Helicoverpa zea (aka corn earworm, bollworm) resistance monitoring update–Aug. 7, 2014

Our corn earworm/bollworm moth catches went up this week allowing us to conduct adult vial tests on 128 moths.  Vials were treated with the standard 5 microgram rate of cypermethrin (a pyrethroid insecticide), or acetone (the untreated check).  This week, 39.4% of moths survived the test, which is high.  The season-long average is now 35% survival (based on 190 moths evaluated) and is higher than what we saw in 2013 (see graphs, below).  Survivorship at this level indicates that non-pyrethroids may need to be considered when an insecticide is needed for this pest in some regions, so please keep this in mind when scouting and then making management decisions in the upcoming days.