Bioactives of Melipona rufiventris Propolis: Exploring its Antimicrobial, Anti-Inflammatory, and Antioxidant Activities.

This study explores the potential of propolis, a resinous substance produced by bees, from Melipona rufiventris species. With its composition encompassing resin, wax, pollen, and soil, propolis holds historical significance in traditional medicine within tropical regions. This research is driven by the scarcity of information surrounding M. rufiventris propolis, prompting an investigation into its chemical constituents, in vivo toxicity, and antimicrobial, antioxidant, and anti-inflammatory properties. This exploration could potentially uncover novel applications for this natural product, bolstering both meliponiculture practices and the preservation of native bee populations. The propolis was sampled in Cabo Verde-MG and underwent ethanolic extraction to yield an extract (EEP) for analysis. Chemical assessments (Folin-Ciocalteau, and UHPLC-HRMS) revealed the presence of polyphenols, including flavonoids. The EEP demonstrated higher antimicrobial activity against Gram-positive bacteria and exhibited efficacy against multiresistant strains isolated from complex wounds. Synergistic interactions with commercial antibiotics were also observed. Furthermore, anti-inflammatory evaluations showcased the EEP's potential in reducing NF-kB activation and TNF-α release at non-toxic concentrations. Despite these promising biological activities, the EEP exhibited no antiproliferative effects and demonstrated safety in both the MTS assay and the G. mellonella model. Collectively, these findings highlight the M. rufiventris propolis extract as a valuable reservoir of bioactive compounds with multifaceted potential.

Evaluation of the antinociceptive activities of natural propolis extract derived from stingless bee Trigona thoracica in mice.

Background: : Stingless bee propolis is a popular traditional folk medicine and has been employed since ancient times. This study aimed to evaluate the antinociceptive activities of the chemical constituents of aqueous propolis extract (APE) collected by Trigona thoracica in a nociceptive model in mice. Methods: : The identification of chemical constituents of APE was performed using high-performance liquid chromatography (HPLC). Ninety-six male Swiss mice were administered APE (400 mg/kg, 1,000 mg/kg, and 2,000 mg/kg) before developing nociceptive pain models. Then, the antinociceptive properties of each APE dose were evaluated in acetic acid-induced abdominal constriction, hot plate test, and formalin-induced paw licking test. Administration of normal saline, acetylsalicylic acid (ASA, 100 mg/kg, orally), and morphine (5 mg/kg, intraperitoneally) were used for the experiments. Results: : HPLC revealed that the APE from Trigona thoracica contained p-coumaric acid (R2 = 0.999) and caffeic acid (R2 = 0.998). Although all APE dosages showed inhibition of acetic acid-induced abdominal constriction, only 2,000 mg/kg was comparable to the result of ASA (68.7% vs. 73.3%, respectively). In the hot plate test, only 2,000 mg/kg of APE increased the latency time significantly compared to the control. In the formalin test, the durations of paw licking were significantly reduced at early and late phases in all APE groups with a decrease from 45.1% to 53.3%. Conclusions: : APE from Trigona thoracica, containing p-coumaric acid and caffeic acid, exhibited antinociceptive effects, which supports its potential use in targeting the prevention or reversal of central and peripheral sensitization that may produce clinical pain conditions.

Pollen chemical and mechanical defences restrict host-plant use by bees.

Plants produce an array of chemical and mechanical defences that provide protection against many herbivores and pathogens. Putatively defensive compounds and structures can even occur in floral rewards: for example, the pollen of some plant taxa contains toxic compounds or possesses conspicuous spines. Yet little is known about whether pollen defences restrict host-plant use by bees. In other words, do bees, like other insect herbivores, tolerate the defences of their specific host plants while being harmed by non-host defences? To answer this question, we compared the effects of a chemical defence from Lupinus (Fabaceae) pollen and a putative mechanical defence (pollen spines) from Asteraceae pollen on larval survival of nine bee species in the tribe Osmiini (Megachilidae) varying in their pollen-host use. We found that both types of pollen defences reduce larval survival rate in some bee species. These detrimental effects were, however, mediated by host-plant associations, with bees being more tolerant of the pollen defences of their hosts, relative to the defences of plant taxa exploited by other species. This pattern strongly suggests that bees are adapted to the pollen defences of their hosts, and that host-plant use by bees is constrained by their ability to tolerate such defences.

