Apis mellifera ligustica, Spinola 1806 as bioindicator for detecting environmental contamination: a preliminary study of heavy metal pollution in Trieste, Italy

Impact of copper and zinc oral chronic exposure on Carniolan honey bee survival and feeding preference

Honey bees are important plant pollinators and honey producers. Contamination of the environment with metals can lead to a decline in honey bee populations. Copper (Cu) and zinc (Zn) salts are commonly used as fungicides and foliar fertilizers. In this study, we investigated the effects of 10-day chronic oral exposure to different concentrations of Cu (CuSO4) and Zn (ZnCl2) on survival and feeding rates of Carniolan honey bees in laboratory conditions. We found that mortality in honey bee workers increased in a concentration-dependent manner and that Cu (lethal concentration [LC50] = 66 mg/l) was more toxic than Zn (LC50 = 144 mg/l). There was no difference in the feeding rate of Cu-treated bees for the different concentrations tested, but the feeding rate decreased with the increase in Zn concentration. To determine feeding preference or avoidance for Cu and Zn, we conducted 2-choice 24-h feeding experiments. We demonstrated that honey bees preferred Zn-containing solutions compared to the control diet. A two-choice experiment with Cu showed a tendency for honey bees to be deterred by Cu at high concentrations; however, it was not statistically significant. In summary, our results suggest that honey bee workers may suffer adverse effects when exposed to ecologically relevant concentrations of Cu and Zn.

Foraging Activity of Honey Bees (Apis mellifera L., 1758) and Exposure to Cadmium: a Review

Honey bees are commonly exposed to a broad spectrum of xenobiotics, including heavy metals. Heavy metal toxicity is of concern in the context of global pollinator declines, especially since honey bees seem to be particularly susceptible to xenobiotics in general. Here we summarize current knowledge on the interplay between cadmium, one of the most toxic and mobile elements in the environment, and honey bees, the primary managed pollinator species worldwide. Overall, cadmium pollution has been shown to be ubiquitous, affecting industrial, urban and rural areas alike. Uptake of this heavy metal by plants serves as the primary route of exposure for bees (through pollen and nectar). Reported cadmium toxicity consists of lethal and sublethal effects (reduced development and growth) in both adult and larval stages, as well as various molecular responses related to detoxification and cellular antioxidant defence systems. Other effects of cadmium in honey bees include the disruption of synaptic signalling, calcium metabolism and muscle function.

Methylation and bio-accessibility assessment of arsenate in crickets (Gryllusbimaculatus)

The ability of an organism to biomethylate toxic inorganic arsenic (As) determines both, the amount of As available for uptake higher up the food chain and the toxicity of bioavailable As. An exposure study was conducted to determine ability of farmed crickets to metabolize dietary arsenate. Crickets were exposed to 1.3 ± 0.1, 5.1 ± 2.5 and 36.3 ± 5.6 mg kg-1 dietary arsenate and quantitation of total As showed retention of 0.416 ± 0.003, 1.3 ± 0.04 and 2.46 ± 0.09 mg kg-1, respectively. Speciation analysis revealed that crickets have well developed ability to biomethylate dietary arsenate and the most abundant methylated As compound was DMA followed by MMA, TMAO and an unknown compound. Arsenobetaine, although present in all feed, control and As-rich, was measured only in the control crickets. To assess the bio-accessibility of the As species, crickets were subjected to simulated gastrointestinal digestion. The results showed that majority of As was extracted in saliva, followed by gastric and intestinal juice, which mass fraction was equal to residue. Over 78% of total As was shown to be bio-accessible with methylated species reaching 100% and iAs over 79% bio-accessibility. Additionally, arsenite and arsenate have shown different distributions between sequential leachate solutions. Bioaccumulation of As was observed in the studied crickets although it does not seem to occur to the same extent at higher exposure levels.

Elemental Fingerprinting Combined with Machine Learning Techniques as a Powerful Tool for Geographical Discrimination of Honeys from Nearby Regions

Discrimination of honey based on geographical origin is a common fraudulent practice and is one of the most investigated topics in honey authentication. This research aims to discriminate honeys according to their geographical origin by combining elemental fingerprinting with machine-learning techniques. In particular, the main objective of this study is to distinguish the origin of unifloral and multifloral honeys produced in neighboring regions, such as Sardinia (Italy) and Spain. The elemental compositions of 247 honeys were determined using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The origins of honey were differentiated using Principal Component Analysis (PCA), Linear Discriminant Analysis (LDA), and Random Forest (RF). Compared to LDA, RF demonstrated greater stability and better classification performance. The best classification was based on geographical origin, achieving 90% accuracy using Na, Mg, Mn, Sr, Zn, Ce, Nd, Eu, and Tb as predictors.

Effects of arsenic and selenium pollution on wild bee communities in the agricultural landscapes

Wild bees play crucial roles in pollinating numerous crops and fruits worldwide. However, these essential insect pollinators are threatened with decline due to a variety of stressors. Among stressors, relatively little work has been done on metalloid pollution. Laboratory experiments have shown that arsenic (As) and selenium (Se) can negatively impact on bees, it is unknown if these effects translate in real-world environments. To address this knowledge gap, wild bee communities were sampled from 18 smallholder farmlands in Kaihua County in Quzhou, Southeast China and As and Se concentrations in three bee species were measured (Xylocopa tranquebarorum, Eucera floralia, and Apis cerana). Analyses revealed that the large carpenter bee, X. tranquebarorum, exhibited significantly lower As and Se concentrations than the other two wild bee species. No significant correlations were found between As and Se concentrations in all three wild bee species. Interestingly, the proportion of semi-natural habitat was found to be significantly related to reduced Se concentration in wild bee bodies, though no such effect was observed for As. As pollution negatively impacted bee diversity but not abundance, whereas Se significantly impacted neither bee diversity nor abundance. Furthermore, both As and Se pollution had no significant effect on the abundance of small-bodied wild bees. Given the essential role of wild bees for pollination services, monitoring of As and Se pollution in wild bee bodies and their food resources (pollen and nectar) is recommended across agricultural and other potentially impacted systems.

Elucidating the Role of Honey Bees as Biomonitors in Environmental Health Research

Recently, the One Health concept, which recognizes the interconnectedness of environmental, animal, and human health, has gained popularity. To collect data on environmental pollutants potentially harmful to human health over time, researchers often turn to natural organisms known as biomonitors. Honey bees, in particular, prove to be exceptionally valuable biomonitors due to their capacity to accumulate pollutants from the air, soil, and water within a specific radius during their foraging trips. This systematic literature review summarizes the previous application of the bee species Apis mellifera in pollutant monitoring in articles published during the period of 2010-2020. Nineteen studies were included in this systematic literature review. Of these studies, the majority (n = 15) focused on the detection of heavy metals in honey bees and beehive products, while 4 studies focused on air pollution by polycyclic aromatic hydrocarbons or particulate matter. The matrix most often applied was the whole honey bee. The included studies demonstrated that honey bees and hive products deliver quantitative and qualitative information about specific pollutants. In this regard, the whole honey bee was found to be the most reliable biomonitor. We found that the included studies differed in design and the methods used. Standardized studies could foster a more consistent interpretation of the levels detected in beehive matrices from an environmental health perspective.

