rb6banjo wrote:
You research is always very interesting Joe. I'm with you on the aluminum foil idea. Does the insect always secrete the pheromone so you're sure you'll get it? Is there something about the filter paper the stimulates the insect to secrete the pheromone? Do you know the identity of the pheromone or are you trying to determine that?
This might be a classic application for your Markes TD system. If you can preclean the aluminum foil in an empty sample tube, then pull it out and expose it to the insects. Put it back in the tube and desorb it into your GCMS system. You could do it with filter paper as well but I'm betting there's a lot more extra "stuff" in filter paper that isn't on aluminum foil.
Thank you, i'm very lucky to be able to work in the field that I do. The behavioural assays indicate that the insects always secrete the trail pheromone, so I'm fairly certain I will collect at least some of it. Having looked through the literature it would appear that the filter paper doesn't serve any purpose and I have placed the insects on both filter paper and aluminium foil to determine whether they show a preference - they don't! I'm afaid that I have no idea on the identification of the pheromone, so it's a bit of a shot in the dark unfortunately.
I am currently awaiting some new O-rings for my TD system (I hope these will be delivered tomorrow), so as soon as they arrive I will try this method out. I think it could work very well!
Rndirk wrote:I think the filter paper is not an issue, if you make sure to also do an extraction of a blank filter paper so you can identify possible background signals.
How will you distinguish between pheromones and other, uh, traces of the insect? Do you know the molecules you're after or you plan to database search?
You could do a sort of quantification with in the x-axis "hours walked on the paper" and the y-axis the area of pheromone
make sure to calculate the linearity!
In order to minimise contamination from other bodily fluids (i.e. faeces and vomit), the insects have been starved for 48 hours before being introduced onto the filter paper. I like the quantification idea!
GOM wrote:Hi Joe
Fascinating query from you as usual
Your idea and RB6 comments about the use of foil make sense.
Some random thoughts in no particular order
The paper may adsorb more but you will lose out on sensitivity on dilution with solvent extraction
see this interesting presentation
http://www.sussex.ac.uk/lasi/documents/ ... _6_120.pdf
You will only get a single track across your substrate?
Decay time appears to be from minutes to days for ants
Is there also a "no food" pheromone track?
As an odd idea - get them to march through a tunnel of an empty glass open injection port liner. That liner could be just dropped into the injection port to be desorbed. You could also use that approach to establish a useful control of a "no food" trail. Alternatively line the liner tube with foil to be removed followed by TD. The no food control is also needed and could be made using this approach
Also see
http://mute-net.sourceforge.net/howAnts.shtmlWhat is the insect?
Cheers
Ralph
I have placed 10 of my insects into a single petri dish:
The insect species I am working on is the soft fruit pest: vine weevil (
Otiorhynchus sulcatus) (
https://www.rhs.org.uk/advice/profile?PID=234). It's bigger than the mites I was previously working on (~ 2 cm), so I don't think i'll be able to get them to walk inside an inlet liner, although this is a nice idea for my mites!
I'm unsure as to whether there is a no food trail. I am mainly trying to figure out why they like to aggregate together. I have undertaken an analysis of the headspace to determine whether there is a volatile aggregation pheromone, but it appears there isn't. I used both TD and SPME to do this.
Cheers,
Joe