Systemic pesticides in a solitary bee pollen food store affect larval development and increase pupal mortality.

Solitary bees are often exposed to various pesticides applied for pest control on farmland while providing pollination services to food crops. Increasing evidence suggests that sublethal toxicity of agricultural pesticides affects solitary bees differently than the social bees used to determine regulatory thresholds, such as honey bees and bumblebees. Studies on solitary bees are challenging because of the difficulties in obtaining large numbers of eggs or young larvae for bioassays. Here we show the toxic and sublethal developmental effects of four widely used plant systemic pesticides on the Japanese orchard bee (Osmia cornifrons). Pollen food stores of this solitary bee were treated with different concentrations of three insecticides (acetamiprid, flonicamid, and sulfoxaflor) and a fungicide (dodine). Eggs were transplanted to the treated pollen and larvae were allowed to feed on the pollen stores after egg hatch. The effects of chronic ingestion of contaminated pollen were measured until adult eclosion. This year-long study revealed that chronic exposure to all tested pesticides delayed larval development and lowered larval and adult body weights. Additionally, exposure to the systemic fungicide resulted in abnormal larval defecation and increased mortality at the pupal stage, indicating potential risk to bees from fungicide exposure. These findings demonstrate potential threats to solitary bees from systemic insecticides and fungicides and will help in making policy decisions to mitigate these effects.

Algerian Propolis from Distinct Geographical Locations: Chemical Profiles, Antioxidant Capacity, Cytotoxicity and Inhibition of 5-Lipoxygenase Product Biosynthesis.

Propolis was collected from honeybee hives in three geographically distinct Algerian climates and extracts were characterized for composition and bioactivity. Bees were identified as native subspecies using an in-silico DraI mtDNA COI-COII test. Over 20 compounds were identified in extracts by LC-MS. Extracts from the Medea region were more enriched in phenolic content (302±28 mg GAE/g of dry extract) than those from Annaba and Ghardaia regions. Annaba extracts had the highest flavonoid content (1870±385 mg QCE/g of dry extract). Medea extracts presented the highest free-radical scavenging activity (IC50=13.5 µg/mL) using the DPPH radical assay while Ghardaia extracts from the desert region were weak (IC50>100 µg/mL). Antioxidant activities measured using AAPH oxidation of linoleic acid were similar in all extracts with IC50 values ranging from 2.9 to 4.9 µg/mL. All extracts were cytotoxic (MTT assay) and proapoptotic (Annexin-V) against human leukemia cell lines in the low µg/mL range, although the Annaba extract was less active against the Reh cell line. Extracts inhibited cellular 5-lipoxygenase product biosynthesis with IC50 values ranging from 0.6 to 3.2 µg/mL. Overall, examined propolis extracts exhibited significant biological activity that warrant further characterization in cellular and in vivo models.

Honey bee colonies change their foraging decisions after in-hive experiences with unsuitable pollen.

Pollen is the protein resource for Apis mellifera and its selection affects colony development and productivity. Honey bee foragers mainly lose their capacity to digest pollen, so we expect that those pollen constituents that can only be evaluated after ingestion will not influence their initial foraging preferences at food sources. We predicted that pollen composition may be evaluated in a delayed manner within the nest, for example, through the effects that the pollen causes on the colony according to its suitability after being used by in-hive bees. To address whether pollen foraging is mediated by in-hive experiences, we conducted dual-choice experiments to test the avoidance of pollen adulterated with amygdalin, a deterrent that causes post-ingestion malaise. In addition, we recorded pollen selection in colonies foraging in the field after being supplied or not with amygdalin-adulterated pollen from one of the dominant flowering plants (Diplotaxis tenuifolia). Dual-choice experiments revealed that foragers did not avoid adulterated pollens at the foraging site; however, they avoided pollen that had been offered adulterated within the nest on the previous days. In field experiments, pollen samples from colonies supplied with amygdalin-adulterated pollen were more diverse than controls, suggesting that pollen foraging was biased towards novel sources. Our findings support the hypothesis that pollen assessment relies on in-hive experiences mediated by pollen that causes post-ingestive malaise.

