>...some removal of  infested brood often took place to some extent, and that uncapping alone might not be enough for full mite control.

Dr. Martin addresses this in his 2021 research out of the UK:

https://link.springer.com/article/10.1007/s13592-021-00852-y


'Mite reproduction was lower in NVR colonies due to increased offspring mortality, although recapping is unlikely the primary mechanism responsible.'

'Martin et al. (2019) support the idea that recapping is associated with infested brood removal behaviour and that recapped cells are evidence for failed instances of brood removal. They added that brood removal behaviour on the other hand, when executed successfully, disrupts the mites’ reproductive cycles and leads to increased levels of nonlaying foundresses.'

This study is interesting that even as they hypothesize that brood removal being a key factor, they actually found that:

'Offspring mortality/underdevelopment was the primary cause of mite reproductive failure in this study as it was significantly higher in NVR populations, as opposed to nonlaying foundresses which were not.'

This lead them to conclude (in part) that:

'Ibrahim and Spivak (2006) showed that failed mite reproduction, which was almost exclusively offspring mortality/underdevelopment, had a significant ‘brood effect’; i.e., the adult bees were not required for the impairment in reproduction to take place. Again, it appears that other mechanism(s) are involved.'

'... it appears that the failed mite reproduction in this population is largely independent from this [hygiene] behaviour. Finding the primary mechanisms behind reduced mite reproduction, with an emphasis on offspring mortality, appears particularly important in understanding mite resistance in the UK (Hudson and Hudson 2020) and beyond (Medina et al. 2002; Locke and Fries 2011; Brettell and Martin 2017).'

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