The effect of adding hydroalcoholic extract of Melissa officinalis to the diet on the development of hypopharyngeal glands, honey production and growth of honey bee colonies (Apis mellifera)

This study was performed to investigate the nutritional effect of lemon balm (Melissa officinalis) hydroalcoholic extract on physiological and performance of honey bee colonies. Experimental treatments included control group and groups fed with one, two and three percent of lemon balm (Melissa officinalis) extract. At the beginning of the experiment, colonies were used with the same population and reserves and homosexual queens. In this experiment, the colonies were fed with lemon balm (Melissa officinalis) extract every other day and after feeding the colonies with experimental treatments for one month, were measured parameters such as population, queen egg laying, brood rearing, honey production and development of the hypopharyngeal glands. Brood rearing and queen egg laying were measured by Lattice frame (size of the squares are 5×5 cm2) .The population of adult honey bee was measured by frame and 30 days after feeding the colonies. To investigate development of the hypopharyngeal glands, length and width of 10 acini from different parts of the gland for age 3, 6, 9, 12 and 15 days were measured using a stereomicroscope and by software (T Capture).This experiment was performed in a completely randomized design with 4 replications. Data were analyzed using SAS software and GLM procedure and means were compared using Duncan test at 5% probability level. The results of this study show that at the level of brood rearing, colonies fed with 2% lemon balm extract had a statistically significant increase compared to the control treatment. For population, queen egg laying and honey production parameters, no significant difference was observed between the experimental treatments, but the 2% treatment of lemon balm extract, although not statistically significant, had a better effect numerically. The highest growth of acini level at 3 days (0.0417 mm2) was for honey bees fed with 2% lemon balm extract (P<0.05).There is also a statistically significant difference in the growth of hypopharyngeal glands at different times for each of the treatments. In general, it can be said that adding 2% of lemon balm extract is recommended as a nutritional supplement to honey bee colonies.