[Syrphidae] RE: Raising Syrphus larvae

Tue Jun 29 09:59:16 BST 2010

Hi Matt,
I don't have any especial experience of this, but I would think putting a small twig in 
might help. If they attach to that rather than the side of the tube it will make it easier
perhaps to remove and place in a clean tube if desired.
All best,
Matthew

Dr Matthew Sullivan DPhil.
Behavioural and Environmental Biology
School of Biology, Chemistry and Health Science
Manchester Metropolitan University
Manchester M1 5GD, UK
Tel +44 (0)161 247 1164
Fax +44 (0)161 247 6325
m.sullivan at mmu.ac.uk

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>>> "Perkins, Matthew" <mjp223 at exeter.ac.uk> 28 June 2010 16:20 >>>
Hi Graham (and Chris),

Thanks very much for your detailed reply - it sounds like the black hoverfly death is
something I will have to live with, and it is has only affected a small proportion of
samples. I am following the specifiations you recommend regarding damp cotton wool and
using soft brushes to move them when their test tubes are fowled.

I am raising them on the grass aphid Sitobian avenae, which they seem to have no trouble
with - I cant feed them fast enough! They are now onto their 8th day and look a good size.
This is the first batch I have reared and wondered if you might also recommend how to
allow for a successful development from larvae to pupae.

Should I leave them in the test tubes with damp wool stoppers and will they just take on
their pupae shape?
Also, will I need to provide them with a substrate to attach to (other than the plastic /
glass test tubes) that they can use to emerge from their casing?

Apologies for all the questions, but I also wondered how many (more!) days they may take
to reach pupae stage, and then emergence as an adult? I used wild gravid females to get
the eggs and hoped the turn around would be quick at this time of year, and hopefully they
will not aestivate / hibernate...

Thanks again,

Matt

________________________________
From: syrphidae-bounces at lists.nottingham.ac.uk [syrphidae-bounces at lists.nottingham.ac.uk]
On Behalf Of Graham Rotheray [G.Rotheray at nms.ac.uk] 
Sent: 28 June 2010 10:13
To: Hoverfly discussion list
Subject: RE: [Syrphidae] RE: Raising Syrphus larvae

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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