Characteristics of some chitin body parts in worker bees (Apis mellifera L.) from hygienic and non-hygienic bee colonies

Abstract. 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 Іst 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.