Monitoring for Pyrethroid Resistance in Bollworm (Helicoverpa zea) Populations in Texas, Tifton, Oklahoma and Tamaulipas, Mexico - 2009

A monitoring program evaluated the susceptibility of male bollworm, Helicoverpa zea (Boddie), populations to the pyrethroid insecticide cypermethrin using the adult vial test. Moths were trapped near cotton fields using a synthetic pheromone trap and glass vials coated with different concentrations of cypermethrin dissolved in acetone were used to assess moth mortality. Eleven Texas counties were surveyed, along with one location in Tamaulipas, Mexico, from March to September in 2009. Data were collected from all collaborators and sent to the Insect Toxicology Laboratory (AgriLife Research) for estimation of lethal concentrations (LC₅₀ and LC₉₀), calculation of resistance ratios, and likelihood ratio tests of equality and parallelism.