Beneficial Bacteria and Plant Extracts Promote Honey Bee Health and Reduce Nosema ceranae Infection.

The research aims to give new insights on the effect of administering selected bacterial strains, isolated from honey bee gut, and/or a commercial plant extract blend (HiveAlive®) on Nosema ceranae. Analyses were first performed under laboratory conditions such as different infective doses of N. ceranae, the effect of single strains and their mixture and the influence of pollen administration. Daily survival and feed consumption rate were recorded and pathogen development was analysed using qPCR and microscope counts. Biomarkers of immunity and physiological status were also evaluated for the different treatments tested using one bacterial strain, a mixture of all the bacteria and/or a plant extract blend as treatments. The results showed an increase of abaecin transcript levels in the midgut of the honey bees treated with the bacterial mixture and an increased expression of the protein vitellogenin in the haemolymph of honey bees treated with two separate bacterial strains (Bifidobacterium coryneforme and Apilactobacillus kunkeei). A significant effectiveness in reducing N. ceranae was shown by the bacterial mixture and the plant extract blend regardless of the composition of the diet. This bioactivity was seasonally linked. Quantitative PCR and microscope counts showed the reduction of N. ceranae under different experimental conditions. The antiparasitic efficacy of the treatments at field conditions was studied using a semi-field approach which was adapted from research on insecticides for the first time, to analyse antiparasitic activity against N. ceranae. The approach proved to be reliable and effective in validating data obtained in the laboratory. Both the mixture of beneficial bacteria and its association with Hive Alive® are effective in controlling the natural infection of N. ceranae in honey bee colonies.

More than mesolectic: Characterizing the nutritional niche of Osmia cornifrons.

Characterizing the nutritional needs of wild bee species is an essential step to better understanding bee biology and providing suitable supplemental forage for at-risk species. Here, we aim to characterize the nutritional needs of a model solitary bee species, Osmia cornifrons (Radoszkowski), by using dietary protein-to-lipid ratio (P:L ratio) as a proxy for nutritional niche and niche breadth. We first identified the mean target P:L ratio (~3.02:1) and P:L collection range (0.75-6.26:1) from pollen provisions collected across a variety of sites and time points. We then investigated the P:L tolerance range of larvae by rearing bees in vitro on a variety of diets. Multifloral and single-source pollen diets with P:L ratios within the range of surveyed provisions did not always support larval development, indicating that other dietary components such as plant secondary compounds and micronutrients must also be considered in bee nutritional experiments. Finally, we used pollen metabarcoding to identify pollen from whole larval provisions to understand how much pollen bees used from plants outside of their host plant families to meet their nutritional needs, as well as pollen from individual forager bouts, to observe if bees maintained strict floral constancy or visited multiple plant genera per foraging bout. Whole larval provision surveys revealed a surprising range of host plant pollen use, ranging from ~5% to 70% of host plant pollen per provision. Samples from individual foraging trips contained pollen from multiple genera, suggesting that bees are using some form of foraging decision making. Overall, these results suggest that O. cornifrons have a wide nutritional niche breadth, but while pollen P:L ratio tolerance is broad, a tolerable P:L ratio alone is not enough to create a quality diet for O. cornifrons, and the plant species that make up these diets must also be carefully considered.

The fa(c)ts that matter: Bumble bees differentially allocate and oxidate three common fatty acids in pollen.

