diapause / voltinism

MKJ jantsa at sci.fi
Tue Aug 15 11:49:13 EDT 2000

In article <v01510101b5b8d9faca83@[]>, lutzrun at AVALON.NET (Martha V. Lutz & Charles T. Lutz) says:
>Kurt Jacobs" <morphidae at earthlink.net> wrote:
>"Some species of lepidoptera are univoltine. I believe univoltine means they
>can diapause, but someone needs to define this word, as its not in my
>Univoltine means one generation per growing season (usually summer); i.e.
>one generation per year. Hyalophora cecropia is an example of a univoltine
>species.   Multivoltine means more than one generation.  Actias luna is
>univoltine in the Northern parts of its range, but multivoltine in the
>Southern parts.  Monarchs (Danaus plexippus) are multivoltine.
>As for diapause:  right from an exam I wrote for Dr. David Stanley's course
>at UNL (Nebraska) last fall:
>        Diapause is an assemblage of phenomena, both physiological and
>behavioral, that serve to synchronize the life cycle of an insect species
>with predictable seasonal changes in its environment.  The unifying feature
>of diapause is that it is a genetically hard-wired phenomenon triggered by
>token stimuli; for example, alterations in day length.  In any given
>insect, diapause occurs during a species-specific phase of the life cycle,
>proceeds according to a 'programmed' plan, and continues until it has run
>its course.  Generally characterized by reduced metabolic activity and
>suppressed reproductive behavior, diapause prepares insects to meet
>approaching environmental changes.  Both the physiological control and the
>visible manifestations of diapause are as complex and diverse as the many
>species, life cycles, and different environments of insects.  Diapause
>confers on an individual insect a higher probability of surviving
>predictable adverse environmental changes, and thereby mediates
>evolutionary adaptation of that species.
>        Diapause is controlled by neurohormones.  Token stimuli in the
>environment cause alterations in neurohormone titres, which in turn induce
>the diapause syndrome.  Diapause is species-specific both as to its timing
>within the life cycle and its manifestations.  However, some species may
>exhibit plasticity, particularly their response to stimuli that break
>        For example, Gypsy Moth eggs have an obligate diapause of 180 days.
>No known stimuli will alter this requirement; there is apparently no
>plasticity.  By contrast, luna moths have a pupal diapause phase which does
>exhibit plasticity.  Actias luna, a multivoltine Saturniid, has a prolonged
>pupal diapause that allows it to survive the inhospitable Iowa winters.
>Ecdysis normally takes place in late May or early June.  Cocoons brought
>indoors in March will hatch in concert after about three weeks-allowing the
>moths and their offspring to attend classes in local grade schools.
>        Saturniid adults are short-lived and do not feed and; they must
>reproduce soon after emergence, or die with a fitness of zero.  Winter
>dormancy implies a need to coordinate adult emergence so that mating is
>possible.  Synchronizing ecdysis via ambient temperature increases the
>probability that diapausing pupae experiencing the same weather will emerge
>together and live happily for long enough to mate and lay eggs.
>Or, put another way:
>There is a key to understanding things like diapause:
>first, it is pre-programmed; second, it has cause-
>called token stimuli, but please don't mind the name.
>It just means things like:  day lengths that do not stay the same.
>As days get shorter (past mid-June) a luna larva 'knows'
>this heralds colder weather.  Maybe even snows.
>It must survive the winter to frolic in the spring.
>How is this done?  Please see line one:  diapause is the thing
>that triggers many changes (like glycerol in the 'blood,')
>to make our little larva ready to get snug.
>Certain neurohormones secreted in the brain
>control the way our little friend will wander the terrain
>and spin a cozy hermitage, a silvery cocoon,
>a refuge against winter wind, cold dry air, and gloom.
>What heralds spring?  Not day-length.  The token now is heat;
>a subtle warming trend foretells winter's slow retreat
>from roots and twigs and buds.  Our luna counts a sum
>of degree-days.  The moth debuts.  And diapause is done.
>Hope this helps.
>In stride,
>Martha Lutz
Thats ok, but there is a difference between diapause and hibernating.
 Butterflies are in stage of diapause only in pupa but they can hibernate in any stage (imago-
-pupa-larva-egg). The diapause has its effects in pupa without stage of hibernate.

I understood that you undertsood diapause same as hibernating.


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