyl transpeptidase [37]. These enzymes are synthesized in the fat body and released into the hemolymph. ...
Honey bees use pollen and nectar from flowers to produce food. Because they often forage on crops, they are at risk of being exposed to plant protection products (PPPs), both directly and in stored food. Due to the adverse effects of synthetic PPPs on pollinators, biopesticides may be a viable alternative. Common tansy extract is used as one of the natural substitutes for synthetic pesticides. In our study, the effect of fermented common tansy extract on aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), and gamma-glutamyl transpeptidase (GGTP) activity and the concentration of triglycerides (TGs), total protein (TP), total antioxidant status (TAS), and glucose in honey bee workers’ hemolymph was assessed. These biochemical markers give valuable information about the immunity, detoxification, and nutrition of a bee’s body. Caged bees were given tansy extract added at various concentrations in sugar syrup for 24 h. Then, they were provided with only sugar syrup. After 7 days of the experiment, hemolymph was collected and analyzed. We observed changes in the activity of AST, ALT, GGTP enzymes and TG, TP, and glucose levels, but not all changes were statistically significant. In terms of AST activity, statistically significant differences were found. All groups tested, including the negative control group, showed reduced enzyme activity values compared to the positive control group. In TG concentration, differences were observed between the groups receiving 2% extract and 1% ethanol. Glucose levels differed between the groups receiving 1% extract and 2% extract and between the positive control group and 1% extract. Bee body proper functioning is affected by changes in enzyme activity, especially those responsible for immunity and detoxification, such as AST, ALT, ALP, and GGTP. Despite the short time of bees’ exposure to the agent, the results of study show visible effects. Our results provide a basis for further research on the impact of tansy extract on honey bees.
... While the impact of environmental pollution on human health is well studied, mechanistic impacts of air pollution on wild systems, including those providing essential ecosystem services, are largely unknown, but directly impact our health and wellbeing. (Renzi, 2016;Abbo, 2017;Berg, 2018;Rabea, 2010). In this review we present findings from various studies that have investigated honey bees and environmental pollutants. ...
... Most of the actual field papers were monitoring studies where accumulation of various contaminants in Apismellifera were investigated; Research papers analysed the sublethal effects of the contaminant mixtures on honeybees. (Williamson, 2013;Renzi, 2016;Prado, 2019;Dabour and Al Naggar, 2020;Schmuck, 2003Almasri, 2020Badiou, 2012). ...
Every year, every living species faces a fresh set of problems. Environmental pollution in the form of smog is currently a major problem. Air pollution is likely to be one component of a larger issue. Because it may impact human health in so many ways, it’s only natural that it affects other animals as well. Air borne pollutants affect all types of life, even insects. The presence of pesticides in the beekeeping environment is generally recognized to be one of the most important concerns that affects the honeybee’s existence. Now, environmental pollution in the form of ‘smog’ can be added to the list of stressors. Polluted environment has negative consequences not just for humans, but also for honeybees, who survive significantly less in such contaminated air and live a handicapped existence in which they are unable to visit the flowers as frequently as they would if the air were cleaner. Furthermore, heavy metal concentration factors for honey appear to be greater in polluted areas than in unpolluted areas. These metals presence in plant flowers is linked to their presence in associated honey and by-products. In our environment, bees play a crucial role as pollinators. Pollution is hurting the health of pollinating insects, which means ecosystems are also being impacted. There are some gaps in our knowledge about environmental pollution and honeybee keeping sector in India
... Although studies of acute toxicity performed under laboratory conditions may overlook sublethal effects that could potentially affect honey bees in the field, the results of this meta-analysis support the conclusion that the Cry proteins, often expressed in genetically modified crops (Mendelsohn et al., 2003), are unlikely to have negative direct effects on the survival of honey bees. Nevertheless, several studies on bacterial biopesticides showed a reduced survival of exposed bees (Vandenberg, 1990;Malone et al., 1999;Bailey et al., 2005;Hassona and Kordy, 2015;Renzi et al., 2016;Potrich et al., 2018) (Fig. 2; Table S2). Moreover, Bt-derived Cry-proteins induce hypoactivity, enzymatic and morphostructural alterations in the midgut of workers and reduce their foraging activity, feeding behavior and learning performance (Ramirez-Romero et al., 2005;Ramirez-Romero et al., 2008;Renzi et al., 2016;D'urso et al., 2017). ...
... Nevertheless, several studies on bacterial biopesticides showed a reduced survival of exposed bees (Vandenberg, 1990;Malone et al., 1999;Bailey et al., 2005;Hassona and Kordy, 2015;Renzi et al., 2016;Potrich et al., 2018) (Fig. 2; Table S2). Moreover, Bt-derived Cry-proteins induce hypoactivity, enzymatic and morphostructural alterations in the midgut of workers and reduce their foraging activity, feeding behavior and learning performance (Ramirez-Romero et al., 2005;Ramirez-Romero et al., 2008;Renzi et al., 2016;D'urso et al., 2017). Recent studies have also highlighted that Bt can alter the gut microbiome of honey bees (Steinigeweg et al., 2022) while another bacterial biopesticide, Bacillus amyloliquefaciens, reduces the expression of genes linked to immunity in adult bees (Sabo et al., 2020). ...
As synthetic pesticides play a major role in pollinator decline worldwide, biopesticides have been gaining increased attention to develop more sustainable methods for pest management in agriculture. These biocontrol agents are usually considered as safe for non-target species, such as pollinators. Unfortunately, when it comes to non-target insects, only the acute or chronic effects on survival following exposure to biopesticides are tested. Although international boards have highlighted the need to include also behavioral and morphophysiological traits when assessing risks of plant protection products on pollinators, no substantial concerns have been raised about the risks associated with sublethal exposure to these substances. Here, we provide a comprehensive review of the studies investigating the potential adverse effects of biopesticides on different taxa of pollinators (bees, butterflies, moths, beetles, flies, and wasps). We highlight the fragmentary knowledge on this topic and the lack of a systematic investigation of these negative effects of biopesticides on insect pollinators. However, we have found that all the major classes of biopesticides, besides their direct toxicity, can also cause a plethora of more subtle detrimental effects in both solitary and social species of pollinators. Although research in this field is growing, the current risk assesment approach does not suffice to properly assess all the potential side-effects that these agents of control could have on pollinating insects. Given the urgent need for a sustainable agriculture and wildlife protection, it appears compelling that these so far neglected detrimental effects should be thoroughly assessed before allegedly safe biopesticides can be used in the field and, in this view, we provide a perspective for future directions.
... G6PDH yields NADPH, which is essential for cytochrome P450 (CYP 450) catalysis 85 . NADPH is also involved in the anti-oxidative defenses through the regeneration of GSH from its oxidized form 86 . LDH is involved in the energy metabolism in insects, precisely in the glycolytic pathway. ...
... G6PDH activity was determined by following the formation of the reduced form of nicotinamide adenine dinucleotide phosphate (NADPH) at 340 nm. The reaction medium contained 10 mM magnesium chloride (MgCl 2 ), 0.5 mM nicotinamide adenine dinucleotide phosphate (NADP + ), 1 mM glucose-6-phosphate (G6P) and 100 mM Tris-HCl pH 7.4 86 . ALP was determined by following the formation of p-nitrophenol at 410 nm. ...
Recent studies highlighted that exposure to glyphosate can affect specific members of the core gut microbiota of honey bee workers. However, in this study, bees were exposed to relatively high glyphosate concentrations. Here, we chronically exposed newly emerged honey bees to imidacloprid, glyphosate and difenoconazole, individually and in a ternary mixture, at an environmental concentration of 0.1 µg/L. We studied the effects of these exposures on the establishment of the gut microbiota, the physiological status, the longevity, and food consumption of the host. The core bacterial species were not affected by the exposure to the three pesticides. Negative effects were observed but they were restricted to few transient non-core bacterial species. However, in the absence of the core microbiota, the pesticides induced physiological disruption by directly altering the detoxification system, the antioxidant defenses, and the metabolism of the host. Our study indicates that even mild exposure to pesticides can directly alter the physiological homeostasis of newly emerged honey bees and particularly if the individuals exhibit a dysbiosis (i.e. mostly lack the core microbiota). This highlights the importance of an early establishment of a healthy gut bacterial community to strengthen the natural defenses of the honey bee against xenobiotic stressors.
... To assess the effect of the pesticides on oxidative stress, the activities of SOD, CAT, GPox, GR, GST and G6PDH were measured in surviving honey bees after 16 days of chronic oral exposure to pesticides. These enzymes work to limit oxidative stress, and they were previously shown to be modulated in honey bees under the pressure of chemical pesticides, spores of the biological pesticide Bacillus thuringiensis and environmental biotic stressors such as Nosema [53,90,[103][104][105][106]. SOD, CAT and GPox are primary antioxidant enzymes that act directly on ROS. ...
... GR converts oxidized glutathione into its reduced form GSH [89]. G6PDH acts in the pentose phosphate pathway and generates NADPH, leading indirectly to the regeneration of reduced GSH [106]. GST, which could be considered a primary antioxidant enzyme, also plays a role in the detoxification process controlled by phase II enzymes. ...
To explain losses of bees that could occur after the winter season, we studied the effects of the insecticide imidacloprid, the herbicide glyphosate and the fungicide difenoconazole, alone and in binary and ternary mixtures, on winter honey bees orally exposed to food containing these pesticides at concentrations of 0, 0.01, 0.1, 1 and 10 µg/L. Attention was focused on bee survival, food consumption and oxidative stress. The effects on oxidative stress were assessed by determining the activity of enzymes involved in antioxidant defenses (superoxide dismutase, catalase, glutathione-S-transferase, glutathione reductase, glutathione peroxidase and glucose-6-phosphate dehydrogenase) in the head, abdomen and midgut; oxidative damage reflected by both lipid peroxidation and protein carbonylation was also evaluated. In general, no significant effect on food consumption was observed. Pesticide mixtures were more toxic than individual substances, and the highest mortalities were induced at intermediate doses of 0.1 and 1 µg/L. The toxicity was not always linked to the exposure level and the number of substances in the mixtures. Mixtures did not systematically induce synergistic effects, as antagonism, subadditivity and additivity were also observed. The tested pesticides, alone and in mixtures, triggered important, systemic oxidative stress that could largely explain pesticide toxicity to honey bees.
... The physiological markers were assessed in tissues in which they are relevant and where their biological activity is particularly high. AChE, GOx and COx were assessed in the head Armengaud et al., 2000;Belzunces et al., 1988); CAT and ALP in the midgut (Badiou-Beneteau et al., 2012;Carvalho et al., 2013); POx and G6PDH in the abdomen Renzi et al., 2016); and GST in the head, abdomen and midgut (Almasri et al., 2020) (Table 1). ...
... POx was measured by following the transformation of L-DOPA into melanin at 490 nm in medium containing the abdominal extract, 0.4 mg/mL L-DOPA, 20 mM NaCl and 10 mM monosodium phosphate, pH 7.2 (Kairo et al., 2017). G6PDH was measured by following the formation of NADPH at 340 nm in medium containing the abdominal extracts, 1 mM G6P, 0.5 mM NADP + , 10 mM MgCl 2 and 100 mM Tris-HCl, pH 7.4 (Renzi et al., 2016). ALP was measured at 410 nm by following the formation of p-nitrophenol in medium containing the midgut extract, 20 µM MgCl 2 , 2 mM p-NPP and 100 mM Tris-HCl, pH 8.5 (Badiou-Bénéteau et al., 2012). ...
Pathogens and pollutants, such as pesticides, are potential stressors to all living organisms, including honey bees. Herbicides and fungicides are among the most prevalent pesticides in beehive matrices, and their interaction with Nosema ceranae is not well understood. In this study, the interactions between N. ceranae, the herbicide glyphosate and the fungicide difenoconazole were studied under combined sequential and overlapping exposure to the pesticides at a concentration of 0.1 µg/L in food. In the sequential exposure experiment, newly emerged bees were exposed to the herbicide from day 3 to day 13 after emerging and to the fungicide from day 13 to day 23. In the overlapping exposure experiment, bees were exposed to the herbicide from day 3 to day 13 and to the fungicide from day 7 to day 17. Infection by Nosema in early adult life stages (a few hours post emergence) greatly affected the survival of honey bees and elicited much higher mortality than was induced by pesticides either alone or in combination. Overlapping exposure to both pesticides induced higher mortality than was caused by sequential or individual exposure. Overlapping, but not sequential, exposure to pesticides synergistically increased the adverse effect of N. ceranae on honey bee longevity. The combination of Nosema and pesticides had a strong impact on physiological markers of the nervous system, detoxification, antioxidant defenses and social immunity of honey bees.
