Question - what stimulates larva to pupate?

[JH]

I remember reading of a study conducted by Thomas Say (who also first described the Potato Beetle) in 1822 of the effects if Apanteles congregatus, a parasitoid wasp on the sphingid, Manduca sexta.  Apparently the more wasps in the caterpillar, the more molts it will go through, allowing more of the wasps to get enough nutrients to develop.  Sometimes the larva will even go into an extra (6th) molt if the wasps need more time.  They are able to induce a high level of juvenile hormone to keep the larva from pupating.

John
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John Himmelman
Killingworth, CT USA
jhimmel at connix.com
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-----Original Message-----
From: gwang <gwang at mb.sympatico.ca>
To: leps-l at lists.yale.edu <leps-l at lists.yale.edu>
Date: Tuesday, July 03, 2001 8:08 PM
Subject: Re: Question - what stimulates larva to pupate?


>Hi,
>
>> It is interesting to note that the injection of this hormone into the
>> 'mature' larval stages of some hawks moths (just prior larval 'shrinkage'
>> and pupation) have been shown to delay the pupation process and induce a
>> further 'giant' larval stage.
>
>Are you saying that instead of pupating, the larva would progress to a
>further instar?  In which case, just what would be the maximum number of
>instars a larva could go through?
>
>Peace,
>Xi Wang
>
> 
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