Unravelling the microplastic menace: Different polymers additively increase bee vulnerability.

Microplastics (MPs) are growing and ubiquitous environmental pollutants and represent one of the greatest contemporary challenges caused by human activities. Current research has predominantly examined the singular toxicological effects of individual polymers, neglecting the prevailing reality of organisms confronted with complex contaminant mixtures and potential synergistic effects. To fill this research gap, we investigated the lethal and sublethal effects of two common MPs, polystyrene (PS - 4.8-5.8 µm) and poly(methyl methacrylate) (PMMA - 1-40 µm), and their combination (MIX), on the pollinating insect Apis mellifera. For each treatment, we evaluated the oral toxicity of two ecologically relevant and one higher concentration (0.5, 5 and 50 mg/L) and analysed their effects on the immune system and worker survival. As immune activation can alter the cuticular hydrocarbon profile of honey bees, we used gas chromatography-mass spectrometry (GC-MS) to investigate whether MPs lead to changes in the chemical profile of foragers and behavioural assay to test whether such changes affect behavioural patterns of social recognition, undermining overall colony integrity. The results indicate an additive negative effect of PS and PMMA on bee survival and immune response, even at ecologically relevant concentrations. Furthermore, alterations in cuticle profiles were observed with both MPs at the highest and intermediate concentrations, with PMMA being mainly responsible. Both MPs exposure resulted in a reduction in the abundance of several cuticular compounds. Hive entry guards did not show increased inspection or aggressive behaviour towards exposed foragers, allowing them to enter the colony without being treated differently from uncontaminated foragers. These findings raise concerns not only for the health of individual bees, but also for the entire colony, which could be at risk if contaminated nestmates enter the colony undetected, allowing MPs to spread throughout the hive.

Microplastics reach the brain and interfere with honey bee cognition.

Scientific research on the impact of microplastics (MPs) in terrestrial systems is still emerging, but it has confirmed adverse health effects in organisms exposed to plastics. Although recent studies have shown the toxicological effects of individual MPs polymers on honey bees, the effects of different polymer combinations on cognitive and behavioural performance remain unknown. To fill this knowledge gap, we investigated the effects of oral exposure to spherical MPs on cognitive performance and brain accumulation in the honey bee Apis mellifera. We evaluated the acute toxicity, after a two-day exposure, of polystyrene (PS - 4.8-5.8 µm) and plexiglass (Poly(methyl methacrylate), or PMMA - 1-40 µm) MPs, and a combination of the two (MIX), at two environmentally relevant and one higher concentration (0.5, 5 and 50 mg L-1) and analysed their effects on sucrose responsiveness and appetitive olfactory learning and memory. We also used fluorescent thermoset amino formaldehyde MPs (1-5 µm) to explore whether microspheres of this diameter could penetrate the insect blood-brain barrier (BBB), using Two-Photon Fluorescence Microscopy (TPFM) in combination with an optimized version of the DISCO clearing technique. The results showed that PS reduced sucrose responsiveness, while PMMA had no significant effect; however, the combination had a marked negative effect on sucrose responsiveness. PMMA, PS, and MIX impaired bee learning and memory in bees, with PS showing the most severe effects. 3D brain imaging analysis using TFPM showed that 1-5 µm MPs penetrated and accumulated in the brain after only three days of oral exposure. These results raise concerns about the potential mechanical, cellular, and biochemical damage that MPs may cause to the central nervous system.

Nectar non-protein amino acids (NPAAs) do not change nectar palatability but enhance learning and memory in honey bees.

Floral nectar is a pivotal element of the intimate relationship between plants and pollinators. Nectars are composed of a plethora of nutritionally valuable compounds but also hundreds of secondary metabolites (SMs) whose function remains elusive. Here we performed a set of behavioural experiments to study whether five ubiquitous nectar non-protein amino acids (NPAAs: ß-alanine, GABA, citrulline, ornithine and taurine) interact with gustation, feeding preference, and learning and memory in Apis mellifera. We showed that foragers were unable to discriminate NPAAs from water when only accessing antennal chemo-tactile information and that freely moving bees did not exhibit innate feeding preferences for NPAAs. Also, NPAAs did not alter food consumption or longevity in caged bees over 10 days. Taken together our data suggest that natural concentrations of NPAAs did not alter nectar palatability to bees. Olfactory conditioning assays showed that honey bees were more likely to learn a scent when it signalled a sucrose reward containing either ß-alanine or GABA, and that GABA enhanced specific memory retention. Conversely, when ingested two hours prior to conditioning, GABA, ß-alanine, and taurine weakened bees' acquisition performances but not specific memory retention, which was enhanced in the case of ß-alanine and taurine. Neither citrulline nor ornithine affected learning and memory. NPAAs in nectars may represent a cooperative strategy adopted by plants to attract beneficial pollinators.

Effects of a Low FODMAP Diet and Specific Carbohydrate Diet on Symptoms and Nutritional Adequacy of Patients with Irritable Bowel Syndrome: Preliminary Results of a Single-blinded Randomized Trial.

BACKGROUND AND OBJECTIVES: IBS is the most common functional disease of the low gastrointestinal tract. Recently, the interest towards a diet approach has increased, for example, a diet with low content of fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAPs). The aim of the present study is to evaluate the efficacy of a low FODMAP diet and a specific carbohydrate diet (SCD) conducted for 3 months on symptoms and to evaluate the deficiencies of vitamin D and folic acid in patients affected by IBS, matching the Rome IV criteria. METHODS: We evaluated 73 patients divided into 2 groups: one submitted to low FODMAP diet and one to SCD, for 3 months. Patients were assigned to one of the 2 groups randomly and blinded. All the patients filled a visual analogue scale (VAS) to evaluate the severity of symptoms and a diary to evaluate the number of days with symptoms, and this was repeated after 3 months. Final evaluation was made by a blinded investigator. RESULTS: In the end, the patients with low FODMAP diet had a significant improvement in bloating and distension (P = 0.000); the group with SCD instead had a low but not a significant improvement. One way ANOVA showed comparable severity of symptoms in the 2 groups pre-diet (P = 0.215), but a difference in the same symptoms after 12 days (P = 0.000). Tukey test showed a significant improvement in the low FODMAP diet group and only a trend of improvement in the second group of SCD. The vitamin D mean value in both groups at the time of enrollment was 38 ng/mL; in the end, the mean value in the low FODMAP diet group was 32 ng/mL and in the SCD group was 22 ng/mL, with a statistically significant difference. The folic acid mean value at the time of enrollment was 18 mg/dL; in the end, the mean value in the low FODMAP diet group was 15 mg/dL and in the SCD group was 8 mg/dL, with a statistically significant difference. CONCLUSION: Patients affected by IBS seem to have benefitted from a low FODMAP diet but not from an SCD, and a low FODMAP diet doesn't seem to cause vitamin D and folic acid deficiencies.