Honey bee larva development
To understand the social organisation of insect colonies, including those of honey bees, cooperative brood care is a common research focus35. However, cooperative brood care remains rather difficult to observe in a living colony because visual inspections must be performed deep within the colonies. There is a current lack of methods available to monitor individual behaviours involved in cooperative brood care, while changes in larval nutrition, which depend on age and caste, make this a complex field in honey bee research. In this report, we describe a novel video-based technique for recording and analysing brood care within honey bee colonies and studying the effects of insecticides on brood care behaviour in living hives. Our approach overcomes the existing gap between laboratory and field effects by providing non-invasive long-term quantifications of within-hive brood care. We monitored larval development and larvae-worker interactions in longitudinal truncated brood cells in undisturbed small observation hives and developed an analysis method to determine the cause, number and duration of brood cell visits over several weeks of continuous recording time. For the very first time, we report that field realistic concentrations (cf.17,31,36,37,38) of neonicotinoids alter nursing behaviour within honey bee colonies.
Varroa Destructor & Varroa Jacobsonii & Apis Cerana collonies
Parasite host shifts can impose a high selective pressure on novel hosts. Even though the coevolved systems can reveal fundamental aspects of host–parasite interactions, research often focuses on the new host–parasite relationships. This holds true for two ectoparasitic mite species, Varroa destructor and Varroa jacobsonii, which have shifted hosts from Eastern honey bees, Apis cerana, to Western honey bees, Apis mellifera, generating colony losses of these pollinators globally. Here, we study infestation rates and reproduction of V. destructor and V. jacobsonii haplotypes in 185 A. cerana colonies of six populations in China and Thailand to investigate how coevolution shaped these features. Reproductive success was mostly similar and low, indicating constraints imposed by hosts and/or mite physiology. Infestation rates varied between mite haplotypes, suggesting distinct local co-evolutionary scenarios. The differences in infestation rates and reproductive output between haplotypes did not correlate with the virulence of the respective host-shifted lineages suggesting distinct selection scenarios in novel and original host. The occasional worker brood infestation was significantly lower than that of drone brood, except for the V. destructor haplotype (Korea) from which the invasive lineage derived. Whether mites infesting and reproducing in atypical intraspecific hosts (i.e., workers and queens) actually predisposes for and may govern the impact of host shifts on novel hosts should be determined by identifying the underlying mechanisms. In general, the apparent gaps in our knowledge of this coevolved system need to be further addressed to foster the adequate protection of wild and managed honey bees from these mites globally.
Reproduction of ectoparasitic mites
K E Y W O R D S: honey bee, host shift, infestation, reproduction, Varroa mites