[Syrphidae] Spring has arrived !

Thu Mar 18 18:34:51 GMT 2010

Hello Pierre,
Here in Southern Norway, the snow is just slipping it's cold grasp. I guess
we'll have to wait another 4 weeks before the syrphids start hovering. But
we may be lucky and find a wintering E. tenax at a sunny spot before that...
Rgds,
Arjen Leendertse

2010/3/16 Pierre MILLE <mille_pierre at yahoo.fr>

>    Hello to all
>
> In my home (Ile-de-France in Herblay in the Val d'Oise) temperature is 10 °
> C and the sun hot ! Have you seen your first hoverflies?This would
> symptahique answer me because I sent two messages of welcome and others
> asking questions but I've never had any answers.
>
> Best wishes
>
> Pierre
>  ------------------------------
> ------------------------------
>  *Pierre MILLE *
> *3 avenue des buttes blanches*
>  *95220 Herblay**
> ------------------------------
> ------------------------------
>
>
>
> *
>
> --- En date de : *Ven 12.2.10, Bartsch, Hans D <hans.bartsch at telia.com>* a
> écrit :
>
>
> De: Bartsch, Hans D <hans.bartsch at telia.com>
> Objet: Re: [Syrphidae] freeze tolerance in tree-hole species
> À: "Hoverfly discussion list" <syrphidae at lists.nottingham.ac.uk>
> Date: Vendredi 12 février 2010, 14h26
>
>  Dear all,
> I can only confirm from the Stockholm area what most allready have written.
> I was breeding Myatropa florea larvae in a small bucket (with wooden chips
> in water) the other year and everything froze to one block of ice.
> Nevertheless the larvae pupated and hatched next spring without problems. So
> do not touch and don´t get worried! The only thing to remember is that there
> should be drier material for the larvae to pupate in when that time cames.
> Best wishes
> Hans
>
>  ----- Original Message -----
> *From:* Frank Van de Meutter<http://fr.mc275.mail.yahoo.com/mc/compose?to=Frank.VandeMeutter@Bio.kuleuven.be>
>   *To:* Hoverfly discussion list<http://fr.mc275.mail.yahoo.com/mc/compose?to=syrphidae@lists.nottingham.ac.uk>
> *Sent:* Tuesday, February 09, 2010 2:27 PM
> *Subject:* Re: [Syrphidae] freeze tolerance in tree-hole species
>
> Thanks to all for the swift responses (including several private ones).
>
> I am well aware that many species may easily cope with frost just by the
> simple observation that they do occur in colder climates than is here the
> case. No doubt frost-tolerance will be species- and possibly
> population-specific. Therefore I still deem it possible that (high)
> mortality may occur in some Belgian species, especially in less optimal
> habitats (small holes that easily freeze, holes that are too open, ...). Ore
> maybe some southern species/populations that had shifted over the past 15
> warm winters to Belgium will now be affected? Also note that species
> distributions in other groups may be directly linked to survival of larvae
> in relation to temperature, why not in treehole syrphids? (we do have
> nothern and southern treehole syrphid species in Europe, don't we?
> As such frost may be responsible for -why not- strong population
> fluctuations in time or range shifts.
> Anyways, I already observed a Myathropa larva caught in ice - within a
> couple of weeks I will  see whether such animals may survive (I now rather
> have the impression I could break it in two if I broke the ice :)).
>
> cheers,
>
> Frank
>
>
>
>
> Wouter van Steenis schreef:
>
> Dear Frank and others,
>
> Don't worry about them larvae and a little frost. In Nebraska (USA) I
> received 6 Mallota bautias larvae from Patrick Monk. He collected them on
> October 4 2003. I kept them in a small plastic container with less than half
> a liter of the substrate collected together with the larvae.
> I had the container in a small shed next to our house with temperatures
> equal to outside temperature.
> Then winter came. It froze 20 degrees Celsius at daytime for some weeks. I
> don't know the minimum temperature, it must have been quite a bit colder.
> Both the larvae and the substrate were completely frozen. Shaking the
> container sounded like rattling a box with small wood pellets or something.
> In spring the larvae came on temperature and went on living as if nothing
> happened. They pupated April 11 and 12 2004. The adults emerged April 27-29
> 2004.
> I know there is quite some literature on how insects manage to freeze and
> stay alive. It has something to do with changing all water content for carbo
> hydroxides so no harm will be done to the cells while freezing.
> Off course these frozen insects won't have any cell activity, so they
> probably do not need any oxygen either.
>
> Good luck with your winter search party!
>
> Wouter
>
> ----- Original Message -----
> From: "Frank Van de Meutter" <Frank.VandeMeutter at Bio.kuleuven.be> <http://fr.mc275.mail.yahoo.com/mc/compose?to=Frank.VandeMeutter@Bio.kuleuven.be>
> To: <syrphidae at lists.nottingham.ac.uk> <http://fr.mc275.mail.yahoo.com/mc/compose?to=syrphidae@lists.nottingham.ac.uk>
> Sent: Tuesday, February 09, 2010 10:55 AM
> Subject: [Syrphidae] freeze tolerance in tree-hole species
>
>
>
>
> Hi all,
>
> I planned this winter to start a search for some rare water filled
> treehole/treecavities inhabiting syrphids in Belgium. Winter is however
> particularly harsh here (and over much of Europe), and all these small
> water bodies that I visited are frozen for more than six weeks now. It
> appears to me that the whole of the water content in the tree rotholes and
> cavities is now frozen. This makes me question whether syrphid larvae will
> be able to survive these conditions? Even if not all is frozen, they
> should experience oxygen shortage? Comparably, in ponds and pools, it is
> known that severe frost may also wipe out a considerable fraction of the
> aquatic community (though I know nothing on syrphids living there). When
> the water starts to melt I will see whether many dead larvae can be found.
> Right now, I would like to ask whether anyone has some previous
> experience/knowledge on this?
>
>
> beste wishes,
>
> Frank
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