... In this reaction, 3phosphoglyceric acid (3-PGA) is converted into 1,3-BPG by phosphoglycerate kinase (PGK), and 1.3-BPG is converted into glyceraldehyde-3-phosphate (GA3P) by GA3PDH in the presence of reduced nicotinamide adenine dinucleotide (NADH), whose transformation into its oxidized form (NAD + ) is followed at 340 nm. The reaction medium contained 7 mM 3-PGA, 120 μM NADH, 2 mM magnesium sulfate (MgSO 4 ), 1.2 mM ATP, 4 mM L-cysteine-HCl neutralized with sodium bicarbonate (NaHCO 3 ), 1 mM ethylenediaminetetraacetic acid (EDTA), 5 units·mL − 1 3p h o s p h o g l yc e r a t e k i n a s e ( 3 -P G K ) , a n d 8 0 m M triethanolamine buffer, pH 7.6 (Kairo et al. 2017;Renzi et al. 2016). CaE-2 and CaE-3 were monitored according to their specific respective substrates β-naphthyl acetate (β-NA) and p-nitrophenyl acetate (p-NPA) at 515 and 410 nm, respectively (Badiou-Beneteau et al. 2012). ...
... G6PDH activity was determined by following the formation of the reduced form of NADP + (NADPH) at 340 nm. The reaction medium contained 10 mM magnesium chloride (MgCl 2 ), 0.5 mM nicotinamide adenine dinucleotide phosphate (NADP + ), 1 mM glucose-6-phosphate (G6P), and 100 mM Tris-HCl pH 7.4 (Renzi et al. 2016). LDH activity was determined by measuring the regeneration of NAD + at 340 nm. ...
During all their life stages, bees are exposed to residual concentrations of pesticides, such as insecticides, herbicides, and fungicides, stored in beehive matrices. Fungicides are authorized for use during crop blooms because of their low acute toxicity to honey bees. Thus, a bee that might have been previously exposed to pesticides through contaminated food may be subjected to fungicide spraying when it initiates its first flight outside the hive. In this study, we assessed the effects of acute exposure to the fungicide in bees with different toxicological statuses. Three days after emergence, bees were subjected to chronic exposure to the insecticide imidacloprid and the herbicide glyphosate, either individually or in a binary mixture, at environmental concentrations of 0.01 and 0.1 μg/L in food (0.0083 and 0.083 μg/kg) for 30 days. Seven days after the beginning of chronic exposure to the pesticides (10 days after emergence), the bees were subjected to spraying with the fungicide difenoconazole at the registered field dosage. The results showed a delayed significant decrease in survival when honey bees were treated with the fungicide. Fungicide toxicity increased when honey bees were chronically exposed to glyphosate at the lowest concentration, decreased when they were exposed to imidacloprid, and did not significantly change when they were exposed to the binary mixture regardless of the concentration. Bees exposed to all of these pesticide combinations showed physiological disruptions, revealed by the modulation of several life history traits related mainly to metabolism, even when no effect of the other pesticides on fungicide toxicity was observed. These results show that the toxicity of active substances may be misestimated in the pesticide registration procedure, especially for fungicides.
... This indicates that the stress exerted by insecticides in the exposed insects was enough to decrease GST activity. A reducing effect on GST activity of honey bees with exposure to fipronil and Bacillus thuringiensis (Bt) was reported, but the combination of Bt spores and fipronil did not induce lethality in the honey bee (Renzi et al., 2016). Although no differences in CAT activity were observed in the two honey bee species, a slight increase in CAT activity suggests the initiation of oxidative stress caused in honey bees due to insecticide exposure. ...
... The results of the present study showed that the honey bees tested are good bioindicators for demonstrating physiological reactions to either a specific insecticide or a mixture of insecticides. In all cases, these reactions proved that various insecticides can show systemic physiological effects, even without exerting significant fatal effect, as also reported elsewhere (Renzi et al., 2016). Moreover, the investigated enzymes correspond to long-lasting physiological variations induced by many insecticides, since physiological stresses are still used to evaluate the insecticide exposure in target and nontarget organisms. ...
Insecticide exposure can affect honey bees in agro-ecosystems, posing behavioral stresses that can lead to population decline. In this study, insecticide incidence, DNA damage, and antioxidant enzyme activity were studied in
Apis florea and A. dorsata honey bee samples collected from insecticide-treated and insecticide-free areas of Punjab, Pakistan. Seven insecticides: chlorpyrifos, dimethoate, imidacloprid, phorate, emamectin, chlorfenapyr, and
acetamiprid were detected in seven samples of A. florea and five samples of A. dorsata. In total, 12 samples (22.2%)
of honey bees were found positive to insecticide presence out of 54 samples. The most frequently detected insecticide was chlorpyrifos, which was found in four samples (7.4%), with a concentration ranging from 0.01 to 0.05
μg/g and an average concentration 0.03 μg/g. The comet assay or single cell gel electrophoresis assay, a simple
way to measure DNA strand breaks in eukaryotic cells, was used to microscopically find damage of DNA at the
level of a single cell. Comet tail lengths of DNA in A. florea and A. dorsata samples from insecticide-treated
areas were significantly higher (P b 0.05) than samples from insecticide-free areas. The highest comet tail length (19.28 ± 2.67 μm) was observed in DNA of A. dorsata from insecticide-treated areas, while the minimum one
(3.18 ± 1.46 μm) was noted in A. dorsata from insecticide-free areas. Catalase (CAT) activity did not vary significantly between honey bee samples from insecticide-treated and insecticide-free areas, while glutathione Stransferase (GST) activity showed a significant reduction in response to insecticide exposure. Significant positive
correlations were detected between enzyme activity and insecticide concentration in honey bee species from
insecticide-treated areas compared with control groups. Toxicity from pesticide exposure at sub-lethal levels
after application or from exposure to pesticide residues should not be underestimated in honey bees, as it may
induce physiological impairment that can decline honey bees' health.
... Simone-Finstrom et al. (2016) indicate that fungi affect bee foraging, development, and pathogen interactions, however, there is evidence that some fungi can be bees symbiotics, but knowledge about this phenomenon is still scarce (Rutkowski et al., 2023). While low quality and shortage of pollen have been raised as hypotheses for fungal spore collection, the nutritional value of fungal spores for honey bees is poorly understood (Renzi et al., 2016b). Fungal spores are also considered as sources of many lipids important in honey bee survival (Bushnell, 1972). ...
Honey bee workers ( Apis mellifera L.) collect nectar, honeydew and pollen from plants in orderto provide the colony with, among others, carbohydrates and protein. Whenever these sources are unavailable in the environment, bees turn to alternatives. An example of this are fungi spores collected accidentally or on purpose. This last phenomenon is the aim of this study, in which we have shown that worker bees can collect willow rust ( Melampsora spp.) spores. We observed as the bees obtained spores and placed them in pollen baskets. The presence of spores was demonstrated with the use of a scanning electron microscope (SEM). This observation indicates that the honey bee may use alternative sources as a potential supplement. There are few studies in this field and it requires a deeper analysis.
... Further research to assess whether changes in the diversity and composition of non-target insect assemblages are a long-term phenomenon, or whether resilience may occur over time, is needed. Although the short-term effect of Foray 76B on non-target organisms might be negligible, the impact of frequent repeated applications of biological agents on most ecosystems is not well known [32,34,93]. It is probable that any regular disruption of insect assemblages, due to chemical or microbial insecticides or natural factors, could have long-term deleterious effects on ecosystem structure [94]. ...
Outbreaks of Lymantria monacha are of great concern, as their occurrence is predicted to become more intense and frequent due to a warming climate. A frequent treatment to control mass outbreaks of the pest is with the bioinsecticide Foray 76B. However, knowledge of how this treatment affects non-target insect species is limited. We surveyed the assemblages of non-target epigeal and arboreal insects in Pinus sylvestris forests in the year following bioinsecticide application. A collection of insects using sweep nets and pitfall traps was carried out in L. monacha-infested pine stands, (i) treated with Foray 76B and (ii) untreated, in three regions of Lithuania from May to October 2021. The results revealed that, in Neringa forests, species richness of the epigeal insects was lower in treated than in untreated sampling plots, with 36 and 41 different insect species, respectively. The relative abundance of epigeal Coleoptera in treated plots was 3.6%, while in untreated it was 53.2%. There was a significant decrease in the relative abundance of Carabus arcencis in Kapčiamiestis (by 7.4%) and Marcinkonys (by 16.7%). Treated plots were distinguished by lower relative abundance of arboreal Hymenoptera at all three study locations.
... It is reported that winter bees have different physiology, e.g., a higher titer of yolk protein Vitellogenin, an enlarged fat body, and a higher number of hemocytes, which may lead to different sensitivity to infections by various microorganisms (Aurori et al. 2014;Remolina and Hughes 2008). While most studies analyzing microbial pesticides' effects on honey bees work with summer bees (e.g., Malone et al. 1999;Renzi et al. 2016;Steinigeweg et al. 2021), the effects on winter bees are less investigated. To this end, the objective of the present study is to evaluate the effects of exposure to a tank mixture of several microbial biopesticides on long-living winter honey bees under laboratory conditions. ...
Biopesticides, having as active ingredients viruses, bacteria, or fungi, are developed to substitute or reduce the use of chemical plant protection products in different agrosystems. Though the application of mixtures containing several products is a common practice, interactions between microbial biopesticides and related effects on bees as non-target organisms have not been studied yet. In the current study, we exposed winter bees to five different microbial-based products and their combinations at the maximum recommended application rate to assess their responses. Laboratory oral exposure tests (acute/chronic) to single or binary products were conducted. Survival and food consumption of the tested bees were evaluated over the experimental duration. Our results show that some product combinations have potential additive or synergistic effects on bees, whereas others did not affect the bee’s survival compared to the control. Exposure of tested bees to the most critical combination of products containing Bacillus thuringiensis aizawai ABTS-1857 and B. amyloliquefaciens QST 713 strongly resulted in a median lifespan of 4.5 days compared to 8.0 and 8.5 days after exposure to the solo products, respectively. The exposure to inactivated microorganisms by autoclaving them did not differ from their respective uncontaminated negative controls, indicating effects on bee mortality might originate in the treatment with the different microorganisms or their metabolites. Further investigations should be conducted under field conditions to prove the magnitude of observed effects on bee colonies and other bee species.
... Increased larval mortality and delayed development have also been observed in many Drosophila species following ingestion of food contaminated with Bt products (Babin et al. 2020). Finally, Bt bioinsecticides are thought to cause gut disturbances in bees (Renzi et al. 2016) and behavioural changes in Trichogramma, a small endoparasitic wasp also used in biological control . ...
Plants host a wide range of viruses and microorganisms collectively referred to as the plant microbiota. This chapter outlines the state of knowledge on the diversity of these communities of microorganisms within different plant compartments, including the rhizosphere and the phyllosphere. The ecological processes (selection, diversification, dispersal and ecological drift) involved in the assembly of the plant microbiota are also briefly introduced. Finally in the last section of this chapter, the associations between plant traits and microbiota structure are highlighted with a specific emphasis on plant adaptation to biotic stresses.
... Increased larval mortality and delayed development have also been observed in many Drosophila species following ingestion of food contaminated with Bt products (Babin et al. 2020). Finally, Bt bioinsecticides are thought to cause gut disturbances in bees (Renzi et al. 2016) and behavioural changes in Trichogramma, a small endoparasitic wasp also used in biological control . ...
Bacillus thuringiensis (Bt) is the most used bacterium worldwide in agriculture and forestry to fight lepidopteran and coleopteran pests. It is also employed in vector control against mosquitoes. Bt belongs to the group of the well-known opportunistic bacteria Bacillus cereus, which are involved both in foodborne outbreaks (B. cereus is the second leading cause of such outbreaks in France and the third in Europe) and sporadically in nosocomial diseases or sepsis. Because of the strong resemblance between the two species, the involvement of Bt in B. cereus-related illnesses is likely underestimated, as highlighted by the French and the European Food Safety Agencies (ANSES and EFSA). Because Bt is a sporulating bacterium, which renders it persistent in the environment, the hypothesis of an agricultural origin of Bt strains isolated from food is raised. Moreover, wildlife could also be affected by the use of Bt. Accordingly, in this chapter, we review what is known about the possible unintended effects of Bt bioinsecticides, and we provide ways to explore to prevent risks and improve their uses.
... Increased larval mortality and delayed development have also been observed in many Drosophila species following ingestion of food contaminated with Bt products (Babin et al. 2020). Finally, Bt bioinsecticides are thought to cause gut disturbances in bees (Renzi et al. 2016) and behavioural changes in Trichogramma, a small endoparasitic wasp also used in biological control . ...
This chapter summarizes the state of the art and some key research and innovation perspectives with regard to three topics that are particularly important for biocontrol deployment. The first topic is the use of seeds as targets and/or vectors of biocontrol organisms or substances, enabling seed or plant protection through direct antagonism towards pathogens, plant defence stimulation and manipulation of the seed or plant microbiota. The second topic is formulation of biocontrol organisms and substances, a key activity with high importance to enhance performance of biocontrol products and compatibility with agricultural equipment. The third topic deals with digital tools and agricultural equipment to facilitate the use of biocontrol methods in the field: new equipment tailored for field release of organisms, devices for diagnosing the state of plant, pest or biocontrol agent monitoring, tools for optimizing the positioning and parsimonious use of biocontrol methods, etc.
