[leps-talk] Re: Inducing Oviposition

[Nigel Venters]

[leps-talk] Re: Inducing OvipositionRobert,
I agree with you! Hand feeding always helps in total numbers of eggs being laid...but unless you have the right conditions, many females are reluctant to lay them!
Nigel
  ----- Original Message ----- 
  From: Robert P. Dana 
  To: leps-l at lists.yale.edu 
  Sent: Monday, May 27, 2002 7:08 AM
  Subject: [leps-talk] Re: Inducing Oviposition


  Tried the other day to post my two cents worth on this thread to the TILS-Leps-Talk list, but for some reason Yahoo decided that I was not a subscriber. Since then I think others have suggested that the idea that butterflies are "forced" to oviposit by the relentless maturation of ova is not necessarily true. But my comments may still be interesting to some.


  Robert Dana




    ----- Original Message -----
    From: <guy_vdp at t-online.de>
    Sent: Thursday, May 23, 2002 6:59 AM
    Subject: Re: [leps-talk] Inducing Oviposition


    > The same works for Pierids,
    > I'd like to add that I usually feed the female using a forceps to hold
    her
    > by the wings and a preparation needle to unroll her tongue.
    > Usually grape-juice works well, I always have some in the deep-freeze as
    > ice-cubes, there are better recipes for this, but the juice is readily
    > available and works good enough for me.
    > The advantage of this is that the female 'has' to lay eggs (because of
    the
    > food supplies her body continues to make eggs - the fresh ones will
    'push'
    > the older ones out of her body).
    >
    > Guy.

  Back in the 80s I worked on various aspects of the biology of Hesperia dacotae here in MN. I needed lots of ova, and so held field-caught females in small cages set out in the prairie. Because I was interested in total potential fecundity, I dissected many specimens at various points in their egg-laying life, from newly emerged (reared) individuals to very worn, nearly depleted individuals that I had held in a cage for many days (removing eggs at the end of each day and keeping a tally). By the way, the data are summarized in my thesis. The point of interest here is that it appeared to me that females of this species are capable of exercising some control over the maturation of ova in their oviducts. Newly emerged females had only a small number of fully mature ova, and if they did not mate, this number did not increase for several days. It also appeared to me that mated females slowed down the rate of egg-maturation when several successive days of inclememt weather occurred. As this was not a focus of my research, I did not conduct these observations according to a strict protocol, so these are only impressions.


  Robert Dana
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