organic farms, like conventional farms, have access to a suite of pesticides; 
the primary difference is that organic regulations prohibit all synthetic
(i.e.: human-made) chemicals but allow a vast array of mineral and
botanical pesticides, whereas conventional pesticides can be
both naturally and synthetically derived and are regulated
individually, on a per active ingredient, per formulation basis

Generalizations about the relative sustainability of one suite of
practices over another are dangerous when integrated into policy

We conducted a two year, five site study to examine the
performance of these insecticides against aphids, and selectivity
with respect to natural enemies under field conditions

We found that in addition to reduced efficacy against aphids compared to novel synthetic insecticides, organic
approved insecticides had a similar or even greater negative impact on several natural enemy species in lab studies, were
more detrimental to biological control organisms in field experiments, and had higher Environmental Impact Quotients at
field use rates.

Conclusions/Significance: These data bring into caution the widely held assumption that organic pesticides are more
environmentally benign than synthetic ones. All pesticides must be evaluated using an empirically-based risk assessment,
because generalizations based on chemical origin do not hold true in all cases.

from:
"Choosing Organic Pesticides over Synthetic Pesticides May Not Effectively Mitigate Environmental Risk in Soybeans"
Christine A. Bahlai, et al. School of Environmental Sciences, University of Guelph
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