... Une mortalité larvaire accrue et un retard de développement ont également été observés chez de nombreuses espèces de drosophile, suite à l'ingestion de nourriture contaminée par des produits Bt (Babin et al., 2019). Enfin, les bioinsecticides Bt seraient à l'origine de perturbations intestinales chez l'abeille (Renzi et al., 2016) et de changements comportementaux chez le trichogramme (petit hyménoptère parasitoïde également employé en lutte biologique) . ...
While biological control has been very successful on high-value crops and in closed environments, its application in arable crops in large fields remains very limited and the substitution of pesticides with biocontrol products remains limited and marginally effective. For this reason, it seems necessary to develop biological control strategies that consider the interactions between agricultural practices, cover crops, pests and beneficial organisms within the agroecosystem. This systemic approach to biocontrol therefore raises questions about the redesign and evaluation of cropping systems. This is why we begin this chapter with an overview of methods for redesigning low-pesticide cropping systems. The second part of this chapter will use different examples to illustrate the interactions within the agricultural system and the need for a systemic approach to make the selected solutions more efficient. For example, we will show how agricultural practices such as tillage, crop succession, and crop association play a role in attacks by pests, colonization by natural enemies, and organism survival. This chapter ends with the challenges posed by the inclusion of biocontrol in terms of cropping system evaluation, regulations and public policies.
... kurstaki harbouring Cry-proteins (4D1-Cry + ) or not (4Q7-Cry -). Missing the plasmid coding the Cry genes, not only affected mortality of honey bees consuming this strain, but it also showed to have comparable and opposing effects on enzyme activity (e.g., alkaline phosphatase, glucose-6-phosphatedehy-drogenase, glutathione-Stransferase activity and glyceraldeyde-3-phosphatedehydrogenase) (Renzi et al., 2016). ...
Pollinating bees are stressed by highly variable environmental conditions, malnutrition, parasites and pathogens, but may also by getting in contact with microorganisms or entomopathogenic nematodes that are used to control plant pests and diseases. While foraging for water, food, or nest material social as well as solitary bees have direct contact or even consume the plant protection product with its active substance (e.g., viruses, bacteria, fungi, etc.). Here, we summarize the results of cage, microcolony, observation hive assays, semi-field and field studies using full-size queen-right colonies. By now, some species and subspecies of the Western and Eastern honey bee (Apis mellifera, A. cerana), few species of bumble bees, very few stingless bee species and only a single species of leafcutter bees have been studied as non-target host organisms. Survival and reproduction are the major criteria that have been evaluated. Especially sublethal effects on the bees' physiology, immune response and metabolisms will be targets of future investigations. By studying infectivity and pathogenic mechanisms, individual strains of the microorganism and impact on different bee species are future challenges, especially under field conditions. Overall, it became evident that honey bees, bumble bees and few stingless bee species may not be suitable surrogate species to make general conclusions for biological mechanisms of bee-microorganism interactions of other social bee species. Solitary bees have been studied on leafcutter bees (Megachile rotundata) only, which shows that this huge group of bees (∼20,000 species worldwide) is right at the beginning to get an insight into the interaction of wild pollinators and microbial plant protection organisms.
... Unlike environmental contamination, some pesticides are applied directly to the hives to maintain healthy bees, such as bactericides (Renzi et al. 2016) and acaricides (Serra et al. 2021). In this context, the queen and bee larvae are exposed to pesticides when poisoned bees offer contaminated glandular secretions (Kopit and Pitts-Singer 2018). ...
Climate change mediated by anthropogenic activity induces significant alterations on pest abundance and behavior and a potential increase in the use of agrochemicals for crop protection. Pesticides have been a tool in the control of pests, diseases, and weeds of agricultural systems. However, little attention has been given to their toxic effects on beneficial insect communities that contribute to the maintenance and sustainability of agroecosystems. In addition to pesticide-induced direct mortality, their sublethal effects on arthropod physiology and behavior must be considered for a complete analysis of their impact. This review describes the sublethal effects of pesticides on agriculturally beneficial insects and provides new information about the impacts on the behavior and physiology of these insects. The different types of sublethal effects of pesticides used in agriculture on pollinators, predators, parasitoids, and coprophagous insects were detailed.
... G6PDH activity was determined by continuously following the formation of NADPH at 340 nm. The reaction medium contained 100 mM Tris-HCl buffer at pH 7.4, 10 mM MgCl2, 1 mM G-6-P, 0.5 mM NADP + and 100 mM Tris-HCl pH 7.4 (see Renzi et al., 2016 for more details). ...
Within the context of climate change, winter temperatures at high latitudes are predicted to rise faster than summer temperatures. This phenomenon is expected to negatively affect the diapause performance and survival of insects, since they largely rely on low temperatures to lower their metabolism and preserve energy. However, some insects like honeybees, remain relatively active during the winter and elevate their metabolic rate to produce endothermic heat when temperatures drop. Warming winters are thus expected to improve overwintering performance of honeybees. In order to verify this hypothesis, for two consecutive years, we exposed honeybee colonies to either a mild or cold winter. We then monitored the influence of wintering conditions on several parameters of honeybee overwintering physiology, such as levels of the cryoprotectant glycerol, expression levels of immune and antioxidant genes, and genes encoding multifunctional proteins, including vitellogenin, which promotes bee longevity. Winter conditions had no effect on the expression of antioxidant genes, and genes related to immunity were not consistently affected. However, mild winters were consistently associated with a lower investment in glycerol synthesis and a higher expression of fat body genes, especially apidaecin and vitellogenin. Finally, while we found that viral loads generally decreased through the winter, this trend was more pronounced under mild winter conditions. In conclusion, and without considering how warming temperatures might affect other aspects of honeybee biology before overwintering, our data suggest that warming temperatures will likely benefit honeybee vitality by notably reducing their viral loads over the winter.
... Despite the extensive adoption of Bt as a biopesticide and its high specifity for certain receptors and alkaline pH in the gut of susceptible species, some strains or isolates have occasionally been reported to impact non-target species [32][33][34][35]. Furthermore, aerial spray operations can result in high concentrations or accumulation of Bt spore, and thus can elevate the impact on biodiversity of non-targeted species [33][34][35][36]. ...
Bacillus thuringiensis (Bt) is used as a bioinsecticide since it effectively kills insect larvae. Bt is also genetically similar to Bacillus cereus (Bc), a well recognized foodborne human pathogen; they are both members of the Bacillus cereus group (BC group). Although approved Bt bioinsecticide products have been confirmed to be non-pathogenic to humans, close monitoring of Bt during dissemination is important for cost considerations and to limit impact on biodiversity towards nontarget organisms. As such, developing rapid, sensitive, and specific tools for quantitative detection of Bt spores during and following spray operations is highly desirable. The goals of this study were to investigate commercially available detection reagents for sensitivity and selectivity in detecting Bt spores, and then functionalize a surface of (001) GaAs used in photonic biosensing. To achieve these goals, we (1) screened commercial antibodies for their capacity to bind recombinant proteins from Bt spores, (2) screened antibodies and aptamers for their sensitivity and selectivity against Bt spores, and (3) tested the efficiency of selected antibodies and aptamers in capturing Bt spores on the surface of functionalized GaAs biochips. Seven genes encoding Bt spore proteins were cloned and expressed in Escherichia coli. The binding of each purified spore antigen was tested by commercially available polyclonal and monoclonal antibodies claimed to exclusively target spores. Of the seven targets, Bacillus collagen-like protein A, was the most abundant protein on Bt spores and demonstrated the strongest binding affinity to all test antibodies. The commercial antibodies (Abs) were also tested for specificity to BC Group versus non-BC Group spores. Three of six commercial antibodies showed selectivity to Bt spores, with recombinant Abs providing the most robust lower range of detection (10² to 6×10³ spores/mL). The sensitivity and selectivity of three published DNA aptamer sequences demonstrated a wide range of detection sensitivity for Bt spores. Two of the three test aptamers also showed reasonable selectivity towards Bt spores while the third demonstrated reactivity to non-BC Group B. megaterium and B. subtilis. Of the reagents tested, a thiolated aptamer and llama recombinant Ab showed highest Bt spore capture efficiency as measured by spore coverage of the GaAs surface. These results confirm that the selected aptamer and llama rAb can be considered strong candidates for the development of GaAs-based biosensing devices.
... In semi-field studies different responses both at macroscopic and microscopic levels were considered; however, in this review, only 14 papers of this kind were found. Honey bees, in the field, are exposed to multiple stressors and most of the field papers were monitoring studies where accumulation of various contaminants in Apis mellifera were investigated; only 8 papers [28,33,50,57,62,71,83,95] analysed the sublethal effects of the contaminant mixtures on Apis mellifera. All these studies highlighted that honey bees are sensitive bioindicators of environmental pollution. ...
Honey bees and the pollination services they provide are fundamental for agriculture and biodiversity. Agrochemical products and other classes of contaminants, such as trace elements and polycyclic aromatic hydrocarbons, contribute to the general decline of bees’ populations. For this reason, effects, and particularly sublethal effects of contaminants need to be investigated. We conducted a review of the existing literature regarding the type of effects evaluated in Apis mellifera, collecting information about regions, methodological approaches, the type of contaminants, and honey bees’ life stages. Europe and North America are the regions in which A. mellifera biological responses were mostly studied and the most investigated compounds are insecticides. A. mellifera was studied more in the laboratory than in field conditions. Through the observation of the different responses examined, we found that there were several knowledge gaps that should be addressed, particularly within enzymatic and molecular responses, such as those regarding the immune system and genotoxicity. The importance of developing an integrated approach that combines responses at different levels, from molecular to organism and population, needs to be highlighted in order to evaluate the impact of anthropogenic contamination on this pollinator species.
... Some acute effects may occur in the long term in the intestinal epithelium of the bees that have ingested Bt, despite the apparent absence of toxicity (i.e., no alteration in survival of the bees). This may mask other physiological disruptions that are harmful to bees, particularly in the case of exposure to biological products in combination with other environmental stressors 32,44 . ...
Bacillus thuringiensis (Bt), an entomopathogenic bacterium, has been used as bioinsecticides for insect pest control worldwide. Consequently, the objective of this work was to evaluate the possible effects of commercial formulations of Bt products, Dipel and Xentari, on the survival and behavior of Africanized honey bees (Apis mellifera). Bioassays were performed on foragers and newly emerged (24-hold) bees that received the products mixed in the food. Their survival and behavior were evaluated through the vertical displacement tests and the walk test, analyzed using software Bee-Move. Then, histological analysis of the mesenterium was performed. As control treatment was used sterile water. The honey bees' survival was evaluated for between 1 and 144 h. No interference of B. thuringiensis, Dipel and Xentari, in the survival of Africanized honey bees were found. Only Xentari interfered with vertical displacement behavior of newly emerged (24-hold) bees. Both the products tested were selective and safe for A. mellifera.
... Numerous impact studies of field application rates and acute intoxications have shown that Bt bioinsecticides are safe or have a limited impact on non-target vertebrates and invertebrates, and associated species communities 19,20 . However, the increasing use of bioinsecticides based on Bt spores and toxins has recently raised concern 21 and led to the assessment of their potential effects on non-target species, such as auxiliary insects of biological control 22 , pollinators 23 and species communities which share their habitat with Bt-targeted insect pests [24][25][26] . There is growing evidence of direct and indirect cross-effects of Bt bioinsecticide formulations and Bt-Cry and Cyt toxins across insect species and orders, or even across phyla, suggesting that Bt targeting is only partly specific 12,26,27 . ...
Bioinsecticides based on Bacillus thuringiensis (Bt) spores and toxins are increasingly popular alternative solutions to control insect pests, with potential impact of their accumulation in theenvironment on non-target organisms. Here, we tested the effects of chronic exposure to commercial Bt formulations (Bt var. kurstaki and israelensis) on eight non-target Drosophila species present in Bt-treated areas, including D. melanogaster (four strains). Doses up to those recommended for field application (~ 106 Colony Forming Unit (CFU)/g fly medium) did not impact fly development, while no fly emerged at ≥ 1000-fold this dose. Doses between 10- to 100-fold the recommended one increased developmental time and decreased adult emergence rates in a dose-dependent manner, with species. and
strain-specific effect amplitudes. Focusing on D. melanogaster, development alterations were due to instar-dependent larval mortality, and the longevity and offspring number of adult flies exposed to bioinsecticide throughout their development were moderately influenced. Our data also suggest a synergy between the formulation compounds (spores, cleaved toxins, additives) might induce the bioinsecticide effects on larval development. Although recommended doses had no impact on nontarget Drosophila species, misuse or local environmental accumulation of Bt bioinsecticides could have side-effects on fly populations with potential implications for their associated communities.
OPEN ACCESS https://doi.org/10.1038/s41598-020-73145-6
... A 14-day chronic toxicity test was conducted, and on the 14 th day after the test began, the whole head and whole abdomen of surviving bees were collected from each cage by dissection on ice (Renzi et al., 2016). Another same treatments were set at the same time, and samples were collected at the 7 th day after test began. ...
... Une mortalité larvaire accrue et un retard de développement ont également été observés chez de nombreuses espèces de drosophile, suite à l'ingestion de nourriture contaminée par des produits Bt (Babin et al., 2019). Enfin, les bioinsecticides Bt seraient à l'origine de perturbations intestinales chez l'abeille (Renzi et al., 2016) et de changements comportementaux chez le trichogramme (petit hyménoptère parasitoïde également employé en lutte biologique) . ...
