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

Abstract

Emerging viruses have caused concerns about pollinator population declines, as multi-host RNA viruses may pose a health threat to pollinators and associated arthropods. In order to understand the ecology and impact these viruses have, we studied their host range and determined to what extent host and spatial variation affect strain diversity. Firstly, we used RT-PCR to screen pollinators and associates, including honey bees (Apis mellifera) and invasive Argentine ants (Linepithema humile), for virus presence and replication. We tested for the black queen cell virus (BQCV), deformed wing virus (DWV), and Kashmir bee virus (KBV) that were initially detected in bees, and the two recently discovered Linepithema humile bunya-like virus 1 (LhuBLV1) and Moku virus (MKV). DWV, KBV, and MKV were detected and replicated in a wide range of hosts and commonly co-infected hymenopterans. Secondly, we placed KBV and DWV in a global phylogeny with sequences from various countries and hosts to determine the association of geographic origin and host with shared ancestry. Both phylogenies showed strong geographic rather than host-specific clustering, suggesting frequent inter-species virus transmission. Transmission routes between hosts are largely unknown. Nonetheless, avoiding the introduction of non-native species and diseased pollinators appears important to limit spill overs and disease emergence.

Deformed Wing Virus in Two Widespread Invasive Ants: Geographical Distribution, Prevalence, and Phylogeny

“…First, the present study demonstrates that DWV persists in the longhorn crazy ant in all "abundant collection" regions, yet the level of prevalence is generally low. As all colonies of this ant were collected from sites geographically distant from any known apiary, such a low level of prevalence is expected and consistent with previous studies concerning invasive ant species (red imported fire ant [17] and Argentine ant [18]). Payne et al [17] found that DWV is four to five times less prevalent in ants collected from non-apiary sites than those from apiary sites.…”

“…Figueroa et al [ 13 ] and Alger et al [ 5 ] extended such a hypothesis and showed that flowers serve as a hub for transmitting honey bee diseases to other pollinators, suggesting that the circulation of honey bee viruses in the pollinator community may be more common than previously thought [ 14 , 15 ]. Indeed, other minor or non-pollinator insect species—such as ants—were also reported to test positive for several honey bee viruses [ 7 , 16 , 17 , 18 ]. This provides additional support to the hypothesis of interspecific associations likely serving as a conduit for virus transmission, given that ants are frequently found to interact with honey bees via activities such as raiding honey bee broods, scavenging honey bees and competing on floral resources [ 7 , 9 , 19 , 20 ].…”

Possible Spillover of Pathogens between Bee Communities Foraging on the Same Floral Resource

“…In addition the high ABPV and IAPV prevalence that we observed in wild bees is to be considered with the ability of ABPV to infect ant species, thereby reducing emergence and colony size, and impairing their locomotion and movement speed [ 59 ]. Ants were also supposed to be host for the close KBV [ 58 ]. Then, viruses from the AKI-complex are clearly not restricted to the honey bee.…”

“…[ 47 ]. All viruses from the AKI-complex replicate in Bombus [ 46 , 54 , 105 , 106 ], and negative replicative forms were also detected in Vespa velutina [ 68 , 107 ], as well as bees from the Halictidae family [ 46 ] and several ant species [ 58 , 59 ]. Finally, BQCV has been shown to replicate in Bombus spp.…”

“…In addition to pollinator hosts, CBPV, DWV, ABPV and KBV have also been detected in ants (Formicidae) and other arthropods. Evidence for their replication has been found in ants [ 57 , 58 , 59 , 60 ]. Further, experimental transmission of ABPV from the honey bee resulted in impaired ants locomotion and decreased emergence and colony size [ 59 ].…”