Abiotic and biotic factors affecting the replication and pathogenicity of bee viruses

Abstract

Bees are important pollinators of plants in both agricultural and non-agricultural landscapes. Recent losses of both managed and wild bee species have negative impacts on crop production and ecosystem diversity. Therefore, in order to mitigate bee losses, it is important to identify the factors most responsible. Multiple factors including pathogens, agrochemical exposure, lack of quality forage, and reduced habitat affect bee health. Pathogen prevalence is one factor that has been associated with colony losses. Numerous pathogens infect bees including fungi, protists, bacteria, and viruses, the majority of which are RNA viruses including several that infect multiple bee species. RNA viruses readily infect bees, yet there is limited understanding of their impacts on bee health, particularly in the context of other stressors. Herein we review the influence environmental factors have on the replication and pathogenicity of bee viruses and identify research areas that require further investigation.

Impact of managed honey bee viruses on wild bees

“…Whether viral emergence in managed Western honey bees leads to host switching through the mass action principle [56,57], that is, through increasing density of infective virions in the environment, versus viral adaptation is another question that would benefit from greater attention, not only in understanding the threat posed to wild bee species by managed Western honey bee viruses but also as a model of EID impacts on wildlife. The impact of viruses may also vary with coinfection by two or more viruses [58] and through interactions with other so-called 'stressors' of wild bee species such as pesticide exposure [8], as has been demonstrated at the molecular level for the Western honey bee [59].…”

“…Wild bee species also make a major contribution to crop pollination [6]. Elevated losses of Western honey bees have been reported across northern temperate regions of the world over the past decade [7], with EIDs considered a primary cause of mortality [8], possibly because of increased viral virulence [9]. Wild bee species are also in decline in northern temperate regions of the world concomitant with a decline in the wild flowers they visit and pollinate [10], though causes of population decline, range contraction and wild bee species loss are diverse [11,12].…”

“…One of these in particular, Deformed wing virus (DWV), has risen to prominence because of its association with the honey bee exotic ectoparasitic mite Varroa destructor [15 ], a possibly synergistic association for virus and mite [16]. Varroa destructor (henceforth varroa mite) was originally an ectoparasite of the Asiatic Eastern honey bee (Apis cerana), but jumped to the Western honey bee and is nowadays widespread across most of the world with its new host, the Western honey bee, on which it vectors DWV and many other viruses [8,14]. Introduction of varroa mites to a naïve population of Western honey bees leads to a tremendous rise in DWV prevalence and titer per individual host [17,18], and DWV is the leading contender as the causal agent of colony decline [14].…”

Investigating the viral ecology of global bee communities with high-throughput metagenomics

“…To date, more than 24 viruses have been identified in western honey bees (Apis mellifera) [2][3][4][5][6][7]. These viral infections can result in a range of symptoms, from no obvious phenotype to rapid death and colony loss, depending on the viral species, viral strain, physiological state of the host, and presence of other stressors (reviewed in [8]). However, despite the importance of bees as pollinators of flowering plants in agricultural and natural landscapes [12,13] and the importance of viruses to bee health, our understanding of bee viruses is surprisingly limited: despite the diversity of bee species and their worldwide distribution, the vast majority of the studies examining bee pathogens have focused on western honey bees (Apis mellifera) populations in North America and Europe [14].…”

Virucides in apiculture: persistence of surrogate enterovirus under simulated field conditions

“…Despite desirable antimicrobial action, disinfectants are potentially harmful substances and may also have an adverse impact on living organisms and the environment . Recently, environmental pollutants including agrochemicals together with other biotic and abiotic stressors were reported to affect the condition of honeybees in a negative way . Thus, considerable attention should be paid to the selection of appropriate disinfectants.…”