Non-Target Impacts of Herbicides on Endangered Butterflies

EPA Grant Number: FP917334
Title: Non-Target Impacts of Herbicides on Endangered Butterflies
Investigators: Hicks, Tyler L
Institution: Washington State University
EPA Project Officer: Lee, Sonja
Project Period: August 1, 2011 through July 31, 2014
Project Amount: $126,000
RFA: STAR Graduate Fellowships (2011) RFA Text |  Recipients Lists
Research Category: Academic Fellowships , Fellowship - Pesticides and Toxic Substances


In cooperation with federal and state land managers, this project intends to identify ways to minimize harmful impacts of herbicide use on at-risk prairie butterfly species in the Pacific Northwest while maximizing control of invasive weeds.


Initially, this project will employ captive greenhouse studies with a non-native forb feeding and a native grass feeding butterfly species. Butterflies will be exposed to various combinations of surfactants and herbicides at different life stages. Impacts will be monitored by measuring survival rates, morphology, development time and fecundity. After identification of an herbicide/ surfactant combination with a minimal impact, greenhouse studies will be scaled up to management landscape scales in the field in prairies occupied by the endangered Fender’s Blue Butterfly (Icaricia icarioides fenderi). Finally, the study will monitor the response of the Fender’s Blue to herbicide exposure and resulting changes in their habitat by measuring responses in survivorship, behavior, reproductive success and dispersal. By comparing multiple species in both controlled greenhouse and field conditions, decisions can be better informed on what, when and how to apply herbicides in the presence of at-risk butterfly species.

Expected Results:

Management and recovery of threatened and endangered species is a priority for a number of federal, state and local land managers. In the Pacific Northwest and in other regions of the world, grassland butterflies are declining dramatically. Invasive weeds represent a major threat to remaining prairie obligate species. Herbicides are an important tool for land managers to use in managing invasive weeds. However, the potential non-target impact of herbicides on butterflies has not been explored thoroughly. Current herbicide usage may be causing harm to at-risk butterfly species. On the other hand, land managers unwilling to risk herbicide use may be missing out on a valuable management tool. This project intends to fill gaps in ecotoxicological knowledge by applying rigorous science to inform prairie management practices. This research project will expand the knowledge of herbicides impacts on prairie butterflies by using multiple species, including the at-risk Fender’s Blue butterfly in both captive greenhouse settings and at practical landscape management scales in the field. With this data, it is hoped to develop recommendations for herbicide use in the presence of at-risk prairies butterfly species in the Pacific Northwest and in grassland systems across the temperate regions of the planet.

Potential to Further Environmental/ Human Health Protection

By identifying herbicide use practices that minimize non-target impacts on native species and maximize control of invasive weeds, ecosystems can be maintained with greater native biodiversity and meet federal and state mandates for recovery of endangered and threatened species.

Supplemental Keywords:

conservation, butterfly, herbicides, ecotoxicology, prairie management, non-target impacts

Progress and Final Reports:

  • 2012
  • 2013
  • Final