Parasites and Monarchs

Paul Cherubini monarch at
Fri Apr 8 23:44:33 EDT 2005

Ed Reinertsen wrote:

> You wrote "To the contrary, we know the monarch migration 
> has been robust for the past 125 years....." Can you tell us 
> more about this 125 years, is this the first recording of a
> Monarch migration? Can you please tell us where you got 
> the information?

Ed, in the publication below Dr. Lincoln Brower provided examples
of naturalists that observed large numbers of fall migrant monarchs
in the upper Midwest in the late 1800's:

Brower, L. P. 1995. Understanding and misunderstanding the 
migration of the monarch butterfly (Nymphalidae) in North 
America: 1857-1995. Journal of the Lepidopterists' Society

> Of course, Monarchs that are HEAVILY infected with O.e. are
> going to be unhealthy. Also they will have higher mortality 
> rates, are going to be smaller, and have deformities.

Not necessarily.  On page 9 of their paper in Ecology Letters 
2005 8: 290-900 the authors wrote: 

"It is important to note that a number of [heavily] parasitized
butterflies demonstrated flight speeds, durations and distances
that were well within the range of the uninfected class."

And on page 8 of their paper the authors wrote:

"repeated sampling of eastern migratory monarchs during 
periods of breeding, migration and overwintering showed
no systemic changes in [parasite] prevalence between these
three stages, as might be expected if parasitized monarchs
are removed from the population during the autumn migration."

Paul Cherubini


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