Our article describing the effects of ethanol concentration on the preservation of insects, a product of collaboration between our lab and the Ronquist Lab at the Swedish Museum of Natural History, was published earlier this week in the journal PeerJ [here]!
Entomologists have known that high concentrations of preservative ethanol can make insects brittle, prone to breaking, and difficult to handle. To counteract this, insects have often been preserved at lower concentrations of ethanol (70 or 80%) - but this is known to negatively affect the preservation of the DNA, an increasingly important target of modern taxonomy and evolutionary biology researchers. This poses a problem, as the concentrations used to preserve insect morphology are too low to optimally preserve the DNA in the long run.
In this work, we analysed how severe the negative effects of high ethanol concentrations on the morphology and of low concentrations on the DNA were in seven insect species. We found that not all species were equally affected. Those more robust suffered less morphological damage at high concentrations, but their DNA was relatively poorly preserved at lower concentrations. On the contrary, weakly sclerotised species were more damaged when preserved and stored at high concentrations of ethanol, but intermediate concentrations had a less severe effect on the DNA preservation. In many cases, ethanol concentrations of 90% resulted in acceptable preservation of both the morphology and the DNA.