Date of Graduation

12-2022

Document Type

Thesis

Degree Name

Master of Science in Entomology (MS)

Degree Level

Graduate

Department

Entomology and Plant Pathology

Advisor/Mentor

Thrash, Benjamin C.

Committee Member

Lorenz, Gustav M. III

Second Committee Member

Bateman, Nicholas R.

Third Committee Member

Ross, William J.

Keywords

ChinNPV; Chrysodeixis includens; Chrysogen; Soybean looper

Abstract

Chrysodeixis includens Nucleopolyhedrovirus (ChinNPV) specifically Chrysogen, has been commercially available in South America since 2016 but is not current available in the U.S. Chrysogen targets soybean looper (Chrysodeixis includens) (SBL), the major defoliator of soybean (Glycine max (L.) Merrill) in the mid-southern region of the U.S. Experiments were conducted during the 2020 and 2021 growing seasons to evaluate effectiveness of three formulations of Chrysogen at multiple rates for control of SBL. Soybean looper larvae used for following experiments were kept in an insect incubator at the University of Arkansas Lonoke Research and Extension Center. The first objective was to evaluate the efficacy of ChinNPV formulations at multiple rates on selected instars. Purified ChinNPV provided greater control of SBL when compared to the commercial formulation with no difference being observed between rates of ChinNPV. Purified ChinNPV provided the greatest level of control when applied to third instar larvae or smaller. The second objective was to determine if commercial Chrysogen combined with insect growth regulators (IGRs) could reduce defoliation between virus exposure and SBL morality. Leaf disks were dipped into solution of Chrysogen combined with 0.5x rate of selected insect growth regulator. Insect growth regulators in combination with Chrysogen provided 100% control when applied to first and third instars. Treatments containing Intrepid 2F and Dimilin alone provided the greatest control compared to all other treatments when applied to fifth instar larvae. The addition of Chrysogen to any insect growth regulator did not improve control. The third objective was to determine chrysogen and purified formulation #1 efficacy on SBL and defoliation levels of V3 growth stage soybean when applied with selected rates of two Chrysogen formulations. All rates of Chrysogen failed to reduce defoliation on soybean, exceeding the defoliation threshold (25%) and never exceeding 50% larval mortality. Soybean plants treated with purified formulation #1 had lesser defoliation (

Download

Included in

Entomology Commons

Share

COinS