Any Polyphemus moth experts?
Chris J. Durden
drdn at mail.utexas.edu
Wed Aug 16 11:08:58 EDT 2000
Has anyone thought about climatic warming to explain the appearance of
double broods in formerly single brood species?
Here in Texas we have tropical periodic colonists establishing breeding
populations farther and farther north every year. For instance *Heliopetes
macaira* was a rare stray in the lower Rio Grande Valley in the 1940's. By
the 1970's it was resident in LRGV. Now it is reproducing almost as far
North as Houston. *Chioides catilius* formerly a rarity in the LRGV, showed
up in Austin in the 1970's and has been swarming along the Texas coast
almost as far as Louisiana this year. *Astraptes fulgerator*, formerly a
rare resident in LRGV now has breeding populations as far north as Austin.
*Danaus eresimus* formerly occasional in the LRGV, reached Austin in the
1970's and showed up at Dallas this year. This all parallels the northward
spread of the whitewing dove, well documented by wildlife biologists.
At 06:19 16/08/00 GMT, you wrote:
>> I've read and heard repeatedly that in the Boston area that Polyphemus
>> multiple broods
>Heres some partial quotes from MONA Fascicle 20.2B(Ferguson, 1972). "There
>is definately only one breed in the North, but two in the South. About the
>latitude of Virginia, there are indications of two generations, ............
>The species is reported to be partially double-brooded in Cape May County,
>New Jersey(Worth, 1970).
>The amount of daylight that your larvae expereinced may effect their
>diapause, but maybe this species diapause is more of a genetic thing.
>Possibly the Polyphemus polyphemus that had genes for double brood were
>eliminated from the Canada area due to the environment. This is just
>speculation on my part, i would like to know if this has been proven through
>genetic research, or if it is faculative light-controlled or temperature
>controlled diapause, or something else, in the Polyphemus polyphemus.
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