The impact of heavy metal pollution on wild bee communities in smallholder farmlands

Wild bees provide important pollination services, but they face numerous stressors that threaten them and their ecosystem services. Wild bees can be exposed to heavy metal pollution through the consumption of nectar, pollen, and water, which might cause bee decline. While some studies have measured heavy metal concentrations in honeybees, few studies have monitored heavy metal concentrations in wild bees or explored their potential effects on wild bee communities. To investigate the impact of heavy metal pollution on wild bee communities, heavy metal concentrations, including vanadium (V), chromium (Cr), nickel (Ni), cadmium (Cd), Zinc (Zn) and lead (Pb) in multiple wild bee species were measured. Multiple wild bee species, including: Xylocopa tranquabaroroum, Eucera floralia, Apis cerana, and small bee mixtures (representing multiple small wild bee species) were sampled from 18 sites in Quzhou, Zhejiang Province, China. The findings demonstrated that there were significant differences in heavy metal concentrations among different bee species. The concentrations of V, Zn, Cd, and Pb in X. tranquabaroroum, the largest bee species in this study, were lower than that in the other three sample groups. Furthermore, there were significant negative correlations between heavy metal pollution and wild bee diversity and species richness, but not with abundance. Particularly, there was no significant relationship between heavy metal pollution and the abundance of small bees. Given these worrying findings, monitoring multiple heavy metals in wild bees should be conducted for protecting wild bee diversity and securing their pollination services.

Applying Artificial Neural Networks to Oxidative Stress Biomarkers in Forager Honey Bees (Apis mellifera) for Ecological Assessment

Insect pollinators provide an important ecosystem service that supports global biodiversity and environmental health. The study investigates the effects of the environmental matrix on six oxidative stress biomarkers in the honey bee Apis mellifera. Thirty-five apiaries located in urban, forested, and agricultural areas in Central Italy were sampled during the summer season. Enzyme activities in forager bees were analyzed using an artificial neural network, allowing the identification and representation of the apiary patterns in a Self-Organizing Map. The SOM nodes were correlated with the environmental parameters and tissue levels of eight heavy metals. The results indicated that the apiaries were not clustered according to their spatial distribution. Superoxide dismutase expressed a positive correlation with Cr and Mn concentrations; catalase with Zn, Mn, Fe, and daily maximum air temperature; glutathione S-transferase with Cr, Fe, and daily maximal air temperature; and glutathione reductase showed a negative correlation to Ni and Fe exposure. This study highlights the importance of exploring how environmental stressors affect these insects and the role of oxidative stress biomarkers. Artificial neural networks proved to be a powerful approach to untangle the complex relationships between the environment and oxidative stress biomarkers in honey bees. The application of SOM modeling offers a valuable means of assessing the potential effects of environmental pressures on honey bee populations.

Triazine Herbicide and NPK Fertilizer Exposure: Accumulation of Heavy Metals and Rare Earth Elements, Effects on Cuticle Melanization, and Immunocompetence in the Model Species Tenebrio molitor

The increasing use of agrochemicals, including fertilizers and herbicides, has led to worrying metal contamination of soils and waters and raises serious questions about the effects of their transfer to different levels of the trophic web. Accumulation and biomagnification of essential (K, Na, Mg, Zn, Ca), nonessential (Sr, Hg, Rb, Ba, Se, Cd, Cr, Pb, As), and rare earth elements (REEs) were investigated in newly emerged adults of Tenebrio molitor exposed to field-admitted concentrations of a metribuzin-based herbicide and an NPK blend fertilizer. Chemical analyses were performed using inductively coupled plasma tandem mass spectrometry (ICP-MS/MS) supported by unsupervised pattern recognition techniques. Physiological parameters such as cuticle melanization, cellular (circulating hemocytes), and humoral (phenoloxidase enzyme activity) immune responses and mass loss were tested as exposure markers in both sexes. The results showed that NPK fertilizer application is the main cause of REE accumulation in beetles over time, besides toxic elements (Sr, Hg, Cr, Rb, Ba, Ni, Al, V, U) also present in the herbicide-treated beetles. The biomagnification of Cu and Zn suggested a high potential for food web transfer in agroecosystems. Gender differences in element concentrations suggested that males and females differ in element uptake and excretion. Differences in phenotypic traits show that exposure affects metabolic pathways involving sequestration and detoxification during the transition phase from immature-to-mature beetles, triggering a redistribution of resources between sexual maturation and immune responses. Our findings highlight the importance of setting limits for metals and REEs in herbicides and fertilizers to avoid adverse effects on species that provide ecosystem services and contribute to soil health in agroecosystems.

Biomonitoring of polycyclic aromatic hydrocarbons, heavy metals, and plasticizers residues: role of bees and honey as bioindicators of environmental contamination

Polycyclic aromatic hydrocarbons (PAHs), heavy metals, and plasticizer residues are continuously released into the environment. The use of living organisms, such as Apis mellifera L. and honey, is advantageous as bioindicator of the environmental health status, instead of traditional monitoring methods, showing the ability to record spatial and temporal pollutant variations. The PAHs and heavy metal presence were determined in two sampling years (2017 and 2018) in five different locations in the Molise region (Italy), characterized by different pollution levels. During 2017, most PAHs in all samples were lower than limit of detection (LOD), while in 2018, their mean concentration in bee and honey samples was of 3 μg kg^-1 and 35 μg kg^-1, respectively. For heavy metals, lower values were detected in 2017 (Be, Cd, and V below LOD), while in 2018, the mean concentrations were higher, 138 μg kg^-1 and 69 μg kg^-1, in bees and honey, respectively. Honey has been used as indicator of the presence of phthalate esters and bisphenol A in the environment. The satisfactory results confirmed that both bees and honey are an important tool for environmental monitoring. The chemometric analysis highlighted the differences in terms of pollutant concentration and variability in the different areas, validating the suitability of these matrices as bioindicators.

Probiotics as a promising prophylactic tool to reduce levels of toxic or potentially toxic elements in bees

Bees are precious living beings for our planet. Thanks to their essential service of pollination, these insects allow the maintenance of biodiversity and the variety and amount of food available. Unfortunately, we are observing an increasingly devastating reduction of bee families and other pollinating insects for factors related to human activities, environmental pollution, diseases and parasites, compromise of natural habitats, and climate change. We show that probiotics can protect bees from element pollution. We collected bees, beeswax, honey, pollen, and propolis directly from hives in a rural area of central Italy to investigate the content of 41 elements in control (not supplemented with probiotics) and experimental (supplemented with probiotics) groups. Our data show a significantly lower concentration of some elements (Ba, Be, Cd, Ce, Co, Cu, Pb, Sn, Tl, and U) in experimental bees than in control groups, indicating a possible beneficial effect of probiotics in reducing the absorption of chemicals. This study presents the first data on element levels after probiotics have been fed to bees and provides the basis for future research in several activities relating to the environment, agriculture, economy, territory, and medicine.

Heavy metal exposure and behavioral assessment of vultures in a captive environment

Heavy metals are a heterogeneous group of metals that can cause detrimental biological disruptions in vultures. Heavy metals play a threatening role and affect vulture populations around the globe. However, various conservation organizations are working for the captive breeding of these endangered animals so that they can reintroduce these captive-bred animals back to their natural environment. This research study was conducted at Changa Manga Vulture Conservatory, Punjab, with the help of Punjab Wildlife Department. A non-invasive technique was used to collect vulture feathers and fecal samples to study the exposure of heavy metals. The behavior of vultures in captivity was also recorded. Samples were chemically digested in aqua regia and analyzed for the detection of five heavy metal concentrations such as chromium (Cr), cadmium (Cd), lead (Pb), zinc (Zn), and magnesium (Mg) using flame atomic absorption spectroscopy (FAAS). Among the selected heavy metals, non-essential metals such as Pb, Cr, and Cd were recorded in the least concentration, whereas essential metals Zn and Mg were recorded in the highest concentration. Behavioral studies showed that vultures in captivity become excessively hostile and afraid of any human interaction; they flew to the top of the trees if they felt any danger. It was concluded in the study that the higher levels of both essential and non-essential metals recorded in feathers and fecal samples might be due to the type of feed, even though a controlled food is provided to vultures in captivity. However, regular monitoring of the environment can bring improvements to the health of vultures in captivity and help to find accurate sources of contamination.

