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HomeArticlesThe terpenes of leaves, pollen and nectar of thyme inhibit growth of...

The terpenes of leaves, pollen and nectar of thyme inhibit growth of bee disease-associated microbes

Honey bees are highly prone to infectious diseases, causing colony losses in the worst case. However, they combat diseases through a combination of their innate immune system and social defence behaviours like foraging for health-enhancing plant products (e.g. nectar, pollen and resin).

Plant secondary metabolites are not only highly active against bacteria and fungi, they might even enhance selective foraging and feeding decisions in the colony. Here, we tested six major plant terpenes and their corresponding acetates, characterizing six natural Thymus vulgaris chemotypes, for their antimicrobial activity on bacteria associated with European foulbrood.

Comparison of the inhibitory activity revealed the highest activity for carvacrol and thymol whereas the acetates mostly did not inhibit bacterial growth. All terpenes and acetates are present in the nectar and pollen of thyme, with pollen containing concentrations higher by several orders of magnitude. The physiological response was tested on forager and freshly emerged bees by means of antennal electroantennography. Both responded much stronger to geraniol and trans-sabinene hydrate compared to carvacrol and thymol.

In conclusion, bee-forageable thyme product terpenes (mainly from pollen) yield effective antibiotic activity by reducing the growth of bee disease-associated bacteria and can be detected with different response levels by the honey bees’ antennae. This is a further step forward in understanding the complex pathogen-pollinator-plant network.

Silvio
Silviohttps://www.researchgate.net/profile/Silvio_Erler/publications
since 2022 - Privatdozent (lecturer) at Technische Universität Braunschweig, Zoological Institute since 2020 - Deputy head of the institute, Institute for Bee Protection at JKI 2019-2020 - Senior research associate at Julius Kühn-Institute (JKI) – Federal Research Centre for Cultivated Plants, Institute for Bee Protection (Germany) 2018-2019 - Deputy chair of 'Animal Ecology' at MLU Halle-W. (Germany) 2013-2018 - Lecturer at MLU Halle-W. (Germany) 2012-2013 - PostDoc (University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca) 2012 - Dr. rer. nat. (Martin-Luther-University Halle-W. Germany) 2008 - Diploma in Biology (Martin-Luther-University Halle-W. Germany)