Mobile samplers of particulate matter - Flying omnivorous insects in detection of industrial contamination

Contaminant-driven midgut histological damage in bees and other aculeate Hymenoptera: A quantitative review

We present a review about histological sub-lethal effects due to anthropogenic contaminants on the midgut of bees and other aculeate hymenopterans. Contaminant types, damage types, and methodology were extracted and summarized from 74 published articles, and then quantitatively analyzed. We found that the Western honeybee (Apis mellifera) is by far the most widely used model. Contaminants have largely been tested under laboratory conditions, particularly insecticides and fungicides. Tissue-level damage (e.g., degradation of epithelium and of peritrophic membrane) were often detected together with cell-level damage (e.g., cell vacuolisation, karyorrhexis). Descriptive statistics and mixed models suggested that herbicides may cause a specific mix of alterations with an overall lower severity compared with other pesticides, while the combined use of light and electron microscopy seemed to detect more damage types. We claim for efforts to reduce biases in future studies on such histological effects, allowing their clearer use as markers of human activities.

Effects of Atmospheric Pollutants on Volatile-Mediated Insect Ecosystem Services

Primary and secondary atmospheric pollutants, including carbon monoxide (CO), carbon dioxide (CO2), nitrogen oxides (NOx), ozone (O3), sulphur dioxide (SO2) and particulate matter (PM2.5/PM10) with associated heavy metals (HMs) and micro- and nanoplastics (MPs/NPs), have the potential to influence and alter interspecific interactions involving insects that are responsible for providing essential ecosystem services (ESs). Given that insects rely on olfactory cues for vital processes such as locating mates, food sources and oviposition sites, volatile organic compounds (VOCs) are of paramount importance in interactions involving insects. While gaseous pollutants reduce the lifespan of individual compounds that act as olfactory cues, gaseous and particulate pollutants can alter their biosynthesis and emission and exert a direct effect on the olfactory system of insects. Consequently, air pollutants can affect ecosystem functioning and the services regulated by plant-insect interactions. This review examines the already identified and potential impacts of air pollutants on different aspects of VOC-mediated plant-insect interactions underlying a range of insect ES. Furthermore, we investigate the potential susceptibility of insects to future environmental changes and the adaptive mechanisms they may employ to efficiently detect odours. The current body of knowledge on the effects of air pollutants on key interspecific interactions is biased towards and limited to a few pollinators, herbivores and parasitoids on model plants. There is a notable absence of research on decomposers and seed dispersers. With exception of O3 and NOx, the effects of some widespread and emerging environmental pollutants, such as secondary organic aerosols (SOAs), SO2, HMs, PM and MPs/NPs, remain largely unexplored. It is recommended that the identified knowledge gaps be addressed in future research, with the aim of designing effective mitigation strategies for the adverse effects in question and developing robust conservation frameworks.

Buff-tailed bumblebee, an underrated indicator of air pollution: a comparison of particulate matter accumulation by Bombus terrestris L. and Apis mellifera L

Anthropogenic and natural particulate matter (PM) affects urban and agricultural areas and contaminates the bodies of Apis mellifera (honeybee) and Bombus terrestris (buff-tailed bumblebee). Although both species accumulate PM, scientific interest has primarily focused on A. mellifera as a pollution indicator. This study directly compared the efficacy of honeybees and bumblebees as indicators of PM and its associated trace elements (TEs). Insects were collected from ecological and conventional apple orchards and underwent quantitative analysis of total PM, PM size fractions, and TEs. To establish an environmental context, plant samples and bee products were obtained from both plantations, and screened for PM and/or TEs. Bombus terrestris accumulated 191.3 μg total PM per individual, whereas A. mellifera accumulated 64 μg. Particular PM size fractions were also significantly more abundant on bumblebees. Accumulation patterns of total and large PM on bumblebees differed between the ecological and conventional orchards. Total PM accumulated by both species combined correlated strongly with the total PM covering apple tree foliage in the ecological orchard (r = 0.836) and with grass in the conventional orchard (r = 0.851). The amount of total PM accumulated by B. terrestris strongly correlated with the concentrations of Fe (r = 0.927) and Mn (r = 0.91) in this species. Accumulation of Fe by A. mellifera correlated with the content of this metal in pollen (r = 0.912) and bee bread (r = 0.91), whereas the reverse trend was found for Mo in bee bread (r = -0.912). The results indicate that B. terrestris is a more accurate pollution indicator, with potentially greater efficacy in more polluted areas. The observed differences are most likely attributed to the distinct morphology and behavior of the species.