Effects of Covid-19 pandemic lockdown and environmental pollution assessment in Campania region (Italy) through the analysis of heavy metals in honeybees

The Covid-19 outbreak had a critical impact on a massive amount of human activities as well as the global health system. On the other hand, the lockdown and related suspension of working activities reduced pollution emissions. The use of biomonitoring is an efficient and quite recent tool to assess environmental pollution through the analysis of a proper bioindicator, such as bees. This study set out to ascertain the impact of the Covid-19 pandemic lockdown on the environmental occurrence of eleven heavy metals in the Campania region (Italy) by analyzing bees and bee products. A further aim of this study was the assessment of the Honeybee Contamination Index (HCI) in three different areas of the Campania region and its comparison with other Italian areas to depict the current environmental pollutants levels of heavy metals. The results showed that the levels of heavy metals bioaccumulated by bees during the pandemic lockdown (T1) were statistically lower than the sampling times after Covid-19 restrictions and the resumption of some or all activities (T2 and T3). A comparable trend was observed in wax and pollen. However, bee, pollen, and wax showed higher levels of Cd and Hg in T1 than T2 and T3. The analysis of the HCI showed a low contamination level of the sampling sites for Cd and Pb, and an intermediate-high level as regards Ni and Cr. The biomonitoring study highlighted a decrease of heavy metals in the environmental compartments due to the intense pandemic restrictions. Therefore, Apis mellifera and other bee products remain a reliable and alternative tool for environmental pollution assessment.

Arsenic speciation analysis in honey bees for environmental monitoring

Arsenic can be toxic to living organisms, depending not only on the concentration, but also its chemical form. The aim of this study was to determine arsenic concentrations and perform arsenic speciation analysis for the first time in honeybees, to evaluate their potential as biomonitors. Highest arsenic concentrations were determined in the vicinity of coal fired thermal power plants (367 µg kg^-1), followed by an urban region (213 µg kg^-1), with much lower concentrations in an industrial city (28.8 µg kg^-1) and rural areas (41 µg kg^-1). Until now, honey bees have never been used to study different arsenic species in the environment. For this reason, four extraction procedures were tested: water, hot water at 90 °C, 20% methanol, and 1% formic acid. Water at 90 °C was able to extract more than 90% of the total arsenic from honey bee samples. Inorganic arsenic (the sum of arsenite and arsenate) accounted for 95% of arsenic species in bees from three locations, except the industrial city, where it represented only 80% of arsenic species, while 15% was present as DMA.

Biomonitoring of element contamination in bees and beehive products in the Rome province (Italy)

In this study, we determined the levels of elements (i.e. As, Be, Cd, Cr, Hg, Ni, Pb, U, and Zn) in bees and edible beehive products (honey, wax, pollen, and propolis) sampled from five selected sites in the Rome province (Italy).

RATIONALE

to increase the information variety endowment, the monitoring breakdown structure (MBS) conceptual model was used (nine elements, 429 samples, and approximately thirteen thousand determinations over a 1-year survey). Thus, we employed Johnson's probabilistic method to build the control charts. Then, we measured the element concentration overlap ranges and the overlap bioaccumulation index (OBI). Subsequently, we evaluated the estimated daily intake (EDI) of the analysed elements and matched them with acceptable reference doses. The human health risk caused by the intake of individual elements found in edible beehive products and their risk summation were evaluated through the target hazard quotient (THQ) and hazard index (HI) methods.

FINDINGS

excluding honey, this study confirms the capacity of wax, pollen, propolis, and bees to accumulate high levels of toxic and potentially toxic elements from the surrounding environment (with high OBI-U, i.e. OBI-Upper values, i.e. the common upper concentration limit of the overlap concentration range). Bees and pollen showed a high bioaccumulation Cd surplus (OBI-U = 44.0 and 22.3, respectively). On the contrary, honey had high OBI-L values (i.e. honey concentrates metals several times less than the common lower concentration limit of the overlap concentration range). This finding implies that honey is useless as an environmental indicator compared with the other biomonitor/indicators. The EDI values for the edible beehive products were lower than the health and safety reference doses for all the considered elements. Our data show that honey, wax, propolis, and pollen are safe for consumption by both adults and children (THQ < 1; HI < 1), even considering the sporadic possibility of consuming them simultaneously.

ORIGINALITY

This study has been conducted for the first time in the Rome province and demonstrates that edible indicators are safe for consumption for the considered elements in bees and edible beehive products. Depending on the ecosystem/pollutants studied, the OBI consents to make a correct choice for environmental biomonitoring studies and to focus the attention on the most sensitive biomonitors/indicators when required at the project level.

Honeybees as Bioindicators of Heavy Metal Pollution in Urban and Rural Areas in the South of Italy

The honeybee (Apis mellifera L.) has been used in several studies for monitoring the environmental health status in terms of pollution, due to its wide-ranging foraging flights. Based on this consideration, this study aimed to analyze heavy metal pollution in Molise Region (Italy), by investigating five sites characterized by different levels of contamination. Furthermore, the authors carried out a sampling activity for a long period, in order to obtain a complete dataset. In this way, detailed information about the status of the environments was able to be obtained. The main purpose of this work was to assess the health status of Molise Region and to confirm the suitability of honeybees as environmental bioindicators of heavy metal pollution, by analyzing their variability over time and space. Furthermore, the study compared the health status associated with contamination in terms of heavy metals with that in two different areas of Italy, using hierarchical cluster analysis and principal component analysis, to evaluate the correlation existing among the three different areas of Italy. Following the findings, the authors suggest the use of honeybees as a bioindicator for heavy metal pollution in air quality studies.

Rethinking the Connections between Ecosystem Services, Pollinators, Pollution, and Health: Focus on Air Pollution and Its Impacts

Ecosystems provide many services that are essential for human activities and for our well-being. Many regulation services are interconnected and are fundamental in mitigating and hindering the negative effects of several phenomena such as pollution. Pollution, in particular airborne particulate matter (PM), represents an important risk to human health. This perspective aims at providing a current framework that relates ecosystem services, regulating services, pollination, and human health, with particular regards to pollution and its impacts. A quantitative literature analysis on the topic has been adopted. The health repercussions of problems related to ecosystem services, with a focus on the effects of atmospheric particulate matter, have been highlighted in the work throughout a case study. In polluted environments, pollinators are severely exposed to airborne PM, which adheres to the insect body hairs and can be ingested through contaminated food resources, i.e., pollen and honey. This poses a serious risk for the health of pollinators with consequences on the pollination service and, ultimately, for human health.

Honeybees as a biomonitoring species to assess environmental airborne pollution in different socioeconomic city districts

Honeybees have been used in Europe as environmental bioindicators for heavy metals and polycyclic aromatic hydrocarbons (PAHs). However, their potential has been little explored in North America, especially between environments which have similar pollution levels. Many urban residents and stakeholders are concerned with air quality, mainly in regard to gradients of exposure to industrial pollution between deprived and privileged subpopulation. Thus, the aim of this study was to evaluate the use of honeybees as bioindicators to assess exposure to heavy metals and PAHs in Québec City, Canada, in different socioeconomic districts of Quebec City (deprivation index). Honeybees were sampled over a 5-month period (May to September) at six locations distributed in two urban areas that are distinct geomorphologically and socioeconomically (lower town socio-economically deprived and upper town socioeconomically privileged) and two control rural locations. Six PAHs were analyzed by ultra-performance liquid chromatography (UPLC), while four heavy metals were analyzed by inductively coupled plasma mass spectrometry. Arsenic was the only measured pollutant that showed a significant gradient of exposure between rural and urban environments, but also between the two urban areas. Furthermore, we were able to detect significant differences at certain sampling times for heavy metals and PAHs. Overall, the results show that honeybees are sensitive enough to detect differences between the differential urban environments of a city presumed to have similar pollution levels and therefore could be used when potential socio-environmental inequalities are present.

