STORAGE FACTORS INFLUENCING ETHANOL CONCENTRATION OF FLUID-PRESERVED INSECTS | CU Experts

Abstract; The scientific value of insect specimens stored in ethanol depends upon their adequate preservation, which is most directly impacted by the preservative solution’s concentration. Determining what storage factors influence ethanol concentration, including the size and type of container and closure, as well as the ratio of specimen to ethanol volume, can inform collections staff on how to manage ethanol-preserved insect specimens ideally. We hypothesize that ethanol solution concentrations would 1) decrease with increasing insect volume to ethanol volume ratios, 2) decrease with time, 3) vary by cap liner material, and 4) decrease more slowly in smaller vials. To test these hypotheses, we measured ethanol solution concentrations in 1,376 vials containing insects collected over an 8-year period and subsequently stored undisturbed for 4–11 yr. The ratio of specimen to ethanol volume was most influential, followed by time in storage, as increasing insect volumes and storage times resulted in lower ethanol concentrations. Cap liner material and vial size did not significantly affect concentration, but human error in ethanol solution mixing and overpacking of specimens in vials created poor preservation conditions. These results can inform collections management methods for ethanol-preserved insects, which are instrumental for keeping specimens scientifically useful in perpetuity.

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