Comparing foraging behaviour of small and large honey bee colonies by decoding waggle dances made by foragers

1. We compared the foraging behaviour of two small (approximately 6000 bees) and two large (approximately 20 000 bees) honey-bee colonies over 6 days. We determined where the bees of each colony foraged, whether they collected nectar or pollen, the number of patches foraged at, the number of bees engaged in foraging, and the concentration of the nectar collected. 2. Even though the colonies were located in the same environment and had the same genetic background, foragers from different colonies used different forage patches. 3. Small and large colonies foraged at a similar distance in July when forage was abundant (mean foraging distance for small and large colonies was 67 and 62 km, respectively) whereas the large colonies foraged significantly further in August when forage was scarce (mean foraging distance for small and large colonies was 43 and 85 km, respectively). 4. Small colonies foraged at approximately the same number of patches as large colonies. The total number of foragers returning to the small colonies per minute was significantly lower than the number of foragers returning to the large colonies. This means that, relative to their size, small colonies foraged at more patches than large colonies. 5. The quality of the nectar collected by foragers of the small and large colonies did not differ. However, small colonies did collect more pollen than large colonies

Ascorbic, Dehydroascorbic and Isoascorbic Acid Simultaneous Determinations By Reverse Phase Ion Interaction Hplc

Detection was by UV absorbance (after pre-column derivatization of dehydroascorbic acid with 1,2-phenylenediamine). When absent, isoascorbic acid could be used as internal standard. Isocratic separation was accomplished in 11 min using the eluent, methanol-water (5:95, v/v) containing potassium dihydrogen phosphate (50 mM) and the counterion hexadecyltrimethylammonium bromide (5 mM). Sample preparation steps using Sep-pak C18 cartridge were minimal. Ten ppm could be detected for each compound with good reproducibility (c.v. < 2%). The method was used to determine vitamin C content in selected foods and beverages

Efeitos da queima seguida de pastejo ou diferimento sobre a produção, qualidade, cobertura do solo e sistema radicular de uma pastagem natural Effects of burning followed by grazing or deferring on production, quality, soil coverage and root system of a natural pasture

Com o objetivo de estimar os efeitos do fogo associado ao pastejo, com ou sem um período de diferimento após a queima, sobre a produção, qualidade da forragem, cobertura do solo e sistema radicular de uma pastagem natural, foi realizado um experimento no Departamento de Zootecnia da UFSM, Santa Maria, RS, Brasil. Os dados dos atributos da pastagem avaliados foram coletados no período de maio de 1993 a junho de 1994. Os tratamentos consistiram em: queimado em 17/09/92 e pastejado; queimado em 17/09/92, diferido, requeimado em 05/09/93 e pastejado; não queimado e pastejado em 1992, queimado em 22/06/93 e diferido. A queima e opastejo não afetaram a taxa de acumulação diária de matéria seca, a produção de matéria seca, a densidade do sistema radicular da pastagem e o teor de proteína bruta da forragem, mas determinaram maiores valores de digestibilidade in vitro da matéria orgânica. O fogo e o paste/o não aumentaram a exposição do solo, mas reduziram a cobertura, pela destruição de parte da vegetação viva e do material morto em pé.<br>A field trial was conducted at the Animal Science Departament, UFSM, Santa Maria, RS, Brazil, aiming to evaluate the effects ofburning, associated with grazing or deferring after burning on natural pasture attributes. Data were cotiected from May, 1993 to June, 1994. Treatments consisted of: burned in 9/17/92 and grazed; burned in 9/17/92 and deferred, reburned m 9/5/93 and grazed; not burned in 1992 and grazed, burned in 6/22/93 and deferred. Daily dry matter accumulation, dry matter produclion, pasture root system density and crude protein contem were not affected by burning and grazing, but in vitro organic matter digestibility was increased. Sou exposure was not increased by burning and grazing, but canopy was reduced, for the partially destruction ofiive vegetation an dead material