Potential risks from the accumulation of heavy metals in canola plants

Concentrations of heavy metals in agricultural land near highways are a major concern for humans. This study was conducted to investigate the contamination level of heavy metals in soil, canola crop, and the potential health risk for honeybee and human. The average concentrations (mg/kg) of Co (15.94), Cr (169.66), Ni (55.39), Mn (765.34) Hg (2.99), and Cu (51.31) were elevated beyond their background reference values in world soil average, while Pb (9.45) was below to their respective background levels. This was confirmed by contamination factor (CF) and ecological risk factors (Er). Heavy metal concentrations in different parts of canola decreased in the following order: Fe> Mn > Cr > Pb > Co > Cu > Ni > Hg. Honey transfer factor (TF_H) of heavy metals was less than unity except Ni and Hg. Human health (non-carcinogenic) risk assessment of heavy metals in the soil through potential exposure pathway (ingestion) recorded a dramatically increased risk for children (hazard index, HI=2.44). Hazard quotient via honey (HQ_H) consumption value of heavy metals were within the safe limits (HQ< 1). Probably, honeybees have a strong ability to transfer Co, Pb, Hg, and Mn (HQ> 1) from the canola to their hives during collecting pollen and nectar. HQ in honeybee workers from the consumption of honey can be used to derive HQ in humans using the hazard factor (HF). HF is 1481.482 (Pb), 2356.902 (Ni), and 3888.889 (Cr), respectively, for adult human (70kg) and 317.460 (Pb), 504.377(Ni), and 832.22 (Cr) for children (15kg).

Pesticides in honey bee colonies: Establishing a baseline for real world exposure over seven years in the USA

Honey bees Apis mellifera forage in a wide radius around their colony, bringing back contaminated food resources that can function as terrestrial bioindicators of environmental pesticide exposure. Evaluating pesticide exposure risk to pollinators is an ongoing problem. Here we apply five metrics for pesticide exposure risk (prevalence, diversity, concentration, significant pesticide prevalence, and hazard quotient (HQ)) to a nation-wide field study of honey bees, Apis mellifera in the United States. We examined samples from 1055 apiaries over seven years for 218 different pesticide residues and metabolites, determining that bees were exposed to 120 different pesticide products with a mean of 2.78 per sample. Pesticides in pollen were highly prevalent and variable across states. While pesticide diversity increased over time, most detections occurred at levels predicted to be of low risk to colonies. Varroacides contributed most to concentration, followed by fungicides, while insecticides contributed most to diversity above a toxicity threshold. High risk samples contained one of 12 different insecticides or varroacides. Exposures predicted to be low-risk were nevertheless associated with colony morbidity, and low-level fungicide exposures were tied to queen loss, Nosema infection, and brood diseases.

The Wasp as a Terrestrial Indicator of Environmental Metal Composition: Evidence from Zimbabwe

We explored metal concentrations in wasps from 4 sites near Harare, Zimbabwe, on a 106 km west-east transect. We found elevated concentrations at 2 presumed-polluted sites (a platinum [Pt] mine and a known polluted lake) located near a metal-enriched geological feature (the Great Dyke). A site in urban Harare and a nature reserve served as reference. Only wasps from the 2 presumed-polluted sites had quantifiable Pt. For Cr, Ni, Mg, Se, Fe, Mn, and V, we report the highest concentrations in wasps yet published. Wasps from the presumed-polluted sites had significantly higher concentrations of most metals when compared with wasps from the reference sites, suggesting pollution as a source. Geology, however, differs between the sites. It is probable, therefore, that both geology and pollution contributed to the differences in metal concentrations. Because of its long and narrow dimensions (550 km long and 4-11 km wide), the Great Dyke offers opportunities for comparative studies. Because wasps form a complex part of the food web and ecology, studies on the transfer of metals to wasps' predators are needed, especially given that some birds specialize in feeding on hymenopterans. The rich diversity of wasps (>145 000 species worldwide) occupying multiple different trophic levels is a good indicator, and wasps have a rich potential to join other invertebrates as terrestrial indicators. Environ Toxicol Chem 2021;40:1726-1739. © 2021 SETAC.

Effects of native forest and human-modified land covers on the accumulation of toxic metals and metalloids in the tropical bee Tetragonisca angustula

The intensive shift on land cover by anthropogenic activities have led to changes in natural habitats and environmental contamination, which can ultimately impact and threat biodiversity and ecosystem services, such as pollination. The aim of this study was to evaluate the effect of native forest and human-modified land covers on the concentrations of chemical elements accumulated in the neotropical pollinator bee T. angustula. Eight landscapes, within an Ecological Corridor in the State of São Paulo, Brazil, with gradients of forest cover, spatial heterogeneity and varying land covers were used as sampling unities. Bees collected in traps or through actives searches had the concentration of 21 chemical elements determined by ICP-MS. Results show a beneficial effect of forested areas on the concentrations of some well-known toxic elements accumulated in bees, such as Hg, Cd, and Cr. Multivariate Redundancy Analysis (RDA) suggests road as the most important driver for the levels of Cr, Hg, Sb, Al, U, As, Pb and Pt and bare soil, pasture and urban areas as the landscape covers responsible for the concentrations of Zn, Cd, Mn, Mg, Ba and Sr in bees. The results reinforce the potential use of T. angustula bees as bioindicators of environmental quality and also show that these organisms are being directly affected by human land use, offering potential risks for the Neotropical ecosystem. Our study sheds light on how land covers (native forest and human-modified) can influence the levels of contaminants in insects within human-dominated landscapes. The generation of predictions of the levels of toxic metals and metalloids based on land use can both contribute to friendly farming planning as well as to support public policy development on the surrounding of protected areas and biodiversity conservation hotspots.

Regional and global perspectives of honey as a record of lead in the environment

Honey from Apis mellifera is a useful and inexpensive biomonitor for mapping metal distributions in urban centers. The sampling resolution of a biomonitoring survey (e.g., city versus global scale) determines which geochemical processes are reflected in the results. This study presents Pb isotopic compositions and metal concentrations in honey from around the world, sampled at varying resolutions: honey from Canada (n = 21), the United States (n = 111), Belgium (n = 25), and New Zealand (n = 10), with additional samples from Afghanistan, Brazil, Cuba, Germany, Liberia, Taiwan, and Turkey. Honey was sampled at high resolution in two uniquely different land-use settings (New York Metro Area and the Hawaiian island of Kaua'i), at regional-scale resolution in eastern North America (including the Great Lakes region), and Pb isotopic compositions of all samples were compared on a global scale. At high sampling resolution, metal concentrations in honey reveal spatially significant concentration gradients: in New York City, metals associated with human activity and city infrastructure (e.g., Pb, Sb, Ti, V) are more concentrated in honey collected within the city compared to honey from upstate New York, and metal concentrations in honey from Kaua'i suggest polluting effects of nearby agricultural operations. At lower resolution (regional and global scales), lead isotopic compositions of honey are more useful than metal concentrations in revealing large-scale Pb processes (e.g., the enduring legacy of global leaded gasoline use throughout the twentieth century) and the continental origin of the honey. Lead isotopic compositions of honey collected from N. America (especially from the eastern USA) are more radiogenic (²⁰⁶Pb/²⁰⁷Pb: 1.132-1.253, ²⁰⁸Pb/²⁰⁶Pb: 2.001-2.129) compared to European honey, and honey from New Zealand, which has the least radiogenic isotopic compositions measured in this study (²⁰⁶Pb/²⁰⁷Pb: 1.077-1.160, ²⁰⁸Pb/²⁰⁶Pb: 2.090-2.187). Thus, biomonitoring using honey at different resolutions reflects differing processes and, to some extent, a honey terroir defined by the Pb isotopic composition. The data presented here provide important (and current) global context for future studies that utilize Pb isotopes in honey. Moreover, this study exhibits community science in action, as most of the honey was collected by collaborators around the world, working directly with local apiarists and hobby beekeepers.

Disentangling multiple PM emission sources in the Po Valley (Italy) using honey bees

Particulate matter (PM) is a complex mixture of airborne chemical compounds commonly classified by their aerodynamic diameter. Although PM toxicity strongly depends on the morphology, chemical composition, and dimensions of particles, exposure limits set by environmental organisations only refer to the mean mass concentration of PM sampled daily or annually by monitoring stations.