... Une mortalité larvaire accrue et un retard de développement ont également été observés chez de nombreuses espèces de drosophile, suite à l'ingestion de nourriture contaminée par des produits Bt (Babin et al., 2019). Enfin, les bioinsecticides Bt seraient à l'origine de perturbations intestinales chez l'abeille (Renzi et al., 2016) et de changements comportementaux chez le trichogramme (petit hyménoptère parasitoïde également employé en lutte biologique) . ...
Protéger les cultures par des moyens naturels est une nécessité pour la transition vers une agriculture respectueuse de l’environnement. Un effort de recherche et développement sans précédent est aujourd’hui mis en œuvre dans le domaine du biocontrôle, qui rassemble des approches basées sur l’usage d’organismes vivants et de produits d’origine biologique. Cet ouvrage en présente un panorama exhaustif et en explique les fondements théoriques et les applications pratiques.
... In particular, Nicodemo et al. (2014) demonstrated that imidacloprid and fipronil reduce oxygen consumption and impair mitochondrial function. This reduction in aerobic respiration is accompanied by an increase in glycolysis and citric acid cycle-related gene expression in exposed honey bees (Roat et al., 2014;Renzi et al., 2016a). Thus, pesticide exposure may be favouring low-efficiency means of ATP production (glycolysis and citric acid cycle) over higher efficiency means (oxidative phosphorylation). ...
Managed populations of the European honey bee (Apis mellifera) support the production of a global food supply. This important role in modern agriculture has rendered honey bees vulnerable to the noxious effects of anthropogenic stressors such as pesticides. Although the deleterious outcomes of lethal pesticide exposure on honey bee health and performance are apparent, the ominous role of sublethal pesticide exposure is an emerging concern as well. Here, we use a data harvesting approach to better understand the toxicological effects of pesticide exposure across the honey bee life cycle. Through compiling adult- and larval-specific median lethal dose (LD50) values from 93 published data sources, LD50 estimates for insecticides, herbicides, acaricides, and fungicides are highly variable across studies, especially for herbicides and fungicides, which are underrepresented in the meta-data set. Alongside major discrepancies in these reported values, further examination of the compiled data suggested that LD50 may not be an ideal metric for honey bee risk assessment. We also discuss how sublethal effects of pesticide exposure, which are not typically measured in LD50 studies, can diminish honey bee reproduction, immunity, cognition, and overall physiological functioning, leading to suboptimal honey bee performance and population reduction. In consideration of actionable solutions to mitigate the effects of sublethal pesticide exposure, we have identified the potential for probiotic supplementation as a promising strategy that can be easily incorporated alongside current agricultural infrastructure and apicultural management practices. Probiotic supplementation is regularly employed in apiculture but the potential for evidence-based targeted approaches has not yet been fully explored within a formal toxicological context. We discuss the benefits, practical considerations, and limitations for the use and delivery of probiotics to hives. Ultimately, by subverting the sublethal effects of pesticides we can help improve the long-term survival of these critical pollinators.
... Scientific evidence shows that the weakening or death of bee colonies is mainly caused by the combined effects of multiple stressors rather than by one-off sudden attacks by a single factor (Goulson et al., 2015;EFSA, 2014a;Potts et al., 2010;Rortais et al., 2017). Such interactions can occur principally between (i) biological factors (Nazzi et al., 2012;Nazzi and Pennacchio, 2014), (ii) environmental factors (Di Pasquale et al., 2016;Goulson et al., 2015;Le Conte and Navajas, 2008), (iii) chemical and nutritional stressors Tong et al., 2019), (iv) chemical and biological factors (Williamson et al., 2013;Klein et al., 2017;Alaux et al., 2010;Vidau et al., 2011;Pettis et al., 2012;Renzi et al., 2016) and (v) multiple chemicals (EFSA, 2013a, b;Robinson et al., 2017;Han et al., 2019;Sanchez-Bayo and Goka, 2016). In particular, the latter is raising concerns among scientists and regulatory bodies since bees can be exposed to a wide range of multiple chemicals, "chemical mixtures", including compounds from anthropogenic (e.g. ...
Bees are exposed to a wide range of multiple chemicals “chemical mixtures” from anthropogenic (e.g. plant protection products or veterinary products) or natural origin (e.g. mycotoxins, plant toxins). Quantifying the relative impact of multiple chemicals on bee health compared with other environmental stressors (e.g. varroa, viruses, and nutrition) has been identified as a priority to support the development of holistic risk assessment methods. Here, extensive literature searches and data collection of available laboratory studies on combined toxicity data for binary mixtures of pesticides and non-chemical stressors has been performed for honey bees (Apis mellifera), wild bees (Bombus spp.) and solitary bee species (Osmia spp.). From 957 screened publications, 14 publications provided 218 binary mixture toxicity data mostly for acute mortality (lethal dose: LD50) after contact exposure (61%), with fewer studies reporting chronic oral toxicity (20%) and acute oral LC50 values (19%). From the data collection, available dose response data for 92 binary mixtures were modelled using a Toxic Unit (TU) approach and the MIXTOX modelling tool to test assumptions of combined toxicity i.e. concentration addition (CA), and interactions (i.e. synergism, antagonism). The magnitude of interactions was quantified as the Model Deviation Ratio (MDR). The CA model applied to 17% of cases while synergism and antagonism were observed for 72% (MDR > 1.25) and 11% (MDR
... A 14-day chronic toxicity test was conducted, and on the 14th day after the test began, the whole head and whole abdomen of surviving bees were collected from each cage by dissection on ice (Renzi et al., 2016). Another same treatments were set at the same time, and samples were collected at the 7th day after test began. ...
Flumethrin is a typical pyrethroid varroacide widely used for mite control in beekeeping worldwide. Currently, information on the toxicological characteristics of flumethrin on bees at sublethal concentrations is still lacking. To fill this gap in information, we performed a 48-h acute oral and 14-day chronic toxicity testing of flumethrin in newly emerged adult honey bees under laboratory conditions. Results showed that flumethrin had high acute toxicity to honey bees with a 48-h LD50 of 0.47 µg/bee (95% CI, 0.39 ∼ 0.57 µg/bee), which is higher than that of many other commercial pyrethroid insecticides, but lower than that of tau-fluvalinate. After 14 days of chronic exposure to flumethrin at 0.01, 0.10, and 1.0 mg/L, significant antioxidant response, detoxification, immune reaction, and apoptosis were observed in the midguts. These findings indicated that flumethrin had potential risks to bees, and it can disturb the homeostasis of bees at sublethal concentrations under longer exposure conditions. Flumethrin is highly lipophilic and easy to accumulate in beeswax; thus, careless practices might pose risks to colony development in commercial beekeeping and native populations. This laboratory study can serve as an early warning, and further studies are required to understand the real residual level of flumethrin in bees and the risks of flumethrin in field condition.
... According to European Commission (2016), around 600,000 European beekeepers (managing around 16 million honey bee colonies) produce around 250,000 tons of honey per year, generating more than 400 million € per year in the EU. The consistent loss of honey bee colonies reported in Europe in the last decade (Neumann and Carreck, 2010;Cepero et al., 2014) was attributed to various factors, acting in isolation or in combination (Goulson et al., 2015;Renzi et al., 2016;Steinhauer et al., 2018). These factors include agrochemicals (Johnson et al., 2010;Henry et al., 2014;Dively et al., 2015;Brandt et al., 2016;Spurgeon et al., 2016), parasites and/or pathogens (Cox-Foster et al., 2007;Higes et al., 2009;Cornman et al., 2012;Zheng et al., 2015;Di Prisco et al., 2016), nutrition (Tosi et al., 2017), landscape management (Brosi et al., 2007;Naug, 2009;Decourtye et al., 2010), climatic conditions (Burkle et al., 2013;Odoux et al., 2014), genetic origin of bees (Büchler et al., 2014) and Beekeeping Management Practices Jacques et al., 2016). ...
The beekeeper plays a key role in maintaining the health status of managed honey bee colonies and ensuring their productivity. However, a clear overview on the main actions carried out by beekeepers and their role for the successful management of honey bees is only partially addressed. In this study, we aim at providing: i) a generalized conceptual framework for the characterization of the Beekeeping Management Practices carried out by the European beekeepers and ii) the definition of their influence on the overall status of the honey bee
colony. Six Beekeeping Management Practices were selected in this study: chemical control; replacement of combs with brood; replacement of combs with feed sources; supplementary feeding; change in the number of workers; beekeeper category and experience. Each Beekeeping Management Practice was characterized in relation to: i) the elements guiding their application, ii) the potential impacts on a honey bee colony and iii) the scenario-based variables that might influence their timing, frequency and/or efficiency. We performed an extensive literature review and an Expert Knowledge Elicitation procedure in order to estimate the uncertainty linked to some major parameters. In this paper, we successfully developed and applied a conceptual framework defining the actions carried out by European beekeepers and quantifying their impacts to a honey bee colony. The conceptual framework might support the definition of realistic scenarios of Beekeeping Management Practices in Europe for the assessment and management of the risks linked to honey bee colonies considering the potential role of the beekeeper.
... Contrasting evidence of effects on non-targets, ranging from unobservable effects of intake of Bt transgenic crops [41,42,43,44], to number of harmful effects (viz. delay in development, reduction in weight gain, changes in behavior or increased mortality) on beneficial organisms like pollinators [45], non-target arthropods [46,47,48], parasitoids [49] and predators [50,51] are present. ...
Bacillus thuringiensis (Bt) is a spore-forming, gram-positive, aerobic, rod-shaped bacterium. During sporulation, Bt
produces proteinaceous crystals called Cry proteins that are lethal to many insects’ species, so are commonly used as biological
pesticide. Transgenic Bt crops are genetically altered to express insecticidal toxins that cause fatality of a number of general
agricultural pests. The insecticidal toxins formed by Bt crops possess narrow range of toxicity and therefore less non-target
impacts as compared to conventional insecticides. A decrease in the amount and regularity of insecticide applications are
financially advantageous. In numerous regions of the world, insecticide inputs have been significantly reduced because of Bt.
The use of Bt crop technology might help in worldwide food security by escalating the amount and steadiness of crop yields.
Though impact of Bt toxin on non-targeted organism is a serious issue yet no conclusion could still be drawn from several
studies. This review summarizes the benefits of Bt crops including the impact on non-targeted organisms and Bt toxins having
potential risks with respect to the environment.
... Biochemical studies are increasingly used in ecological risk assessments to identify the incidence of exposure to xenobiotics (Renzi et al. 2016). Terrestrial organisms, including herbivorous insects, are subjected to oxidative stress resulting from overproduction of reactive oxygen species (ROS) under exposure to insecticides including organophosphates, carbamates, and pyrethroids (Ranjbar et al. 2002). ...
The aim of this study was to analyze the impact of
organophosphorus (OP) pollutants on oxidative stress and ultrastructural
biomarkers in the midgut of the honeybee Apis
mellifera collected from three locations that differ in their
extent of spraying load with OP insecticides: a weakly
anthropised rural site, Bolin which is considered as a reference
site; moderately spraying site, El Kaza; and a strongly
anthropised urban site, Tiba with a long history of pesticide
use. Results showed that high concentrations of chlorpyrifos,
malathion, diazinon, chlorpyrifos-methyl, and pirimiphosmethyl
were detected in midgut at locations with extensive
pesticide spraying. Reduced glutathione content, superoxide
dismutase, catalase, and glutathione peroxidase displayed
lowest activities in the heavily sprayed location (Tiba). Lipid
peroxidation level in the midgut of honeybees in the sprayed
locations was found to be significantly higher compared to the
reference values. Meanwhile, various ultrastructural abnormalities
were observed in the epithelial cells of the midgut of
honeybees collected from El Kaza and Tiba, included confluent
and disorganized microvilli and destruction of their brush
border, the cytoplasm with large vacuoles and alteration of
cytoplasmic organelles including the presence of swollen mitochondria
with lysis of matrices, disruption of limiting membranes,
and disintegration of cristae. The nuclei with indented
nuclear envelope and disorganized chromatin were observed.
... For example, exposure to sublethal levels of pesticides in honey bees can affect behavior (Henry et al. 2012;Matsumoto 2013;Yang et al. 2008), learning (Decourtye et al. 2004a;Decourtye et al. 2004b), colony development (Wu et al. 2011), sperm viability (Chaimanee et al. 2016;Collins and Pettis 2013), and susceptibility to several pathogens . However, to date, most studies of toxicity effects of pesticides on bees have tested the effects of single compounds, only several studies have investigated the effects of pesticides associations (Domingues et al. 2017;Gill et al. 2012;Renzi et al. 2016;Sgolastra et al. 2017;Zhu et al. 2017b). Pesticides mixtures can have additive effects through the same or different mode of action or even synergism or antagonism in toxicity. ...