Pollen serves as a crucial source of protein and lipids for numerous insects. Despite the importance of pollen lipids for nutrient regulation in bees, the digestibility and absorption of different fatty acids (FAs) by bees remain poorly understood. We used 13C labeled fatty acids (FAs) to investigate the absorption and allocation of three common dietary FAs in pollen by bumble bees. Palmitic acid, the most common saturated FA in pollen, was poorly absorbed, even when supplied as tripalmitate, emulsified, or mixed in vegetable oil. In contrast, the essential linoleic acid was absorbed and allocated at the highest rate among the three FAs tested. Oleic acid, a non-essential monounsaturated FA, was absorbed and oxidized at lower rates than linoleic acid. Notably, a feeding rate experiment revealed that different fatty acids did not affect the consumption rate of pollen. This results suggests that the specific FA's absorption efficiency and allocation differ in bumble bees, impacting their utilization. These findings demonstrate the importance of considering the digestibility and absorption of different FAs. Furthermore, the study highlights the influence of pollen lipid composition on the nutritional content for pollinators and raises questions about the utilization of polyunsaturated FAs in insect metabolism.

Female solitary bees flexibly change foraging behaviour according to their floral resource requirements and foraging experiences.

Intraspecific variation in foraging behaviour is related to the floral resource requirements and foraging experiences of social bees. These behavioural changes influence their pollination efficiency. However, the extent of such behavioural changes in solitary bees, which constitute the majority of bee species, remains largely unknown. As pollen contains essential nutrients for ovarian and offspring development, a relationship between the resource requirements of female bees and their ovarian development is expected. Additionally, wing damage could reflect foraging experiences, as the wings are damaged during foraging. Here, we aimed to clarify the relationships between ovarian development, wing damage, foraging behaviours, and pollination efficiency in female long-horned bees (Eucera nipponensis and Eucera spurcatipes) visiting red clovers. The bee handling times were recorded. Wing damage and pollen load on the hind legs were confirmed and the number of pollen grains on bee's bodies was counted. We then dissected the bees and recorded the presence or absence of nectar and pollen in the digestive tubes, as well as the mature egg number. The mature egg number positively correlated with nectar feeding and pollen collection, whereas handling time decreased with wing damage. Bees with pollen loads on their legs attach more pollen grains to their bodies. Therefore, solitary bees flexibly change their foraging behaviour based on resource requirements and foraging experiences, and these behavioural changes can influence pollination efficiency. The asynchrony of foraging behaviours and pollination efficiency within a bee population may provide stable pollination for flowering plants throughout the season.

Negative effects of urbanisation on diurnal and nocturnal pollen-transport networks.

Pollinating insects are declining due to habitat loss and climate change, and cities with limited habitat and floral resources may be particularly vulnerable. The effects of urban landscapes on pollination networks remain poorly understood, and comparative studies of taxa with divergent niches are lacking. Here, for the first time, we simultaneously compare nocturnal moth and diurnal bee pollen-transport networks using DNA metabarcoding and ask how pollination networks are affected by increasing urbanisation. Bees and moths exhibited substantial divergence in the communities of plants they interact with. Increasing urbanisation had comparable negative effects on pollen-transport networks of both taxa, with significant declines in pollen species richness. We show that moths are an important, but overlooked, component of urban pollen-transport networks for wild flowering plants, horticultural crops, and trees. Our findings highlight the need to include both bee and non-bee taxa when assessing the status of critical plant-insect interactions in urbanised landscapes.

Honeybees (Apis mellifera) decrease the fitness of plants they pollinate.

Most flowering plants require animal pollination and are visited by multiple pollinator species. Historically, the effects of pollinators on plant fitness have been compared using the number of pollen grains they deposit, and the number of seeds or fruits produced following a visit to a virgin flower. While useful, these methods fail to consider differences in pollen quality and the fitness of zygotes resulting from pollination by different floral visitors. Here we show that, for three common native self-compatible plants in Southern California, super-abundant, non-native honeybees (Apis mellifera L.) visit more flowers on an individual before moving to the next plant compared with the suite of native insect visitors. This probably increases the transfer of self-pollen. Offspring produced after honeybee pollination have similar fitness to those resulting from hand self-pollination and both are far less fit than those produced after pollination by native insects or by cross-pollination. Because honeybees often forage methodically, visiting many flowers on each plant, low offspring fitness may commonly result from honeybee pollination of self-compatible plants. To our knowledge, this is the first study to directly compare the fitness of offspring resulting from honeybee pollination to that of other floral visitors.