In this study, we used honey bees as sensors of airborne PM₁₀ and PM_2.5 in a highly polluted area of the Po Valley, northern Italy. Honey bees are an efficient sampler of airborne PM because, during flight and foraging activities, their pubescence promotes the accumulation of electrical charge on the body surface owing to air resistance, thus enhancing airborne PM attraction. Particles attached to the body of bees are readily accessible for physico-chemical characterisation using a scanning electron microscope coupled with X-ray spectroscopy (SEM/EDX). Our results demonstrate that residents in the study area are intermittently but chronically exposed to a well-defined spectrum of metal-bearing particles and mineral phases known to induce specific health outcomes.

The morphology, size, and chemical composition of PM₁₀ and PM_2.5 detected on bees in the monitoring area were indicative of traffic, agricultural operations, and high-temperature combustion processes. The contribution of the A1 Milano-Bologna highway, local wheat and alfalfa cultivation, and the Parma incineration plant were clearly distinguishable. Our data also demonstrated that PM exposure levels may vary sharply throughout the year based on recurrent local activities.

Set of stress biomarkers as a practical tool in the assessment of multistress effect using honeybees from urban and rural areas as a model organism: a pilot study

A decrease among honey bee populations (Apis mellifera) in the traditional apiaries has been observed in recent years. In light of this negative phenomenon, urban beekeeping seems to be an appropriate alternative solution for the bee population in reducing the toxic effects of a large number of pesticides that are commonly used in agricultural ecosystems. Despite the rapid development of urban beekeeping, there is little information regarding the different aspects of the defense effectiveness of bees from the urban and rural areas. The study was aimed to show whether honey bees from these two locations differ in the level of the valuable biomarkers of stress exposure helpful in establishing which bees, from urban or rural areas, are under greater environmental pressure. For this purpose, foragers from an urban rooftop apiary and a traditional rural apiary were collected. The chosen biomarkers were measured in various tissues of bees. The activity of glutathione S-transferase and acetylcholinesterase, the level of total antioxidant capacity, heat shock protein 70 (Hsp70), and defensin were selected for the analyses. In our opinion, the Hsp70 and defensin levels seemed to be important in the indication of urban multistress factors. The higher level of heat shock proteins and defensins in tissues/organs of bees from the urban apiary-in the gut (an increase, respectively, 92% and 7.3%) and fat body (an increase, respectively, 130% and 7.8%), known as targets of environmental toxins, pointed out the urban environment as highly stressful at both the individual and colony levels. In turn, high total antioxidant capacity was measured in the guts of honey bees from rural area (an increase 107%). Such a situation suggests a different mechanism of defense and specificity of rural and urban environmental stressors and also honey bees foraging activity.

Agrochemical treatments as a source of heavy metals and rare earth elements in agricultural soils and bioaccumulation in ground beetles

The continuous and extensive application of agrochemicals leads to the accumulation of heavy metals (HMs) and rare earth elements (REEs) in agricultural soils and their transfer in the food web with consequent relevant risks for human and ecosystem health. In this study, HM and REE concentrations were quantified in the soil of wheat crop fields conventionally managed in the agricultural areas of Sila Mountain (Southern Italy) and compared with the concentration in a field of wild herbs, used as control. Statistical analyses and principal component analysis suggested that the use of pesticides, herbicides and fertilizers contributes to the accumulation of HMs and REEs in the soil. Different accumulation patterns were recorded in treated fields as a consequence of the type and amount of agrochemical used and the crop rotation. The exposure risk associated with the transfer through the tropic levels of agroecosystem was carried out measuring the concentration of HMs and REEs in adults of Harpalus (Pseudoophonus) rufipes (De Geer, 1774) collected from each monitored site. Different accumulation patterns found in specimens from the monitored sites highlighted the ability of this generalist predator to regulate metal uptake under field conditions. The values of bioaccumulation factor (BAF) allow to defining the order of accumulation in P. rufipes which was classified as a macroconcentrator of Cd, Cu, Mg and Zn. Our results can supplement the limited information regarding the REE accumulation in soil invertebrates and may provide reference data for assessing potential environmental risks in croplands.

Joint effects of cadmium and copper on Apis mellifera forgers and larvae

Honey bees (Apis mellifera L.) are important ecological and agricultural resources. They are among the most widely available pollinators and provide products as well as services. Unfortunately, honey bee populations are susceptible to several environmental threats, including heavy metal exposure. Honey bees can be exposed to heavy metals when foraging on contaminated honey and pollen resources, and in some cases by airborne exposure. We studied the joint acute and chronic effects of cadmium (Cd) and copper (Cu) on A. mellifera. A 1:1 solution of the two heavy metals increased larval developmental duration and the mortality of both larvae and foragers in a dose-dependent way, decreased forager feeding, increased body metal burdens, and disrupted the sucrose response behavior of foragers. In combination, Cd and Cu demonstrated a weakly synergistic effect on foragers, but for larvae an initially antagonistic effect at low doses changed to strongly synergistic response at higher concentrations. The sucrose response threshold of foragers decreased significantly when they were dosed with increasing concentrations of the metal mixtures. Overall, the fitness of honey bee larvae and foragers is detrimentally affected when these metals co-occur.

Effectiveness of Different Sample Treatments for the Elemental Characterization of Bees and Beehive Products

Bee health and beehive products’ quality are compromised by complex interactions between multiple stressors, among which toxic elements play an important role. The aim of this study is to optimize and validate sensible and reliable analytical methods for biomonitoring studies and the quality control of beehive products. Four digestion procedures, including two systems (microwave oven and water bath) and different mixture reagents, were evaluated for the determination of the total content of 40 elements in bees and five beehive products (beeswax, honey, pollen, propolis and royal jelly) by using inductively coupled plasma mass and optical emission spectrometry. Method validation was performed by measuring a standard reference material and the recoveries for each selected matrix. The water bath-assisted digestion of bees and beehive products is proposed as a fast alternative to microwave-assisted digestion for all elements in biomonitoring studies. The present study highlights the possible drawbacks that may be encountered during the elemental analysis of these biological matrices and aims to be a valuable aid for the analytical chemist. Total elemental concentrations, determined in commercially available beehive products, are presented.

Mineral and Trace Element Analysis of Australian/Queensland Apis mellifera Honey

Honey is an extensively utilized sweetener containing sugars and water, together with small quantities of vitamins, minerals, fatty acids, amino acids and proteins. Naturally produced by honeybees (Apis mellifera) from floral nectar, honey is increasingly sold as a health food product due to its nutritious features. Certain honeys are retailed as premium, trendy products. Honeybees are regarded as environmental monitors, but few reports examine the impact of environment on Australian honey trace elements and minerals. In higher density urban and industrial environments, heavy metals can be common, while minerals and trace elements can have ubiquitous presence in both agricultural and urban areas. Honey hives are traditionally placed in rural and forested areas, but increasingly the trend is to keep hives in more urban areas. This study aimed to determine the levels of 26 minerals and trace elements and assess elemental differences between honeys from various regional Queensland and Australian sources. Honey samples (n = 212) were acquired from markets, shops and supermarkets in Queensland while urban honeys were purchased online. The honey samples were classified into four groups according to their regional sources: urban, rural, peri-urban and blend honey. Elemental analyses of honey were performed using ICP-MS and ICP-OES after microwave and hot block digestion. Considerable variations of essential trace elements (Co, Cu, Cr, Fe, Mn, Mo and Zn) and mineral levels (Ca, K, Mg, Na and P) were found in honeys surveyed. There were significant differences (p < 0.05) between urban and rural honey samples for B, Na, P, Mn, K, Ca and Cu. Significant differences (p < 0.05) were also found between blend and urban honey samples for K, Cu, P, Mn, Sr, Ni, B and Na. Peri-urban versus urban honeys showed significant differences in P, K and Mn. For rural and peri-urban honeys, the only significant difference (p < 0.05) was for Na. Toxic heavy metals were detected at relatively low levels in honey products. The study revealed that the Queensland/Australian honey studied is a good source of K and Zn and would constitute a good nutritional source of these elements.

