Differential expression of hygienic trait characteristics between hygienic and non-hygienic Apis mellifera Linnaeus colonies

Hygienic behaviour in honey bees is a defence mechanism against diseases and parasites. Young worker bees showing hygienic behaviour detect, uncap and remove infested and dead brood from their colonies. The present studies were conducted to evaluate the time taken by the hygienic and non-hygienic colonies to remove the dead brood from the cells killed by pin-killed brood assay. Seven most hygienic and three non-hygienic colonies selected from the stock of 100 colonies screened for hygienic behaviour were used to evaluate the time taken by the designated colonies to exhibit the hygienic trait and the observations were recorded after every 2 h for three days. After 2 h of pricking, the worker bees in the hygienic colonies started uncapping the dead brood. The relative distribution of uncapping the pricked brood in hygienic colonies followed a decreasing rate with the passage of time. An increasing rate of hygienic behaviour was observed in the hygienic colonies with mean dead brood removal in the range of 86.97 ± 2.73 to 94.48 ± 1.04% between the time span of 20 to 48 h after pricking. Hygienic colonies on an average took 20.6 h to exhibit the hygienic behaviour while the non-hygienic colonies took 44.6 h to reach the same. As this trait is associated with resistance to pests and diseases, it should be considered in selective bee breeding programme for honey bees stock improvement.