An
exemplar of misunderstanding and misplaced emotions:
In
Longview, Washington birch trees planted along streets have become infested
with aphids (so the reports say, I have not checked to confirm that they are
aphids and not a different hemipteran taxon). The city’s solution to this problem
appeared to be removal of the trees, a solution that met with some resistance
from tree lovers. The city council proposed applying imidacloprid in granular
form around the bases of the trees. Not surprisingly, given the outcry against neonicotinoids,
there was an outcry against this idea. A group of school girls, pictured in the
news at their ‘pollination garden’, put together a presentation for the city
council to ‘save the bees’ and when the motion came up for a vote it could not
even find anyone to second it. The girls were lauded as having succeeded in
‘saving the bees’.
The
problem with this story is the neglect in paying attention to the biology of
the situation and acting in a rational way in the light of the biological
knowledge: honey bees generally don’t spend time foraging at a wind pollinated
plant such as the birch. It’s not worth their while and optimal foraging theory
and empirical observation would suggest scout bees would not recruit other bees
to such a resource. There is evidence of solitary bees and even honey bees using
birch pollen though, especially when other resources are scarce. Birch blooms
in the early spring and this can be accounted for by avoiding this time for
treating the trees. Given the proper timing, the risk to bees from this
application of imidacloprid would be very low and a cost/benefit analysis would
suggest the treatment should go ahead.
Other
solutions to the aphid problem are possible, of course, such as release of lady
beetles, spraying with soaps or botanical oils, or even high pressure water
treatment, but it’s a bit disconcerting that biology is often ignored when
people attempt to ‘save’ the players involved in a biological game. This result
is a clear abrogation of the basic principles of Integrated Pest Management
(IPM).
