Downregulation of Mrjp2 and Mrjp3 genes in tandem with histological and locomotor changes in dehydrated and starved Apis mellifera workers

Abstract

Abstract Background Nutritional stress in honey bees Apis mellifera remains a major challenge. This study raises questions about the extreme levels of this stress: dehydration and starvation. Water and food deprivation experiments were conducted separately on caged nurse bees. The impacts of these stresses were inspected twice through 24 h. Transcriptional levels of Mrjp2 and Mrjp3 genes in hypopharyngeal glands (HPGs) were measured. Sections of HPGs underwent histological inspections. Locomotor activities of worker bees were also evaluated. Results Our results showed that both stresses caused significant declines in the expression of the Mrjp2 and Mrjp3 genes in the HPGs. The light micrographs showed cytoplasmic vacuolations and less secretion in the acinar cells of the dehydrated and starved bees over 24 h. This happened simultaneously with significant reductions in the acini diameters of the affected HPGs. Surprisingly, only the starvation stress evoked a temporary increase in the locomotor activity. Conclusion This study indicates that nurse bees are sensitive to dehydration and starvation stresses. The negative impact of these pressures on the hypopharyngeal glands and locomotor activity in nurse bees necessitates finding urgent solutions to the problem of water and food scarcity.