My colleague is doing a study on the nutritional composition of invertebrates. She is catching them in the field in pitfall traps, and is considering ethylene glycol as the killing agent. We are wondering if this might effect the end results of the nutritional analysis, or if there are other recommendations for effective killing agents in the field.
Dear Emma,
I won't profess to have knowledge of the impacts of ethylene glycol on a nutritional analysis - others will have a more informed opinion. I suspect there will be trade-offs between a cost-effective preservative you can place in a bucket outdoors for weeks, and the effect that preservative has on the chemical make-up of the invertebrates.
However, I strongly suggest propylene glycol over ethylene glycol. It is all we use at the Queensland Museum for pitfall traps: because it's an excellent preservative in pitfall traps, and significantly less toxic. Propylene glycol is a common food additive, and fairly safe; ethlene glycol is moderately toxic. Ethylene glycol is also awful if your colleague is intending to buy it as anti-freeze for vehicles. Pulling out invertebrates from green soup is more time consuming and revolting. The only downside is that propylene glycol is more expensive, but not prohibitively so. It's worth the extra cost for safe handling alone.
I'm aware that propylene glycol has been used as a DNA preservative, but with mixed results (but surely no worse than ethylene glycol). Your colleague should test some fresh versus preserved invertebrates to examine nutritional changes, no matter what preservative is used, as part of their study.
Kind regards, Owen.
Hi Emma,
Ethylene glycol is inherently toxic to mammals and does not absorb moisture as opposed to propylene glycol which is more friendly to handle.
I have no idea on the effect it has on nutritional content. Analysis before and after preservation may give a hint.
Regards.
Hi,mam,
My suggestion is, the killing agents used in fields are ethyl acetate, ethylene glycol,ammonium carbonate
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