Nada Lakic

Morphological, biochemical and hematological characterization of endangered Balkan donkey breed.

Abstract The aim of the study was to establish morphometric, biochemical and hematological values for the endangered Balkan donkey breed (Serbia) and to explore the possible age dependence of the parameters tested. Inter-breed similarity of morphometric parameters was assessed by comparing the data obtained for the Balkan donkey with morphometric measurements of several previously characterized domestic donkey breeds. The study population included 74 donkeys, divided in two age groups (group A ≤ 3 years; group B > 3 years). In total, 18 morphometric, 13 hematological and 14 biochemical parameters were assessed. Significant morphometric differences (p<0.05) in body length, head length, chest circumference and body weight were found between the two age groups. Significant differences in morphological parameters were revealed among the Balkan donkey and other donkey breeds (Catalonian, Croatian and Albanian), but results of cluster analysis demonstrated the smallest distance between the Balkan donkey and Albanian donkeys. The results of morphometric analyses showed consistency of the obtained values within the breed, and diversity as compared to other donkey breeds, and, thus, could be taken as referent for the Balkan donkey. Hematological and biochemical profiles obtained for the Balkan donkey were consistent with previous reports and within the recommended reference ranges. White blood cell, mid cell and granulocyte counts, showed significantly higher (p<0.05) values in donkeys under 3 years of age, while the only biochemical parameter affected by age was alkaline phosphatase. The information gained through characterization of the Balkan donkey breed provides a basis for conservation and development of the breed standard.

Stimulating effect of sugar dusting on honey bee grooming behaviour

The aim of this research was to investigate whether or not sugar dusting can stimulate the grooming behaviour in Apis mellifera L. (Hymenoptera: Apidae), an important defensive mechanism against Varroa destructor Anderson & Trueman (Acari: Varroidae), and to assess the most effective dose and frequency of treatment. The criterion for evaluation of grooming potential was the percentage of damaged mites (PDM) among the total number collected on the bottom boards of the hives. In each sugar‐treated group PDM was significantly higher in comparison both with the negative control (no treatment) and with the values preceding the treatment. The results point to a stimulating effect of sugar on the grooming behaviour at all doses and frequencies tested. Treatment frequency influenced the stimulating effect of sugar: treatments at 3‐ and 7‐day intervals with 30 and 40 g resulted in significantly higher PDMs than the least frequent treatment (every 14 days); dusting with 20 g influenced PDM only when repeated at 3‐day intervals. Because treatments at 3‐day intervals are time‐consuming, those with 40 or 30 g repeated every 7 days may be recommended. In the positive control (hives treated with amitraz), average PDM was significantly lower than in the negative control and all sugar‐treated groups. Possible causes of the stimulating effect of sugar dusting on bee grooming behaviour are discussed.

Nosema ceranae and queen age influence the reproduction and productivity of the honey bee colony

Summary The strength of the honey bee colony and the quality concerning brood production, number of worker bees and honey yield depend substantially upon the characteristics of the queen. Reproductive and productive capacities of the colony, as two important physiological qualities can depend a great deal on the age of the queen. Over the years, the laying ratio of queens could decrease depending on the age; therefore colonies headed by one-year-old queens have proven to be more efficient considering colony population and honey production than ones with older queens. Nosema ceranae infection is a possible reason for the decrease in reproductive capacities and the reduction in the honey production of infected colonies. With the help of numerous pheromones, the queen can preserve colony homeostasis, however exhausted by N. ceranae infection she might compromise the renewal of worker population. The aim of this research is to investigate the influence of N. ceranae on reproduction and productivity of honey bee colonies headed by queens of different age. Experiment was conducted on 27 honey bee colonies equalized with regard to brood, food source, number of worker bees and Nosema infection. In the three year investigation period (2009–2012), Nosema detection, identification and spore load per each colony, as well as parameters of colony reproduction (such as uncapped and capped brood area, queen egg-laying rate and colony strength) and productivity (the total extracted honey and the winter honey stores) were recorded. Concerning the influence of the age of the queens on followed parameters we compared one, two and three-years old queens and found significantly higher reproductive and productive values in favour of younger ones. Significant differences regarding the effects of N. ceranae infection on productive and reproductive characteristics could be explained with a higher capacity of one year old queens to compensate the effects of Nosema infection; a capacity which gradually declines in the second and the third year.

Efficacy of plant-derived formulation “Argus Ras” in Varroa destructor control

Abstract Varroa destructor is the most important honey bee parasite. There are various methods used in the control of this mite, but none of them meets all requested criteria, to be safe, effective and easy to apply. The objective of this study was to evaluate the varroacidal efficacy of newly created plant-derived formulation Argus Ras (mixture of extracts of Sophora flavescens, Ginkgo biloba, Gleditsia chinensis and Teucrium chamaedrys) in a field trial. The investigation was conducted on 240 Apis mellifera colonies equalized in respect of brood amount, adult bee population and food reserves. Efficiency was evaluated by applying Argus Ras consecutively with two other acaricides, amitraz and oxalic acid. Average acaricidal efficacy of Argus Ras was 80.89%, being higher of other previously tested essential oils. Besides, it showed a potential in knocking down the mites resistant to other acaricides. It should not be neglected that Argus Ras requires a smaller number of treatments and financial investments than other formulations used for the control of Varroa mites.

Dietary amino acid and vitamin complex protects honey bee from immunosuppression caused by Nosema ceranae

Microsporidium Nosema ceranae is well known for exerting a negative impact on honey bee health, including down-regulation of immunoregulatory genes. Protein nutrition has been proven to have beneficial effects on bee immunity and other aspects of bee health. Bearing this in mind, the aim of our study was to evaluate the potential of a dietary amino acid and vitamin complex “BEEWELL AminoPlus” to protect honey bees from immunosuppression induced by N. ceranae. In a laboratory experiment bees were infected with N. ceranae and treated with supplement on first, third, sixth and ninth day after emergence. The expression of genes for immune-related peptides (abaecin, apidaecin, hymenoptaecin, defensin and vitellogenin) was compared between groups. The results revealed significantly lower (p<0.01 or p<0.001) numbers of Nosema spores in supplemented groups than in the control especially on day 12 post infection. With the exception of abacein, the expression levels of immune-related peptides were significantly suppressed (p<0.01 or p<0.001) in control group on the 12th day post infection, compared to bees that received the supplement. It was supposed that N. ceranae had a negative impact on bee immunity and that the tested amino acid and vitamin complex modified the expression of immune-related genes in honey bees compromised by infection, suggesting immune-stimulation that reflects in the increase in resistance to diseases and reduced bee mortality. The supplement exerted best efficacy when applied simultaneously with Nosema infection, which can help us to assume the most suitable period for its application in the hive.

The effect of Agaricus brasiliensis extract supplementation on honey bee colonies

This study was done to discover any beneficial effect of a medicinal mushroom Agaricus brasiliensis extract on the honey bee. Firstly, a laboratory experiment was conducted on 640 bees reared in 32 single-use plastic rearing cups. A. brasiliensis extract proved safe in all doses tested (50, 100 and 150 mg/kg/day) irrespective of feeding mode (sugar syrup or candy). Secondly, a three-year field experiment was conducted on 26 colonies treated with a single dose of A. brasiliensis extract (100 mg/kg/day) added to syrup. Each year the colonies were treated once in autumn and twice in spring. The treatments significantly increased colony strength parameters: brood rearing improvement and adult population growth were noticed more often than the increase in honey production and pollen reserves. These positive effects were mainly observed in April. In conclusion, A. brasiliensis extract is safe for the bees and helps maintaining strong colonies, especially in spring.