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In the conducted study the level of manifestation of hygienic behavior of 25 bee colonies was tested from the honey bee (Apis mellifera L.) in Bulgaria. During the testing the method used for killing the brood was with an entomological pin. Based on the results two types of colonies were determined - hygienic (where 48 h after killing the brood the percentage of cleaned cells with dead brood was over 95%) and non-hygienic (where 48 h after killing the brood the percentage of cleaned cells with dead brood was lower than 95%). From each bee colony young non-flying worker bees were taken and the morphometric measurements of their chitin body parts were made. In the study 18 morphological traits were tested and 2 indexes were calculated. High degree of reliability (p=0.001) between hygienic and non-hygienic bee colonies was determined for 2 morphological traits - Total length of fore wing and Length of proboscis. For the traits Length of tibia and Width of Ist tarsus of fore leg and Width and Surface of the left wax mirror of IIIrd sternit medium degree of reliability (p=0.01) was determined. In 3 other traits - Length of femur of fore leg, Length of IIIrd sternit and Length of IInd part of the cubital cell of the fore wing low reliability (p=0.05) was established. The results obtained from the present study indicate the existence of statistically significant differences between the morphometric characteristics of worker bees from hygienic and non-hygienic bee colonies. These traits are related to the productivity of worker bees. [ABSTRACT FROM AUTHOR]

Testing for the level of manifestation of the hygienic behavior of 32 bee colonies from the local honey bee (Apis mellifera L.) from three apiaries has been carried out. Depending on the level of manifestation of the cleansing instinct, two groups of bee colonies have been formed - hygienic (these clean over 95% of the cells with dead brood up to the 48th hour after killing the brood) and non-hygienic (these clean less than 95% of the cells with dead brood up to the 48th hour). Woiker bee samples have been taken from the tested bee colonies to determine the level of fat body development. The fat body is important for the bee organism, since in addition to being a fat and carbohydrate storage depot, it is also considered to be the center of metabolism in insects. The analysis of the results from the present study revealed that the mean value of the level of fat body development in worker bees from the group of hygienic bee colonies was 2.76±0.038. In the group of non-hygienic colonies this value was 7.61% lower (2.55±0.079). This difference is statistically significant at p<0.05. Significant differences have been found in the development of the fat body in worker bees from apiaries at a distance of 100 km without regard to hygienic behavior and according to hygienic behavior. The results obtained suggest that there is a correlation between the level of fat body development and the hygienic behavior in bees. [ABSTRACT FROM AUTHOR]

The objective of the present study is to examine the changes in some indicators characterizing the winter hardiness of bee colonies settled in hives made of different material (polystyrene, wood, ceramics) and with different type of bottom (lattice or solid). Some parameters which characterize the wintering of bee colonies (amount of dead bees and quantity of food consumption in winter) have been investigated. The bee colonies were housed in 10-frame Dadant Blatt hives with a lattice and solid bottom situated at the Training Apiary of the Faculty of Agriculture, Trakia University, Stara Zagora, Bulgaria. Two inspections of the bee colonies were carried out (during wintering in November 2020 and at the beginning of the active season in March 2021). Amount of bees in the bee hive (strength) and amount of capped honey in the honeycombs were reported. In bee colonies wintering in hives with a lattice bottom, the consumption of food per 1 kg of bees was 1.639 kg (50%) higher than in hives with a solid bottom. Winter mortality of bees in hives with a lattice bottom was higher compared to this indicator in the hives with a solid bottom, 16.19±10.72% and 12.59±3.57%, respectively, which can be considered excellent wintering below 15% and good wintering in the range of 15.0-19.99%. [ABSTRACT FROM AUTHOR]

The hygienic behaviour of 26 bee colonies of apiaries in different regions of Bulgaria was tested. The degree of expression of hygienic behaviour was evaluated by the pin-killing method. A test field of square 5 x 5 cm was stuck onto a section of a honeycomb with a sealed worker brood. The bee colonies are divided into two groups: hygienic (cleaned over 95% of cells in the testing area on the 48th hour) and nonhygienic (cleaned less than 95% of the cells in the testing area on the 48th hour). Haemolymph has been taken from bees from each bee colony at 48th hour and lysozyme levels and total protein content has been defined. Multivariate analysis (ANOVA) was used to determine significant differences between hygienic and nonhygienic colonies. The results obtained show significant differences between both groups (P<0.05) according to percent cleaned cells after killing the brood at 3rd, 24th and 48th hours and insignificant differences between hygienic and nonhygienic colonies (P<0.05) for both parameters-lysozyme and total protein. Bivariate correlation was applied to investigate the impact of hygienic behaviour on lysozyme levels and total protein content. Low negative correlation (r=-0.33) between total protein and hygienic behaviour was established which means that an increase of the activities related to the cleansing of honeycomb cells leads to a decrease in the total protein content. Low correlation (r=0.35) between hygienic behaviour and lysozyme levels was found i.e. higher levels of lysozyme are reported with more pronounced hygiene behaviour. The calculated regression model for lysozyme (P=0.24826) is statistically insignificant but the regression model for total protein is statistically significant (P=0.003153) and can be used to predict the relation between total protein content in the haemolymph and hygienic behaviour of bee colonies. [ABSTRACT FROM AUTHOR]