In order to study the distribution of pesticide residues in beekeeping matrices, samples of live in-hive worker honey bees (Apis mellifera), fresh stored pollen and beeswax were collected during 2016–2017 from 45 apiaries located in different landscape contexts in Spain. A total of 133 samples were screened for 63 pesticides or their degradation products to estimate the pesticide exposure to honey bee health through the calculation of the hazard quotient (HQ). The influence of the surrounding environment on the content of pesticides in pollen was assessed by comparing the concentrations of pesticide residues found in apiaries from intensive farming landscapes to those found in apiaries located in mountainous, grassland and urban contexts. Beeswax revealed high levels of miticides used in beekeeping such as coumaphos, chlorfenvinphos, fluvalinate and acrinathrin, which were detected in more than 75% of samples. Pollen was predominantly contaminated by miticides but also by insecticides used in agriculture such as chlorpyrifos and acetamiprid, which showed concentrations significantly higher in apiaries located in intensive farming contexts. Pesticides residues were less frequent and at lower concentrations in live honey bees. Beeswax showed the highest average hazard scores (HQ > 5000) to honey bees. Pollen samples contained the largest number of pesticide residues and relevant hazard (HQ > 50) to bees. Acrinathrin was the most important contributor to the hazard quotient scores in wax and pollen samples. The contributions of the pesticides dimethoate and chlorpyrifos to HQ were considered relevant in samples.

In the last decades a dramatic loss of Apis mellifera hives has been reported in both Europe and USA. Research in this field is oriented towards identifying a synergy of contributing factors, i.e. pathogens, pesticides, habitat loss and pollution to the weakening of the hive. Cadmium (Cd) is a hazardous anthropogenic pollutant whose effects are proving to be increasingly lethal. Among the multiple damages related to Cd contamination, some studies report that it causes immunosuppression in various animal species. The aim of this paper is to determine whether contamination by Cd, may have a similar effect on the honey bees’ immunocompetence. Our results, obtained by immune challenge experiments and confirmed by structural and ultrastructural observations show that such metal causes a reduction in immunocompetence in 3 days Cd exposed bees. As further evidence of honey bee response to Cd treatment, Energy Dispersive X-ray Spectroscopy (X-EDS) has revealed the presence of zinc (Zn) in peculiar electron-dense granules in fat body cells. Zn is a characteristic component of metallothioneins (MTs), which are usually synthesized as anti-oxidant and scavenger tools against Cd contamination. Our findings suggest that honey bee colonies may have a weakened immune system in Cd polluted areas, resulting in a decreased ability in dealing with pathogens.

Three beehive matrices, sampled in eighteen apiaries from West France, were analysed for the presence of lead (Pb). Samples were collected during four different periods in both 2008 and 2009. Honey was the matrix the least contaminated by Pb (min = 0.004 μg g⁻¹; max = 0.378 μg g⁻¹; mean = 0.047 μg g⁻¹; sd = 0.057). The contamination of bees (min = 0.001 μg g⁻¹; max = 1.869 μg g⁻¹; mean = 0.223 μg g⁻¹; sd = 0.217) and pollen (min = 0.004 μg g⁻¹; max = 0.798 μg g⁻¹; mean = 0.240 μg g⁻¹; sd = 0.200) showed similar levels and temporal variations but bees seemed to be more sensitive bringing out the peaks of Pb contamination. Apiaries in urban and hedgerow landscapes appeared more contaminated than apiaries in cultivated and island landscapes. Sampling period had a significant effect on Pb contamination with higher Pb concentrations determined in dry seasons.

This study investigates trace element concentrations (arsenic (As), manganese (Mn), lead (Pb) and zinc (Zn)) and Pb isotopic compositions in an Australian native bee species, Tetragonula carbonaria, and its products of honey and wax. Co-located soil and dust samples were simultaneously analysed with the objective of determining if the bees or their products had potential application as a proxy for monitoring environmental contamination. The most significant relationships were found between Pb concentrations in honey (r = 0.814, p = 0.014) and wax (r = 0.883, p = 0.004) and those in co-located dust samples. In addition, Zn concentrations in honey and soil were significantly associated (r = 0.709, p = 0.049). Lead isotopic compositions of native bee products collected from background sites adjacent to Sydney national parks (²⁰⁶Pb/²⁰⁷Pb = 1.144, ²⁰⁸Pb/²⁰⁷Pb = 2.437) corresponded to local geogenic rock and soil values (²⁰⁶Pb/²⁰⁷Pb = 1.123–1.176, ²⁰⁸Pb/²⁰⁷Pb = 2.413–2.500). By contrast, inner Sydney metropolitan samples, including native bees and wax (²⁰⁶Pb/²⁰⁷Pb = 1.072–1.121, ²⁰⁸Pb/²⁰⁷Pb = 2.348–2.409), co-located soil and dust (²⁰⁶Pb/²⁰⁷Pb = 1.090–1.122, ²⁰⁸Pb/²⁰⁷Pb = 2.368–2.403), corresponded most closely to aerosols collected during the period of leaded petrol use (²⁰⁶Pb/²⁰⁷Pb = 1.067–1.148, ²⁰⁸Pb/²⁰⁷Pb = 2.341–2.410). A large range of Pb isotopic compositions in beehive samples suggests that other legacy sources, such as Pb-based paints and industrials, may have also contributed to Pb contamination in beehive samples. Native bee data were compared to corresponding samples from the more common European honey bee (Apis mellifera). Although Pb isotopic compositions were similar in both species, significant differences in trace element concentrations were evident across the trace element suite, the bees and their products. The statistical association between T. carbonaria and co-located environmental contaminant concentrations were stronger than those in European honey bees, which may be attributable to its smaller foraging distance (0.3–0.7 km versus 5–9 km, respectively). This implies that T. carbonaria may be more suitable for assessing small spatial scale variations of trace element concentrations than European honey bees.

