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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
Author(s) -
Redmond Carl T,
Wallis Lindsey,
Geis Matthew,
Williamson R Chris,
Potter Daniel A
Publication year - 2020
Publication title -
pest management science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.296
H-Index - 125
eISSN - 1526-4998
pISSN - 1526-498X
DOI - 10.1002/ps.5532
Subject(s) - danaus , bacillus thuringiensis , popillia , biopesticide , biology , japanese beetle , monarch butterfly , lepidoptera genitalia , botany , pest analysis , larva , agronomy , pesticide , genetics , bacteria
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. © 2019 Society of Chemical Industry