In 1976, as an undergraduate taking a BSc degree in Ecology at the University of Ulster, I was shown a tape of a BBC science program on evolution. Appearing in the program was the late Professor John Maynard Smith of Sussex University. He was commenting, among other things, on honey bee hygienic behaviour, for which there was a short clip showing brood infected with American foulbrood. (I am not sure why I can remember this, as at the time I had no particular interest in honey bees.)
Maynard Smith referred to the work of the late Professor Walter Rothenbuhler of the Ohio State University, in Columbus, Ohio, carried out in the 1960s. By crossing honey bees of a non-hygienic line with a hygienic line, Rothenbuhler had convincingly shown that hygienic behaviour was under genetic control. Rothenbuhler’s research became a textbook example of the fact that behaviour could be under the control of genes. This had been controversial. Some scientists had argued that behaviour was learned rather than genetically programmed. (This topic is still controversial when we talk of our own species. See Stephen Pinker’s book, The Blank Slate.)
In his research, Rothenbuhler used the Brown hygienic line. I was told an interesting story about Mr. Brown and his bees by the late Harold Merrill, an expert commercial beekeeper from New York State whom I met while I was a PhD student at Cornell University while we were on a beekeeping tour of Ontario arranged by the late Professor Roger A. “Doc” Morse, the head of Dyce Laboratory for Honey Bee Studies at Cornell. (Merrill was also very generous. He had donated to Dyce Lab a brand new pick up truck and 80 of the best bee hives we had ever seen, all full of bees, equal in population, and in perfect equipment.)
Merrill had visited Brown. Brown ran a wax rendering plant in Iowa. He would melt down wax brought to him by beekeepers, including combs from dead hives. As these would often have honey residues, he had an apiary beside the plant for robbing this out. As some hives would have died due to American foulbrood, his robbing hives would frequently come down with AFB. According to Merrill, Brown would kill the queen in hives with AFB and requeen them with queens or cells from hives that did not have AFB.
What Brown was doing was breeding for resistance to AFB. Without knowing it, what he was actually doing was breeding for hygienic behaviour. As you may have seen in another of my blog pages, research by Professor Marla Spivak of the University of Minnesota has shown that hygienic bees are resistant to AFB. In his research, Rothenbuhler also worked with AFB. He would introduce AFB spores into the brood food of young worker larvae. He showed that the Brown line bees would clean out the diseased brood after capping. Rothenbuhler also went on to study the removal of brood killed by cyanide gas or freezing. Working with AFB is not the easiest thing to do. Working with a serious and contagious honey bee disease is not only risky, it is also hard work. To treat a defined patch of brood Rothenbuhler introduced spores, in suspension in water, into cells with very young larvae one cell at a time.
© F. Ratnieks, July 2016