Acetamiprid and ergosterol-inhibiting fungicide (EBI) are frequently applied to many flowering plants, while honey bees are pollinating agents or pollinators of the flowers. Hence honey bees are often exposed to these pesticides. But until now, the effects of theses combinations at field-realistic doses on honey bee health have been poorly investigated. In this study, we explore the synergistic mortality and some physiological effects in surviving honey bees after chronic oral exposure to acetamiprid and/or propiconazole in the laboratory. The results indicated that chronic combined exposure to acetamiprid and propiconazole produced a significant synergistic effect on mortality both for newly emerged bees (50% mortality in 7.2 days) and forager bees (50% mortality in 4.8 days). Honey bee weight of newly emerged bees was decreased after feeding food with a field concentration of acetamiprid and propiconazole, alone or combined for 10 days. Combination of acetamiprid and propiconazole also modulated the activities of P450s, GST and CAT in newly emerged bees and forager bees than either alone, but neither pesticide affected the activity of AChE. These results show that chronic combined exposure to pesticides of relatively low toxicity may caused severely physiological disruptions that could be potentially damaging for the honey bees.
... Hence, subtle adverse mechanisms and effects can occur, even at low dose levels, thus revealing the sensitivity of the honeybee to ionizing radiation. Such discrete physiological modulations, in the absence of significant lethal effect, were also demonstrated with chemicals, like the insecticide fipronil, in the honeybee, which shows that stressors can impair physiological functions at low noise (Renzi et al., 2016). Thus, the honeybee can be used as a pertinent bioindicator not only to detect exposure to chemical pollutants, including pesticides (Badiou-Bénéteau et al., 2013b), but also to physical agents such as ionizing radiation or electromagnetic fields (Shepherd et al., 2018). ...
Terrestrial ecosystems are exposed to various kinds of pollutants, including radionuclides. The honeybee, Apis mellifera, is commonly used in ecotoxicology as a model species for evaluating the effects of pollutants. In the present study, honeybees were irradiated right after birth for 14 days with gamma rays at dose rates ranging between 4.38 × 10 ⁻³ and 588 mGy/d. Biological tissues (head, intestine and abdomen) were sampled at D3, D10 and D14. Ten different physiological markers involved in nervous (acetylcholinesterase (AChE)), antioxidative (catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione-S-transferase (GST)), immune system (phenoloxidase (PO)) and metabolism (carboxylesterases (CaEs) and alkaline phosphatase (ALP)) were measured. Univariate analyses were conducted to determine whether each individual biomarker response was positively or negatively correlated with the dose rate. Then, multivariate analyses were applied to investigate the relationships between all the biomarker responses. Although no mortality occurred during the experiment, several biomarkers varied significantly in relation to the dose rate. Globally, the biomarkers of antioxidant and immune systems decreased as the dose rate increased. Reversible effects on the indicator of the neural system were found. Concerning indicators of metabolism (carboxylesterases), variations occurred but no clear pattern was found. Taken altogether, these results help better understand the effects of ionizing radiation on bees by identifying relevant physiological markers of effects. These results could improve the assessment of the environmental risk due to ionizing radiation in terrestrial ecosystems.
... Second, residual wasp bait that is not taken by pest wasps becomes a dry solid within 3 days and is removed from the bait stations after 3-8 days without replacement. Consequently, the environmental exposure of bee colonies to the toxicant (or its environmental or metabolic breakdown products) and the period over which they could develop sub-lethal effects is shorter than indicated by published toxicity tests [36,40,[52][53], although even brief periods of exposure can result in subtle sub-lethal effects with both immediate and delayed effects. ...
Introduced wasps (Vespula germanica and V. vulgaris) are costly invertebrate pests in New Zealand, with large impacts on the local ecology and economy. Wasps eat honeybees (Apis mellifera), which has potentially devastating effects on hive health, as well as agricultural and horticultural industries. Vespex bait, which contains fipronil in a proteinaceous carrier, has recently been introduced for wasp control. In over a decade of reported trials, honeybees have never been observed foraging on Vespex, likely because the bait contains no sugars to serve as a bee food source. However, the potential for the control agent fipronil to enter beehives has not been tested. Therefore, here, we investigated this using a liquid chromatography–mass spectrometry assay of fipronil and two of its environmental breakdown and metabolic derivatives, fipronil desulfinyl and fipronil sulfone. We did not detect fipronil in any of the worker bee, bee larva, honey or pollen samples (n = 120 per product) collected from 30 hives over a 2-year period. Furthermore, although we detected fipronil desulfinyl in one honeybee sample, this is thought to have originated from a single individual, representing a rare occurrence of intoxication, and there was no evidence that Vespex was the toxicant source. There was also no evidence of trophallactic transfer of fipronil or its derivatives in any of the hives sampled. Previous studies have reported the impairment of individual bee performance at fipronil doses similar to the detection limit of our study. However, our results provide confidence that if undetectable intoxication was occurring, it would involve an acute exposure for those few individuals affected, with minimal impairment to colonies. Therefore, we conclude that the use of Vespex in the vicinity of honeybees does not result in significant hive uptake while effectively reducing wasp pressure on honeybee colonies.
... Several ecotoxicological studies of various biopesticides on diverse non-targeted organisms have already been published such as arthropods (Biondi et al. 2012a;Biondi et al. 2012b;Nakasu et al. 2014;Renzi et al. 2016;Amichot et al. 2016), soil organisms (Ipsilantis et al. 2012;Romdhane et al. 2016;Chelinho et al. 2017), aquatic organisms (Duchet et al. 2010;Manachini et al. 2013), or mammals (Rahioui et al. 2014). The choice of such non-target organisms reflects on one hand the ecosystem service they provide: the beneficial arthropods are involved in biocontrol and pollination services when the beneficial soil organisms are involved in decomposition or nutrient transfer (e.g., mycorrhizas) services. ...
The impact of the programmatic use of larvicides for mosquito control on native stingless bees (e.g., Apidae, Meliponini) is a growing concern in Australia due to heightened conservation awareness and the growth of hobbyist stingless bee keeping. In Australia, the two most widely used mosquito larvicides are the bacterium Bacillus thuringiensis var. israelensis (Bti) and the insect hormone mimic methoprene (as S-methoprene). Each has a unique mode of action that could present a risk to stingless bees and other pollinators. Herein, we review the potential impacts of these larvicides on native Australian bees and conclude that their influence is mitigated by their low recommended field rates, poor environmental persistence, and the seasonal and intermittent nature of mosquito control applications. Moreover, evidence suggests that stingless bees may display a high physiological tolerance to Bti similar to that observed in honey bees (Apis mellifera), whose interactions with B. thuringiensis-based biopesticides are widely reported. In summary, neither Bti or methoprene is likely to pose a significant risk to the health of stingless bees or their nests. However, current knowledge is limited by regulatory testing requirements that only require the use of honey bees as toxicological models. To bridge this gap, we suggest that regulatory testing is expanded to include stingless bees and other nontarget insects. This is imperative for improving our understanding of the potential risks that these and other pesticides may pose to native pollinator conservation.
Taking into consideration that bees can be contaminated by pesticides through the ingestion of contaminated floral resources, we can utilize genetic techniques to assess effects that are scarcely observed in behavioral studies. This study aimed to investigate the genetic effects of ingesting lethal and sublethal doses of the insecticide fipronil in foraging honey bees during two periods of acute exposure. Bees were exposed to fipronil through contaminated honey syrup at two dosages (LD50 = 0.19 μg/bee; LD50/100 = 0.0019 μg/bee) and for two durations (one and four hours). Following exposure, we measured syrup consumption per bee, analyzed the transcriptome of bee brain tissue, and identified differentially expressed genes (DEGs), categorizing them functionally based on Gene Ontology (GO). The results revealed a significant genetic response in honey bees after exposure to fipronil, regardless of the dosage used. Fipronil affected various metabolic, transport, and cellular regulation pathways, as well as detoxification processes and xenobiotic substance detection. Additionally, downregulation of several DEGs belonging to the Olfactory Binding Protein (OBP) family was observed, suggesting potential physiological alterations in bees that may lead to disoriented behaviors and reduced foraging efficiency.
The study objective was a comparative analysis of rapeseed and multifloral honey enriched by flowers of six plant species: lungwort (Pulmonaria officinalis L.), high mallow (Malva sylvestris L.), cowslip primrose (Primula veris L.), coltsfoot (Tussilago farfara L.), lawn daisy (Bellis perennis L.), and black elderberry (Sambucus nigra L.). The honey was enriched with dry flowers and plant extracts at a level of 1%, 2%, and 4% (w/w). Antioxidant capacity was measured via two different methods: DPPH and ABTS assay. Total phenolic content and total flavonoid content were determined using colorimetric methods. The highest radical scavenging capacity determined by the DPPH assay was observed in rapeseed honey with a 4% dried cowslip primrose (Primula veris L.) flower addition, which was more than 50 times higher than the activity for pure rapeseed honey. Almost 100% of the radical scavenging capacity was found for rapeseed and multifloral honeys with cowslip primrose (Primula veris L.), especially for the 4% dried flower addition, more than six times that of the control samples measured using the ABTS test. Multifloral honeys enriched with black elderberry (Sambucus nigra L.) and cowslip primrose (Primula veris L.), with a 2% and 4% plant material addition, both as an extract and as dried flowers, were characterised by the highest total phenolic content. The highest enrichment effectiveness was observed for dried flowers of lungwort (Pulmonaria officinalis L.), black elderberry (Sambucus nigra L.), and high mallow (Malva sylvestris L.), where the flavonoid content increased more than nine times compared to the honey samples without additions. The content of biologically active substances in honey enriched with flowers gives hope for new applications of the health-promoting substances contained in wild plants.
The honey bee obtains food from bee forage, which comprises crops grown in multi-hectare agricultural fields where various types of plant protection products such as pesticides are used. Some of these negatively affect the honey bee organism. In our research, we aimed to evaluate the effects of three pesticide groups: fungicides (tebuconazole), insecticides (acetamiprid), herbicides (glyphosate), and their mixtures on the functioning of honey bee workers (A. mellifera carnica). Pesticides in various proportions and dilutions were added to sugar syrups and then fed to the bees. Mortality and food intake were recorded daily, while hemolymph analysis was performed after seven days of exposure. Food intake, mortality, and the results of various biochemical analyses differed between the experimental group and the control group receiving untreated sugar syrup. PPP’s mixture of glyphosate tebuconazole and acetamiprid is more toxic to bees than single pesticides. Certain protection products such as pesticides can disrupt the antioxidant and detoxification systems associated with immunity in honey bees. Consequently, honey bees experience weaker conditions and their proper functioning deteriorates. The results obtained from biochemical changes provide a basis for field studies.
Bacillus thuringiensis (Bt) est une bactérie sporulante Gram-positive. Elle a synthétise des toxines (Cry) entomopathogènes qui sont enfermées dans un cristal au sein de la spore. Les produits Bt sont les bioinsecticides les plus efficaces contre les lépidoptères ravageurs de cultures et prédominent en agriculture biologique, occupant 70 % des parts de marché des bioinsecticides. La surface mondiale en agriculture biologique a doublé en 10 ans induisant de facto une augmentation de 4% par an de l'utilisation des bioinsecticides. Cette tendance va s'accentuer dans les années à venir suite aux incitations nationales et internationales visant à réduire l’utilisation des produits chimiques. Avec cette forte croissance, les populations sont de plus en plus exposées aux bioinsecticides via l’alimentation, ce qui soulève la question de leurs effets potentiels à long terme sur la santé. Le premier organe en contact avec de la nourriture contaminée par les bioinsecticides Bt est donc le tube digestif.Mon projet de thèse s'intéresse aux conséquences physiopathologiques intestinales liées à l'ingestion chronique de Bt aux doses retrouvées sur les légumes "bio" après traitement en utilisant la drosophile comme modèle. La drosophile permet d'identifier les mécanismes physiologiques, cellulaires et génétiques impliqués dans les effets observés. La conservation de ces mécanismes entre la drosophile et les vertébrés permet ensuite de rapidement aborder les problèmes chez les mammifères. J'ai ainsi montré que l'ingestion de bioinsecticides Btk kurstaki (Btk) aux doses environnementales par des drosophiles adultes induisait sous 24h une apoptose modérée des entérocytes. J'ai montré que cette apoptose est causée par les toxines Cry de Btk. Qui dit apoptose d'entérocytes, dit mise en route du processus de remplacement cellulaire via la différentiation des progéniteurs en entéroblastes puis en entérocytes. Etonnamment, j'ai observé une forte augmentation du nombre de cellules entéroendocrines à partir du premier jour suivant l'ingestion. Par lignage cellulaire, j'ai démontré que peu de nouveaux entérocytes apparaissaient, en tous cas pas suffisamment pour remplacer tous ceux mourant. De fait, le nombre total d'entérocytes dans l'intestin diminue alors que le nombre de cellules entéroendocrine augmente. Ensuite j'ai démontré que les cristaux de toxines de Btk détournaient les progéniteurs de leur destin initial d'entérocytes vers un destin de cellules entéroendocrines, à cause d'un affaiblissement de l'interaction cellule-cellule entre les cellules souches intestinales mères et les cellules filles progénitrices. J'ai pu sauver l'excès de cellules entéroendocrines dépendant du bioinsecticides Btk en augmentant la force des jonctions adhérentes entre les cellules souches et les progéniteurs. La souche Btk composant les produits commerciaux produit 5 toxines Cry différentes (Cry1Aa, Cry1Ab, Cry1Ac, Cry2Aa, et Cry2Ab) ciblant les larves de lépidoptères. J'ai montré que les toxines de type Cry1A sont capables, seules, d'induire l'augmentation du nombre de cellules entéroendocrines.En conclusion, une partie de mes travaux participent aux connaissances sur les mécanismes physiologiques, génétiques et cellulaires fondamentaux nécessaires au maintien de l'intégrité de l'épithélium intestinale après une agression modérée. D'autre part, mes travaux montrent que l’ingestion de bioinsecticides Btk aux doses utilisées en agriculture induit une perturbation de l’équilibre physiologique de l'intestin d'un organisme non-cible. La poursuite de ce type de travaux est essentielle pour arriver à évaluer minutieusement les risques consécutifs à une exposition aux biopesticides Btk par les organismes non-cibles. Il est important d’obtenir des données précises pour mettre en place des mesures préventives et/ou curatives pour la santé humaine et l'environnement.
