Honey Bee Suppresses the Parasitic Mite Vitellogenin by Antimicrobial Peptide.

Yunfei Wu,Martin Kaltenpoth,Benjamin Weiss,Qiushi Liu,Tatsuhiko Kadowaki

doi:10.3389/fmicb.2020.01037

Yunfei Wu, Martin Kaltenpoth + Show 3 more

Open Access

https://doi.org/10.3389/fmicb.2020.01037

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Abstract

The negative effects of honey bee parasitic mites and deformed wing virus (DWV) on honey bee and colony health have been well characterized. However, the relationship between DWV and mites, particularly viral replication inside the mites, remains unclear. Furthermore, the physiological outcomes of honey bee immune responses stimulated by DWV and the mite to the host (honey bee) and perhaps the pathogen/parasite (DWV/mite) are not yet understood. To answer these questions, we studied the tripartite interactions between the honey bee, Tropilaelaps mercedesae, and DWV as the model. T. mercedesae functioned as a vector for DWV without supporting active viral replication. Thus, DWV negligibly affected mite fitness. Mite infestation induced mRNA expression of antimicrobial peptides (AMPs), Defensin-1 and Hymenoptaecin, which correlated with DWV copy number in honey bee pupae and mite feeding, respectively. Feeding T. mercedesae with fruit fly S2 cells heterologously expressing honey bee Hymenoptaecin significantly downregulated mite Vitellogenin expression, indicating that the honey bee AMP manipulates mite reproduction upon feeding on bee. Our results provide insights into the mechanism of DWV transmission by the honey bee parasitic mite to the host, and the novel role of AMP in defending against mite infestation.

Highlights

Large-scale loss of managed honey bee colonies has been recently reported across the globe (Goulson et al, 2015)
Our results show that the artificial infestation of honey bee pupae with T. mercedesae increases deformed wing virus (DWV) copy number in pupae, and transfers the variant present in the mite to the pupa
These results demonstrate that T. mercedesae functions as a bona fide vector for DWV and stimulates replication of the endogenous DWV in honey bee pupae

Summary

Introduction

Large-scale loss of managed honey bee colonies has been recently reported across the globe (Goulson et al, 2015). In the absence of mites, DWV copy numbers remain low in honey bees without specific symptoms (covert infection). DWV levels associated with honey bees are dramatically increased in mite infested colonies (Shen et al, 2005; Forsgren et al, 2009; Khongphinitbunjong et al, 2015; Wu et al, 2017). These honey bees often show multiple symptoms (overt infection), which

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