Market Farming

["Bill Shoemaker" <wshoemak AT inil.com>]

>Hello,
     I used Sevin as a well-researched example that illustrates both the
extreme toxicity of the pesticide to bees and the fact that bees carry it
back to the hive, with toxic effects on the entire colony. While I'm sure
most growers would not willingly poison area bees by applying such toxins
during pollination -- the timing of treatments is subject to a host of
other economic, weather, pest pressure, time pressure, etc. constraints
that can easily put pollinator safety lower down on the list. Further, I
am not so sure homeowners have an equal awareness or understanding and
sevin is a major garden pesticide.  Also, this ignores what else may be
happening in the vicinity. Bees find many common weed plants very
attractive, for example, leading to additional exposure to toxins applied
to nearby crops.
     While sevin has been proven to be a smoking gun with direct links to
killing bees, other pesticides may have somewhat lesser effects (ie they
don't kill outright) but still have a major impact on bees and other
pollinators.For example..............


     The 90% figure (90% of applied pesticides miss their targeted
species entirely) is from Pimentel. I had generally thought of it as
having to do more with insecticides and fungicides that have well
>demonstrated toxic effects on beneficial insects and soil microbes.



While David Pimental is a fine researcher, I believe that he is probably
contending something with a very important context that should be included
with the 90% figure. It would be a mistake to "think of it as having more to
do with insecticides and fungicides". They constitute a much smaller
fraction of total pesticide use than herbicides, and cover much less
territory geographically, unlike mites, which are extremely widespread.




> But
since you raise the question of herbicides, since pre-emergence
herbicides are applied to the SOIL at the time of planting and SOIL is
alive with millions (per teaspoonful) of microbes, soil animals, flora
and fauna as the basis for the entire soil foodweb (which includes bees
-- and humans) then I'd have to say there's a HUGE impact upon
non-targeted species here too. High power microscopy reveals there are
very definite biocidal effects on soil organisms from the use of
pesticides. Some are translocated to the soil via the root exudates
plants put out to colonize symbiotic beneficial soil organisms for
mineralizing nutrients, transporting water, etc.
     A study I came across a while back says there is a global shortage
of pollinators with declines in pollinator abundance, diversity and
>availability. Mites alone do not account for this phenomenon.


You're right. Probably the biggest reason pollinators are in decline, like
most declining species, is overpopulation of Homo sapiens and resultant loss
of habitat for all other species.




>It is highly reductionist to claim that pesticides have nothing to do with
>the health status of bees (and their ability to resist mites).

It would be considerable conjecture to claim that pesticides are responsible
for the decline of bees rather than the activity of parasitic mites.




>Pesticide use has increased some 50 fold since DDT was first used in 1945.
During
that same time, however, the toxicity of new pesticides has also
increased 10 fold. This environmental factor has to be included in any
assessment -- the agroecosystem has to be considered as a whole. Bees and
other pollinators perform an incredibly important role in the foodweb and
have now become an important canary in the coal mine for conventional
agricultural practices and our food supply. Sure, mites are the immediate
problem (symptom) but the question is why they have gained such
ascendancy after years of relative peaceful co-evolution and coexistence
with bees. It is simply not accurate to say pesticides have no effects in
>this process....


Because nature is really a process of dog-eat-dog rather than peaceful
coexistence. To suggest that parasitic mites and bees have led a peaceful
evolutionary coexistence that man has somehow upset and turned them against
each other is lunacy. Too many Disney movies. Were the bees and mites
friendly neighbors in the 1800's?



>Steve Gilman
>Ruckytucks Farm





While all of this is very interesting, it really is very loose conjecture
and is not supported in research literature as an argument for the recent
decline in honeybee populations. On the other hand, we know that the
explosion of population of varroa mites and trachea mites has led to a crash
in the population of wild and commercial honeybees. Direct cause and effect.
It would be interesting to conduct research to support your contentions and
arrive at your conclusions. In the meantime, it's very important to address
the problem of mites in the honeybee population for the sake of all of us,
who depend on them for our food.

Bill Shoemaker
Sr Research Specialist, Food Crops
Univ of Illinois - St Charles Hort Research Center