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Article
Monarch Butterfly (Danaus plexippus) Life‐Stage Risks from Foliar and Seed‐Treatment Insecticides
Environmental Toxicology and Chemistry
  • Niranjana Krishnan, Iowa State University
  • Yang Zhang, Beijing Great‐Agri Institute of Pesticide Technology
  • Melanie E. Aust, Conservation Corp Minnesota and Iowa
  • Richard L. Hellmich, U.S. Department of Agriculture
  • Joel R. Coats, Iowa State University
  • Steven P. Bradbury, Iowa State University
Document Type
Article
Publication Version
Published Version
Publication Date
1-1-2021
DOI
10.1002/etc.5016
Abstract

Conservation of North America's eastern monarch butterfly (Danaus plexippus) population would require establishment of milkweed (Asclepias spp.) and nectar plants in the agricultural landscapes of the north central United States. A variety of seed‐treatment and foliar insecticides are used to manage early‐ and late‐season pests in these landscapes. Thus, there is a need to assess risks of these insecticides to monarch butterfly life stages to inform habitat conservation practices. Chronic and acute dietary toxicity studies were undertaken with larvae and adults, and acute topical bioassays were conducted with eggs, pupae, and adults using 6 representative insecticides: beta‐cyfluthrin (pyrethroid), chlorantraniliprole (anthranilic diamide), chlorpyrifos (organophosphate), imidacloprid, clothianidin, and thiamethoxam (neonicotinoids). Chronic dietary median lethal concentration values for monarch larvae ranged from 1.6 × 10–3 (chlorantraniliprole) to 5.3 (chlorpyrifos) μg/g milkweed leaf, with the neonicotinoids producing high rates of arrested pupal ecdysis. Chlorantraniliprole and beta‐cyfluthrin were generally the most toxic insecticides to all life stages, and thiamethoxam and chlorpyrifos were generally the least toxic. The toxicity results were compared to insecticide exposure estimates derived from a spray drift model and/or milkweed residue data reported in the literature. Aerial applications of foliar insecticides are expected to cause high downwind mortality in larvae and eggs, with lower mortality predicted for adults and pupae. Neonicotinoid seed treatments are expected to cause little to no downslope mortality and/or sublethal effects in larvae and adults. Given the vagile behavior of nonmigratory monarchs, considering these results within a landscape‐scale context suggests that adult recruitment will not be negatively impacted if new habitat is established in close proximity of maize and soybean fields in the agricultural landscapes of the north central United States.

Comments

This article is published as Krishnan, Niranjana, Yang Zhang, Melanie E. Aust, Richard L. Hellmich, Joel R. Coats, and Steven P. Bradbury. "Monarch Butterfly (Danaus plexippus) Life Stage Risks from Foliar and Seed‐Treatment Insecticides." Environmental Toxicology and Chemistry (2021). doi:10.1002/etc.5016,

Rights
Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.
Language
en
File Format
application/pdf
Citation Information
Niranjana Krishnan, Yang Zhang, Melanie E. Aust, Richard L. Hellmich, et al.. "Monarch Butterfly (Danaus plexippus) Life‐Stage Risks from Foliar and Seed‐Treatment Insecticides" Environmental Toxicology and Chemistry (2021)
Available at: http://works.bepress.com/joel_coats/135/