Tracking fine particles in urban and rural environments using honey bees as biosamplers in Mexico

This work explores the efficiency of honey bees (Apis mellifera) as biosamplers of metal pollution. To understand this, we selected two cities with different urbanization (a medium-sized city and a megacity), and we collected urban dust and honey bees captured during flight. We sampled two villages and a university campus as control areas. The metal content in dust was analyzed by inductively coupled plasma mass spectrometry (ICP-MS). Atomic Force Microscopy (AFM) and Scanning electron microscopy (SEM) were used to investigate the shape and size distribution of the particles, and to characterize the semiquantitative chemical composition of particles adhered to honey bee's wings. Principal Component Analysis (PCA) shows a distinctive urban dust geochemical signature for each city, with component 1 defining V-Cr-Ni-Tl-Pt-Pb-Sb as characteristic of Mexico City and Ce-As-Zr for dust from Hermosillo. Particle count using SEM indicates that 69% and 63.4% of the resuspended dust from Hermosillo and Mexico City, respectively, corresponds to PM2.5. Instead, the particle count measured on the honey bee wings from Hermosillo and Mexico City is mainly PM2.5, 91.4% and 88.9%, respectively. The wings from honey bees collected in the villages and the university campus show much lower particle amounts. AFM-histograms confirmed that the particles identified in Mexico City have even smaller sizes (between 60 and 480 nm) than those in Hermosillo (between 400 and 1400 nm). Particles enriched in As, Zr, and Ce mixed with geogenic elements such as Si, Ca, Mg, K, and Na dominate honey bee' wings collected in Hermosillo. In contrast, those particles collected from Mexico City contain V, Cr, Ni, Tl, Pt, Pb, and Sb. Such results agree with the urban dust data. This work shows that honey bees are suitable biosamplers for the characterization of fine dust fractions by microscopy techniques and reflect the urban pollution of the sites.

The use of honey bees (Apis mellifera L.) to monitor airborne particulate matter and assess health effects on pollinators

The honey bee Apis mellifera has long been recognized as an ideal bioindicator for environmental pollution. These insects are exposed to pollutants during their foraging activities, making them effective samplers of environmental contaminants, including heavy metals, pesticides, radionuclides, and volatile organic compounds. Recently, it has been demonstrated that honey bees can be a valuable tool for monitoring and studying airborne PM pollution, a complex mixture of particles suspended in the air, known to have detrimental effects on human health. Airborne particles attached to the bees can be characterised for their morphology, size, and chemical composition using a scanning electron microscopy coupled with X-ray spectroscopy, thus providing key information on the emission sources of the particles, their environmental fate, and the potential to elicit inflammatory injury, oxidative damage, and other health effects in living organisms. Here, we present a comprehensive summary of the studies involving the use of honey bees to monitor airborne PM, including the limits of this approach and possible perspectives. The use of honey bees as a model organism for ecotoxicological studies involving pollutant PM is also presented and discussed, further highlighting the role of the bees as a cornerstone of human, animal, and environmental health, according to the principles of the "One Health" approach.

Short-term particulate matter contamination severely compromises insect antennal olfactory perception

The consequences of sub-lethal levels of ambient air pollution are underestimated for insects, for example, the accumulation of particulate matter on sensory receptors located on their antennae may have detrimental effects to their function. Here we show that the density of particulate matter on the antennae of houseflies (Musca domestica) collected from an urban environment increases with the severity of air pollution. A combination of behavioural assays, electroantennograms and transcriptomic analysis provide consistent evidence that a brief exposure to particulate matter pollution compromises olfactory perception of reproductive and food odours in both male and female houseflies. Since particulate matter can be transported thousands of kilometres from its origin, these effects may represent an additional factor responsible for global declines in insect numbers, even in pristine and remote areas.

Ingestion of polystyrene microparticles impairs survival and defecation in larvae of Polistes satan (Hymenoptera: Vespidae)

Microplastics (MPs) are widespread pollutants of emerging concern, and the risks associated with their ingestion have been reported in many organisms. Terrestrial environments can be contaminated with MPs, and terrestrial organisms, including arthropods, are predisposed to the risk of ingesting MPs. In the current study, the larvae of the paper wasp Polistes satan were fed two different doses (6 mg or 16 mg at once) of polystyrene MPs (1.43 mm maximum length), and the effects of these treatments on immature development and survival till adult emergence were studied. Ingestion of the two doses resulted in mortality due to impaired defecation prior to pupation. The survival of larvae that ingested 16 mg of MPs was significantly lower than that of the control. The ingestion of 16 mg of MPs also reduced the adult emergence (11.4%) in comparison to the control (44.4%). MPs were not transferred from the larvae to the adults that survived. These findings demonstrate that MP ingestion can be detrimental to P. satan, e.g. larval mortality can decrease colony productivity and thus the worker force, and that MPs can potentially affect natural enemies that occur in crops, such as predatory social wasps.