Bumblebee (Hymenoptera: Apidae) sample storage for a posteriori molecular studies: Interactions between sample storage and DNA-extraction techniques.

Abstract

A global decline in pollinator abundance and diversity has demanded increased research attention to the ecology and genetics of bumblebees. However, as progressively more restrictions are placed on sampling for insects, researchers are increasingly obliged to use archival specimens collected for purposes other than genetic analyses. In this study we assessed the suitability, for population genetic studies, of popular, low-cost methods for preservation and storage of bumblebee specimens. Specimens of Bombus terrestris L. were held under six storage regimes for up to two years. DNA was extracted from the samples using three extraction protocols and the quality of the DNA was examined using PCR amplification of a mitochondrial and a nuclear gene. All extraction and storage methods provided sufficient DNA for successful PCR amplification. However, samples preserved in acetone or at freezing temperatures yielded the highest DNA concentrations. DNA yields from pinned specimens at room temperature declined over time, particularly when using standard extraction techniques. DNA concentrations were significantly lower from specimens preserved in 70% ethanol compared to all other extraction techniques and declined linearly over the two years of storage. These results indicate that two of the most popular insect storage methods (pinning and storage in ethanol) should be avoided for the long-term preservation of genetic material for future studies. We suggest that optimal insect preservation methods should be incorporated into research protocols in order to best capitalise on limited collection opportunities.