Preventative insecticides reduce seedling injury, but do not increase yield in Bt and non-Bt corn grown in the Mid-Atlantic

BACKGROUND: Field corn production systems rely on preventative insect
management tactics, including hybrids expressing plant incorporated
protectants that are treated with neonicotinoid seed treatments, and
sometimes in-furrow pyrethroids. While effective seedling pest control can
be crucial because of the cost of replanting, these treatments target many
of the same pests and may add unnecessary costs for growers. Further,
seedling pests in the Mid-Atlantic tend to be sporadic, and preventative
insecticides may negatively impact natural enemies. To better understand
the value of common preventative tactics, we evaluated pest pressure and
compared a neonicotinoid seed treatment (clothianidin) and an in-furrow
pyrethroid (bifenthrin) in Bt and non-Bt corn hybrids. RESULTS: In Bt
hybrids, the in-furrow pyrethroid did not decrease pest injury, increase
stand, or increase yield, while the neonicotinoid seed treatment decreased
pest injury and increased stand but did not increase yield. In a non-Bt
hybrid, both insecticides decreased pest injury, but neither increased
stand or yield. Above- and below-ground pest injury was scarce throughout
the study, but even in the site-year with the most extensive injury,
insecticides did not result in yield gains. CONCLUSION: Implementing
efficient economically and environmentally sustainable corn pest
management requires a thorough understanding of the contributions of each
component of the pest control system. By thoroughly exploring pest
pressure in Bt and non-Bt systems, this study shows that preventative
insecticide use could be scaled back in many cases, especially given the
environmental and economic costs associated with them.