[Odonata-l] [NEodes] Re: Emergence Triggers

[Dennis Paulson]

Just to add to Hal's remarks, I reared many individuals of many  
species in North Carolina (Paulson, D. R., and C. E. Jenner. 1971.  
Population structure in overwintering larval Odonata in North  
Carolina in relation to adult flight season. Ecology 52: 96-107.),  
all under constant temperature and day length longer than that  
prevailing at the time of collection. All of those collected in last  
instar during the winter emerged fairly soon after collection. Those  
collected in earlier instars went on to molt and, in those that  
molted into the last instar, emerge in the laboratory well before  
their normal emergence time in nature. I suspect any species will  
undergo accelerated development in that way. We reared them mostly to  
identify them so we could determine which species overwintered in  
which instars, not to distinguish between temperature and photoperiod  
as factors.

Corbet's book includes a table that indicates that both water temps  
and photoperiod can play a part in the processes that lead to  
emergence in spring.

Dennis


On Apr 25, 2008, at 8:19 AM, Hal White wrote:

> Paul and others,
>
> I really would be careful trying to make conclusions about the factors
> critical for emergence from nymphs kept inside during the winter in
> uncontrolled circumstances. Anecdotally, I too have had emergence much
> earlier than in the field. The temperatures were different for a long
> time and the photoperiods were quite different as well. Also water
> temperatures where the larva live are less variable and slower to
> respond than air temperature.
>
> Corbet is an excellent place to start for anyone wishing to study this
> issue systematically for particular species. Clearly, there are many
> interesting issues about Odonate biology that warrant further study.
>
> Hal
>
>
>
> .
>

-----
Dennis Paulson
1724 NE 98 St.
Seattle, WA 98115
206-528-1382
dennispaulson at comcast.net



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