THE SCIENTIST’S PERSPECTIVE


clever PhD student in my lab, decided to dissolve propolis in alcohol. He collected propolis from colonies in our area of Minnesota (mostly from the genus Populus, same as the Biblical Balm of Gilead; and in particular, Populus deltoi- des, or cottonwood trees,) and had some shipped from Brazil where propolis is harvested en masse for human medicine. To make a usable solution, he dissolved the propolis in 70% lab-grade ethanol, the percentage of solvent known to main- tain the highest amount of antimicrobial activity from the resin. Then he painted the interior of one set of bee boxes with the Minnesota propolis extract, in known quantity and concentration. He painted another set of boxes with the Bra- zilian propolis extract and a third set with just 70% ethanol as a control, in case the alcohol itself had antimicrobial proper-  pollen, brood and bees. Mike marked newly emerged adult bees from each colony with a dot of paint on their thorax, so we could recollect them, then left them alone in the colony for a week. When the week was up, he retrieved the paint-marked


bees, and compared their immune system function. He mea- sured the production (or expression) of genes that make an- timicrobial proteins, using a molecular technique called re- al-time quantitative PCR (Polymerase Chain Reaction). Our prediction was borne out: The immune gene expression of bees hived in colonies with a propolis envelope, whether the


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Hive entrance lined with propolis


propolis was derived from local resins or Brazilian resin, was lower compared to bees in colonies without the propolis en-  - ing for the bees. To verify our results, another PhD student, Renata Bor- ba, repeated the study, adding on additional measures of im-


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