With this project, we will study how the epidemiology and evolution of viral bee pathogens are affected by the introduction of vector-borne transmission. 

The emergence of novel transmission routes can have profound impact on the ecology and evolution of infectious diseases, with potentially dramatic effects on host populations. This can be particularly drastic when transmission changes from direct to vector-borne transmission, where prevalence and virulence are expected to increase. Despite its importance for disease prevention and control, we lack empirical and theoretical understanding of this process. The emergence of Varroa destructor in honeybees provides a unique opportunity to study how a novel vector affects pathogen ecology and evolution: this blood-feeding mite is a novel vector for Deformed Wing Virus (DWV), a disease linked to severe increases in hive mortality. To study the fundamental evolutionary ecology of emerging vector-borne diseases, we will exploit a unique natural experiment, the presence of Varroa-free island refugia, to test how this novel vector affects epidemiology and evolution in the field. Using this system, we have already shown that the acquisition of Varroa as a viral vector in honeybees has virus-dependent knock-on effects in wild bees (Manley et al. 2019, Ecology Letters; Manley et al. 2020, Molecular Ecology). We will adapt cutting-edge single molecule sequencing to compare viral evolution in the wild and in controlled lab experiments, where I will establish novel reverse genetics approaches in DWV to test hypotheses on specific viral genotypes. Like all emerging diseases, DWV is a multi-host pathogen that also infects wild bee species not infested by Varroa, such as bumblebees. This raises an additional question, highly relevant for zoonotic diseases: does this specialist honeybee vector impact disease in wild bee populations? This system will not only provide fundamental insights into the evolutionary ecology of disease, but is also of immediate applied importance: bees are key pollinators of crops and wildflowers, and halting population declines facilitated by infectious disease is crucial for food security and biodiversity. We will model the effect of vector acquisition and evolving pathogens on host populations and test potential prevention and mitigation strategies to safeguard these crucial pollinators. 

Zwei ERC Consolidator Grants für die Uni Ulm - Professorinnen erforschen Bienen-Virus und schwere Depressionen

A short movie (in german) about our work on vector-borne transmission in bees
3sat Wissen nano - Gefahr für Wildbienen