Manipulating the light/dark cycle: effects on dopamine levels in optic lobes of the honey bee (Apis mellifera) brain

A new, practicable and economical cage design for experimental studies on small honey bee colonies

Bees are in decline globally due to multiple stressors including pests, pathogens and contaminants. The management of bees in enclosures can identify causes of decline under standardized conditions but the logistics of conducting effect studies in typical systems used across several colonies is complex and costly. This study details a practicable, new and economical cage system that effectively houses live honey bee colonies to investigate the impact of physical conditions, biological factors and environmental contaminants on honey bee health. The method has broad application for a range of effect studies concerning honey bee development, physiology, survival and population dynamics because it enables entire colonies to be managed well in captivity, as opposed to individual workers.

Dopamine enhances locomotor activity for mating in male honeybees (Apis mellifera L.)

Dopamine plays multiple roles in the regulation of reproduction in female honeybees where it appears to act independently of juvenile hormone (JH). In males the role of dopamine and its relationship to JH control have not been elucidated. In the present study we determined hemolymph levels of dopamine and its metabolite (N-acetyldopamine) in males at post-emergence days 0-16. The development of locomotor and flight activities were recorded over the same period. Hemolymph levels of dopamine and N-acetyldopamine were found to increase at the time of onset of mating flight activity and those of dopamine decreased thereafter. Both locomotor and flight activities increased in parallel with hemolymph dopamine levels but the increased activity levels were maintained following decline of dopamine levels. Brain and meso-metathoracic ganglia levels of dopamine showed a similar developmental profile to hemolymph dopamine levels. Locomotor activities were temporarily inhibited by injection of a dopamine-receptor antagonist (cis(Z)-flupenthixol) into the thorax, and were enhanced by injection of a dopamine-receptor agonist (6,7-ADTN). These results suggest that dopamine regulates locomotor activities for mating and plays a role downstream of JH in premature males in honeybees.