Hicham El Alaoui

Honeybees are chronically exposed to complex mixtures of chemical and biological stressors in agricultural environments, yet the combined effects of fungicide formulations and pathogens remain insufficiently understood. Fungicides targeting mitochondrial respiration and the widespread microsporidian parasite Nosema ceranae are of particular concern, as both directly interfere with host energy metabolism. In this study, we investigated the effects of chronic oral exposure to three commercial fungicide formulations, Luna Privilege® (fluopyram), Flint® (trifloxystrobin), and Luna Sensation® (fluopyram + trifloxystrobin), administered at environmentally relevant concentrations, alone or in combination with N. ceranae infection, in newly emerged Apis mellifera workers under controlled laboratory conditions. We assessed survival, lipid reserves, parasite load, and midgut transcriptomic responses. While fungicide exposure alone had limited effects on uninfected bees, N. ceranae infection markedly increased sensitivity to all formulations, resulting in significantly elevated mortality under co-exposure conditions. Transcriptomic analyses revealed formulation-dependent patterns of gene deregulation, with the strongest effects observed for Luna Sensation®, including downregulation of genes involved in energy metabolism, mitochondrial function, cofactor metabolism, and stress responses. Flint® also exhibited synergistic effects with N. ceranae, affecting distinct mitochondrial gene subsets, whereas Luna Privilege® induced more limited transcriptional changes. Co-exposure was associated with reduced parasite loads, suggesting that host mitochondrial disruption may indirectly affect N. ceranae development. Infection strongly depleted lipid reserves, with no additional effect of fungicides. Overall, these findings demonstrate that interactions between fungicide formulations and N. ceranae exacerbate honeybee mortality and metabolic disruption, highlighting the need to integrate multi-stressor and formulation-based approaches into pollinator risk assessment.

Several microsporidia, obligate intracellular parasites, have evolved through genome reduction and compaction. Other microsporidia contrast with this trend exhibiting larger genomes, in part through the expansion of transposable elements (TEs). Anncaliia algerae belongs to the latter, and boasts an especially diverse host range. Exploring whether A. algerae’s wide host range is a consequence of TE expansion requires high-quality genomic and transcriptomic data. However, due to an AT-rich genome and abundant TE content, previous sequencing efforts yielded fragmented and/or incomplete genome assemblies. Here, using PacBio Hifi sequencing, we produced a near chromosome-level assembly and extensively annotated the genome through: a microsporidia specific annotation tool (MicroAnnot), de novo TE prediction, and a dual RNA-seq dataset. This approach allowed an in depth look into the genome architecture and ploidy of A. algerae, along with fine characterisation of the TEs. We also highlight three proteins likely involved in TE regulatory machinery in A. algerae.

American and European foulbroods, which are among the most severe honeybee diseases, are caused by Paenibacillus larvae and Melissococcus plutonius, respectively. Both bacteria pose a significant threat to larval health and colony survival. Due to the lack of safe and effective treatments, there is growing interest in using beneficial bacterial supplements as a promising alternative to antibiotics. This study evaluated both the probiotic and postbiotic potential of selected bacterial strains against foulbrood pathogens with the aim of gaining a better understanding of their modes of action. An initial screening of 25 strains for anti-foulbrood activity using agar diffusion techniques was conducted to select the most active candidates for further investigation. We investigated the role of their cell-free supernatants (CFS) and initiated the characterisation of their activity and mechanisms of action. The minimal inhibitory dose of the CFS, the nature of the active compounds, and their antibacterial effect were determined. Finally, the probiotic and postbiotic properties were assessed using P. larvae-infected larvae reared under laboratory conditions. Five lactic acid bacteria exhibited antagonistic activity against one or both pathogens, with two of them showing particularly strong inhibitory effects through their CFS. The CFS of Lactobacillus crispatus and Lactiplantibacillus plantarum achieved complete inhibition of P. larvae at a concentration of 12.5% (v/v). Subsequent characterisation suggested that their activity was primarily bacteriostatic, likely mediated by lactic acid. In vivo assays demonstrated a significant 42.5% increase in larval survival when supplemented with live L. plantarum, whereas CFS treatments failed to rescue infected larvae. These results emphasise the potential of probiotic- and postbiotic-based strategies as a sustainable approach to managing foulbrood in beekeeping.

The honey bee Apis mellifera is exposed to a variety of biotic and abiotic stressors, such as the highly prevalent microsporidian parasite Nosema (Vairimorpha) ceranae and neonicotinoid insecticides. Both can affect honey bee physiology and microbial gut communities, eventually reducing its lifespan. They can also have a combined effect on the insect’s survival. The use of bacterial probiotics has been proposed to improve honey bee health, but their beneficial effect remains an open question. In the present study, western honey bees were experimentally infected with N. ceranae spores, chronically exposed to the neonicotinoid thiamethoxam, and/or supplied daily with the homofermentative bacterium Pediococcus acidilactici MA18/5M thought to improve the honey bees’ tolerance to the parasite. Deep shotgun metagenomic sequencing allowed the response of the gut microbiota to be investigated with a taxonomic resolution at the species level. All treatments induced significant changes in honey bee gut bacterial communities. Nosema ceranae infection increased the abundance of Proteus mirabilis, Frischella perrara, and Gilliamella apicola and reduced the abundance of Bifidobacterium asteroides, Fructobacillus fructosus, and Lactobacillus spp. Supplementation with P. acidilactici overturned some of these alterations, bringing back the abundance of some altered species close to the relative abundance found in the controls. Surprisingly, the exposure to thiamethoxam also restored the relative abundance of some species modulated by N. ceranae. This study shows that stressors and probiotics may have an antagonistic impact on honey bee gut bacterial communities and that P. acidilactici may have a protective effect against the dysbiosis induced by an infection with N. ceranae.

11. The Challenges of Educational Reform in the Arab World was published in The Political Economy of Education in the Arab World on page 239.

Red maple leaf extracts (RME) were tested for their plant defense inducer (PDI) properties. Two extracts were obtained and compared by different approaches: RME1 using ethanol–water (30–70%, v/v, 0.5% HCl 1N) and RME2 using pure water. Both extracts titrated at 1.9 g L⁻¹ in polyphenols and infiltrated into tobacco leaves efficiently induced hypersensitive reaction-like lesions with topical accumulation of auto-fluorescent compounds noted under UV and scopoletin titration assays. The antimicrobial marker PR1, β⁻¹,3-glucanase PR2, chitinase PR3, and osmotin PR5 target genes were all upregulated in tobacco leaves following RME1 treatment. The alkaline hydrolysis of RME1 and RME2 combined with HPLC titration of gallic acid revealed that gallate functions were present in both extracts at levels comprised between 185 and 318 mg L⁻¹. HPLC-HR-MS analyses and glucose assay identified four gallate derivatives consisting of a glucose core linked to 5, 6, 7, and 8 gallate groups. These four galloyl glucoses possessed around 46% of total gallate functions. Their higher concentration in RME suggested that they may contribute significantly to PDI activity. These findings define the friendly galloyl glucose as a PDI and highlight a relevant methodology for combining plant assays and chemistry process to their potential quantification in crude natural extracts.