Infected honeybee foragers incur a higher loss in efficiency than in the rate of energetic gain

Abstract

Parasites, by altering the nutritional and energetic state of their hosts, can significantly alter their foraging behaviour. In honeybees, an infection with Nosema ceranae has been shown to lower the energetic state of individual bees, bringing about changes in behaviours associated with foraging. Comparing the foraging trip times, hive times in between trips, and the crop contents of uninfected and infected foragers as they depart on foraging trips and return from them, this study examined how any differences in these variables influence alternative foraging currencies. The results show that infected bees take longer foraging trips, spend shorter time in the hive between successive trips and bring back less sugar from each trip. These changes have a stronger adverse effect on their efficiency of energetic gain as compared with their rate of energetic gain, which has important implications for individual and colony life history.

Nosema ceranae in Apis mellifera: a 12 years postdetection perspective

“…As indicated above, bees respond to many stressors by foraging earlier in life (e.g., N. ceranae infection), yet this is not without significant cost to the individual bees and to the colony as a whole. These precocious foragers (also indicated in Naug, ) have a greatly reduced effective foraging life and efficiency compared to normal aged foragers. Such colonies stabilize their populations for a period and brood rearing continues (as described in Higes et al ., ), yet the population ultimately declines if the stress is maintained chronically as the colony's capacity to buffer its effects becomes exhausted ( N. ceranae is constantly present in colonies in warm areas).…”

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

“…ceranae . This gut parasite has been shown to modify many aspects of honey bee behaviour, including increased maturation (Dussaubat et al ., ; Goblirsch et al ., ), impaired learning (Mallon et al ., ; Kralj and Fuchs, ), enhanced energetic stress (Mayack and Naug, ; Mayack and Naug, ) and changes to flight and homing behaviour (Alaux et al ., ; Naug, ; Wolf et al ., ; Perry et al ., ). N .…”

“…N . ceranae has previously been shown to increase the number of foraging trips and flight duration, reduce the time spent in the hive (Alaux et al ., ; Naug, ; Retschnig et al ., ) and reduce foraging efficiency (Naug, ), but since individuals were not tracked once they had left the hive, the proportion of the time spent flying or resting was unknown. In contrast, exploring whether DWV affects flight behaviour in bees that do not exhibit the visual symptoms of deformed wings typical of high levels of infection (de Miranda and Genersch, ), yet may already be suffering altered physiological, neurological or immunological function remains to be done.…”

Nosema spp. infections cause no energetic stress in tolerant honeybees

“…Thus, a well-adapted host might be able to either allocate resources more efficiently or has acquired a mechanism to compensate for any resource losses due to parasitic infection. In social insect societies such as honeybees, sterile workers contribute to the fitness of the colony without receiving direct fitness benefits (Hamilton, 1964;Moritz & Southwick, 1992). Hence, it is the fraction of infected workers in a colony which is a critical parameter in determining tolerance to an infectious disease rather than the infection level of an individual worker (Straub et al, 2015).…”