Les données scientifiques actuelles suggèrent un déclin de la diversité et de l’abondance des insectes, y compris les abeilles domestiques Apis mellifera. Ces dernières sont confrontées à de fortes pertes de colonies dans plusieurs régions du monde telles que l’ouest de l’Europe et les États-Unis. De nombreuses études suggèrent que l’origine du déclin des colonies d’abeilles est multicausale et identifient les pesticides et les agents pathogènes comme étant les principaux contributeurs à ce déclin. La co-exposition des abeilles à de multiples pesticides et l’infection par plusieurs pathogènes constituent un phénomène courant. Cependant, les recherches sur les effets des mélanges de pesticides n’ont pas fait l’objet d’un intense développement. Ainsi, les travaux conduits dans le cadre de cette thèse ont été focalisés sur la détermination de la toxicité des mélanges de pesticides, appliqués à des niveaux d’exposition environnementaux, en présence d’un agent pathogène. Le choix s’est porté sur l’étude des interactions entre un insecticide néonicotinoïde, l’imidaclopride, un fongicide azole, le difénoconazole, et un herbicide, le glyphosate, en présence de l’agent pathogène Nosema ceranae. Les résultats des différentes études effectuées durant cette thèse, révèlent la complexité des études sur les mélanges de pesticides. Ces travaux nous ont permis de constater que les effets d’un mélange de pesticides peuvent fortement varier en fonction des concentrations des pesticides constituant le mélange. L’augmentation du nombre de substances et du niveau d’exposition, n’induit pas nécessairement une augmentation de la toxicité du mélange. De plus, les effets du mélange peuvent varier en fonction de la séquence d’exposition aux pesticides et de l’état sanitaire des abeilles. Les mélanges de pesticides affectent l’état physiologique des abeilles suite à une réponse systémique liée à des perturbations de mécanisme généraux tels que le stress oxydant. Cependant, ces trois pesticides, seuls et en mélanges n’ont aucun effet sur l’installation du microbiote intestinal à des niveaux d’exposition environnementaux.
This study was aimed at evaluating the effect of a microbial pest-controlling product (MPCP) with the active substance Bacillus thuringiensis ssp. aizawai (strain: ABTS-1857) on adults and larvae of honeybees. To determine the contamination levels of Bt spores in different matrices, a colony-feeding study under semi-field conditions was performed. Furthermore, two chronic adult trials and a chronic larval study were conducted under laboratory conditions to test the effects of different concentrations of the plant protection product (PPP) on the development and mortality. Possible modifications of the chronic oral toxicity test were assessed by additional pollen feeding. Our results showed that Bt spores were detected in all matrices over the entire test duration in different concentrations, decreasing over time. The survival of adult bees and larvae was negatively affected in laboratory conditions after a chronic exposure to the MPCP depending on the tested concentrations. Moreover, the earliest sign of bee mortality, resulting from exposure to ABTS-1857, was recorded only after 96 h at the highest tested concentration. Pollen feeding to adults significantly increased the survival of the treated bees. In conclusion, the PPP with the Bt strain ABTS-1857 showed an effect on the mortality of adults and larvae under laboratory conditions. Further studies with Bt-based PPPs under realistic field conditions are necessary to evaluate the potential risk of those MPCPs on honeybees.
Multiple pesticides originating from plant protection treatments and the treatment of pests infecting honey bees are frequently detected in beehive matrices. Therefore, winter honey bees, which have a long life span, could be exposed to these pesticides for longer periods than summer honey bees. In this study, winter honey bees were exposed through food to the insecticide imidacloprid, the fungicide difenoconazole and the herbicide glyphosate, alone or in binary and ternary mixtures, at environmental concentrations (0 (controls), 0.1, 1 and 10 μg/L) for 20 days. The survival of the honey bees was significantly reduced after exposure to these 3 pesticides individually and in combination. Overall, the combinations had a higher impact than the pesticides alone with a maximum mortality of 52.9% after 20 days of exposure to the insecticide-fungicide binary mixture at 1 μg/L. The analyses of the surviving bees showed that these different pesticide combinations had a systemic global impact on the physiological state of the honey bees, as revealed by the modulation of head, midgut and abdomen glutathione-S-transferase, head acetylcholinesterase, abdomen glucose-6-phosphate dehydrogenase and midgut alkaline phosphatase, which are involved in the detoxification of xenobiotics, the nervous system, defenses against oxidative stress, metabolism and immunity, respectively. These results demonstrate the importance of studying the effects of chemical cocktails based on low realistic exposure levels and developing long-term tests to reveal possible lethal and adverse sublethal interactions in honey bees and other insect pollinators.
Exposure to plant protection products (PPPs) is one of the causes for the population decline of pollinators. In addition to direct exposure, pollinators are exposed to PPPs by pollen, nectar and honey that often contain residues of multiple PPPs. While in legislation PPPs are regarded mainly for their acute toxicity in bees, other effects such as neurotoxicity, immunotoxicity, behavioural changes, stress responses and chronic effects that may harm different physiologically and ecologically relevant traits are much less or not regarded. Despite the fact that endocrine disruption by PPPs is among key effects weakening survival and thriving of populations, pollinators have been poorly investigated in this regard. Here we summarize known endocrine disruptive effects of PPPs in bees and compare them to other chronic effects. Endocrine disruption in honey bees comprise negative effects on reproductive success of queens and drones and behavioural transition of nurse bees to foragers. Among identified PPPs are insecticides, including neonicotinoids, fipronil, chlorantraniliprole and azadirachtin.
So far, there exists no OECD guideline to investigate possible endocrine effects of PPPs. Admittedly, investigation of effects on reproduction success of queens and drones is rarely possible under laboratory conditions. But the behavioural transition of nurse bees to foragers could be a possible endpoint to analyse endocrine effects of PPPs under laboratory conditions. We identified some genes, including vitellogenin, which regulate this transition and which may be used as biomarkers for endocrine disruptive PPPs. We plea for a better implementation of the adverse outcome pathway concept into bee's research and propose a procedure for extending and complementing current assessments, including OECD guidelines, with additional physiological and molecular endpoints. Consequently, assessing potential endocrine disruption in pollinators should receive much more relevance.
This study aimed to determine the residues of fipronil, metabolites, and enantiomers in tea (Camellia sinensis) during tea planting and green tea manufacture. An AD-RH chiral column was used to separate the fipronil enantiomers. During tea planting, the half-lives of the sum of fipronil and metabolites were similar to those of fipronil, which were 2.37 and 3.88 days for tea shoots and mature leaves, respectively. The residues of fipronil and its metabolites increased 2.3-3.6-fold during green tea manufacture. The values for the processing factors of fipronil and metabolites ranged from 1.0 to 2.1. A slightly significant enantioselectivity of (R)- and (S)-fipronil was observed during tea planting and green tea manufacturing. The residue pattern indicated that fipronil should not be applied in tea gardens due to its long persistence. The maximum residual limits of fipronil and metabolites at 2 μg kg-1 were considered optimal.
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Field studies were conducted to evaluate the transfer of active ingredients (AIs) of plant protection products (PPPs) to beehives. They were applied in two commodity red raspberry plantations of two varieties: Laszka (experiment 1) and Seedling (experiment 2). Samples of flowers, leaves, bees, brood, and honey were examined for the presence of chlorpyrifos, cypermethrin, difenoconazole, cyprodinil, and trifloxystrobin (experiment 1) and chlorpyrifos, boscalid, pyraclostrobin, cypermethrin, difenoconazole, and azoxystrobin (experiment 2). In experiment 1, the highest levels of trifloxystrobin were observed on the surface of flowers, (0.04 μg/flower) and for difenoconazole on the inside (0.023 μg/flower). Leaves contained only trace residues of cypermethrin and cyprodinil (0.001 μg/cm2 of leaves each) and trifloxystrobin (0.01 μg/cm2 of leaves) on the surface; inside the leaves, the highest levels of trifloxystrobin were observed (0.042 μg/cm2 of leaves). In experiment 2, boscalid was found on the surface and inside the flowers and leaves (0.063 and 0.018 μg/flower and 0.057 and 0.033 μg/cm2 of leaves, respectively). In bees, brood, and honey (experiment 1), chlorpyrifos was present in the highest quantity (7.3, 1.6, and 4.7 μg/kg, respectively). Additionally, cypermethrin and trifloxystrobin were found in bees, and trifloxystrobin was present in honey. Bees, brood, and honey from plantation 2 contained all studied AIs, with the highest levels of boscalid (28.6 μg/kg of bees, 37.0 μg/kg of brood, and 33.9 μg/kg of honey, respectively). In no case did the PPP residues in honey exceed acceptable maximum residue levels (MRLs)—from a formal and legal point of view, in terms of the used plant protection products, the analysed honey was fit for human consumption.
The glutathione transferases (GSTs; also known as glutathione S-transferases) are major phase II detoxification enzymes found mainly in the cytosol. In addition to their role in catalysing the conjugation of electrophilic substrates to glutathione (GSH), these enzymes also carry out a range of other functions. They have peroxidase and isomerase activities, they can inhibit the Jun N-terminal kinase (thus protecting cells against H(2)O(2)-induced cell death), and they are able to bind non-catalytically a wide range of endogenous and exogenous ligands. Cytosolic GSTs of mammals have been particularly well characterized, and were originally classified into Alpha, Mu, Pi and Theta classes on the basis of a combination of criteria such as substrate/inhibitor specificity, primary and tertiary structure similarities and immunological identity. Non-mammalian GSTs have been much less well characterized, but have provided a disproportionately large number of three-dimensional structures, thus extending our structure-function knowledge of the superfamily as a whole. Moreover, several novel classes identified in non-mammalian species have been subsequently identified in mammals, sometimes carrying out functions not previously associated with GSTs. These studies have revealed that the GSTs comprise a widespread and highly versatile superfamily which show similarities to non-GST stress-related proteins. Independent classification systems have arisen for groups of organisms such as plants and insects. This review surveys the classification of GSTs in non-mammalian sources, such as bacteria, fungi, plants, insects and helminths, and attempts to relate them to the more mainstream classification system for mammalian enzymes. The implications of this classification with regard to the evolution of GSTs are discussed.
Systemic insecticides are applied to plants using a wide variety of methods, ranging from foliar sprays to seed treatments and soil drenches. Neonicotinoids and fipronil are among the most widely used pesticides in the world. Their popularity is largely due to their high toxicity to invertebrates, the ease and flexibility with which they can be applied, their long persistence, and their systemic nature, which ensures that they spread to all parts of the target crop. However, these properties also increase the probability of environmental contamination and exposure of nontarget organisms. Environmental contamination occurs via a number of routes including dust generated during drilling of dressed seeds, contamination and accumulation in arable soils and soil water, runoff into waterways, and uptake of pesticides by nontarget plants via their roots or dust deposition on leaves. Persistence in soils, waterways, and nontarget plants is variable but can be prolonged; for example, the half-lives of neonicotinoids in soils can exceed 1,000 days, so they can accumulate when used repeatedly. Similarly, they can persist in woody plants for periods exceeding 1 year. Breakdown results in toxic metabolites, though concentrations of these in the environment are rarely measured. Overall, there is strong evidence that soils, waterways, and plants in agricultural environments and neighboring areas are contaminated with variable levels of neonicotinoids or fipronil mixtures and their metabolites (soil, parts per billion (ppb)-parts per million (ppm) range; water, parts per trillion (ppt)-ppb range; and plants, ppb-ppm range). This provides multiple routes for chronic (and acute in some cases) exposure of nontarget animals. For example, pollinators are exposed through direct contact with dust during drilling; consumption of pollen, nectar, or guttation drops from seed-treated crops, water, and consumption of contaminated pollen and nectar from wild flowers and trees growing near-treated crops. Studies of food stores in honeybee colonies from across the globe demonstrate that colonies are routinely and chronically exposed to neonicotinoids, fipronil, and their metabolites (generally in the 1-100 ppb range), mixed with other pesticides some of which are known to act synergistically with neonicotinoids. Other nontarget organisms, particularly those inhabiting soils, aquatic habitats, or herbivorous insects feeding on noncrop plants in farmland, will also inevitably receive exposure, although data are generally lacking for these groups. We summarize the current state of knowledge regarding the environmental fate of these compounds by outlining what is known about the chemical properties of these compounds, and placing these properties in the context of modern agricultural practices.
