Association of Nosema ceranae Infection with Honey Bee (Apis meillfera) Exposome Profiles and Affected Biological Pathways

Significance of the Topic

The western honey bee (Apis mellifera) faces dramatic population declines due to complex environmental stressors. Integrating exposomics with genetic disease profiling offers a novel multi-omics approach to unravel non-genetic factors driving colony collapse. This methodology can reveal chemical biomarkers linked to pathogen load and disrupted biological pathways in bees.

Objectives and Study Overview

This study aimed to correlate Nosema ceranae infection levels with comprehensive exposome profiles and to identify affected biochemical pathways. Foraging bees were sampled from 30 hives at the end of the foraging season. PCR determined parasite load, and discovery-based exposomics characterized chemical signatures associated with hive health status.

Methodology and Instrumentation

Sample Collection and PCR:

• 60–100 bees per hive collected from seven locations and frozen.
• DNA extracted via phenol/chloroform and ethanol precipitation.
• Semiquantitative PCR targeting N. ceranae with RpS5 reference gene; band intensities quantified by gel electrophoresis and Bioanalyzer.

Exposome Profiling:

• QuEChERS-style extraction: water/acetonitrile/acetic acid, carbon/PSA cleanup, MgSO4/sodium acetate partitioning.
• SPE concentration on carbon cartridges; elution with acetone/toluene.
• GC/Q-TOF analysis on Agilent 7890B GC coupled to 7200B GC/Q-TOF; DB-5MS column, helium constant flow, EI high-res TOF mode, mass range 50–800 Da.

Data Analysis:

• Feature extraction and deconvolution with MassHunter Unknowns Analysis.
• Annotation via NIST library; retained features with S/N > 3 and match score > 0.7.
• Statistical testing, alignment, log2 transformation, and pathway mapping using MassProfiler Professional and Pathway Architect.

Main Results and Discussion

Statistical analysis identified 20 chemical entities significantly (p < 0.05) associated with N. ceranae infection. Key findings:

• Ubiquinone and terpenoid-quinone pathway: β- and γ-tocopherol levels rose with higher parasite loads, indicating oxidative stress response.
• Nicotinate/nicotinamide metabolism: Nicotinamide was strongly upregulated in unhealthy hives (p ≪ 0.00001).
• Oxalic acid, a common treatment marker, correlated with infection status.
• Other markers included 1-methyl-1H-imidazole, 1-tridecyn-4-ol, flavinone derivative, and a plasticizer, suggesting metabolic and environmental influences.

Fold-change analysis revealed many biomarkers exhibiting >10-fold concentration shifts between healthy and infected hives.

Benefits and Practical Applications of the Method

The integrated exposomic and genetic profiling platform enables:

• Discovery of novel chemical biomarkers for early disease detection.
• Insights into disrupted metabolic pathways in infected colonies.
• Hypothesis generation for targeted follow-up studies and intervention strategies.

Future Trends and Potential Applications

Scaling the approach with larger, longitudinal cohorts can validate biomarkers and refine predictive models. Combining exposomics with other omics layers (transcriptomics, proteomics) and deploying field-portable MS instruments may permit real-time colony monitoring. Advanced bioinformatics will enhance pathway integration and risk assessment.

Conclusion

This pilot study demonstrates that multi-omic exposome profiling, coupled with semiquantitative PCR, can reveal chemical signatures linked to N. ceranae infection and hive health. Identified biomarkers and pathways warrant validation in expanded studies to support honey bee conservation and management.

Instrumentation Used

• Agilent 7890B Gas Chromatograph
• Agilent 7200B GC/Q-TOF Mass Spectrometer
• Agilent 2100 Bioanalyzer

References

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