Residual effects of imidacloprid on japanese beetle (coleoptera: Scarabaeidae) oviposition, egg hatch, and larval viability in turfgrass

Justine George, Carl T. Redmond, Reed N. Royalty, Daniel A. Potter

Research output: Contribution to journalArticlepeer-review

19 Scopus citations


Preventive control of turf-infesting scarabaeid grubs by neonicotinoid insecticides is presumed to mainly result from residues killing first instars in the soil. The extent to which sublethal behavioral effects or intoxication of other life stages contribute to such control is poorly known. We tested whether Japanese beetle, Papillia japonica Newman, females lay fewer eggs in turf treated with imidacloprid (Merit 75 WP) or an imidacloprid-bifenthrin combination (Allectus GC SC), and whether exposure to those residues in thatch and soil reduces their survival and subsequent ability to feed or take flight. Effects of imidacloprid residues on egg hatch and viability of successive larval instars also were studied. In two sets of choice tests, 68 and 82% fewer eggs were laid in Kentucky bluegrass with Allectus residues than in controls. When females were confined in treated turf, however, neither insecticide consistently reduced their fecundity or affected depth at which eggs were laid, although exposure to fresh Allectus residues reduced the beetles' subsequent viability. Imidacloprid residues up to 2 ppm in soil did not affect egg viability or days to hatch, but they killed neonates soon after eclosion. Imidacloprid curatively applied at label rate (0.34 kg active ingredient/ha) reduced weight gain, burrowing capability, frass production, and survival of second and third instars in turfgrass cores, with high mortality within 30 d. Intoxication and behavioral impairment of third instars also occurred in autumn field trials. Our data suggest that imidacloprid has greater activity against late instars than is generally appreciated.

Original languageEnglish
Pages (from-to)431-439
Number of pages9
JournalJournal of Economic Entomology
Issue number2
StatePublished - Apr 2007

Bibliographical note

Funding Information:
★J. Gabarró and M. Serna are partially supported by TIN-2007-66523 (FORMAL-ISM), and SGR 2009-2015 (ALBCOM). Alan Stewart is partially supported by EP-SRC project EP/I03405X/1 (ECHO).


  • Neonicotinoid
  • Popillia japonica
  • Sublethal effects
  • Toxicology

ASJC Scopus subject areas

  • Ecology
  • Insect Science


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