Evaluating Spatiotemporal Resolution of Trace Element Concentrations and Pb Isotopic Compositions of Honeybees and Hive Products as Biomonitors for Urban Metal Distribution

Assessing metal distributions in cities is an important aspect of urban environmental quality management. Western honeybees (Apis mellifera) and their products are biomonitors that can elucidate small-scale metal distribution within a city. We compare range and variations in trace element (TE) concentrations and lead (Pb) isotopic compositions of honey, bee tissue, bee pollen, and propolis collected throughout Metro Vancouver (BC, Canada). Honey, bee, and bee pollen results have similar TE and isotopic trends; samples collected in urban and industrialized areas exhibit elevated concentrations of anthropogenically influenced TE (e.g., Pb, Zn, V, and Ti) and a less radiogenic Pb isotopic composition (i.e., lower 206Pb/207Pb and elevated 208Pb/206Pb) relative to their suburban and rural counterparts. For example, 206Pb/207Pb, 208Pb/206Pb in honey range from 1.126, 2.131 and 1.184, 2.063; extremes measured in honey from urban and suburban/rural areas, respectively. Except for propolis, measured and interpolated (kriged) results in all materials reflect the immediate zoning or land use setting near the hive, providing kilometer-scale geospatial resolution, suitable for monitoring urban systems. Statistical analysis reveals that no systematic variations or intra- or inter-annual trends exist in TE concentrations or Pb isotopic compositions, including among sampling and field methods (i.e., old vs. new hive equipment and honey from the brood nest box vs. honey super). The results of this systematic study using honeybees and hive products in Metro Vancouver provide a robust, current baseline for future comparison of local land use and environmental policy change.

Vehicular Emission: Estimate of Air Pollutants to Guide Local Political Choices. A Case Study

The aim of this case study was to show how, with the use of software, is it possible to carry out a preventive screening of vehicular emissions. Moreover, thanks to this preliminary analysis, some areas that are potentially polluted can be identified in advance and suitable samplings on small-scale on them would help to verify the effectiveness of policies that can be adopted for the reduction of pollution. To this end, this paper reports a case study on vehicle traffic pollution in Calabria, a region in the south of Italy. We used the methodology called Corinair (Coordination Information AIR), developed by the EEA (European Environment Agency) and uses the software Copert4 (Computer Program to calculate Emission from Road Traffic). The total emissions per area were analyzed and the emissions for particular pollutants per unit area (km²) and per citizen were considered. The obsolete vehicles determined a substantial impact on the local atmospheric pollution. It was demonstrated how it is possible to substantially reduce the pollution of an area by adopting policies that encourage, for example, through tax concessions, the replacement of old cars of private citizens.

Identifying the influencing factors controlling the spatial variation of heavy metals in suburban soil using spatial regression models

Determining the factors that control the spatial variation of heavy metals in suburban soil is important in identifying and preventing pollution sources. Soil intrinsic factors combined with environmental variables can effectively explain the spatial distribution of heavy metals. Compared with classical statistical methods, such as multiple linear regression (MLR) models, spatial regression models that can cope with the spatial dependence of heavy metals have greater potential in establishing an accurate relationship between influencing factors and heavy metals. This study aims to identify the factors that influence the spatial variation of lead (Pb) and cadmium (Cd) in 138 topsoil samples from the suburbs of Wuhan City, China, by using spatial regression models with MLR as the reference. Moran's I values reveal the spatial autocorrelation of Pb and Cd. The spatial lag model (SLM) outperforms MLR and has higher R² and lower spatial dependence of residuals. The significant coefficients of the spatial lag term in SLMs indicate that the spatial variation of Pb and Cd depends on their surrounding observations. SLM results show that Pb content depends on the distance from the nearest industrial enterprises and suggest that industrial pollution is the main source of Pb. Cd content depends on pH, soil organic matter, and the topographic wetness index, indicating that intrinsic and topographical factors contribute to the spatial variation of Cd. Parent materials and application of phosphorus fertilizer are the most likely sources of Cd. The findings highlight the spatial autocorrelation of heavy metals and the effects of intrinsic factors and environmental variables on the spatial variation of such metals. Moreover, this study reveals the effectiveness of spatial regression models in identifying the influencing factors of heavy metals.

Assessing heavy metal pollution by biomonitoring honeybee nectar in Córdoba (Spain)

Nectar of honeybee colonies has been used in order to identify heavy metals and establish the benefit of this type of studies as a tool for environmental management. For these goals, samples of nectar were obtained from Apis mellifera hives placed in the city of Córdoba (Spain) and its surroundings. Five stations (each with two hives) were selected and samples were collected from May to July of 2007, 2009 and 2010. Concentrations of Pb, Cr, Ni and Cd in nectar were determined by graphite furnace atomic absorption spectrophotometry. Substantial spatial and temporal differences were detected and compared with the values found in bee bodies in a previously published study based on samples obtained simultaneously with those presented in this work. Upper reference thresholds established for this investigation were surpassed frequently by the measures obtained, being Cr (21.43% of samples), stations S3 (22.22%) and S4 (11.12%) year 2009 (22.22%) and the month of July (23.68%) the metal, the locations and the periods that exceeded more times these references. Regarding the Cd, which was studied only in 2010, 33.33% of the nectar samples exceeded the upper reference thresholds. Comparing the biomonitoring of bee bodies and nectar, some coincidences were found, although they showed different results for highest worrisome values of metal, station and year. This suggests that both methods can give complementary information in the surveillance systems of atmospheric pollution.

Cross-sectional study to identify risk factors associated with the occurrence of antimicrobial resistance genes in honey bees Apis mellifera) in Umbria, Central Italy

The use antimicrobials for therapeutic and metaphylactic purpose in humans and agriculture exerts selective pressure on animal and environmental microbiota resulting in the survival and spread of antimicrobial resistance genes among bacteria and subsequent development of resistance in bacteria. Previous studies have shown that honey bees' microbiota (Apis mellifera) can accumulate antimicrobial resistance genes in their microbiome and act as collectors and disseminators of resistance genes. The aim of this study was to investigate to what extent honey bees act as reservoir of select antimicrobial resistance genes. This study was conducted on 35 groups of bees. Bees were collected from 35 sites in Umbria, Italy. PCR was used to screen pooled ground bees' specimens for genes that code for resistance against antimicrobials that are commonly used in humans and in veterinary medicine including aminoglycosides (aph), beta-lactams (blaZ), tetracycline (tetM) and sulphonamides (sul1 and sul2). Twenty-four samples out of 35 (68.57%) were positive for at least one antimicrobial resistance gene. Two samples were positive for the aph, 5.71%; eight for blaZ, 22.86%; three for tetM, 8.57%; ten for sul1, 28.57% and eighteen for sul2, 51.43%. Positivity to more than one antimicrobial resistance gene was observed in nine samples, 25.71%. The multivariate analysis identified "presence of farms nearby" as the factor most closely related to PCR positivity. Honey bees (Apis mellifera) from Umbria, Italy, carry antimicrobial resistance genes and can be used as indicators of the presence of resistance genes in the environment.

