Vragen aan EFSA en antwoorden over de bijenkomst over het bijenrichtsnoer van 13 januari 2021 en
het bijbehorende achtergronddocument.

(1) We kindly request that EFSA provide further advice regarding the choice of a threshold value
on the basis of the modelling, particularly concerning the practical implementation and
(field) measurement of the eventual protection goal.
Answer
EFSA is not in the position to provide further advice regarding the choice of a threshold
concerning the practical implementation and field measurement of the protection goal.
What EFSA can do (and has done) is to transparently reflect how field studies requirements
will likely (see point 4) change to address different tolerable effects. Also, what EFSA can do
(and has done) is to collect examples from literature/dossier to inform risk managers about
what was possible to achieve in the past. Feasibility of larger field studies mainly entails
considerations on availability of resources that EFSA cannot and should not estimate.
(2) Considering that the variability in the model is already lower than the variability in the field
(Figure 4), we wonder whether there is a specific scientific reason to restrict the OR (i.e. to
remove a percentage of the weakest hives from the analysis)? Could the EFSA please provide
further explanation of the choice of the restricted ORs presented?
Answer
First of all, let us stress once again one aspect: the simulated variabilities are well in the
range of the experimental variabilities observed in control field studies. It is however
acknowledged that the median variability calculated across all field studies is generally higher
than the variabilities simulated with BEEHAVE. The choice of removing a percentage of the
weakest colonies or, in other word, to restrict the operating range, is entirely up to the risk
managers, and will reflect the level of conservativism that the risk managers wish to have.
This is because risk managers may decide that the strength of absolute weakest colony in the
simulated “control” is not a suitable reference for setting the threshold for tolerable effect.
What EFSA has done was to further inform this aspect by quantifying different potential
tolerable effect thresholds on the basis of the fraction of colonies retained in the operating
range. Furthermore, EFSA has provided a ‘cap’, over which risk managers should not go. This
is represented by that ‘one-third reduction’ that was considered by experts in 2012 to lead to
colonies not being viable anymore.

(3) EFSA points out that the largest studies have to be performed in larger areas (i.e. multiple
different countries), which increases variability, using the example of a study performed with
90 hives. From this, we interpret that studies with 90 (or more) hives, would likely not have
the same theoretical increase in power indicated in Table 4, due to increased variability
based on largely differing environmental scenarios. Is it possible to indicate a “sweet spot”
for number of hives that would be optimal without introducing higher variability due to the
requirement of larger testing areas?
Answer
This is very appropriate comment/question. Indeed, the risk that using larger areas (i.e.
across several countries) would cause an increase in variability compared to our estimation
(and thus a decrease in power) is well possible. Unfortunately, at the moment, information

about variability among such large areas used for single studies (thus with homogeneous
practices and experimental design) is limited to 2-3 studies. This makes any predictive
estimation about a ‘sweet spot’ not so straightforward and quite uncertain. In fact, one could
potentially carry out a study with a similar design (i.e. up to 10-11 replicate fields per
treatment) while remaining in a more homogenous area. Just after the meeting, Spain
submitted two literature studies where 3 to 10 replicate fields (over 3 years) were used in a
much smaller area (central-south Spain). The practical limitation of this aspect regards mainly
the possibility to access/use an appropriate number of fields in a certain area, which is not
something that EFSA can estimate on a scientific basis.
(4) Could the EFSA address the possible variability in Table 4 more concretely? It is stated that
several assumptions still should be discussed within the WG, but it is not directly stated
which assumptions those might be, nor where these “preliminary” values stand within the
possible range. Would it be possible to present a range of the possible power levels (as
exemplified in the varying power analyses of Rolke, et. al. 2014)?
Answer
As correctly pointed out, the estimations in table 4 still need to be considered preliminary, as
some of the assumptions are still to be discussed within the WG. However, the document
already lists what these are:
a. variability in colony size - not just between colonies on the same field, but also
between colonies in different fields. This can be further informed by some of the
data we have already collected/generated for the sake of the exercise presented in
the info session
b. type I error (alpha value)
c. type II error (beta value)
We envisage that more precise estimations can be presented in the future, but it is unlikely
that those will present large difference compared the values currently presented in table 4.

(5) EFSA indicates that SPGs for bumble bees and solitary bees might be determined based on
addition of a “safety factor” to the values for honey bees. We agree that the ecology of
bumble bees and particularly solitary bees is not at all appropriately represented by the
Behave model. However, if a safety factor is chosen in order to address non-apis bees, we
would request that the EFSA update the toxicological sensitivity analysis based on the
available toxicity data (which, while still limited for non-apis bees, is nevertheless likely larger
than in 2011/12) to provide some indication as to species (population) sensitivity? We
suggest that data for other solitary pollinating non-target arthropods might be included in
the analysis for solitary bees, though these data are, of course, also likely limited.
Answer
It is clear that the exercise performed with BEEHAVE should be considered informative for
honey bees only. Unfortunately, at the moment we cannot provide more scientific ground to
the risk managers for setting SPGs. The application of uncertainty factors to the effect
percentages identified for honey bees was suggested by the PPR Panel (2012) as a pragmatic
solution for this lack of information. Concerning your request, please be informed that the
WG is already updating the toxicological sensitivity analysis for bumble bees and solitary
bees. The envisaged strategy for this is described in the methodological protocol for the
revision of the EFSA Bee Guidance document which was shared, in its draft version, with
Member States and stakeholders.