[Syrphidae] RE: Raising Syrphus larvae

[Graham Rotheray]

Dear Matt (& Chris), Re your queries about rearing aphidophagous larvae,
I have reared many species over the years.  Under the rearing conditions
Matt describes, you shouldn't have any particular problems.  

 

However, I know well the dead 'blackened' larvae you have encountered.
Some mortality is to be expected in cultures and there is nothing
special you can do to prevent it, other than carrying on and hoping the
proportion dying remains small.  The main dangers to larvae in culture
are desiccation and the quality and quantity of prey.  Use of damp
cotton wool plugs should ensure there is enough (& not too much)
moisture in your tubes and providing small to medium sized aphids until
larvae have reached the 3rd stage when they will take a wider range of
prey sizes, should be OK.  

 

Not all aphid species are suitable even for a polyphagous species like
S. ribesii, and although you don't mention what aphid species you are
offering, I assume that is something you are aware of.   Also switching
between aphid species presented as prey can sometimes cause mortality
and should be avoided.  Larvae, especially small ones, are obviously
more vulnerable and require care in handling, i.e. use a brush to move
them about rather than tweezers or forceps.  

 

After larvae have finished feeding and emptied the hind gut, they are
best removed to clean tubes and gently wrapped in slightly moistened
tissue paper.  Tubes should be stored in cool, dark conditions.
Depending on time of year, it will be 2-3 weeks before adults appear or
larvae will aestivate for several weeks or hibernate for several months.
The tissue paper should be replaced every few weeks to prevent fungal
infection.

 

Hope this is helpful.

 

All best wishes,

 

Graham

 

Graham E Rotheray

National Museums Collection Centre

242 West Granton Road, 

Edinburgh EH5 1JA

Tel 0131 247 4243

________________________________

From: syrphidae-bounces at lists.nottingham.ac.uk
[mailto:syrphidae-bounces at lists.nottingham.ac.uk] On Behalf Of Bergh,
Chris
Sent: 27 June 2010 13:57
To: 'Hoverfly discussion list'
Subject: [Syrphidae] RE: Raising Syrphus larvae

 

Matt,

 

I have had this experience with larvae of Heringia calcarata. It has
been sporadic and unpredictable, but like you, I would be interested to
know if anyone has an explanation.

 

Cheers - Chris

 

Chris Bergh

Associate Professor of Entomology

540-869-2560 ext. 32

 

-----Original Message-----
From: syrphidae-bounces at lists.nottingham.ac.uk
[mailto:syrphidae-bounces at lists.nottingham.ac.uk] On Behalf Of Perkins,
Matthew
Sent: Sunday, June 27, 2010 8:28 AM
To: syrphidae at lists.nottingham.ac.uk
Subject: [Syrphidae] Raising Syrphus larvae

 

Good afternoon,

 

I could do with some advice on my hoverflies! Thanks already for those
who have already offered much useful advice on my first PhD experiemnt
examining food chain lengths... this email list has proved invaluable.

 

I have two new querries though if anyone could help: 

 

I am raising Syrphus ribesii larvae and am keeping each larvae
individually in small glass / plastic test tubes and provide them with a
small leaf and lots of fresh aphids every day. I clean the tubes every
day, and use damp cotton wool to plug the ends of the tube. They are
kept at 70% humidity, 16:8 hours light: dark.

 

1. My larvae are now 6 days old and I need to know if they have any
requirements for successful development into pupae - do they require
something to stick too or do they need to hang upside down etc. Also
should I need to keep them moist throughout their pupae stage? 

 

2. I have recently had many (less than 25%) of different age classes
turn black and die. It appears on first glance like they have not
discharged their gut... but I have no idea. Does anyone recognise these
symptoms or could provide advice or keeping more alive?

 

Thanks,

 

Matt Perkins

 

PhD Researcher

Center for Ecology & Conservation

University of Exeter,

Cornwall Campus

 


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