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Honey bees collect resin from various plant species and transform it into propolis that is incorporated into the nest. The role of resins in the bee health field is poorly understood. The aim was to evaluate the effects of forced consumption of propolis on the physiological condition and short-term survival of Apis mellifera worker bees. It was tested if the number of circulating hemocytes in hemolymph, the abdominal fat bodies and the hypopharyngeal glands development were affected by the feeding with propolis extracts in laboratory conditions during the warm and the cold seasons. Propolis added to sugar candy was consumed by workers for fourteen days without affecting the bee survival. The number of circulating hemocytes in hemolymph remained constant despite the differential diet during the experiment. However, the development of fat bodies and hypopharyngeal glands was altered by propolis ingestion. The abdominal fat body development in winter bees diminished after fourteen days of propolis consumption, while it increased in summer bees. The hypopharyngeal gland development decreased for the assayed period in workers from both seasons. Our results encourage us to continue exploring this research field and learn how long-term forced ingestion of a plant-derived compound, a non-nutritive substance, can modify physiological bee parameters. A broader understanding of the multiple roles of propolis in the health of the honey bee colonies could be obtained by studying the ways in which it is processed and metabolized and the effect that generates in another physiological responses.

The impact on the integrity of epithelium tissues caused by Paenibacillus larvae in Apis mellifera larvae affected by American foulbrood (AFB) disease may generate oxidative stress. However, the relation between AFB and the oxidative stress status of the larvae remains unknown. In this study, we provide the first evidence that inoculation with P. larvae spores on in vitro reared larvae disturbs the balance between pro-oxidants and antioxidants, influencing enzymatic activity and producing lipid peroxidation. We suggest that the oxidative stress observed in larvae treated with P. larvae would constitute a cytotoxic additional factor, besides virulence components, in the AFB progress [ABSTRACT FROM AUTHOR]

The oil obtained by hydrodistillation of the floral bottom of Syzygium aromaticum (L.) Merr. et Perry was analyzed by GC and GC/MS. Eugenol was the main constituent in the oil (86.7%). The biological activity of the oil applied to Varroa destructor and Apis mellifera was evaluated in two laboratory tests. Mite lethality was estimated using a complete exposure method test with the oil at different concentrations, and a systemic administration method of oil at different concentrations diluted in syrup was placed in feeders for bees. The LC50 for complete exposure method at 24 h was 0.59 μL/dish. The inferior and superior limits obtained were 0.47 x 10-6 μL/dish and 1.22 μL/dish, respectively. LC50 estimated at 48 h showed a slight decrease as compared to that recorded at 24 h. Ratio selection (LC50 of A. mellifera/LC50 of V. destructor) for complete exposure method was 26.46 and 13.35 for 24 h and 48 h, respectively. Regarding the systemic administration method, mites LC50 at 24 h was 12,300 ppm. The inferior and superior limits calculated were 9,214 ppm and 15,178 ppm, respectively. LC50 estimated at 48 h showed a slight decrease as compared to that recorded at 24 h. Ratio selection for systemic administration method was 3.05 and 2.22 for 24 h and 48 h, respectively. Syzygium aromaticum oil was found to be an attractant for V. destructor at 4.8% (w/w) concentration. The results showed that oil toxicity against V. destructor differed depending upon its administration. Nevertheless, the ratio selection calculated by this oil is expected to enable its application under field conditions with a good safety margin. This oil could also be used in combination with other oils in integrated pest management strategies in bee colonies. [ABSTRACT FROM AUTHOR]

The essential oil obtained by hydrodistillation from the fruits of Pimpinella anisum L. (green anise) and Foeniculum vulgare Miller (fennel) were analyzed by GC and GC/MS and physicochemical properties. The oils of P. anisum and F. vulgare were found to be especially rich in (E)-anethole, 96.3% and 92.7%, respectively. The MICs were determined by the tube dilution method against Paenibacillus larvae. The oils showed MICs values were 300 μg/mL and 250 μg/mL for P. anisum and F. vulgare, respectively. Both oils presented great similarity in physiochemical properties values and antimicrobial activity. [ABSTRACT FROM AUTHOR]