REVIEW: Emerging viral disease risk to pollinating insects: ecological, evolutionary and anthropogenic factors

Abstract

The potential for infectious pathogens to spillover and emerge from managed populations to wildlife communities is poorly understood, but ecological, evolutionary and anthropogenic factors are all likely to influence the initial exposure and subsequent infection, spread and impact of disease. Fast-evolving RNA viruses, known to cause severe colony losses in managed honeybee populations, deserve particular attention for their propensity to jump between host species and thus threaten ecologically and economically important wild pollinator communities. We review the literature on pollinator viruses to identify biological and anthropogenic drivers of disease emergence, highlight gaps in the literature, and discuss potential management strategies. We provide evidence that many wild pollinator species are exposed to viruses from commercial species, resulting in multiple spillover events. However, it is not clear whether species become infected as a result of spillover or whether transmission is occurring within these wild populations. Ecological traits of pollinating insects, such as overlapping ranges, niches and behaviours, clearly promote cross-species transmission of RNA viruses. Moreover, we conclude that the social behaviour and phylogenetic relatedness of social pollinators further facilitate within- and between-host transmission, leaving these species particularly vulnerable to emerging diseases. We argue that the commercial use of pollinators is a key driver of disease emergence in these beneficial insects and that this must be addressed by management and policy. Synthesis and applications. There are important knowledge gaps, ranging from disease distribution and prevalence, to pathogen life history and virulence, to the impacts of disease emergence, which need to be addressed as research priorities. It is clear that avoiding anthropogenic pathogen spillover is crucial to preventing and managing disease emergence in pollinators, with far-reaching effects on our food security, ecosystem services and biodiversity. We argue that it is crucial to prevent the introduction of diseased pollinators into natural environments, which can be achieved through improved monitoring and management practices.

Covert deformed wing virus infections have long-term deleterious effects on honeybee foraging and survival

“…We hope that in the future, these approaches may continue to be used to further our understanding of the factors involved in the ongoing pollinator declines [1 -5] and how they interact with each other in exerting long-term stress [2,[5][6][7][8][9][10].…”

Evidence of Varroa-mediated deformed wing virus spillover in Hawaii

“…Re-emerging viral diseases such as DWV represent one of the major threats to honey bee health, and the "spillover" of pathogens to wild bees and other insects may also contribute to the current global pollinator decline (Fürst et al, 2014;Genersch et al, 2006;Graystock et al, 2013a;Graystock et al, 2013b;Manley et al, 2015;Tehel et al, 2016). Here we carry out a preliminary comparison of the incidence of DWV on non-Apis insects in areas with and without V. destructor.…”

Neonicotinoids override a parasite exposure impact on hibernation success of a key bumblebee pollinator

“…A variety of factors have been proposed to be related to population declines, including climate change, fragmentation and decline in habitat quality, pesticides in agroecosystems, and invasive or native parasites (Vanbergen et al, 2013;Goulson et al, 2015). Colony losses of managed honeybees and population losses of bumblebees and other important pollinating insects have been linked to parasites (Moritz et al, 2005;Cameron et al, 2011;Dainat et al, 2012;Fürst et al, 2014;Manley et al, 2015). Parasites themselves can present a substantial threat, especially after host shifts (Woolhouse et al, 2005;Fürst et al, 2014), but the detrimental effects they precipitate on host individuals and populations may be exacerbated in the presence of other environmental stressors (Vanbergen et al, 2013).…”