Pollutants and Their Interaction with Diseases of Social Hymenoptera

Many insect species, including social insects, are currently declining in abundance and diversity. Pollutants such as pesticides, heavy metals, or airborne fine particulate matter from agricultural and industrial sources are among the factors driving this decline. While these pollutants can have direct detrimental effects, they can also result in negative interactive effects when social insects are simultaneously exposed to multiple stressors. For example, sublethal effects of pollutants can increase the disease susceptibility of social insects, and thereby jeopardize their survival. Here we review how pesticides, heavy metals, or airborne fine particulate matter interact with social insect physiology and especially the insects’ immune system. We then give an overview of the current knowledge of the interactive effects of these pollutants with pathogens or parasites. While the effects of pesticide exposure on social insects and their interactions with pathogens have been relatively well studied, the effects of other pollutants, such as heavy metals in soil or fine particulate matter from combustion, vehicular transport, agriculture, and coal mining are still largely unknown. We therefore provide an overview of urgently needed knowledge in order to mitigate the decline of social insects.

Biomonitoring of Atmospheric Aerosol with the use of Apis mellifera and Pleurozium schreberi

The aim of the carried out research was to assess atmospheric aerosol pollution levels in the area of three apiaries located in the Opole Province and to analyse heavy metals pollution in bee honey and western honey bees. Pleurozium schreberi moss was used in analysing atmospheric aerosol pollution with the active biomonitoring method, whereas heavy metals levels were determined with flame atomic absorption spectrometry method (F-AAS). Relative Accumulation Factors (RAF) were used in determining increases of analytes concentrations in the moss samples. As a result of the carried out study, the following conclusions have been reached: mosses are good bioindicators of environment pollution thanks to their sorption qualities, similarly to honey bees, which are a bioindicator of environment pollution. According to the Commission Regulation of European Union of 2015 regarding the maximum levels of lead in certain foods (honey), it should not exceed 0.1 mg/kg. On the basis of the carried out study it can be stated that the concentration of this analyte in the analysed honey was below the limit of quantification of the applied analytical method.

Heavy metal bioaccumulation in honey bee matrix, an indicator to assess the contamination level in terrestrial environments

The most significant risk factor for organisms living in an environment contaminated by heavy metals is the metal bioavailability. Therefore, an efficient ecotoxicological approach to metal contamination is the measure of bioaccumulation level in target organisms. In this work, we characterized the heavy metal bioaccumulation in honey bees, Apis mellifera ligustica, collected at 35 sites from Umbria (Central Italy). The comparison of our data with selected Italian investigations revealed metal bioaccumulation in honey bee matrix of the same order of magnitude, with Cd showing a higher variability. To generalize the results, we developed a Honeybee Contamination Index (HCI) based on metal bioaccumulation in honey bees. An application of the HCI to the present dataset revealed cases of low (sixteen sites), intermediate (eighteen sites), and high (one site) metal contaminations. The comparison of HCI values from the Umbrian dataset with values calculated for other Italian and European metadata showed that most of the Umbrian sites fell in the portion of low and intermediate contamination conditions. HCI represented a reliable tool that provided a piece of concise information on metal contamination in terrestrial environments. Parallel to this effort, we have determined, the metal concentrations in the airborne particulate matter (PM₁₀) at three regional background-monitoring stations in Umbria. These stations are representative of the average air quality of the areas of the investigated apiaries. A comparative analysis of metal enrichment factors in PM₁₀, and honey bees suggested that the contamination in the bees was related to the PM₁₀ values only to a minor extent. On the other side, a clear enrichment of metals such as Cd, Mn, Zn, and Cu in the honey bees appeared to depend on very local conditions and was probably related to the use of pesticides and fertilizers, and the resuspension of the locally contaminated soils and agriculture residues.

Mineral Content in Honeybee Wax Combs as a Measurement of the Impact of Environmental Factors

Environmental pollution from metals needs to be constantly monitored due to their predominantly negative impacts on living organisms. As apian products stored in hives are considered useful bioindicators, the objective of this study was to: (a) investigate and compare the essential and toxic metal concentrations in freshly constructed combs (light combs, LC) and old combs (dark combs, DC) in use for two to three beekeeping seasons, and (b) compare the mineral content of beeswax combs from apiaries exposed to different levels of environmental pollution using the energy dispersive x-ray fluorescence method. Concentrations of ten elements (Cr, Pb, Cu, Ni, Fe, Zn, Mn, Sr, Rb, Ca) were determined in 18 honeybee wax comb samples from three apiaries in continental Croatia. The results showed that the influence of comb age and/or geographical origin (representing varying levels of environmental pollution exposure) on the elemental composition of beeswax was evident for the toxic elements Cr, Pb, Cu and Ni, and for the essential elements Fe, Zn, Mn and Sr, but not Rb. In addition to monitoring the environmental element content, wax combs can be used to determine contamination levels. Additionally, in-time analysis results can enable beekeepers to adjust management practices, such as moving apiaries to better positions. They can also be useful in the creation of policies on acceptable limits for toxic metal levels in particular geographical areas.

Behavior and gut bacteria of Partamona helleri under sublethal exposure to a bioinsecticide and a leaf fertilizer

The exposure of bees to agrochemicals during foraging and feeding has been associated with their population decline. Sublethal exposure to agrochemicals can affect behavior and the microbiota. Gut microbiota is associated with insect nutritional health, immunocompetence, and is essential for neutralizing the damage caused by pathogens and xenobiotics. Research on the effect of the bioinsecticides and fertilizers on the microbiota of bees remains neglected. In this study, we assessed the sublethal effect of both bioinsecticide spinosad and the fertilizer copper sulfate (CuSO₄) on the behavior and gut microbiota in forager adults of the stingless bee Partamona helleri (Friese), which is an important pollinator in the Neotropical region. Behavioral assays and gut microbiota profiles were assessed on bees orally exposed to estimated LC₅ values for spinosad and CuSO₄. The microbiota were characterized through 16S rRNA gene target sequencing. Acute and oral sublethal exposure to spinosad and CuSO₄ did not affect the overall activity, flight take-off, and food consumption. However, CuSO₄ decreased bee respiration rate and copper accumulated in exposed bees. Exposure to spinosad increased the proportional abundance of the genus Gilliamella, but CuSO₄ did not alter the composition of the gut microbiota. In conclusion, sublethal exposure to CuSO₄ induces changes in respiration, and spinosad changes the abundance of gut microorganisms of P. helleri.

Honeybees (Apis mellifera L.) as a Potential Bioindicator for Detection of Toxic and Essential Elements in the Environment (Case Study: Markazi Province, Iran)

Honeybees, due to their wide-ranging foraging behaviour, have great potentials for monitoring environmental quality. Therefore, the purpose of this study was to use honeybees as bioindicators for the detection of toxic and essential metals (Cd, Cr, Cu, and Fe) in the environment. Totally, 180 soil, plant (including root and aerial part), honeybees, and honey samples were collected from 12 sites within the main beekeeping and honey production regions in Markazi Province, Iran in 2016. After acid digestion of samples, the metal concentrations were measured by inductively coupled plasma-optical emission spectrometers. The translocation factor (TF), and bioconcentration factor (BCF) of metals were computed. The results showed that among the analyzed bee samples, Cd (mg kg^-1) was detected in amounts ranging from 0.01 to 2.35, Cr (mg kg^-1) ranged from 0.02 to 18.10, Cu (mg kg^-1) ranged from 2.00 to 39.11, and Fe (mg kg^-1) ranged from 163 to 1695. BCF and TF values obtained showed that the Astragalus gossypinus would have a great accumulation ability for Cd and Cr. The results indicated that honeybees could be used to detect the spatial patterns of metal contaminations in the environment they dwell in.

Levels of heavy metals in a multifloral Saudi honey

The presence of chemical pollutants, especially heavy metals, affects the quality of honey. The objective of this study was to determine the levels of eight heavy metals (As, Cd, Co, Cr, Cu, Ni, Pb, and Zn) in honey samples from Al-Baha region in Saudi Arabia, using inductively coupled plasma with optical emission spectroscopy (ICP-OES). The highest concentration was found for Zn (1707.93 μg kg^-1), while the lowest was found for Co (3.04 μg kg^-1). Cluster analysis and principal component analysis showed that two groups are recognized indicating two different metal sources. The first group includes only Zn and the second group includes the rest of the metals. In view of the recommended and established heavy metal intakes for humans, consumption of Saudi honey from Al-Baha should not be deemed a matter of concern for human health.

