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

Abstract

Viruses are known to contribute to bee population decline. Possible spillover is suspected from the co-occurrence of viruses in wild bees and honey bees. In order to study the risk of virus transmission between wild and managed bee species sharing the same floral resource, we tried to maximize the possible cross-infections using Phacelia tanacetifolia, which is highly attractive to honey bees and a broad range of wild bee species. Virus prevalence was compared over two years in Southern France. A total of 1137 wild bees from 29 wild bee species (based on COI barcoding) and 920 honey bees (Apis mellifera) were checked for the seven most common honey bee RNA viruses. Halictid bees were the most abundant. Co-infections were frequent, and Sacbrood virus (SBV), Black queen cell virus (BQCV), Acute bee paralysis virus (ABPV) and Israeli acute paralysis virus (IAPV) were widespread in the hymenopteran pollinator community. Conversely, Deformed wing virus (DWV) was detected at low levels in wild bees, whereas it was highly prevalent in honey bees (78.3% of the samples). Both wild bee and honey bee virus isolates were sequenced to look for possible host-specificity or geographical structuring. ABPV phylogeny suggested a specific cluster for Eucera bees, while isolates of DWV from bumble bees (Bombus spp.) clustered together with honey bee isolates, suggesting a possible spillover.

Pathogens Spillover from Honey Bees to Other Arthropods

“…The results of this systematic review highlights that the case history of spillover events involving honey bee pathogens increased over the past six decades. This is consistent with the growing interest of the scientific community in understanding the underlying factors [ 12 , 20 , 22 , 54 ]. The higher incidence of spillover cases recorded in Europe, New Zealand, and the Americas may reflect their advances in research and apiculture compared to other regions [ 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 ].…”

“…Spillover events are difficult to prove. Indeed, viral infection and replication in new hosts, which may not develop under artificial conditions, can occur in nature [ 36 , 54 , 55 ]. The increasing number of reports about honey bee pathogens found in new hosts contributes to depict a scenario including one reservoir species and multiple spillover events.…”

Replicative Deformed Wing Virus Found in the Head of Adults from Symptomatic Commercial Bumblebee (Bombus terrestris) Colonies

“…Several studies highlight that bees other than A. mellifera can be infected by the DWV [ 22 , 24 , 25 , 26 , 41 , 52 ]. Additionally, the virus has been detected in the hornets Vespa crabro and Vespa velutina [ 19 , 20 ], wasp Vespula vulgaris [ 53 ], invasive ant Linepithema humile [ 21 ], and beetle Aethina tumida [ 27 , 54 , 55 ].…”

“…In Bombus spp., DWV has been found in several instances worldwide and considered a significant factor of decline in both wild and managed bumblebee populations [ 56 , 57 ]. DWV infections have been reported in B. terrestris [ 25 , 40 , 52 , 58 , 59 , 60 ], B. pascuorum [ 25 , 41 , 52 , 58 , 60 ], B. impatiens [ 24 , 25 , 61 , 62 , 63 ], B. atratus [ 64 , 65 ], B. vagans [ 24 , 62 ], B. huntii [ 63 ], B. ruderatus [ 59 ], B. ternarius [ 24 ], B. lapidarius, B. lucorum , and B. monticola [ 40 ].…”

“…Although the investigated colonies were fed fresh frozen pollen in our laboratory, they already had adults with crippled wings when they arrived, indicating that possible pollen-mediated DWV infections must have occurred at the breeding site. Furthermore, flowers may become contaminated with DWV when visited by infected honey bees, thus representing sites for interspecific transmission to other pollinators, wild bumblebees included [ 16 , 17 , 52 , 69 ].…”