Mike, I cannot recall where I saw it but it was in an article and referencing actually several researchers all basically saying that yes hygienic behavior can bee over done. I do not recall exactly where I saw the article and have no idea in what papers it would actually be claimed. I do know it was not the run of the mill beekeeper conversation. It may have been on vsh.org that I first ran across it. I do know there are more reliable claims so it might be worth the time to search.