Host plant species mediates impact of neonicotinoid exposure to monarch butterflies

Cody Prouty, Paola Barriga, Andrew K. Davis, Vera Krischik, Sonia Altizer

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

Neonicotinoids are the most widely used insecticides in North America. Numerous studies document the negative effects of neonicotinoids on bees, and it remains crucial to demonstrate if neonicotinoids affect other non-target insects, such as butterflies. Here we examine how two neonicotinoids (imidacloprid and clothianidin) affect the development, survival, and flight of monarch butterflies, and how these chemicals interact with the monarch’s milkweed host plant. We first fed caterpillars field-relevant low doses (0.075 and 0.225 ng/g) of neonicotinoids applied to milkweed leaves (Asclepias incarnata), and found no significant reductions in larval development rate, pre-adult survival, or adult flight performance. We next fed larvae higher neonicotinoid doses (4–70 ng/g) and reared them on milkweed species known to produce low, moderate, or high levels of secondary toxins (cardenolides). Monarchs exposed to the highest dose of clothianidin (51–70 ng/g) experienced pupal deformity, low survival to eclosion, smaller body size, and weaker adult grip strength. This effect was most evident for monarchs reared on the lowest cardenolide milkweed (A. incarnata), whereas monarchs reared on the high-cardenolide A. curassavica showed no significant reductions in any variable measured. Our results indicate that monarchs are tolerant to low doses of neonicotinoid, and that negative impacts of neonicotinoids depend on host plant type. Plant toxins may confer protective effects or leaf physical properties may affect chemical retention. Although neonicotinoid residues are ubiquitous on milkweeds in agricultural and ornamental settings, commonly encountered doses below 50 ng/g are unlikely to cause substantial declines in monarch survival or migratory performance.

Original languageEnglish (US)
Article number999
JournalInsects
Volume12
Issue number11
DOIs
StatePublished - Nov 2021

Bibliographical note

Funding Information:
Funding: C.P. was partially supported during this project by the inaugural Lincoln P. Brower Award, administered by the Monarch Butterfly Fund. S.A. and P.B. were supported by NSF DEB-1754392 and by SERDP-RC2700.

Publisher Copyright:
© 2021 by the authors. Licensee MDPI, Basel, Switzerland.

Keywords

  • Asclepias
  • Clothianidin
  • Danaus plexippus
  • Flight
  • Imidacloprid
  • Milkweed
  • Sub-lethal effects
  • Toxicity

PubMed: MeSH publication types

  • Journal Article

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