CEW(corn earworm) and SBL (soybean looper) are annual pests of soybean and corn in Louisiana. Unlike SBL, CEW infest every major row crop grown in Louisiana with corn being the preferred host. CEW produce three-four generations per year in Louisiana. Typically, the first generation migrates to corn (May/June) with the subsequent second generation (July/August) migrating into soybeans and cotton. Often late-planted soybeans, on wide rows that have open canopies, are most susceptible. Cultural practices can be used to lessen the likelihood of economically damaging populations of CEW. Early planting of early maturing varieties, narrow row spacing and irrigation all contribute to lessen economic injury sustained by CEW populations. However, insecticides are often the primary mode to control CEW populations in soybeans.
SBL migrate to Louisiana every year from Central and South America. Populations often appear in Louisiana’s southernmost soybean growing parishes and migrate north as the season progresses. Like CEW, late planted soybeans are often impacted most by SBL populations and require multiple insecticide applications to control damaging populations. Conventional insecticides used to control both pests are realistically effective for <14 days and new alternatives are needed.
Therefore, we propose to investigate the use of nuclear polyhedrosis virus (NPV) as an unconventional control tactic for SBL and CEW that brings minimal negative side effects typically experienced with traditional insecticides (reduced efficacy overtime and insecticide resistance). Once ingested, NPV kills larvae by replicating within the host cells. Small larvae (less than 0.5 inch) typically die within 3 to 5 days after infection. When the insect dies, they liquefy and release millions of viral particles back into the crop canopy. Thus, each infected insect causes the virus to cascade across the field effectively controlling the target insects while spreading. When utilized in corn, the CEW NPV may cause a substantial decrease in CEW populations primed for migration into soybeans. When utilized in soybeans, the SBL NPV has the potential to effectively control looper populations season long. The novel mode of action effectively prohibits resistance formation by CEW or SBL and it is the only insecticide that demonstrates increased control with moderate rainfall.