Honey bee colonies are highly dependent upon the availability of floral resources from which they get the nutrients (notably pollen) necessary to their development and survival. However, foraging areas are currently affected by the intensification of agriculture and landscape alteration. Bees are therefore confronted to disparities in time and space of floral resource abundance, type and diversity, which might provide inadequate nutrition and endanger colonies. The beneficial influence of pollen availability on bee health is well-established but whether quality and diversity of pollen diets can modify bee health remains largely unknown. We therefore tested the influence of pollen diet quality (different monofloral pollens) and diversity (polyfloral pollen diet) on the physiology of young nurse bees, which have a distinct nutritional physiology (e.g. hypopharyngeal gland development and vitellogenin level), and on the tolerance to the microsporidian parasite Nosemaceranae by measuring bee survival and the activity of different enzymes potentially involved in bee health and defense response (glutathione-S-transferase (detoxification), phenoloxidase (immunity) and alkaline phosphatase (metabolism)). We found that both nurse bee physiology and the tolerance to the parasite were affected by pollen quality. Pollen diet diversity had no effect on the nurse bee physiology and the survival of healthy bees. However, when parasitized, bees fed with the polyfloral blend lived longer than bees fed with monofloral pollens, excepted for the protein-richest monofloral pollen. Furthermore, the survival was positively correlated to alkaline phosphatase activity in healthy bees and to phenoloxydase activities in infected bees. Our results support the idea that both the quality and diversity (in a specific context) of pollen can shape bee physiology and might help to better understand the influence of agriculture and land-use intensification on bee nutrition and health.
Synergistic combinations of biological and chemical insecticides might yield promising alternatives for soil insect pest management. In turfgrass of the Northeast U.S., control of root-feeding scarab larvae is highly dependent on conventional insecticides. Studies on interactions between entomopathogenic nematodes and neonicotinoid insecticides, however, demonstrate the feasibility of synergies as an approach for reduced-risk curative control. To understand the breadth of potential synergies, we screened numerous combinations of biological control agents with sublethal doses of neonicotinoids against third instars. Interactions were characterized as synergistic, additive or antagonistic. The most promising combinations identified in laboratory bioassays were advanced to greenhouse pot studies and then to field trials featuring microplots with artificially infested populations. To reveal variation across scarab species, trials were conducted on Amphimallon majale and Popillia japonica. Synergies were consistent across trials and specific to white grub species. For A. majale, synergistic combinations of Heterorhabditis bacteriophora with imidacloprid and clothianidin were discernible in laboratory, greenhouse and field trials. For P. japonica, synergistic combinations of Beauveria bassiana and Metarhizium anisopliae with both neonicotinoids were discernible in the laboratory and greenhouse, but not in the field. For both species, antagonistic interactions were discernible between Bt-products and both neonicotinoids. While nematode-neonicotinoid synergies among scarab larvae have been examined before, fungi-neonicotinoid synergies are unreported. In the context of previous studies, however, no patterns emerge to explain variation across target species or control agent. Further study of non-additive interactions will guide how biological and chemical products could be combined to enhance soil insect pest management.
This work was intended to evaluate the responses of enzymes in the honey bee Apis mellifera upon exposure to deltamethrin, fipronil and spinosad and their use as biomarkers. After LD50 determination, honey bees were exposed at doses of 5.07 and 2.53 ng/bee for deltamethrin, 0.58 and 0.29 ng/bee for fipronil and 4.71 and 2.36 ng/bee for spinosad (equivalent to LD50 /10 and LD50 /20, respectively). The responses of acetylcholinesterase (AChE), carboxylesterases (CaEs1-3), glutathione-S-transferase (GST), catalase (CAT) and alkaline phosphatase (ALP) were assessed. The results showed that deltamethrin, fipronil and spinosad modulated these biomarkers differentially. For the enzyme involved in the defense against oxidative stress, fipronil and spinosad induced CAT activity. For the remaining enzymes, three response profiles were identified: (i) Exposure to deltamethrin induced slight effects and modulated only CaE-1 and CaE-2 with opposite effects. (ii) Spinosad exhibited an induction profile for most of the biomarkers except AChE. (iii) Fipronil did not modulate AChE, CaE-2 or GST, increased CAT and CaE-1, and decreased ALP. Thus, this set of honey bee biomarkers appears to be a promising tool to evaluate environmental and honey bee health, and it could generate fingerprints to characterize exposures to pesticides. Environ Toxicol Chem © 2013 SETAC.
Adult honey bees are maintained in vitro in laboratory cages for a variety of purposes. For example, researchers may wish to perform experiments on honey bees caged individually or in groups to study aspects of parasitology, toxicology, or physiology under highly controlled conditions, or they may cage whole frames to obtain freshly emerged workers of known age cohorts. Regardless of purpose, researchers must manage a number of variables, ranging from selection of study subjects (e.g. honey bee subspecies) to experimental environment (e.g. temperature and relative humidity). Although decisions made by researchers may not necessarily jeopardize the scientific rigour of an experiment, they may profoundly affect results, and may make comparisons with similar, but independent, studies difficult. Focusing primarily on workers, we provide recommendations for maintaining adults under in vitro laboratory conditions, whilst acknowledging gaps in our understanding that require further attention. We specifically describe how to properly obtain honey bees, and how to choose appropriate cages, incubator conditions, and food to obtain biologically relevant and comparable experimental results. Additionally, we provide broad recommendations for experimental design and statistical analyses of data that arises from experiments using caged honey bees. The ultimate goal of this, and of all COLOSS BEEBOOK papers, is not to stifle science with restrictions, but rather to provide researchers with the appropriate tools to generate comparable data that will build upon our current understanding of honey bees.
In 2008 the COLOSS network was formed by honey bee experts from Europe and the USA. The primary objectives set by this scientific network were to explain and to prevent large scale losses of honey bee (Apis mellifera) colonies. In June 2008 COLOSS obtained four years support from the European Union from COST and was designated as COST Action FA0803 - COLOSS (Prevention of honey bee COlony LOSSes). To enable the comparison of loss data between participating countries, a standardized COLOSS questionnaire was developed. Using this questionnaire information on honey bee losses has been collected over two years. Survey data presented in this study were gathered in 2009 from 12 countries and in 2010 from 24 countries. Mean honey bee losses in Europe varied widely, between 7-22% over the 2008-9 winter and between 7-30% over the 2009-10 winter. An important finding is that for all countries which participated in 2008-9, winter losses in 2009-10 were found to be substantially higher. In 2009-10, winter losses in South East Europe were at such a low level that the factors causing the losses in other parts of Europe were absent, or at a level which did not affect colony survival. The five provinces of China, which were included in 2009-10, showed very low mean (4%) A. mellifera winter losses. In six Canadian provinces, mean winter losses in 2010 varied between 16-25%, losses in Nova Scotia (40%) being exceptionally high. In most countries and in both monitoring years, hobbyist beekeepers (1-50 colonies) experienced higher losses than practitioners with intermediate beekeeping operations (51-500 colonies). This relationship between scale of beekeeping and extent of losses effect was also observed in 2009-10, but was less pronounced. In Belgium, Italy, the Netherlands and Poland, 2008-9 mean winter losses for beekeepers who reported 'disappeared' colonies were significantly higher compared to mean winter losses of beekeepers who did not report 'disappeared' colonies. Mean 2008-9 winter losses for those beekeepers in the Netherlands who reported symptoms similar to "Colony Collapse Disorder" (CCD), namely: 1. no dead bees in or surrounding the hive while; 2. capped brood was present, were significantly higher than mean winter losses for those beekeepers who reported 'disappeared' colonies without the presence of capped brood in the empty hives. In the winter of 2009-10 in the majority of participating countries, beekeepers who reported 'disappeared' colonies experienced higher winter losses compared with beekeepers, who experienced winter losses but did not report 'disappeared' colonies.
In a comparative approach, we evaluated the effects of Cry1Ab protoxin, deltamethrin and imidacloprid insecticides on mortality, syrup consumption, foraging activity and olfactory learning capacities of free-flying honeybees. In an indoor flight cage we exposed bee colonies to different syrups containing Cry1Ab protoxin, deltamethrin or imidacloprid at 1000 mu g/kg, 500 mu g/kg and 48 mu g/kg, respectively. Cry1Ab did not affect mortality, syrup consumption or learning capacities. However, foraging activity was reduced during and after the treatment. Deltamethrin and imidacloprid both affected syrup consumption and foraging activity. Deltamethrin also induced a reduction in learning capacities. With the tested concentrations, our study suggests that for honeybees, synthetic insecticides such as deltamethrin may induce a greater hazard than Cry1Ab protein, potentially expressed in Bt corn pollen at concentrations lower than 1000 mu g/kg.
The impact of pesticides on honey bees is an issue that has been studied for many years and is now being reconsidered because con-troversy still exists with the relationship of insecticides and Colony Collapse Disorder (CCD). It is insufficient to explain CCD with only bee pathology studies. Research must be conducted on a wider series of causes: i) in open field and agroecosystems, to under-stand the fate of pesticide blends, ii) in the hives, to determine ways to enhance honey bee defence to diseases and parasites. Refer-ences regarding imidacloprid and CCD in the maize agroecosystems are critically reviewed. Pesticides and the thechniques to ra-tionally use them (in particular following the integrated pest management guidelines) represent one of the several puzzles regarding the mystery of CCD or honey bee vanishing. An appendix, i.e., a rejected letter to Science and relevant reply, is also reported.
The microsporidium Nosema ceranae is a newly prevalent parasite of the European honey bee (Apis mellifera). Although this parasite is presently spreading across the world into its novel host, the mechanisms by it which affects the bees and how bees respond are not well understood. We therefore performed an extensive characterization of the parasite effects at the molecular level by using genetic and biochemical tools. The transcriptome modifications at the midgut level were characterized seven days post-infection with tiling microarrays. Then we tested the bee midgut response to infection by measuring activity of antioxidant and detoxification enzymes (superoxide dismutases, glutathione peroxidases, glutathione reductase, and glutathione-S-transferase). At the gene-expression level, the bee midgut responded to N. ceranae infection by an increase in oxidative stress concurrent with the generation of antioxidant enzymes, defense and protective response specifically observed in the gut of mammals and insects. However, at the enzymatic level, the protective response was not confirmed, with only glutathione-S-transferase exhibiting a higher activity in infected bees. The oxidative stress was associated with a higher transcription of sugar transporter in the gut. Finally, a dramatic effect of the microsporidia infection was the inhibition of genes involved in the homeostasis and renewal of intestinal tissues (Wnt signaling pathway), a phenomenon that was confirmed at the histological level. This tissue degeneration and prevention of gut epithelium renewal may explain early bee death. In conclusion, our integrated approach not only gives new insights into the pathological effects of N. ceranae and the bee gut response, but also demonstrate that the honey bee gut is an interesting model system for studying host defense responses.
Chlorpyrifos (O,O′-diethyl O-3,5,6-trichloro-2-pyridyl phosphorothionate, CPF) exposure in rats causes elevation in the levels of thiobarbituric acid reactive substances (TBARS) and inhibition of acetylcholinesterase (AChE), superoxide dismutase (SOD), catalase (CAT), and glucose-6-phosphate dehydrogenase (G6PDH) activities in the liver, kidney, spleen, and brain of rats. The sublethal exposure of CPF also causes decrease in the levels of reduced glutathione (GSH) and consequent increase in oxidized glutathione (GSSG) levels, resulting in a significant decrease in GSH/GSSG ratio in all the rat tissues tested. These results clearly indicate that CPF exposure causes oxidative stress in rat tissues. However, CPF exposure to rats fed with antioxidant vitamins (vitamin A, E, and C) for 1 month, prevented derangement of these antioxidant parameters. The accumulation of TBARS was also not seen in tissues of rats fed with antioxidant vitamins on CPF exposure. AChE activity, which is sensitive to OP pesticides, was also not significantly inhibited in these rats on CPF exposure. The present findings clearly show that oral intake of a mixture of vitamin A, E, and C, protects the rats from CPF induced oxidative stress and suggesting that this treatment alleviates the toxicity of this pesticide.
In ecosystems, a variety of biological, chemical and physical stressors may act in combination to induce illness in populations of living organisms. While recent surveys reported that parasite-insecticide interactions can synergistically and negatively affect honeybee survival, the importance of sequence in exposure to stressors has hardly received any attention. In this work, Western honeybees (Apis mellifera) were sequentially or simultaneously infected by the microsporidian parasite Nosema ceranae and chronically exposed to a sublethal dose of the insecticide fipronil, respectively chosen as biological and chemical stressors. Interestingly, every combination tested led to a synergistic effect on honeybee survival, with the most significant impacts when stressors were applied at the emergence of honeybees. Our study presents significant outcomes on beekeeping management but also points out the potential risks incurred by any living organism frequently exposed to both pathogens and insecticides in their habitat.
