Lysozyme levels in haemolymph of worker bees (Apis mellifera L.) from bee colonies with different degree of expression of hygienic behaviour

S. Lazarov1, I. Zhelyazkova1*, D. Salkova2, R. Shumkova3, S. Takova4

1Department of Animal Science-Non-ruminants and other Animals, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria 2Bulgarian Academy of Sciences, Institute of Experimental Pathology and Parasitology, Fauna and circulation of parasites, 1000 Sofia, Bulgaria 3Experimental Station in Animal Husbandry and Farming, 4700 Smolyan, Bulgaria
4National Diagnostic Scientific Research Veterinary Medical Institute, 1000 Sofia, Bulgaria

(Manuscript received 1 June 2016; accepted for publication 10 August 2016)

Abstract. A total of 24 bee colonies of apiaries with different business orientation were tested for the degree of expression of hygienic behaviour by modified method, different from the traditionally used for this purpose method. To outline the test field a square sized 5 x 5 cm was used, stuck onto a section of a honey comb with sealed worker brood (the area bounded by the stencil is equal to 100 worker bee cells). The brood in the outlined square is killed by a thin entomological needle by jabbing the sealed cells, without destroying their caps. Depending on the time and extent of cleaning bee colonies are divided into 3 groups: super hygienic – colonies which of the 24th hour after the jabbing have uncovered and cleaned over 95% of the outlined area; hygienic – colonies which on the 48th hour after the jabbing have uncovered and cleaned over 95% of the outlined area; non- hygienic – colonies which have cleaned less than 95% of the cells in the area on the 48th hour. From each bee colony samples of worker bees (200-250 pcs.) have been taken and haemolymph obtained. The amount of lysozyme has been defined at the Reference Laboratory “Honeybee health” at the National Diagnostic Scientific Research Veterinary Medical Institute – Sofia by the method of Motavkina et al. (1979), modified by Kostov et al. (1983). The results obtained show different values for the amount of lysozyme in haemolymph of worker bees, depending on the degree of expression of their hygienic behaviour – 10.49 ± 1.86 μg/ml for the group of super hygienic colonies; 9.11 ± 1.37 μg/ml for the group of hygienic ones; 15.22 ± 2.37 μg/ml for the group of non-hygienic bee colonies, respectively. The established values range from 4.59 μg/ml to 38.28 μg/ml, the greatest variation being in the group of non-hygienic colonies. The data suggests that in positive direction compared to the average for the model is the deviation of LS-means of bee colonies with low level of hygiene (non-hygienic). The reported LS-estimates suggest that in the non- hygienic bee colonies there is a tendency of increase the lysozyme content in the haemolymph.

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