Hine's Emerald Dragonfly
Evaluating Surrogate Species
BY DARIN SIMPKINS, GREEN BAY FWCO
Experimentation is often necessary to determine if management actions have positive or negative impacts on a population of interest. Unfortunately, many of these populations for the US Fish and Wildlife Service are threatened or endangered, with few specimens available for experimentation. One solution to this conundrum is using surrogate species to approximate responses of an endangered species from those of similar, but more numerous species. Hine’s emerald dragonfly (Somatochlora hineana) is an endangered species that occupies rare wetland habitats that frequently are invaded by reed canary grass (Phalaris arundinacea) and common reed (Phragmites australis). In an effort to control their spread, management actions often include spraying invasive plants with herbicides containing various mixtures of glyphosate. The effects of glyphosate on Hine’s emerald dragonfly and other similar dragonflies are unknown. To determine if other species of dragonfly could serve as surrogates for evaluating the effects of herbicide treatment on Hine’s emerald dragonfly, static acute toxicity tests for glyphosate were conducted using the larvae of four dragonfly species: Aeshna umbrosa, Boyeria vinosa, Epitheca princeps, and Somatochlora williamsoni. Results of these tests were then compared to those of two age classes of endangered Somatochlora hineana. Significant differences were observed in sensitivity among species and between the two age classes of S. hineana. Though younger larvae were more sensitive to glyphosate than older larvae, S. hineana were the least sensitive (i.e., most tolerant) dragonfly species evaluated. Results of this study suggest that a surrogate species approach may be possible to indirectly evaluate the effects of glyphosate-based herbicides on Hine’s emerald dragonfly. For more information, contact University of South Dakota professor Dr. Jake Kerby at (605) 677-6170.