Supplemental Control of Bollworm in Bt Cotton with Microbial and Chemical Insecticides

SUPPLEMENTAL CONTROL OF BOLLWORM IN BT COTTON

WITH MICROBIAL AND CHEMICAL INSECTICIDES

Nathan S. Little

Randall G. Luttrell

Michelle Mullen

K. Clint Allen

Omaththage P. Perera

USDA – ARS, Southern Insect Management Research Unit

Stoneville, MS

Abstract

Supplemental control of bollworm, Helicoverpa zea (Boddie), in Bt cotton is becoming more frequent in the MidSouth. Production-level field evaluations of supplemental bollworm control in non-Bt (DP1441RF®) and Bt (DP1321B2RF®) cottons with chemical and microbial insecticides were conducted in 2014 and 2015 in Stoneville, MS. During both years of the field study, all chemical and microbial treatments were successful in suppressing bollworm larval densities in non-Bt cotton below economic threshold levels. No differences were detected in yield among treatments in Bt cotton at the insect pressures observed for this study. This information may be utilized to evaluate the use of microbial insecticides on Bt crops for supplemental control of bollworms.