>I have to wonder if the variability we are seeing can be attributed to viruses?

Interesting bit of "science" out this week explores this question at both the individual and stock level:

Honey bee stocks exhibit high levels of intra-colony variation in viral loads (attached).

'Here, we take a crucial first step to providing empirical data on the field relevant level of variation in viral titers among individuals within colonies using five stocks commonly used in the United States: California, Georgia, Russian, Pennsylvania survivors, and Indiana survivors.'

'Our study demonstrates that viral titers are generally highly variable among colony individuals, but this variation is more pronounced in some stocks.'

'Stock was only an important predictor of viral titers for DWV-A and marginally significant for LSV2. Our results showed that, among the five stocks compared, Georgia and California stocks show the highest
viral titers for DWV-A. The DWV complex (DWV-A and DWV-B) is transmitted by the ectoparasitic mite V. destructor (Posada-Florez et al., 2019). Therefore, the low observed levels of DWV titers in the Russians,
Pennsylvania survivors, and Indiana survivors are likely the result of breeding for Varroa mite resistance in these stocks (Morfin et al., 2020; Rinderer & Guzman, 2001). However, the direct connection between differences in virus and mite levels among stocks should be explicitly investigated in the future.'

And while looking for this research, I ran across the following, which looks at this same question at the patriline level:

Intra-Colonial Viral Infections in Western Honey Bees (Apis Mellifera) - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8158351/

'Comparing the levels of DWV variants between the different subfamilies within colonies and sampling periods revealed some significant differences across the groups tested. More precisely, significant differences were found when comparing two and three patrilines for their infection levels with DWV-A and DWV-B, respectively (Table S2, Figure 4). Interestingly, these results varied for the two DWV variants investigated, i.e., some patrilines were differentially infected by one variant, but not with the other.'

'The results of this study also showed that patterns of DWV-A and DWV-B infections can differ significantly across honey bee pupae, even when these hosts belong to the same colony and share the same environment (i.e., the pupae were all infested by a V. destructor foundress and were collected on the same frame). Moreover, when individuals were grouped by subfamilies, significant differences in DWV-A and/or DWV-B genome copies were found. Notably, the significant variation of virus genome copies across subfamilies is in line with previous work showing differential infection in honey bee subfamilies with two other pathogens: Paenibacillus larvae [48] and Ascosphaera apis [49].'

Merry Christmas to one and all!

Russ

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