Insect screening results: multiple insect resistance in 49 commercial corn hybrids, 2025

Authors: Ni, Xinzhi; MAILHOT, DANIEL - University Of Georgia; TOEWS, MICHAEL - University Of Georgia; BUNTIN, G. DAVID - University Of Georgia

Submitted to: Experiment Station Publication
Publication Type: Experiment Station
Publication Acceptance Date: 12/16/2025
Publication Date: 12/17/2025
Citation: 1. Ni, X., Mailhot, D.J., Toews, M.D. and Buntin, G.D. Insect screening results: multiple insect resistance in 49 commercial corn hybrids, 2025. In: D. J. Mailhot, A. Sutton, J. Arrington, D. Dunn, D. Buntin, X. Ni, and M. Toews (eds.), Georgia 2025 Corn, Sorghum, and Summer Annual Forages Performance Tests. Georgia Agricultural Experiment Stations, Annual Publication 101-17, pp. 41-43.

Interpretive Summary: not required

Technical Abstract: Commercial corn hybrids were screened for ear- and kernel-feeding insect resistance under field conditions at Tifton, GA, and the results are summarized in the following table. A total of 49 transgenic hybrids were included in this year’s trial; 12 hybrids were rated Very Good (VG), the highest rating for multiple insect resistance in 2025; 13 were Good (G); 11 were Fair (F), and 13 were Poor (P) as shown in Table 1. Seven hybrids are non-Bt, which has only herbicide-resistant roundup ready (RR) trait; five have SmartStax™ (SS); one has YHR traits (also known as Optimum® Intrasect™); 13 have VC trait, or VT2P, denoting for vector-stacked transformation (VecTran or VT), which combines two (double) Bt traits into a single DNA insertion process; 15 have TC or TRE (denotes for Trecepta Technology) and a total of 17 hybrids contain Vip3A trait, which is shown as 3110, TC or TRE (Trecepta), VIP(or Viptera), or VYHR as shown in Table 1. SmartStax™ combined multiple transgenic technologies to control both above- and below-ground insect pests, as well as for herbicide tolerance. The Optimum® Intrasect™ insect protection traits (or YHR) include a combination of two insect protection traits – Herculex® I and YieldGard® Corn Borer, while the VC or VT2P (denoted for Genuity Double PRO®) trait contains a stack of two Bt genes (Cry1A.105 + Cry2Ab2), which target foliar- and ear-feeding lepidopteran pests. For hybrids contain Vip3A trait as shown in Table 1, TC or TRE for Cry1A.105 + Cry2Ab2 + Vip3A; VIP for Viptera (Cry1Ab + Cry1F + Vip3A); and VYHR for Intrasect + Vip3A. Please refer to column of “Bt designation” in Table 1 for Bt trait packages in each hybrid. Flowering time of all entries was between 51 and 58 days after planting (on April 14, 2025) due to relatively warm weather in May in comparison with 2024 data (58-63 days after planting). Ear-feeding insect damage was lower, while kernel-feeding insect damage was higher in 2025 when compared with the 2024 data. However, six types of ear- and/or kernel-feeding insects in order of damage severity still similar; they were corn earworm and fall armyworm, sap beetles, stink bugs, pink scavenger caterpillar, and maize weevil. Corn earworm and fall armyworm damage was measured by the length (cm) of feeding damage penetrated from the tip of the ear toward the base. Feeding penetration by natural infestation of these lepidopteran pests (from the means of the five sampled ears per plot) was between 0.07 and 2.03 cm per ear, which was less than the damage observed in 2024 (0.15 - 3.25). Kernel-feeding insect damage was assessed by percentage (%) of damaged kernels per ear. The number of kernels per ear were estimated by multiplying the number of kernels per row by the number of rows from a representative ear for each plot. All combined kernel feeding insect damage (including maize weevil, stink bug, sap beetle, and pink scavenger caterpillar) ranged between 0.61-6.62%, which was higher than that (0.15-3.58%) in 2024. The data related to insect damage were subjected to the principal component analysis using percentage of damaged kernels and three traits related to corn earworm and fall armyworm damage, that is, husk tightness and extension, and pest penetration on corn cobs. During the field season of 2025, corn rootworm and corn borer damage was not detected at the Tifton trial. The data from 2025 were also used for multiple year performance assessment as shown in Table 1. Because corn husk tightness and extension are considered important traits for ear- and kernel-feeding insect resistance, the husk features of the sampled ears were examined. Husk tightness was assigned using a scale of 1 to 5, in which 1 = very loose and 5 = very tight. Average ratings for husk tightness in 2025 were at medium (3.07- 3.93). Husk extension ranged from 0.4 to 4.27 cm. Husk tightness was surprisingly po