How do herbicides impact non-target species?

Next to habitat loss and fragmentation, invasive plant species represent the second largest threat to several endangered prairie butterfly species in the Pacific Northwest as well as other regions of the world. Control of invasive woody plants, forbs, and grasses has historically focused on the use of mowing, fire, and biological control to manage invasive plant species. However, these methods can have severe impacts on species occupying those systems. For example, fire can kill a large percentage of larvae and pupa butterfly in the path of the flames. For this reason land managers and conservation biologists working with endangered butterflies are unable to employ these methods at effective invasive weed management scales for fear of extirpating or severely impacting local butterfly populations. Increasingly land managers and conservation biologists have turned to herbicides as alternative management tool. Many herbicides have been developed to target specific taxa (e.g. grasses) while causing little to no visible impact on native non-target plant species. However, little research has been conducted to date on the potential impacts, both positive and negative, of herbicide exposure on butterflies. Through a combination of greenhouse and field studies I am investigating the impacts of grass-specific and broad-spectrum herbicides on butterfly behavior, morphology, survival, and fecundity.