Back to the butterfly release debate!

Paul Cherubini cherubini at
Thu Oct 12 21:14:59 EDT 2000

Pat Foley wrote:

> I offer these old remarks of mine... they do suggest that there may 
> be unresolved dangers to butterfly releases, even in widespread species.
> Here is my short list of problems to solve before accepting
> scientifically unregulated butterfly release.

>1.)  Let us first decide how many species we are willing to open to
> release.

Pat, this was decided several years ago by the Federal Government: 
Monarch, Painted Lady, Red Admiral, Buckeye, Giant Swallowtail, 
Black Swallowtail, Gulf Fritillary, Zebra (Heliconian), and Mourning 
Cloak.  In States where some of these species do not occur naturally,
releases are not permitted (example: Gulf Fritillaries are not allowed
to be shipped to Oregon).

> Pro-releasers often state that most releases are of monarchs and 
> painted ladies, so this issue is small.

Yes, monarchs and painted ladies are used for nearly all releases. 

> The evolution of painted lady species around the world could be 
> a great future revelation that I hate to give up.

Painted ladies and monarchs are not shipped across any oceans
for release.

>Several monarch researchers are already in print against 
>unregulated release.

These monarch researchers (Dr's Lincoln Brower, Chip Taylor, 
Karen Oberhauser and eleven of their colleagues) did not consult 
with insect population geneticists or insect pathologists prior to 
publishing their opinions about the theoretical genetic and
disease related risks involved with coast to coast transfers of

Geneticist Bruce Walsh made the following comment earlier this 
year:  "Brower et al. (1995) raise the concern that "transfers could 
result in considerable genetic disequilibrium and force massive 
selective reorganization and genetic deaths."   This has no
foundation in population-genetic theory.  Introduced (nonneutral)
alleles will be either deleterious or beneficial, and I'll discuss these 
in turn."

> 2) ...local, semi-isolated to isolated populations 
> are critical to the production of new adaptive types...the point
> here is that it is scientifically controversial whether isolation is 
> critical to future evolution.

I am unaware of any evidence that would suggest there are 
any local, semi-isolated or isolated populations of monarch
butterflies or painted ladies within the 48 US states.

Several studies have failed to find any clear evidence that 
the eastern and western populations of monarchs or painted ladies
are genetically distinct.

> 3) What is the geographic distribution of infectious diseases in
> butterflies and how critical is isolation to avoid endemic
> (enzootic if you must) and epidemic outbreak dangers? 

No outbreaks of any infectious diseases have
been known to occur in wild populations of the monarch 
butterfly. The O.elektroscirrha protozoan has been shown to 
have minor effects on the  survival and reproduction of 
monarch butterflies (based on lab studies). 
Bruce Walsh has commented: 

"suppose the worst case: that the western monarch
indeed harbors a killer strain absent in the eastern population.  
Western monarchs would also have to have evolved defensive
genes to counter this parasite, and these would be cospread 
with the parasite, minimizing the fitness effects.   Such genes 
are highly liked to be single gene (as opposed to polygenic) 
and hence readily transmitted along with the parasite."

> 4) What roles do various forms of (loosely-defined) selfish 
> DNA play in butterfly species? Included here are any forms
> of DNA that might spread to the detriment of most of the 
> genome, e. g. transposons, sexually selected runaway traits.

This is over my head. Perhaps you or Bruce could comment
on how any of this is relevant to the question of whether
releases of captive reared monarchs and painted ladies within 
the 48 states could be dangerous to wild populations.

> Low Fst species are plausible candidates for release. 
> But don't set the bar too low. Local populations of smallish
> size or unknown genetic structure might make relatively little 
> contribution to the species Fst and yet be worth preserving 
> intact for all of worries 1 through 4.

Several studies have failed to find any clear evidence that 
the eastern and western populations of monarchs or painted ladies
are genetically distinct. 
> consider that there are four species of _Vanessa_ in North America 
> that arose despite the famous wandering tendencies of the clan 
> and a presumably low Fst. Either this happened despite
> constant migration (supporting some level of uncontrolled release) or
> geographic isolation (or at least attenuation of gene flow) was 
> required. We don't know!

Since the mid-1800's monarchs have been introduced inadvertently
around much of the world via our vast transportation network.
Thus, monarchs and painted ladies are continually being moved
around the 48 states and occassionally across the oceans 
even in the absense of a commercial butterfly release industry.
Example: monarchs are usually sighted along the western coast of 
northern Europe each summer or fall.

Paul Cherubini

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