Date of Graduation

7-2026

Document Type

Thesis

Degree Name

Master of Science in Entomology (MS)

Degree Level

Graduate

Department

Entomology and Plant Pathology

Advisor/Mentor

Thrash, Benjamin

Committee Member

Studebaker, Glenn

Second Committee Member

Bateman, Nicholas

Third Committee Member

Towles, Tyler

Keywords

Tarnished Plant Bug (TPB), Thresholds, Mid-south Cotton, novaluron, ThryvOn

Abstract

Tarnished plant bug (TPB) is the most economically damaging insect pest of Mid-South cotton. TPB reduces yield is reduced by damaging squares, terminal growth, and small bolls, resulting in reduced yield. Currently, cotton grown in the Mid-South averages 1-6 insecticide applications per year for control of TPB. The introduction of ThryvOn® cotton technology provides a new management strategy for TPB control. ThryvOn® technology produces the Bacillus thuringiensis (Bt) protein Mpp51Aa2, which has insecticidal activity on TPB. A field study was conducted at five locations in 2024 and seven locations in 2025 across the Mid-South to evaluate different threshold levels for TPB in ThryvOn® cotton. Threshold treatments tested consisted of combinations of the 1x and 2x for TPB nymphs and adults based on the current threshold of 3 TPB nymphs per 1.5 row m and 8 TPB adults per 100 sweeps. Results suggest TPB adults caused more damage to square retention per insect caught than TPB nymphs did. Adult TPB sampling using a sweep net proved to be a better indicator for square damage than sampling for TPB nymphs using a drop cloth. Treatments 1x adult, 1x nymph or 2x adult, 1x nymph and adult, and 2x adult all yielded greater than the untreated. Results indicate that scouting methods in ThryvOn® cotton should emphasize TPB adult populations to assess damage accurately. A separate test was conducted in 2024 and 2025 to evaluate the fecundity of TPB on ThryvOn® and non-ThryvOn® cotton, with and without an application of novaluron made at the third week of squaring. Samples were recorded by small nymphs, large nymphs, and adults, along with square retention. In this study ThryvOn® cotton paired with an application of novaluron maintained the highest mean square retention when compared to other treatments, and the ThryvOn®-novaluron combination reduced TPB damage when compared to untreated ThryvOn®. This study indicated that integrating ThryvOn® technology with early season insecticide applications could have the potential to increase square retention and suppress TPB damage.

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