Date of Graduation


Document Type


Degree Name

Master of Science in Entomology (MS)

Degree Level





Benjamin C. Thrash

Committee Member

Gustav M. Lorenz III

Second Committee Member

Nicholas R. Bateman

Third Committee Member

William J. Ross


ChinNPV, Chrysodeixis includens, Chrysogen, Soybean Looper


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 (<10.5%) while observing 100% control between 6 and 7 DAT. The fourth objective was to compare experimental techniques implemented in evaluating ChinNPV. Higher mortality was observed in diet overlay techniques, with closest related results between diet overlay and leaf dip techniques compared to greenhouse rate response. The last research objective was to evaluate purified formulation #3 capabilities of reducing defoliation and SBL densities when applied in a field setting. Field locations were located in Tillar and Marianna, AR with randomized complete block and strip trial design being used respectively. Intrepid Edge was the only treatment to significantly reduce SBL density when compared to the untreated check for all three observation dates.

Included in

Entomology Commons