OE in Rearing Stock / OE in Wild Caught

[Mona Miller]

http://www.monarchwatch.com/biology/control.htm
Parasite Control : Ophryocystis elektroscirrha
[This is Monarch Watch's current protocol on OE for rearing butterflies.]

My question is there a consensus on what should be done with heavily infected butterflies in the wild? When we are netting, testing, tagging butterflies wild butterflies, do we kill those that are heavily infected or do we release them back into the wild?

I've been having a long discussion with Dr. Altizer at the University of Georgia on this topic. Here are her thoughts on what should be done with reared and wild butterflies that have OE infections, which she gave me permission to post:

"First, we have overwhelming evidence from published studies that OE causes harm to monarchs in the form of smaller body size, reduced survival, lower flight performance and a lower probability of
reproduction. The fact that a percentage of monarchs are able to deal with these debilitating effects and survive the long-distance migration does not mean that the parasite causes no harm. To think
about this another way, we certainly would not say that because 78% of people exposed to SARS survive the infection that we shouldn't be concerned about limiting it's spread!

Second, yes, OE is a naturally occurring infection that has been in monarch populations for a long time. I don't think we're going to eliminate this parasite from monarchs, but we should be careful about
not assisting its spread, either. With that in mind, I'd encourage anyone who collects and rears monarch eggs and larvae to educate themselves about the signs of infection and take measures to prevent unintentional transmission in captivity, because this parasite can spread rapidly among captive-reared monarchs. Carefully sterilizing plastic rearing containers, mesh cages, surfaces that contact adult butterflies is very important for preventing human-assisted OE transmission.

In terms of killing OE-infected adults, my thoughts are that if a person is rearing monarchs in their home and finds that a large portion (over half) are OE-positive, they probably should not release
those monarchs into the wild, as chances are that some form of contamination in captivity caused those infections to spread. If, on the other hand, a person catches wild adults that are OE-positive and has no reason to think those were infected in captivity, then I'd encourage them to release those adults back into the wild.

And of course, I'd strongly urge folks not to transport OE-positive butterflies for release into new areas, which would be assisting the spatial spread of the parasite and possibly transferring novel strains into new areas.

Hope these thoughts help!

All the best, Sonia"

[Mom2RJA]

This is interesting. Thanks for sharing. For me it raises another question: if you are rearing monarchs in captivity and occasionally finds one with OE, what should you do? I understand her point about contamination in captivity if a large percentage test positive, but if an occasional one does, this seems to be just like finding one in the wild with OE. Should that one then be released?

[Mona Miller]

This is what Dr. Altizer said on that topic:

"In terms of killing OE-infected adults, my thoughts are that if a person is rearing monarchs in their home and finds that a large portion (over half) are OE-positive, they probably should not release those monarchs into the wild, as chances are that some form of contamination in captivity caused those infections to spread."

[Mom2RJA]

Yes, I read that, but does that mean that as long as less than 50% are infected the infected ones should be released?

[Paul Cherubini]

In terms of killing OE-infected adults, my thoughts are that if a person is rearing monarchs in their home and finds that a large portion (over half) are OE-positive, they probably should not release those monarchs into the wild, as chances are that some form of contamination in captivity caused those infections to spread. If, on the other hand, a person catches wild adults that are OE-positive and has no reason to think those were infected in captivity, then I'd encourage them to release those adults back into the wild.

Double standard. Sonia doesn't explain why a different Oe infection standard should be applied to farmed monarchs vs wild ones. In other words, if the wild adults are routinely about 10-50% infected then why do the farmed ones need be any "cleaner" of Oe spores than the wild ones; i.e. cleaner than 10-50% infected?

Sonia also hasn't explained the consequences that would result to the wild populations if the farmed monarchs are not cleaner than 10-50% infected.

I'd strongly urge folks not to transport OE-positive butterflies for release into new areas, which would be assisting the spatial spread of the parasite and possibly transferring novel strains into new areas.

It's now mid-June and millions of Oe-positive butterfies have spread across the map as far as 500 miles north of the Canadian border. So what "new areas" could folks conceivably be transporting OE-positive butterflies to for release? Also, the population of monarchs entering the northern USA and Canada this year has been especially large which means the number of Oe infected butterflies that have entered those areas is especially large - and monarch enthusiasts are thrilled about that fact. Therefore why shouldn't enthusiasts also be thrilled if breeders release 1000's of monarchs in northern USA and Canada in May-Sept. even if 10-50% of them are Oe infected?

[Mona Miller]

Yes, I read that, but does that mean that as long as less than 50% are infected the infected ones should be released?

I think Dr. Altizer is leaving that up to the individual to choose which course to take.