Trypanosomatid parasites infecting managed honeybees and wild solitary bees

Verena Strobl,Orlando Yañez,Lars Straub,Matthias Albrecht,Peter Neumann

doi:10.1016/j.ijpara.2019.03.006

Verena Strobl, Orlando Yañez + Show 3 more

Open Access

https://doi.org/10.1016/j.ijpara.2019.03.006

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Abstract

The parasite Crithidia mellificae (Kinetoplastea: Trypanosomatidae) infects honeybees, Apis mellifera. No pathogenic effects have been found in individual hosts, despite positive correlations between infections and colony mortalities. The solitary bee Osmia cornuta might constitute a host, but controlled infections are lacking to date. Here, we challenged male and female O. cornuta and honeybee workers in laboratory cages with C. mellificae. No parasite cells were found in any control. Parasite numbers increased 6.6 fold in honeybees between days 6 and 19 p.i. and significantly reduced survival. In O. cornuta, C. mellificae numbers increased 2–3.6 fold within cages and significantly reduced survival of males, but not females. The proportion of infected hosts increased in O. cornuta cages with faeces, but not in honeybee cages without faeces, suggesting faecal – oral transmission. The data show that O. cornuta is a host of C. mellificae and suggest that males are more susceptible. The higher mortality of infected honeybees proposes a mechanism for correlations between C. mellificae infections and colony mortalities.

Highlights

Declines in wild bee species have been reported from several regions of the world (IPBES, 2016a,b), and pathogen spillover from managed honeybees (Apis mellifera) may contribute to these declines (Cameron et al, 2011; Szabo et al, 2012; Burkle et al, 2013; Fürst et al, 2014)
Our results provide clear evidence that the honeybee parasite C. mellificae can infect O. cornuta and further suggest that there are sex-specific differences in host susceptibility in this solitary bee species
There was no significant effect of C. mellificae infection on host body mass in any group of bees, probably because all bees were fed ad libitum

Summary

Introduction

Declines in wild bee species have been reported from several regions of the world (IPBES, 2016a,b), and pathogen spillover from managed honeybees (Apis mellifera) may contribute to these declines (Cameron et al, 2011; Szabo et al, 2012; Burkle et al, 2013; Fürst et al, 2014). A variety of pathogens so far exclusively known for honeybees were detected in several wild bee species The detection of a pathogen in another species does not necessarily imply that this species can serve as a novel host. Without clear evidence that the pathogen is replicating, such observations only indicate that a host shift may have occurred. Being a novel host does not necessarily lead to the same progresq Note: Nucleotide sequence data reported in this paper are available in the European Nucleotide Archive (ENA) databases under the accession number(s), PRJEB26880 (ERP108906)

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