Regional plant abundance explains patterns of host use by pollen-specialist bees in eastern North America.

Specialist insect herbivores make up a substantial fraction of Earth's biodiversity; however, they exploit a minority of plant lineages. For instance, in the eastern United States and Canada, ~25% of bee species are pollen specialists, but they are hosted by a small fraction of the native, animal-pollinated angiosperms in the region: Only 6% of plant genera and 3% of families support pollen-specialist bees. It is unclear why some plant lineages host specialist bees while others do not. We know that at least some specialist bees use plant taxa that are avoided by generalists, suggesting that specialist bees favor plants with low-quality pollen, potentially as a strategy to escape competition or obtain protection from natural enemies. There is also evidence that specialist bees prefer superabundant host plants. Here we investigate whether pollen quality and plant abundance predict patterns of host use by specialist bees in eastern North America. Through field observations, we find that plants hosting specialist bees are frequent sources of pollen for generalists, suggesting that their pollen is not generally avoided by bees due to poor pollen quality. In addition, our analysis of a large citizen-science data set shows that regional abundance strongly predicts which plant genera in the eastern United States host pollen-specialist bees. Our results show that bees specialize on regionally abundant-but not necessarily low-quality-plant lineages. These plant lineages may provide more opportunities for the evolution of specialists and lower likelihood of specialist extinction.

Pollinators differ in their contribution to the male fitness of a self-incompatible composite.

PREMISE: Reproductive fitness in plants is often determined by the quantity and quality of pollen transferred by pollinators. However, many fitness studies measure only female fitness or rely on proxies for male fitness. Here we assessed how five bee taxon groups affect male fitness in a prairie plant by quantifying pollen removal, visitation, and siring success using paternity assignments and a unique pollinator visitation experiment. METHODS: In Echinacea angustifolia, we measured per-visit pollen removal for each pollinator taxon and estimated the number of pollen grains needed for successful ovule fertilization. Additionally, we directly measured pollinator influence on siring by allowing only one bee taxon to visit each pollen-donor plant, while open-pollinated plants acted as unrestricted pollen recipients. We genotyped the resulting offspring, assigned paternity, and used aster statistical models to quantify siring success. RESULTS: Siring success of pollen-donor plants differed among the five pollinator groups. Nongrooming male bees were associated with increased siring success. Bees from all taxa removed most of the flowering head's pollen in one visit. However, coneflower-specialist bee Andrena helianthiformis removed the most pollen per visit. Female fitness and proxy measures of male fitness, such as pollinator visitation and pollen removal, did not align with our direct quantifications of male fitness. CONCLUSIONS: Our results illustrate the need for more studies to directly quantify male fitness, and we caution against using male fitness proxy measures. In addition, conservation efforts that preserve a diverse pollinator community can benefit plants in fragmented landscapes.

Seasonal patterns of beneficial phytochemical availability in honey and stored pollen from honey bee colonies in large apiaries.

Honey bees (Apis mellifera L.; Hymenoptera, Apidae) are the most efficient pollinators in agroecosystems, responsible for the successful production of fruits, nuts, and vegetables, but they continue to face debilitating challenges. One of the major factors leading to these challenges could be linked to poor nutrition that results in weakening the colony, increasing susceptibility to pests and pathogens, and reducing the ability of bees to adapt to other abiotic stresses. Extensively used for commercial pollination, honey bee colonies regularly face exposure to limited diversity in their pollen diet as they are placed in flowering monocrops. Lack of access to diverse plant species compromises the availability of plant secondary compounds (phytochemicals), which, in small amounts, provide significant benefits to honey bee health. We analyzed the beneficial phytochemical content of honey and stored pollen (bee bread) samples from colonies in large apiaries through the active bee season. Samples were evaluated for 4 beneficial phytochemicals (caffeine, kaempferol, gallic acid, and p-coumaric acid), which have previously been shown to improve honey bee health. Our results, as relevant to the apiary locations in the study, indicated that p-coumaric acid is uniformly available throughout the season. Caffeine is completely absent, and gallic acid and kaempferol are not regularly available. Our results suggest the need to explore the potential to deliver beneficial phytochemicals as nutritional supplements to improve bee health. It may be vital for the pollination industry to consider such targeted dietary supplementation as beekeepers strive to meet the increasing demand for crop pollination services.