Honeybees as sentinels of lead pollution: Spatio-temporal variations and source appointment using stable isotopes and Kohonen self-organizing maps

In this study, honeybees were used to determine spatio-temporal variations and origin sources of Pb. Lead concentrations and isotopic composition were used in combination with selected statistical methods. The sampling was carried out at five different locations in Serbia: urban region (BG), petrochemical industry (PA), suburban region (PV), rural region (MS) and thermal power plant region (TPP) during 2014. At PA and PV locations, samples were taken during multiple years. This is the first use of Kohonen self-organizing map (SOM) in combination with honeybees as bioindicators to determine spatio-temporal variations and origin of Pb pollution. It was observed that during the years Pb concentrations were in decline. Anthropogenic sources are most dominant in BG and TPP, in PA there are mixed sources of natural and anthropogenic origin and in PV Pb is of natural origin. It can be concluded that honeybees in combination with SOM can be used to differentiate between slight changes in spatio-temporal variations of Pb, as well as for source appointment.

Assessment of spatial and temporal variations in trace element concentrations using honeybees (Apis mellifera) as bioindicators

With the increase in anthropogenic activities metal pollution is also increased and needs to be closely monitored. In this study honeybees were used as bioindicators to monitor metal pollution. Metal pollution in honeybees represents pollution present in air, water and soil. Concentrations of As, Cs, Hg, Mo, Sb, Se, U and V were measured. The aim of this study was to assess spatial and temporal variations of metal concentrations in honeybees. Samples of honeybees were taken at five different regions in Serbia (Belgrade - BG, Pančevo - PA, Pavliš - PV, Mesić - MS, and Kostolac - TPP) during 2014. Spatial variations were observed for Sb, which had higher concentrations in BG compared to all other regions, and for U, with higher concentrations in the TPP region. High concentrations of Sb in BG were attributed to intense traffic, while higher U concentrations in the TPP region are due to the vicinity of coal fired power plants. In order to assess temporal variations at two locations (PA and PV) samples were taken during July and September of 2014 and June, July, August and September of 2015. During 2014 observing months of sampling higher concentrations in July were detected for Sb and U in BG, which is attributed to lifecycle of plants and honeybees. During the same year higher concentrations in September were observed for As, Sb in PA and Hg in PV. This is due to high precipitation during the peak of bee activity in spring/summer of 2014. No differences between months of sampling were detected during 2015. Between 2014 and 2015 statistically significant differences were observed for Hg, Mo and V; all elements had higher concentrations in 2014. This is in accordance with the trend of reduction of metal concentrations in the bodies of honeybees throughout the years in this region.

Identifying Sources of Environmental Contamination in European Honey Bees (Apis mellifera) Using Trace Elements and Lead Isotopic Compositions

Trace element concentrations (As, Mn, Pb, and Zn) and Pb isotopic compositions were analyzed in honey bees, wax, and honey along with co-located soil and dust samples from Sydney metropolitan and Broken Hill, Australia. Compared with the other trace elements, Pearson correlations show that Pb concentrations in soil and dust had the strongest relationship to corresponding values in honey bees and their products. Dust Pb was not only highly correlated to corresponding soil values (r = 0.806, p = 0.005), it was the strongest predictor of Pb concentrations in honey bees, wax, and honey (p = 0.001, 0.007, 0.017, respectively). Lead isotopic compositions (²⁰⁶Pb/²⁰⁷Pb and ²⁰⁸Pb/²⁰⁷Pb) showed that honey bees and their products from Broken Hill were nearly identical (95-98%) to the composition of the local ore body. Samples of honey bees and their products collected from background sites adjacent to national parks in Sydney had Pb isotopic compositions (²⁰⁶Pb/²⁰⁷Pb = 1.138-1.159, ²⁰⁸Pb/²⁰⁷Pb = 2.417-2.435) corresponding to local geogenic values (²⁰⁶Pb/²⁰⁷Pb = 1.123-1.176, ²⁰⁸Pb/²⁰⁷Pb = 2.413-2.500). By contrast, honey bees and their products from Sydney metropolitan (²⁰⁶Pb/²⁰⁷Pb = 1.081-1.126, ²⁰⁸Pb/²⁰⁷Pb = 2.352-2.408) were similar to aerosols measured during the period of leaded petrol use (²⁰⁶Pb/²⁰⁷Pb = 1.067-1.148, ²⁰⁸Pb/²⁰⁷Pb = 2.341-2.410). These measurements show Pb concentrations and its isotopic compositions of honey bees, and their products can be used to trace both legacy and contemporary environmental contamination, particularly where sources are well documented. Moreover, this study demonstrates that legacy Pb emissions continue to be remobilized in dust, contaminating both food and ecological systems.

Heavy metal pollution in immobile and mobile components of lentic ecosystems-a review

With growing population and urbanization, there is an increasing exploitation of natural resources, and this often results to environmental pollution. In this review, the levels of heavy metal in lentic compartments (water, sediment, fishes, and aquatic plants) over the past two decades (1997-2017) have been summarized to evaluate the current pollution status of this ecosystem. In all the compartments, the heavy metals dominated are zinc followed by iron. The major reason could be area mineralogy and lithogenic sources. Enormous quantity of metals like iron in estuarine sediment is a very natural incident due to the permanently reducing condition of organic substances. Contamination of cadmium, lead, and chromium was closely associated with anthropogenic origin. In addition, surrounding land use and atmospheric deposition could have been responsible for substantial pollution. The accumulation of heavy metals in fishes and aquatic plants is the result of time-dependent deposition in lentic ecosystems. Moreover, various potential risk assessment methods for heavy metals were discussed. This review concludes that natural phenomena dominate the accumulation of essential heavy metals in lentic ecosystems compared to anthropogenic sources. Amongst other recent reviews on heavy metals from other parts of the world, the present review is executed in such a way that it explains the presence of heavy metals not only in water environment, but also in the whole of the lentic system comprising sediment, fishes, and aquatic plants.

Use of honeybees (Apis mellifera L.) as bioindicators for assessment and source appointment of metal pollution

The ability of honeybees to collect particulate matter (PM) on their bodies makes them outstanding bioindicators. In this study, two cities, Pančevo (PA) and Vršac (VS), South Banat district, Vojvodina, Serbia, were covered with two sampling sites each. The aims of this study were to determine concentrations of Al, Ba, Cd, Co, Cr, Cu, Fe, Mn, Na, Ni, Sr, and Zn in the bodies of honeybees during July and September of 2013, 2014, and 2015 and to analyze their spatial and temporal variations and sources of analyzed elements, as well as to assess pollution levels in the two cities. Significant temporal differences were found for Al, Ba, Cd, Co, Cr, Cu, Fe, Mn, Na, Ni, and Zn. Trend of reduction in metal concentrations in bodies of honeybees during the years was observed. Statistically significant spatial variations were observed for Al, Ba, and Sr, with higher concentrations in VS. PCA and CA analyses were used for the first time to assess sources of metals found in honeybees. These analyses showed two sources of metals. Co, Cd, Na, Fe, Mn, Zn, and partly Cu were contributed to anthropogenic sources, while Ca, Al, Mg, Cr, Ba, Sr, and Ni were contributed to natural sources.

The essential roles of metal ions in insect homeostasis and physiology

Metal ions play distinct roles in living organisms, including insects. Some, like sodium and potassium, are central players in osmoregulation and 'blood and guts' transport physiology, and have been implicated in cold adaptation. Calcium is a key player as a second messenger, and as a structural element. Other metals, particularly those with multiple redox states, can be cofactors in many metalloenzymes, but can contribute to toxic oxidative stress on the organism in excess. This short review selects some examples where classical knowledge has been supplemented with recent advances, in order to emphasize the importance of metals as essential nutrients for insect survival.