Photos of urban monarch overwintering sites California

[Stanley A. Gorodenski]

>
> Yes, but I have never seen any evidence of butterfly kills.
 
Paul Cherubini wrote:
>
> Thus we have direct evidence that monarchs overwintering
> on golf courses in the San Francisco Bay Area live a normal lifespan.
 
 
Paul,
You say "…but I have never seen any  evidence of butterfly kills…" by
pesticide drift or accidental direct spray.  This is a casual
observation and is far from being a definitive study that shows
pesticides have no affect.  Thus, the question is still open.  However,
for the sake of argument, assume that pesticide and other chemical use
has a negligible effect on adults.  This, in fact, may be the case
because the Monarch appears to be a pretty hardy (I realize this is an
ambiguous term) individual as an adult.  It has a relatively long life
span (compared to most lepidoptera), and it can migrate thousands of
miles.
 
The significant impact of pesticide and other chemical use may be on
fertility and/or fecundity.  My question to you is:  Does drift and
accidental spray from pesticides and other chemical applications affect
the fertility and/or fecundity of the Monarch?
 
Please be specific in your response by citing studies that may have been
done in this regard.  Although you claim "Thus, we have direct evidence
that monarchs overwintering on golf courses in the San Francisco Bay
area live a normal lifespan", the evidence you have presented is
anecdotal in nature and does not take into consideration the entire life
cycle.  The few observations you have related is a long way from proving
the point that the urban environment is a healthy environment for the
Monarch.  In this regard, we need to keep in mind that the Monarch is
not the cabbage butterfly.  Both have different life histories.
 
I think an interesting study would be to tag Monarchs who overwinter in
urban areas (such as parks, cemeteries, trees bordering golf courses,
etc.) and  those who overwinter under natural conditions in the same
geographic area.  The tagged butterflies could be followed through their
normal life cycle (I realize this would be difficult to do) to determine
if there are any differences between the two classes of overwintering
adults with respect to fecundity, fertility, or fitness (wrightian
fitness).  If naturally overwintering populations cannot be found in the
same geographic area, then maybe some inferences could be obtained by
comparing different parts of urban areas if a temporal record of
chemical applications is known.
 
Perhaps some of these questions can be answered through physiological
studies on other lepidpotera that have already been done.
 
Stan
 
 
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