ilsa wrote: Where can we find the statistics on what percentage of OE-positive adults look normal?
Here's a typical February view of a California overwintering colony:http://saber.net/~monarch/nb75.jpg
Tests show that 98% of those 90,000 monarchs have some OE spores and 25% have 1000 or more spores and are considered heavily infected. Yet they migrated successfully to the coast in Sept and survived the winter well until the photo was taken in February.
Now if in February, you take a bunch of those heavily infested butterflies out of that overwintering colony and put them into an outdoor tent you end up finding many live a normal lifespan (until late April - mid-May) as these three heavily infected, overwintered monarchs did:http://saber.net/~monarch/1c.jpghttp://saber.net/~monarch/2c.jpghttp://saber.net/~monarch/4c.jpg
So the bottom line is that the wild monarchs that emerge from their chrysalids with heavy spore loads still live a normal or near normal lifespan (in the wild).
There is no evidence that OE causes heavy mortality in wild, free living monarch populations. No one here, for example, has seen an OE deformed monarch hatch from a chrysalis they collected in the wild because it's very rare that OE causes such serious problems in the wild.
OE can cause these serious deformities in LAB and HOME reared monarchs, mainly because the great majority of hobby breeders feed the butterflies milkweed cuttings instead of milkweed that's growing in the ground (cuttings are partly dehydrated so less healthy) and they rear indoors instead of outdoors (indoor rearing is less heathy). These artificial rearing conditions cause OE to have much more serious consequences. But its a mistake to think these serious consequences frequently occur in wild monarch chrysalids.
So because OE doesn't cause serious problems for wild monarchs it is not really harmful to release adults that have spores. It is more harmful NOT to release them because then they won't be able to reproduce and help the wild populations grow.