Effects of two Commercial Neem-based insecticides on lone star tick, Amblyomma Americanum (L.) (Acari: Ixodidae): Deterrence, mortality, and reproduction

Allan T. Showler, Weste L.A. Osbrink, Jay Morris, Michael J. Wargovich

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


The lone star tick, Amblyomma americanum (L.), is a widely distributed three-host obligate blood-feeding ectoparasite in the United States and Mexico. It mostly attaches to white-tailed deer, Odocoileus virginianus (Zimmerman) and wild Turkey, Meleagris gallopavo L., as well as a wide variety of other, domestic and wild hosts such as cattle, dogs, horses, goats, quail, squirrels, opossums, hares, coyotes, and humans. Diseases known to be transmitted by A. americanum include ehrlichiosis, rickettsiosis, tularemia, and protozoan infections. Two commercial neem-based products registered for home and garden use, Neemix (a viscous liquid) and AzaSol (a powder), containing 4.5 and 6% azadirachtin (a limonoid), respectively, as the labeled active ingredient, were assessed for contact toxicity, fumigant toxicity, deterrence, and sublethal effects on egg laying and hatching. We determined that Neemix also contained high concentrations of three additional bioactive limonoids: Nimbolide, nimbin, and salannin. When concentrations of azadirachtin were approximately the same, the two neem-based formulations caused similar contact mortality against larvae. High concentrations of Neemix-induced complete mortality from volatiles when larvae and adults were exposed and nonazadirachtin compounds appeared to be the cause. Neem-based products can induce multiple bioactive effects that differ from other neem-based products because the products might be comprised different bioactive constituents and because the products might have the same constituents but in substantially different amounts. Only Neemix was deterrent against larvae, which might have resulted from the presence of the bioactive compounds other than azadirachtin. Growth regulator and sublethal effects on egg laying and egg hatchability were not observed. The feasibility of protecting hosts against A. americanum using the neem-based products is discussed.

Original languageEnglish (US)
Pages (from-to)1-12
Number of pages12
JournalBiopesticides International
Issue number1
StatePublished - 2017


  • Azadirachtin
  • Bioactive compounds
  • Egg hatchability
  • Fecundity
  • Insect growth regulator
  • Sublethal effects
  • Toxicity

ASJC Scopus subject areas

  • Agronomy and Crop Science
  • Plant Science
  • Management, Monitoring, Policy and Law


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