>  honey yields started to drop right when varroa started to be a problem.  We have known for a long time  that honey yields were a direct exponential function of how strong the hive is.

This is from the supplementy data for the report (https://iopscience.iop.org/article/10.1088/1748-9326/acff0c/meta#)

> According to NASS methodology and quality reports (2011-2021), about 7,000 beekeepers are surveyed across the United States (US) each year, with about a ~70% response rate. Survey responses have a coefficient of variation < 2% each year on average (2019-2021 quality report). Therefore, survey estimates are a precise representation of honey yield across states.

> Unfortunately, the survey did not historically collect data on beekeeper practices or colony health and thus these variables could not be used in our analysis. While factors such as Varroa destructor infestation levels (a parasite of honey bee colonies, commonly considered the greatest threat to colony health and productivity can have a significant effect on honey production, a recent longitudinal study found that Varroa management technique (organic versus conventional) is not associated with differences in honey yields. Only colonies managed without chemical intervention have higher Varroa infestation and lower honey yields (3), but this type of natural management is very uncommon among US beekeepers (2% of surveyed beekeepers).

* This sidesteps the issue of what caused an apparent two decade decline. *

PLB

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