Individual bee foragers are less-efficient transporters of pollen for plants from which they collect the most pollen in their scopae.

PREMISE: Bees provision most of the pollen removed from anthers to their larvae and transport only a small proportion to stigmas, which can negatively affect plant fitness. Though most bee species collect pollen from multiple plant species, we know little about how the efficiency of bees' pollen transport varies among host plant species or how it relates to other aspects of generalist bee foraging behavior that benefit plant fitness, such as specialization on individual foraging bouts. METHODS: We compared the pollen collected and transported by three bee species for 46 co-occurring plant species. Specifically, we compared the relative abundance of pollen taxa in the individual bees' scopae, structures where bees store pollen to provision larvae, with the relative abundance of pollen taxa on the rest of bees' bodies, which is more likely to be transferred to stigmas. RESULTS: Bees carried five times more pollen grains in their scopae than elsewhere on their bodies. Within foraging bouts, bees were relatively specialized in their pollen collection, but transported proportionally less pollen for the host plants on which they specialized. Across foraging bouts, two bee species transported proportionally less pollen for some of their host plants than for others, though differences didn't consistently follow the same trend as at the foraging bout scale. CONCLUSIONS: Our results suggest that foraging-bout specialization, which is known to reduce heterospecific pollen transfer, also results in less-efficient pollen transport. Thus, bee foragers that visit predominantly one plant species may have contrasting effects on that plant's fitness.

Survivorship and food consumption of immatures and adults of Apis mellifera and Scaptotrigona bipunctata exposed to genetically modified eucalyptus pollen.

Eucalyptus comprises the largest planted area of cultivated production forest in Brazil. Genetic modification (GM) of eucalyptus can provide additional characteristics for increasing productivity and protecting wood yield, as well as potentially altering fiber for a diversity of industrial uses. However, prior to releasing a new GM plant, risk assessments studies with non-target organisms must be undertaken. Bees are prominent biological models since they play an important role in varied ecosystems, including for Eucalyptus pollination. The main goal of this study was to evaluate whether a novel event (Eucalyptus 751K032), which carries the cp4-epsps gene that encodes the protein CP4-EPSPS and nptII gene that encodes the protein NPTII, might adversely affect honey bees (Apis mellifera) and stingless bees (Scaptotrigona bipunctata). The experiments were performed in southern Brazil, as follows: (i) larvae and adults were separately investigated, (ii) three or four different pollen diets were offered to bees, depending on larval or adult status, and (iii) two biological attributes, i.e., survivorship of larvae and adults and food intake by adults were evaluated. The diets were prepared with pollen from GM Eucalyptus 751K032; pollen from conventional Eucalyptus clone FGN-K, multifloral pollen or pure larval food. The insecticide dimethoate was used to evaluate the sensitivity of bees to toxic substances. Datasets were analyzed with Chi-square test, survival curves and repeated measures ANOVA. Results indicated no evidence of adverse effects of Eucalyptus pollen 751K032 on either honey bees or stingless bees assessed here. Therefore, the main findings suggest that the novel event may be considered harmless to these organisms since neither survivorship nor food consumption by bees were affected by it.

Abamectin and difenoconazole monitoring in strawberry flowers and pollen sampled from Tetragonisca angustula (Latreille) (Hymenoptera: Apidae) hives located in crop vicinities.

