gene pool and releases

[Paul Cherubini]

Pat Foley wrote 6-17-01:

> As we have already pointed out on this list, Monarchs and 
> Painted Ladies seem the safest candidates for unregulated release
> due to their migratory habits, BUT ...Even Painted Ladies occasionally
> achieve reproductive isolation and speciate as is evident from the four 
> mainland species of Vanessa. If Australopithecus had colonized 
> North America and practiced wedding releases, we might have just two
> species on the continent. This may seem trivial to you, but the long term
> consequences are profound.

Planes, trains, trucks, automobiles and ships have been moving Painted Ladies
and Monarchs and their larval host plants around the USA for the past 100+ years. 
As Ken Philip noted on 6-13, "North America has not had an ecosystem 
unaffected by humans since the first humans arrived many thousands of years 
ago." Pat, given this background of past and ongoing human assisted dispersal
and tremendous habitat alteration, is it reasonable to expect that wedding and 
school releases could play a substantial role in determining whether or not Painted 
Ladies and Monarchs might or might not achieve reproductive isolation within
the USA at some point in the future?

> What we don't know about insect diseases and parasites is far greater
> than what we do. Do you think we know all the diseases of
> butterflies, or their potential for spread? I don't. Is this scientific arrogance
> on my part?

Pat, there is no substantial evidence that monarchs and Painted Ladies
experience serious disease epidemics in the wild to begin with. 

For many decades monarch and painted lady researchers and commercial
breeders have been collecting tens of thousands of wild caterpillars in the field 
and raising them to adulthood. They have found that tachinid flies and 
hymenopteran wasps are the only parasites/parasitoids that occasionally 
kill these wild collected caterpillars. 

Researchers and breeders rarely see substantial mortality 
from other pathogens such as fungal, bacterial, protozoan or viral diseases
unless they rear under crowded and unsanitary rearing conditions.

In other words, researchers and breeders don't encounter "mystery"
pathogens that they don't know how to control - if mystery diseases
really existed, Monarch and Painted Lady breeders would have a hard time
staying in business.
 
In sum, while I agree we may not know all the possible 
fungal, bacterial, protozoan or viral pathogens that affect Monarchs
and Painted Ladies we do not see these species suffering from 
serious disease epidemics in the wild to begin with. 

We also know that despite the tremendous increase in human assisted
dispersal of Painted Ladies, and Monarchs and their host plants over the past 
100 years, these butterflies continue to be among our most common 
butterflies (look at what happened with Vanessa butterflies this past spring). 
There is not the slightest hint that all this human assisted dispersal and habitat 
alteration has been harmful to these species within the USA. To the contrary, 
there is massive evidence that such assistance has greatly increased 
the range and abundance of both butterflies and their caterpillar host plants 
around the world.

Paul Cherubini., Placerville, Calif.

 
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