I finally got my hands on the paper by Axel DeCourtye, etc.
My congratulations to anyone who tries to better quantify the effects of
pesticides. Back in the 60s and 70s, when the US and European guidelines
for testing for pesticide regulations were promulgated, the authors were more
or less constrained to acute toxicity as one of the few metrics that could
be done quickly and relatively inexpensively. Its easy to see and count
dead bees, plot that against dose and time (how many hours). Hence, we have
LD and LC 50s - what combination of dose and time results in loss of 50% of
the bees?
Today, technology offers many options. The question now becomes, which of
these provides a real improvement.
As many of you know, Steve Buchmann tried bar codes on bees - I've even
seen Museum displays of his technology, and he got an award for it. Problem
was, bees didn't cooperate well at the readers - a bee had to pass through
just right in order to reliably read the tag.
Radio tags reduce/eliminate the orientation to the reader problem. The
first transmitter tags were placed on bees by Howard Kerr at Oak Ridge - but
the world failed to beat a path to his door. Then, researchers in the UK
started 'tracking' bees - but the tags were large, with a long, trailing
antennae.
We then got in to this area of research in partnership with the
developers/scientists who designed the first RFID tags for Walmart, and we had a bee
chip - but we abandoned it when we found that it altered bee flight. Next,
I pulled together a workshop for DARPA, and the MAYO clinic built what
was dubbed ' the grain of salt' tag. At the time, it was the smallest tag
available for tracking bees.
Again, no one beat a path to the door - and by that time we had abandoned
RFID chips and moved to using lasers to track bees - we don't have to glue
on tags, we don't have to handle bees, we don't injure the bees, and there's
no interference with flight. We can see the locations of individual
bees, and we could use refective tags to ID the individual bees, but we're more
interested in the overall movements and locations of free-flying bees. If
human eye-safety isn't of concern, we can image individual bees a mile
away. But, eye-safety is a concern, unless you can keep people far away (like
shooting a gun, you're probably ok if you aren't down range. So, our
lasers are set to work at shorter distances, generally about 100 yards, so we
can ensure eye-safety.
In the meantime, while we were working on lasers (2003-present) there was
a push in Europe to provide smaller RFID tags, and recently one of the US
military contractors has also produced a new bee transmitter tag.
Here's the rub - if you want to truly track - monitor the path of a bee
using RFIDs, you need a sophisticated antennae, transmitter, receiver
combination, and small tag - not cheap. And there's still the question of what
are the effects, if any, of handling the bee to glue on the tag, and the
effect of the tag glued to the bee has on its flight.
Or, you can take the DeCourteye group's approach, place readers at the hive
and at the feeder. You can use a smaller tag - less likely to alter
flight dynamics, but your 'read range' is small - a bee has to pass very close
to the reader. You can 'track' the activities of an individual bee - how
many flights, when and if she fails to come back to the hive of bees, how
long a trip takes, but you can't track her path. Back in the 70s, I used to
use a modification of a method developed by Norm Gary - glue small metal
disks on the backs of bees, then use a magnetic system on the hive and
feeder - a primitive version of the DeCourteye method.
But, once again, with any tag, you have to handle, glue, etc. Note, the
authors refer to a cage of bees used to replace bees that died or escaped -
I'd like to see the numbers for these. Note, I'm not belittling this work
- we need innovation. However, I have been down this path and I've some
strong opinions.
I have to confess to some real biases, based on many years of working
with bees, tags, and tents.
1) Any tent affects bee flight - its not uncommon for the reduction of
solar radiation by the tent material to produce a drop in overall flight from a
colony of as much as 50% (based on our work with bee colonies inside and
outside of tents, fitted with bi-directional counters that monitor the
number of flights per colony per day (number of bees exiting, number of bees
returning)). And bee colonies generally dwindle inside cages, cease brood
rearing after a few weeks, etc. So - whether you call these 'semi-field'
trials, or my preference 'tent trials' - there is usually a big tent effect on
bee activity and bee colony dynamics. That said, admittedly, there are
times when tent trials make sense, and newer materials seem to have reduced
bees wastage (trapping in the corners).
2) Handling bees and gluing tags on them has an inherent risk of injury,
and the tag is likely to alter flight dynamics. This also presents a
difficult question - one can monitor the activities of control bees (bees with
tags but no exposure to pesticides), and dosed bees (bees with tags at varying
treatment levels), but how do you compare the control (bees with tags)
against bees without tags? You can't use a reader to document the activities
of bees without tags. Then, take this to the next step - how do the bees
with tags in a tent compare to free flying bees (with and without tags)
outside the tent? That test needs to be performed in order to fully evaluate
the usefulness of the RFID method.
3) Tracking - the use of this term in the title of the DeCourtye paper may
be misleading - or maybe its just that my definition is different. I was
excited to see how they tracked bees.
I just want to be sure everyone on Bee-L understands how the term was
used in this case.
I reserve the word tracking to 'following a route'. In the case of the
DeCourteye article, their 'tracking' was an inventory of when a bees passed
by the readers at the entrance of the hive containing the bees and at the
feeder. This is a form of tracking - similar to when Fed Express date
stamps the location of a package, but I think there may be a better, more
descriptive term for what was done in the RFID tent trial.
I applaud the efforts of this team to provide better quantification. I'd
really like to see the tent/open flight comparisons, as well as the
tagged/untagged bee comparisons - although how to do the latter is problemmatic.
Jerry
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