The increase in agricultural productivity associated with the emergence and the extensive use of pesticides is undeniable. However, strong evidence indicates that this continuous demand is causing serious environmental impacts and bringing toxic effects to associated biota as pollinating insects. The present work aims the determination of the insecticide abamectin (ABA) and the fungicide difenoconazole (DIF) in strawberry flowers (Fragaria x ananassa DUCH.) and pollen sampled from beehives of the stingless bee Tetragonisca angustula Latreille (Hymenoptera: Apidae) located nearby strawberry fields. For analysis, QuEChERS method was optimized, and the analytical performance of those two pesticides was verified. Then, the method was applied to strawberry flowers and the pollen was sampled during three field campaigns. While abamectin was not detected, the systemic fungicide difenoconazole was determined in almost all flowers and pollen samples, demonstrating the major persistence of this pesticide in investigated matrices. The results were then discussed about the difenoconazole application rate and transport to colonies to estimate a preliminary environmental risk assessment for stingless native bees. All calculations were proceeded considering exposure rates and toxicity data from the literature, adapted from Apis mellifera studies. In this sense, the determination, application, and discussion about risk assessment figure out as an important tool to the knowledge about the preliminary risks of native bees exposed to pesticides.

Lipidomic analysis of geopropolis of Brazilian stingless bees by LC-HRMS.

Stingless bees (Meliponini) represent over than 500 species, found in tropical and sub-tropical regions of the world. They produce geopropolis, a resinous natural product containing bioactive compounds, which is commonly used in folk medicine. In the current study, LC-HRMS and bioinformatic tools were used to carry out for the first time the lipidomic analysis of geopropolis from indigenous Brazilian stingless bees. As a result, 61 compounds of several lipid classes were identified with elevated degree of confidence. Then, we demonstrated that lipids in geopropolis are not restricted to waxes and fatty acids; but fatty amides and amines, phenolic lipids, resorcinols, retinoids, abietanoids, diterpenoids, pentacyclic triterpenoids, prostaglandins, retinoids, and steroids were found. In addition, multivariate analysis, based on the lipidomic profile of extracts, reinforces the assumption that the species of stingless bees, as well as the geographical origin are relevant factors to affect geopropolis composition once that the lipidic profile allowed the discrimination of geopropolis in groups related to the geographical origin, bee specie or bee genus. The lipidic profile also suggest a selective forage habits of T. angustula, which seems to collect resins from more specific vegetal sources regardless geographic origin, while other stingless bees, such as M. marginata and M. quadrifasciata, are less selective and may adapt to collect resins from a wider variety of plants.

Pesticide residues in nectar and pollen of melon crops: Risk to pollinators and effects of a specific pesticide mixture on Bombus terrestris (Hymenoptera: Apidae) micro-colonies.

Residues detected in pollen collected by honey bees are often used to estimate pesticide exposure in ecotoxicological studies. However, for a more accurate assessment of pesticides effect on foraging pollinators, residues found directly on flowers are a more realistic exposure approximation. We conducted a multi-residue analysis of pesticides on pollen and nectar of melon flowers collected from five fields. The cumulative chronic oral exposure Risk Index (RI) was calculated for Apis mellifera, Bombus terrestris and Osmia bicornis to multiple pesticides. However, this index could underestimate the risk since sublethal or synergistic effects are not considered. Therefore, a mixture containing three of the most frequently detected pesticides in our study was tested for synergistic impact on B. terrestris micro-colonies through a chronic oral toxicity test. According to the result, pollen and nectar samples contained numerous pesticide residues, including nine insecticides, nine fungicides, and one herbicide. Eleven of those were not applied by farmers during the crop season, revealing that melon agroecosystems may be pesticide contaminated environments. The primary contributor to the chronic RI was imidacloprid and O. bircornis is at greatest risk for lethality resulting from chronic oral exposure at these sites. In the bumblebee micro-colony bioassay, dietary exposure to acetamiprid, chlorpyrifos and oxamyl at residue level concentration, showed no effects on worker mortality, drone production or drone size and no synergies were detected when pesticide mixtures were evaluated. In conclusion, our findings have significant implications for improving pesticide risk assessment schemes to guarantee pollinator conservation. In particular, bee pesticide risk assessment should not be limited to acute exposure effects to isolated active ingredients in honey bees. Instead, risk assessments should consider the long-term pesticide exposure effects in both pollen and nectar on a range of bees that reflect the diversity of natural ecosystems and the synergistic potential among pesticide formulations.