North Carolina State University Plymouth, North Carolina
Helicoverpa zea has evolved resistance against some Bt traits deployed against lepidopteran pests. The polyphagous nature of this pest, coupled with other characteristic life history traits, complicate the development of an effective resistance management strategy in the southeastern United States. This pest can reproduce several generations throughout the growing season for corn and cotton which both express Bt, increasing the selection for resistance. To maintain the effectiveness of these traits, current recommendations for this region highlight the importance of limiting their usage in corn. More information is necessary, but corn can compensate some feeding damage from H. zea before exhibiting yield loss. The exception is if H. zea co-occurs with Spodoptera frugiperda in late-planted corn, or in the extreme sub-tropical regions of the US, then H. zea may become a yield limiting pest. However, this pest can significantly limit yields in cotton; therefore, foliar applications of chlorantraniliprole are relied on for effective control. Chlorantraniliprole is also currently used in soybeans, but in comparison to cotton, H. zea is relatively easy to control with alternative modes of action. Reduction of chlorantraniliprole in soybeans will help maintain efficacy of this insecticide in cotton. Future resistance management for H. zea will require an integrated approach across different cropping systems for effective IPM.