Populations of honey bees and other pollinators have declined worldwide in recent years. A variety of stressors have been implicated as potential causes, including agricultural pesticides. Neonicotinoid insecticides, which are widely used and highly toxic to honey bees, have been found in previous analyses of honey bee pollen and comb material. However, the routes of exposure have remained largely undefined. We used LC/MS-MS to analyze samples of honey bees, pollen stored in the hive and several potential exposure routes associated with plantings of neonicotinoid treated maize. Our results demonstrate that bees are exposed to these compounds and several other agricultural pesticides in several ways throughout the foraging period. During spring, extremely high levels of clothianidin and thiamethoxam were found in planter exhaust material produced during the planting of treated maize seed. We also found neonicotinoids in the soil of each field we sampled, including unplanted fields. Plants visited by foraging bees (dandelions) growing near these fields were found to contain neonicotinoids as well. This indicates deposition of neonicotinoids on the flowers, uptake by the root system, or both. Dead bees collected near hive entrances during the spring sampling period were found to contain clothianidin as well, although whether exposure was oral (consuming pollen) or by contact (soil/planter dust) is unclear. We also detected the insecticide clothianidin in pollen collected by bees and stored in the hive. When maize plants in our field reached anthesis, maize pollen from treated seed was found to contain clothianidin and other pesticides; and honey bees in our study readily collected maize pollen. These findings clarify some of the mechanisms by which honey bees may be exposed to agricultural pesticides throughout the growing season. These results have implications for a wide range of large-scale annual cropping systems that utilize neonicotinoid seed treatments.
The influence of insecticides commonly used for agricultural purposes on beehive depopulation in Uruguay was investigated. Honeycombs, bees, honey and propolis from depopulated hives were analyzed for pesticide residues, whereas from active beehives only honey and propolis were evaluated. A total of 37 samples were analyzed, representing 14,800 beehives. In depopulated beehives only imidacloprid and fipronil were detected and in active beehives endosulfan, coumaphos, cypermethrin, ethion and chlorpyrifos were found. Coumaphos was present in the highest concentrations, around 1,000 μg/kg, in all the propolis samples from active beehives. Regarding depopulated beehives, the mean levels of imidacloprid found in honeycomb (377 μg/kg, Standard Deviation: 118) and propolis (60 μg/kg, Standard Deviation: 57) are higher than those described to produce bee disorientation and fipronil levels detected in bees (150 and 170 μg/kg) are toxic per se. The other insecticides found can affect the global fitness of the bees causing weakness and a decrease in their overall productivity. These preliminary results suggest that bees exposed to pesticides or its residues can lead them in different ways to the beehive.
One of the factors that may explain nowadays honeybees' colonies losses is the increasing presence of chemicals in the environment. The aim of this study is to obtain a global view of the presence of environmental contaminants in beehives and, develop a fast, cheap and sensitive tool to analyze environmental contaminants in apiarian matrices. A multi residue analysis was developed to quantify 80 environmental contaminants, pesticides and veterinary drugs, belonging to different chemical classes, in honeys, honeybees and pollens. It consists in a single extraction, based on a modified "QuEChERS method", followed by gas chromatography coupled with Time of Flight mass spectrometry (GC-ToF) and liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). The "QuEChERS method" combines salting-out liquid-liquid extraction with acetonitrile and a dispersive-SPE clean up. It was adjusted to honey and especially to honeybee and pollen, by adding a small fraction of hexane in acetonitrile to eliminate lipids that interfere with mass spectrometry analysis. This method, combined with accurate and sensitive detection, allowed quantification and confirmation at levels as low as 10 ng/g, with recoveries between 60 and 120%. Application to more than 100 samples of each matrix was achieved for a global view of pesticide presence in the honeybee environment. Relatively high percentages of honeys, honeybees and pollens were found to be contaminated by pesticides used to combat varroa but also by fungicides like carbendazim and ubiquitous contaminants.
Background:
The honeybee, Apis mellifera, is undergoing a worldwide decline whose origin is still in debate. Studies performed for twenty years suggest that this decline may involve both infectious diseases and exposure to pesticides. Joint action of pathogens and chemicals are known to threaten several organisms but the combined effects of these stressors were poorly investigated in honeybees. Our study was designed to explore the effect of Nosema ceranae infection on honeybee sensitivity to sublethal doses of the insecticides fipronil and thiacloprid.
Methodology/finding:
Five days after their emergence, honeybees were divided in 6 experimental groups: (i) uninfected controls, (ii) infected with N. ceranae, (iii) uninfected and exposed to fipronil, (iv) uninfected and exposed to thiacloprid, (v) infected with N. ceranae and exposed 10 days post-infection (p.i.) to fipronil, and (vi) infected with N. ceranae and exposed 10 days p.i. to thiacloprid. Honeybee mortality and insecticide consumption were analyzed daily and the intestinal spore content was evaluated 20 days after infection. A significant increase in honeybee mortality was observed when N. ceranae-infected honeybees were exposed to sublethal doses of insecticides. Surprisingly, exposures to fipronil and thiacloprid had opposite effects on microsporidian spore production. Analysis of the honeybee detoxification system 10 days p.i. showed that N. ceranae infection induced an increase in glutathione-S-transferase activity in midgut and fat body but not in 7-ethoxycoumarin-O-deethylase activity.
Conclusions/significance:
After exposure to sublethal doses of fipronil or thiacloprid a higher mortality was observed in N. ceranae-infected honeybees than in uninfected ones. The synergistic effect of N. ceranae and insecticide on honeybee mortality, however, did not appear strongly linked to a decrease of the insect detoxification system. These data support the hypothesis that the combination of the increasing prevalence of N. ceranae with high pesticide content in beehives may contribute to colony depopulation.
In the last decade, an increase in honey bee (Apis mellifera L.) colony losses has been reported in several countries. The causes of this decline are still not clear. This study was set out to evaluate the pesticide residues in stored pollen from honey bee colonies and their possible impact on honey bee losses in Spain. In total, 1,021 professional apiaries were randomly selected. All pollen samples were subjected to multiresidue analysis by gas chromatography-mass spectrometry (MS) and liquid chromatography-MS; moreover, specific methods were applied for neonicotinoids and fipronil. A palynological analysis also was carried out to confirm the type of foraging crop. Pesticide residues were detected in 42% of samples collected in spring, and only in 31% of samples collected in autumn. Fluvalinate and chlorfenvinphos were the most frequently detected pesticides in the analyzed samples. Fipronil was detected in 3.7% of all the spring samples but never in autumn samples, and neonicotinoid residues were not detected. More than 47.8% of stored pollen samples belonged to wild vegetation, and sunflower (Heliantus spp.) pollen was only detected in 10.4% of the samples. A direct relation between pesticide residues found in stored pollen samples and colony losses was not evident accordingly to the obtained results. Further studies are necessary to determine the possible role of the most frequent and abundant pesticides (such as acaricides) and the synergism among them and with other pathogens more prevalent in Spain.
Transgenic Cry1Ac+CpTI cotton (CCRI41) is a promising cotton cultivar throughout China but side effects and especially sublethal effects of this transgenic cultivar on beneficial insects remain poorly studied. More specifically potential sublethal effects on behavioural traits of the honey bee Apis mellifera L. have not been formally assessed despite the importance of honey bees for pollination. The goal of our study was to assess potential effects of CCRI41 cotton pollen on visual and olfactory learning by honey bees. After a 7-day oral chronic exposure to honey mixed with either CCRI41 pollen, imidacloprid-treated conventional pollen (used as positive sublethal control) or conventional pollen (control), learning performance was evaluated by the classical proboscis extension reflex (PER) procedure as well as a T-tube maze test. The latter assay was designed as a new device to assess potential side effects of pesticides on visual associative learning of honey bees. These two procedures were complementary because the former focused on olfactory learning while the latter was involved in visual learning based on visual orientation ability. Oral exposure to CCRI41 pollen did not affect learning capacities of honey bees in both the T-tube maze and PER tests. However, exposure to imidacloprid resulted in reduced visual learning capacities in T-tube maze evaluation and decreased olfactory learning performances measured with PER. The implications of these results are discussed in terms of risks of transgenic CCRI41 cotton crops for honey bees.
Background
Honey bees are an essential component of modern agriculture. A recently recognized ailment, Colony Collapse Disorder (CCD), devastates colonies, leaving hives with a complete lack of bees, dead or alive. Up to now, estimates of honey bee population decline have not included losses occurring during the wintering period, thus underestimating actual colony mortality. Our survey quantifies the extent of colony losses in the United States over the winter of 2007–2008.
Methodology/Principal Findings
Surveys were conducted to quantify and identify management factors (e.g. operation size, hive migration) that contribute to high colony losses in general and CCD symptoms in particular. Over 19% of the country's estimated 2.44 million colonies were surveyed. A total loss of 35.8% of colonies was recorded; an increase of 11.4% compared to last year. Operations that pollinated almonds lost, on average, the same number of colonies as those that did not. The 37.9% of operations that reported having at least some of their colonies die with a complete lack of bees had a total loss of 40.8% of colonies compared to the 17.1% loss reported by beekeepers without this symptom. Large operations were more likely to have this symptom suggesting that a contagious condition may be a causal factor. Sixty percent of all colonies that were reported dead in this survey died without dead bees, and thus possibly suffered from CCD. In PA, losses varied with region, indicating that ambient temperature over winter may be an important factor.
Conclusions/Significance
Of utmost importance to understanding the recent losses and CCD is keeping track of losses over time and on a large geographic scale. Given that our surveys are representative of the losses across all beekeeping operations, between 0.75 and 1.00 million honey bee colonies are estimated to have died in the United States over the winter of 2007–2008. This article is an extensive survey of U.S. beekeepers across the continent, serving as a reference for comparison with future losses as well as providing guidance to future hypothesis-driven research on the causes of colony mortality.
Newly emerged adult honey bees, Apis mellifera L., were fed with a pollen-based food containing various additives: purified and activated Cry 1Ba δ-endotoxin, from Bacillus thuringiensis Bt4412 (Bt) (1, 0.25 and 0.025 % w/w), Bt biopesticide preparations, Dipel 2X (1 and 0.25 %) and Foray 48B (0.25 %), and Kunitz soybean trypsin inhibitor (SBTI) (1, 0.5 or 0.05 %). The bees received these foods for 7 days and were then given control food without additives for the rest of their lives. Bee survival time was unaffected, and the food was consumed at the same rate as control food for all treatments, except 1 % Dipel, where both survival and food consumption were significantly reduced. A second experiment showed that bees completely deprived of the pollen-based food also had poorer survival than those fed with the control food. Adult bees are unlikely to be harmed by transgenic plants expressing Cry1Ba or SBTI, or by Bt biopesticides that are used as recommended. © Inra/DIB/AGIB/Elsevier, Paris
Recent declines in honey bees for crop pollination threaten fruit, nut, vegetable and seed production in the United States. A broad survey of pesticide residues was conducted on samples from migratory and other beekeepers across 23 states, one Canadian province and several agricultural cropping systems during the 2007-08 growing seasons.
We have used LC/MS-MS and GC/MS to analyze bees and hive matrices for pesticide residues utilizing a modified QuEChERS method. We have found 121 different pesticides and metabolites within 887 wax, pollen, bee and associated hive samples. Almost 60% of the 259 wax and 350 pollen samples contained at least one systemic pesticide, and over 47% had both in-hive acaricides fluvalinate and coumaphos, and chlorothalonil, a widely-used fungicide. In bee pollen were found chlorothalonil at levels up to 99 ppm and the insecticides aldicarb, carbaryl, chlorpyrifos and imidacloprid, fungicides boscalid, captan and myclobutanil, and herbicide pendimethalin at 1 ppm levels. Almost all comb and foundation wax samples (98%) were contaminated with up to 204 and 94 ppm, respectively, of fluvalinate and coumaphos, and lower amounts of amitraz degradates and chlorothalonil, with an average of 6 pesticide detections per sample and a high of 39. There were fewer pesticides found in adults and brood except for those linked with bee kills by permethrin (20 ppm) and fipronil (3.1 ppm).
The 98 pesticides and metabolites detected in mixtures up to 214 ppm in bee pollen alone represents a remarkably high level for toxicants in the brood and adult food of this primary pollinator. This represents over half of the maximum individual pesticide incidences ever reported for apiaries. While exposure to many of these neurotoxicants elicits acute and sublethal reductions in honey bee fitness, the effects of these materials in combinations and their direct association with CCD or declining bee health remains to be determined.
The hazard posed to honeybees by systemic insecticides is determined by toxicity tests that are designed to study the effects of insecticides applied on the aerial parts of plants, but are not adapted to systemic substances used as soil or seed treatments. Based on the available data found in the literature, this paper proposes modes of honeybees exposure to systemic insecticides by estimating their pollen and nectar consumption. Estimates are given for larvae and for the categories of adults which consume the highest amounts of – pollen, the nurse bees, and – nectar, the wax-producing bees, the brood attending bees, the winter bees, and the foraging bees. As a case study, we illustrate these estimates with the example of imidacloprid because its concentrations in sunflower nectar and in sunflower and maize pollens of seed-dressed plants have been precisely determined, and because its levels of lethal, sublethal, acute, and chronic toxicities have been extensively investigated.