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Q&A ViewAttendees 5

Physiology, Biochemistry, and Toxicology

Student Competition 10-Minute Paper

Grad PBT: IPM, Biocontrol, and Pests

Evaluation of the current bollworm (Helicoverpa zea (Boddie)) threshold recommendations in cotton and determination of the threshold effects on bollworm control and profitability

Monday, November 1, 2021
8:24 AM – 8:36 AM MT
Location: Colorado Convention Center, Meeting Room 405-407
In-Person Student Competition

    Presenting Author(s)

  • WC

    Wilfrid Calvin

    Graduate Research Assistant
    Texas A&M University
    College Station, Texas

    • Co-Author(s)

  • David L. Kerns

    Texas A&M University
    College Station, Texas

  • JG

    Jeremy Greene

    Clemson University
    Blackville, South Carolina

  • JG

    Jeff Gore

    Mississippi State University Delta Research and Extension Center
    Stoneville, Mississippi

  • SV

    Suhas Vyavhare

    Texas A&M AgriLife Research and Extension Center
    Lubbock, Texas

  • Megha N. Parajulee

    Regents Fellow Professor
    Texas A&M AgriLife Research and Extension Center
    Lubbock, Texas

  • RS

    Ronnie Schnell

    Texas A&M AgriLife Extension
    College Station, Texas

  • Lindsey Perkin

    Research Molecular Biologist
    USDA-ARS
    College Station, Texas

The bollworm (Helicoverpa zea (Boddie)) had largely been relegated as a minor pest since the introduction and widespread adoption of genetically modified cotton expressing Bt toxins. Recently, due to practical and field-evolved resistance to some Bt toxins, bollworm has re-emerged as a major economic pest of cotton in much of the southern U.S. resulting in renewed emphasis on the implementation of action thresholds for bollworm management. Field experiments were conducted (2020-2021) in College Station, TX; Stoneville, MS; and Blackville, SC to evaluate the current bollworm threshold recommendations. A 3 x 5 factorial design were utilized, with factor A being the cotton Bt technology (Non-Bt, Bollgard® 2 (Cry 1 Ac + Cry2Ab2), Bollgard® 3 (Cry 1 Ac + Cry2Ab2 + Vip3A) and factor B being the action threshold (non-treated, treatment triggered on a 20% egg lay, on a 6% fruit injury, on 3 or more ≥3rd instar larvae per 100 plants, and preventively). The threshold effects did not differ for damaged square, damaged boll, damaged fruit and number of fruit large larvae. However, all evaluated thresholds differed to the untreated. Yield responses among the 20% egg lay, ≥3% large larvae, and 6% fruit injury thresholds were comparable. However, the 20% egg lay threshold did not differ to the untreated. The threshold effects on profitability were insignificant. However, the 20% egg lay, ≥3% large larvae, and 6% fruit injury thresholds provided measurable reduction in insecticide application relative to preventive spray. Thus, these thresholds are viable and can be implemented toward bollworm management.