Strengths and limitations of Bacillus thuringiensis galleriae for managing Japanese beetle (Popillia japonica) adults and grubs with caveats for cross-order activity to monarch butterfly (Danaus plexippus) larvae

Carl T. Redmond, Lindsey Wallis, Matthew Geis, R. Chris Williamson, Daniel A. Potter

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

BACKGROUND: Target-selective biopesticides are needed to facilitate integrated pest and pollinator management in urban landscapes and gardens. Bacillus thuringiensis galleriae, strain SDS-502 (Btg), recently registered in the USA and Canada, produces Cry8Da protein active against scarab beetles. We evaluated Btg formulations for managing the Japanese beetle [Popillia japonica Newman (JB)], a polyphagous invasive pest, including residual spray effectiveness for reducing adult feeding on Rosa and Tilia spp., and granular formulations for early- or late-curative control of root-feeding grubs in turfgrass. We also tested for cross-order activity to monarch butterfly (Danaus plexippus L.) larvae and other non-target insects. RESULTS: Field-weathered Btg residues reduced JB feeding on foliage for 3–14 days. Most beetles were still flight-capable after 24 h confinement with Btg-treated leaves. Granular Btg failed to control early- or late-instar JB grubs in soils under several turfgrass species at multiple field sites. In three trials, feeding on Btg-sprayed milkweed resulted in 97–100% mortality of early instar monarchs, with symptoms of B. thuringiensis pathogenesis. Fall armyworms (Spodoptera frugiperda (J.E. Smith)) fed Btg-treated grass had reduced body mass, but there were no adverse effects on lady beetle larvae preying on Btg-sprayed aphids or on the aphids themselves. CONCLUSION: This study supports efficacy of Btg strain SDS-502 for reducing defoliation by adult JB in urban landscape settings. Granular formulations, however, failed to control JB grubs in turfgrass soils. Btg should not be used in gardens with larval host plants of the monarch butterfly or other non-pest Lepidoptera, especially species of conservation concern.

Original languageEnglish
Pages (from-to)472-479
Number of pages8
JournalPest Management Science
Volume76
Issue number2
DOIs
StatePublished - Feb 1 2020

Bibliographical note

Publisher Copyright:
© 2019 Society of Chemical Industry

Keywords

  • Bacillus thuringiensis galleriae
  • Cry8Da toxin
  • cross-order activity
  • microbial control
  • turfgrass

ASJC Scopus subject areas

  • Agronomy and Crop Science
  • Insect Science

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