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ViewAttendees 3

10-Minute Paper

Medical, Urban, and Veterinary Entomology

MUVE: Urban Entomology - Behavior and Management

Toxicity and repellency of carvacrol, thymol, and their acetates against imported fire ants

Tuesday, November 7, 2023
4:18 PM – 4:30 PM ET
Location: Gaylord National Resort & Convention Center, National Harbor 3
In-Person

    Presenting Author(s)

  • FS

    Farhan Mahmood Shah

    Principal Scientist
    National Center for Natural Products Research
    Oxford, Mississippi

    • Co-Author(s)

  • PP

    Pradeep Paudel

    National Center for Natural Products Research
    Oxford, Mississippi

  • DG

    Dileep Kumar Guddeti

    National Center for Natural Products Research
    Oxford, Mississippi

  • AA

    Abbas Ali

    National Center for Natural Products Research
    Oxford, Mississippi

  • JC

    Jian Chen

    Research Entomologist
    USDA
    Stoneville, Mississippi

  • IK

    Ikhlas A. A. Khan

    Director, National Center for Natural Products Research
    National Center for Natural Products Research
    Oxford, Mississippi

  • XL

    Xing-Cong Li

    National Center for Natural Products Research
    Oxford, Mississippi

Imported fire ants (Hymenoptera: Formicidae) are pests of urban, agricultural, and medical importance. Plant-derived natural products may offer novel alternatives to chemicals and effective means of managing populations of imported fire ants. In this study, we tested carvacrol, thymol, and their acetate derivatives for repellency and toxicity, using high throughput toxicity and repellency bioassays. Based on the mean amount of sand removed, carvacrol showed strong repellency with a minimum repellent effective dose (MRED) of 0.98, 3.90, and 0.98 µg/g, against RIFA, BIFA, and HIFA workers, respectively. Thymol exhibited repellency with MREDs of 31.25, 31.25, and, 7.8 µg/g, respectively. The acetate derivatives, carvacrol acetate and thymol acetate, appeared to possess weaker activity, exhibiting MREDs of 31.25, 31.25, and 15.6 µg/g and 62.5, 31.25, and 125 µg/g, respectively, against RIFA, BIFA, and HIFA, respectively. DEET, (N, N-diethylmeta-toluamide) was active at MREDs of 62.5, 125, and 31.25 µg/g, against RIFA, BIFA, and HIFA, respectively. These two compounds and their acetate derivatives demonstrated mild-to-moderate toxicity (LC50s; 50-160 µg/g), whereas bifenthrin with an LC50 of 0.03-0.018 µg/g was the most toxic. In conclusion, carvacrol is the most promising repellent, followed by thymol, carvacrol acetate, and thymol acetate.