4.3.2. When to measure reproductive success?
The most accurate evaluation of mite reproductive success can be obtained just prior to worker emergence. However, the hours before emergence is not optimal since the last stage of bee development makes mite recognition difficult. It is therefore recommended to assess this parameter latest one day before emergence and to project in the future the development of the varroa offspring by comparing the developmental stage of the pupae to the developmental stage of the mite offspring. If direct comparisons between studies for several reproductive traits are required then the data must be collected over the same time period. That is, fecundity cannot be accurately measured until 220 hours after cell capping in workers and 240 hours in drone cells, as it is only after this period that all the potential eggs may be laid. It is only possible to determine various abnormal reproductive patterns 60 hours post capping. Table 2 gives the time after capping for which several traits related to reproductive success can be accurately measured.
To obtain a high amount of brood of relevant age in which reproductive success of the mite can be evaluated, cage the queen of a highly infested colony on an empty frame for several hours at the appropriate time before measurement.
Pros: mites are easily recognisable on the pupae.
Cons: a drawback is that the male or the daughters might die before emergence and been counted as part of reproductive success; determining of pupal age based on appearance is approximate.