Flight performance of actively foraging honey bees is reduced by a common pathogen

Abstract

SummarySudden and severe declines in honey bee (Apis mellifera) colony health in the US and Europe have been attributed, in part, to emergent microbial pathogens, however, the mechanisms behind the impact are unclear. Using roundabout flight mills, we measured the flight distance and duration of actively foraging, healthy‐looking honey bees sampled from standard colonies, before quantifying the level of infection by Nosema ceranae and Deformed Wing Virus complex (DWV) for each bee. Neither the presence nor the quantity of N. ceranae were at low, natural levels of infection had any effect on flight distance or duration, but presence of DWV reduced flight distance by two thirds and duration by one half. Quantity of DWV was shown to have a significant, but weakly positive relation with flight distance and duration, however, the low amount of variation that was accounted for suggests further investigation by dose‐response assays is required. We conclude that widespread, naturally occurring levels of infection by DWV weaken the flight ability of honey bees and high levels of within‐colony prevalence are likely to reduce efficiency and increase the cost of resource acquisition. Predictions of implications of pathogens on colony health and function should take account of sublethal effects on flight performance.

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

“…Although DWV infection could in principle also have affected the number of foraging trips and the duration of the trips carried out by individuals that survived to foraging age [33], our statistical analyses revealed that there was no strong evidence for this. For example, the effect of treatment on the number of trips performed was inconsistent and different across the replicate host colonies used (quasi-Poisson GLM, effects of treatment in colonies A, B and C: A.…”

“…Furthermore, two studies in which natural variation in infection levels of DWV was combined with experimentally manipulated variation in infection levels with the microsporidian parasite Nosema showed that DWV-infected bees displayed shortened flight distances and flight durations in flight mill experiments [33], but no differences in orientation flight behaviour in a harmonic radar tracking set-up [34], whereas the reverse pattern was seen for Nosema [33,34]. As yet, however, effects of DWV on honeybee flight behaviour and foraging patterns have not yet been investigated using controlled infection set-ups.…”

Effects of parasites and pathogens on bee cognition

“…Parasitised foragers show an increased activity (Dussaubat et al ., ; Alaux et al ., ; Wells et al ., ), by performing more foraging trips of shorter duration with many stops between them (Dussaubat et al ., ; Wolf et al ., ; Dosselli et al ., ), and spending more time outside the colony (Kralj & Fuchs, ). In addition, honey bees infected with the DWV virus show reduced flight distances and durations when tested in a flight mill arm (Wells et al ., ). These changes in flight behaviour have been associated with the energetic stress caused by the parasites and pathogens that obtain resources from their hosts, who in turn lack nutrients to perform their tasks adequately.…”

“…have reduced foraging performances when compared with uninfected conspecifics. Parasitised foragers show an increased activity (Dussaubat et al, 2013;Alaux et al, 2014;Wells et al, 2016), by performing more foraging trips of shorter duration with many stops between them (Dussaubat et al, 2013;Wolf et al, 2014;Dosselli et al, 2016), and spending more time outside the colony (Kralj & Fuchs, 2010). In addition, honey bees infected with the DWV virus show reduced flight distances and durations when tested in a flight mill arm .…”

Acute and chronic toxicity of acetamiprid, carbaryl, cypermethrin and deltamethrin to Apis mellifera larvae reared in vitro

“…However, no single causative factor has been identified as being responsible for this phenomenon . Several factors, in combination with other stressors, have been identified to explain this decline, including Varroa destructor infestations, deformed wing virus (DWV) infections and the overuse of insecticides . Insecticides may not directly cause colony decline, but they can potentially affect honey bees and/or compromise the bees and increase vulnerability to a range of other stressors .…”