Phd in CHEMICAL SCIENCES

Thesis title: Probiotics and medicinal plants as "green" tools to protect bees and hive products from chemicals

Honeybee’s role in pollination is crucial for maintaining a high grade of biodiversity in ecosystems and for supporting the whole agricultural sector. Its worldwide population has been under a serious decline for decades; the causes are also attributed to environmental pollution. Chemicals collected by exposed honeybees can induce an oxidative stress response, caused by their bioaccumulation, and lead to various diseases. Potentially, they can also be transferred from the bees to the beehive products, presenting a risk to the final consumer. In this study, the use of probiotics and medicinal plants has been investigated on their capability to reduce pollutants impact, in terms of oxidative stress, and their bioaccumulation in honeybees and beehive products, with a focus on toxic (or potentially toxic) elements. (A) Oxidative stress is a condition that occurs when oxidant agents (i.e., reactive oxygen and nitrogen species) effect overwhelms the cellular antioxidant defenses. To establish a state of health, it can be quantified by measuring specific biomarkers through solid methodologies (mostly colorimetric or fluorometric assays) improved concurrently with the technological development across the years (A1). Pollutants-induced oxidative stress in insects is of great interest in literature for the meaning it has when model organisms are investigated or when insects’ preservation is sought. (B) Honeybees (Apis mellifera), exposed to different levels of environmental pollution through two long-term field biomonitoring campaigns, were administrated with probiotics (two lactic acid bacteria strains) or Quassia amara (Simaroubaceae) containing feedings. The content of about 40 elements in bees and beehive products (B1, B2), oxidative stress levels (B2), and metabolic profiles (B2) in bees were compared against a control (placebo-fed bees). A lesser content of some toxic, or potentially toxic, elements and lower levels of oxidative stress were observed in both the treated groups, revealing a detoxifying action towards elements bioaccumulation and a protective effect against oxidative stress. First in-field data on the potentialities of probiotics and medicinal plants as green remedies to sustain this precious insect’s health against environmental pollution are reported. (C) Airborne particulate matter (PM10) is an environmental pollutant whose composition and chemical-physical parameters are extremely variable. Its potential capability of inducing oxidative stress in cells (namely oxidative potential, OP) can be directly evaluated by rapid acellular chemical assays on PM samples. OP assays are known to produce complementary information on the impact of a PM (in its entirety) on living organisms; little is known about the dependency of each assay with the PM components. Responses of three OP assays (OP_DTT, OP_AA and OP_DCFH) on PM10 samples, collected in an urban-industrial context, were compared with PM’s chemical components (major elements, inorganic ions, elemental and organic carbon, levoglucosan) and spatially resolved source apportionment data to improve knowledge on the meaning of OP assays and provide valuable information into planning effective air pollution mitigation policies (C1). (A1) Contaminant-induced oxidative stress in insects: an overview on the current analytical methods. Trends in Environmental Analytical Chemistry (2025), Under Review (B1) Probiotics as a promising prophylactic tool to reduce levels of toxic or potentially toxic elements in bees. Chemosphere (2022), 308(1), 136261 (B2) Landfill fire impact on bee health: beneficial effect of dietary supplementation with medicinal plants and probiotics in reducing oxidative stress and metal accumulation. Environmental Science and Pollution Research (2023), Dec 30 (C1) Spatially resolved chemical data for PM10 and oxidative potential source apportionment in urban-industrial settings. Urban Climate (2024), 57, 102113