Age-related changes in the hypopharyngeal gland size and invertase activity in Apis cerana worker bees in queenright and queenless colony contitions.

Abstract

The present study investigated whether Apis cerana worker bees in queenless and queenright colonies varied in their hypopharyngeal gland sizes and levels of invertase activities. It was hypothesized that the worker bees in queenright colonies would exhibit lagged shrinkage of the hypopharyngeal glands as their foraging behavior is delayed. Those from the queenright colonies would also have higher invertase specific activities as they are tasked to provide food to the growing bee population. Microscopic examinations of the hypopharyngeal glands and assays for invertase activity of the crop were conducted on works aged 1, 2, 3, 4, 7, 10, and 17 days old. Following statistical analysis of data gathered, the results revealed that the changes in hypopharyngeal gland size were more prominently influenced by the age of workers up to 17 days from the time of emergence, rather than by the presence of the queen. However, one-way analysis of variance for invertase activity levels revealed the effect of the presence of the queen when workers were 3 to 17 days old. The relationship of the studied parameters, including the sucrose response time of 1- to 4-day-old bees, were discussed in terms of the physiological and behavioral changes undergone by the worker bees with and without the presence of a queen in the colony.