Published in Scientific Papers. Series D. Animal Science, Vol. LXII, Issue 1
Written by Valentina CEBOTARI, Ion BUZU, Olga POSTOLACHI, Adrian SICEANU, Eliza CĂUIA
The aim of the researches was to reveal the particularities of natural varroa-resistance of honey bees of Carpathian race from the Moldavian Codri and their use in the selection and genetic amelioration of the local bee subpopulation. Scientific researches were a part of the SMARTBEE / FP7.Eu-KBBE.2013.1.3-02 Sustainable Management of Resilient Bee Populations project, in collaboration with the Institute for Beekeeping Research and Development in Bucharest, Romania. In order to achieve the purpose, at the experimental apiary of the Institute of Zoology of the Academy of Sciences of Moldova an experiment was carried out, on a batch of 25 bee families, choosed randomly, supplemented with young queens, obtained conducting from the same apiary. The experiment lasted three years (March 2015-March 2018), in which the queens were not replaced, and the bee families during the entire experimental period were not subjected to any anti-varroa or other disease treatment, nor additional feeding in spring or autumn with nutritional stimulators has not been applied. It was found that under natural conditions, without anti-varroa drug interventions and without the change of queens, from 25 colonies at the begining of experiment only 11 survived, which is 44%. In the bee families that survived in the third year of experiment, the index of natural Varroa mite fall during September- October was higher, compared to the first-year bee families by 42.7-43.0% (td=2.3-1.3; P<0.05 and P>0.1) and 2.7-3.0 times compared to the bee families of the second year (td=4.9-3.0; P<0.001 and P<0.01). Infestation degree of bees with Varroa mite increased, reaching peak values in the third experimental year, up to 4.81 ± 1.00 mites/10 grams of bees, which led to the inhibition of the main physiological functions of reproduction and developing of bee families. The infestation of capped brood cells with Varroa mite progressed in the third year of experiment, being significantly higher in September by 11.5% (td=2.9; P<0.01), compared with the same month of the previous year, which lead to a decrease in the quantity of capped brood, of the colonies strength and the weakening of the vital activity of the bee families as a whole. Queens prolificity declined significantly in October from 700 eggs/24 hours in the first year, to 234 eggs/24 hours in the third year, being less in the last year with 466 eggs/24 hours, or 66.6% (td=5.1; P<0.001). Out of the 11 bee families, which survived in natural conditions for three years, 5 more valuble families were selected in the breeding batch for reproduction. The bee families of the breed batch significantly exeeded the families from experimental batch after the queens prolificity – with 18.4% (P<0.05), the amount of capped brood – with 18.6% (P<0.05) and honey production – with 6.8% (P<0.01). At the same time, in the bee families of the breeding batch, the degree of infestation with mites was lower, the index of natural mites fall and the colonies strength – higher, as well as the boosted wintering resistance, ranging from 82.3-89.0%.
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