Due to their extensive use in both agricultural and non-agricultural applications, pesticides are a major source of environmental contamination. Honey bee colonies are proven sentinels of these and other contaminants, as they come into contact with them during their foraging activities. However, active sampling strategies involve a negative impact on these organisms and, in most cases, the need of analyzing multiple heterogeneous matrices. Conversely, the APIStrip-based passive sampling is innocuous for the bees and allows for long-term monitorings using the same colony. The versatility of the sorbent Tenax, included in the APIStrip composition, ensures that comprehensive information regarding the contaminants inside the beehive will be obtained in one single matrix. In the present study, 180 APIStrips were placed in nine apiaries distributed in Denmark throughout a six-month sampling period (10 subsequent samplings, April to September 2020). Seventy-five pesticide residues were detected (out of a 428-pesticide scope), boscalid and azoxystrobin being the most frequently detected compounds. There were significant variations in the findings of the sampling sites in terms of number of detections, pesticide diversity and average concentration. A relative indicator of the potential risk of pesticide exposure for the honey bees was calculated for each sampling site. The evolution of pesticide detections over the sampling periods, as well as the individual tendencies of selected pesticides, is herein described. The findings of this large-scale monitoring were compared to the ones obtained in a previous Danish, APIStrip-based pilot monitoring program in 2019. Samples of honey and wax were also analyzed and compared to the APIStrip findings.

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.

COVID-19 pandemic has passed to the front all the contradictions of the beekeeping sector: the valuable role of bee products as immune enhancers and antiviral agents and the impact that unsustainability of human activities has on bees’ health and survival. The COVID-19 emergency led several countries to adopt severe restriction measures to contrast the infection. The lowering of industrial and commercial activities, transports, and the general lockdown had immediate consequences on the air quality, significantly improving environmental conditions. This had a positive impact on honeybees’ life’s quality. On the other hand, the bee and beehive transportation limitations threaten to hit food production by affecting the pollinator service, and this is particularly true in large, food-exporting countries like the USA and China where due to the few numbers of local bees, beekeepers import them by other countries and convey by truck hives for thousands of kilometers to pollinate crops. Furthermore, honeybee products, focusing on their natural pharmacological properties, can play an essential role as a potential natural contrast to the virus by enhancing the immunity defenses of both humans and animals, and their demand by consumers is expected to increase. Several researchers in the last months focused their attention on bee products to evaluate their effect in the cure of COVID-19 patients to ameliorate the symptoms or to contrast the coronavirus directly. This review reports these preliminary results.

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.

Honeybees forage a large spatial area around the hives. In addition, honey production takes place in various environments, and polluted environment is often hard to detect. It impacts both human and beehive health, especially through honey which is used for human consumption. Pollen analysis was conducted by a novel approach through a multivariate principal component analysis where it was possible to obtain grouping patterns related to foraging plant species. Samples of honey were acquired from three different environmental production systems: (i) honey from the apiaries in the vicinity of thermal power plant, (ii) apiary of certified organic production and (iii) the conventional production with semi-controlled production. Significantly higher contents of the Pb, Cd and Zn are found in the analysed honeys taken near the thermal power plant compared with those of the other analysed honeys. The origin of Zn, Pb and Cd in the honey is the contaminated forage plants and foraging honeybees. Honey from certified organic production differentiated significantly from other two types of production by the water content, electrical conductivity and total soluble solids and notably it contained significantly less ash and lead. There is a clear advantage of certified organic honey in terms of heavy metal residues as the most prominent pollution factor in honey. Therefore, honey can be used as the broad range environmental pollution indicator, as bees will forage on polluted plants and bring the pollutant from a wide spatial range inside the hive, where it can be traced in the honey. Graphical abstract

Thymol is a natural substance increasingly used as an alternative to pesticides in the fight against the Varroa destructor mite. Despite the effectiveness of this phenolic monoterpene against Varroa, few articles have covered the negative or side effects of thymol on bees. In a previous study, we have found an impairment of phototaxis in honeybees following application of sublethal doses of thymol—lower or equal to 100 ng/bee—under laboratory conditions. The present work shows the same behavioral effects on bees from hives treated with Apilife Var®, a veterinary drug containing 74 % thymol, with a decrease in phototactic behavior observed 1 day after treatment. Thus, thymol causes disruption of bee phototactic behavior both under laboratory conditions as well as in beehives. The bee exposure dose in treated hives was quantified using gas chromatography coupled to mass spectrometry (GC–MS), giving a median value of 4.3 μg per body 24 h after treatment, with 11 ng in the brain. The thymol level in 20 organic waxes from hives treated with Apilife Var® was also measured and showed that it persists in waxes (around 10 mg/kg) 1 year after treatment. Thus, in the light of (1) behavioral data obtained under laboratory conditions and in beehives, (2) the persistence of thymol in waxes, and (3) the high load on bees, it would appear important to study the long-term effects of thymol in beehives.