Non-lethal DNA extraction methods for genetic analyses of endangered bumble bee species

Several North American bumble bees (Hymenoptera: Bombus) are faced with decline as factors such as climate change, pollution, and urbanization threaten their existence, thus raising concern regarding genetic diversity as populations diminish. Consequently, genetic analysis of these susceptible species is essential when considering appropriate conservation efforts. One species, Bombus affinis, has experienced such sharp population declines that it was listed as federally endangered within the United States and Canada. This necessitates methods for collecting genetic samples from bumble bees that do not require euthanizing specimens or removing legs. A previous pilot study used 50 mL conical tubes fitted with sugar water soaked swabs to passively collect genetic material from Bombus affinis. Approximately 50% of the 63 samples obtained contained usable amounts of DNA. To further improve this technique, samples were collected from Bombus impatiens using two non-lethal, minimally-invasive DNA extraction methods that can be applied to declining and endangered species. In one method, bumble bee thoraxes were swabbed directly to collect hairs from the immobilized bumble bees, whereas the second technique involved the passive DNA collection method utilized in the pilot study. The results of these two techniques were compared using PCR and gel electrophoresis to determine which of these methods worked best for gathering genetic samples without causing unnecessary harm to susceptible and endangered species. While neither method significantly outperformed the other, passive and active DNA collection still proves beneficial for threatened species over euthanization or tarsal clip collection, which are better reserved for well-established species.