Evidence of Varroa-mediated deformed wing virus spillover in Hawaii

Abstract

Abstract:Varroa destructor, a parasitic mite of honey bees, is also a vector for viral diseases. The mite displays high host specificity and requires access to colonies of Apis spp. to complete its lifecycle. In contrast, the Deformed Wing Virus (DWV), one of the many viruses transmitted by V. destructor, appears to have a much broader host range. Previous studies have detected DWV in a variety of insect groups that are not directly parasitized by the mite. In this study, we take advantage of the discrete distribution of the Varroa mite in the Hawaiian archipelago to compare DWV prevalence on non-Apis flower visitors, and test whether Varroa presence is linked to a "viral spillover". We selected two islands with different viral landscapes: Oahu, where V. destructor has been present since 2007, and Maui, where the mite is absent. We sampled individuals of Apis mellifera, Ceratina smaragdula, Polistes aurifer, and Polistes exclamens, to assess and compare the DWV prevalence in the Hymenoptera community of the two islands. The results indicated that, as expected, honey bee colonies on Oahu have much higher incidence of DWV compared to Maui. Correspondingly, DWV was detected on the Non-Apis Hymenoptera collected from Oahu, but was absent in the species examined on Maui. The study sites selected shared a similar geography, climate, and insect fauna, but differed in the presence of the Varroa mite, suggesting an indirect, but significant, increase on DWV prevalence in the Hymenoptera community on mite-infected islands.

Pathogen shifts in a honeybee predator following the arrival of the Varroa mite

“…We did not observe an increase in DWV abundance or prevalence in Vespula individuals with the arrival of Varroa, in contrast to recent work on Polistes wasps, which only possess DWV on Hawaiian islands where Varroa is present [27]. Instead, we observed a marked change in strain diversity, demonstrating that spillover may result in subtle effects on pathogen diversity, rather than overall pathogen load.…”

“…Our work suggests that alongside these direct effects there has been a hidden, yet remarkable, change in the genetic diversity of a key virus, perhaps influencing larger pathogen webs, in both honeybees and in an associated predatory insect. We confirm that the effects of Varroa introduction have cascaded through entire communities [27].…”

“…DWV strains vary in their virulence [19,20,26], therefore understanding the factors that shape DWV variant communities is critical to managing this disease. There is also evidence of viral spillover on Hawaii: a recent study found DWV in populations of a solitary bee and a paper wasp only on Oahu where Varroa occurs, not on Maui where Varroa is absent, suggesting a role of Varroa in mediating DWV spillover from honeybees [27].…”

Knock‐on community impacts of a novel vector: spillover of emerging DWV‐B from Varroa‐infested honeybees to wild bumblebees

“…In direct comparison, the prevalence of Nosema species (N. ceranae and N. bombi), an emerging bee disease (F€ urst et al 2014) whose oral-faecal transmission is not linked to Varroa, is unaffected by the presence of this honeybee ectoparasite. These results support reports from Hawaii of increased DWV prevalence in two sympatric pollinators (Polistes wasp species and solitary bee Ceratina smaragdula) (Santamaria et al 2018) and a honeybee predator, Vespula pensylvanica (Loope et al 2019) following the invasion of V. destructor (Martin et al 2012). Data are scarce on DWV prevalence, titre and diversity preceding the arrival of Varroa into western honeybee populations, especially in relation to wild bees.…”

Genetic Strain Diversity of Multi-Host RNA Viruses that Infect a Wide Range of Pollinators and Associates is Shaped by Geographic Origins

“…Increasing evidence suggests that many of these pathogens are not specific to honey bees and instead are shared between many pollinator species and associated arthropods, including bumble bees and other wild bees [10][11][12]; bee predators, such as wasps [10,11]; and scavenging insects, such as ants, cockroaches, and beetles [10,[13][14][15]. Many of these host species have been found cohabiting in bee hives [13,15,16] or share floral resources with honey bees [17][18][19][20]. Although arthropods harbour an enormous diversity of viruses [21,22], little is known about the host range and dynamics of viruses within pollinator communities.…”