Insecticide Bioassays Against Florida's Most Destructive Sweet Corn Pests

The silk fly complex that infests sweet corn in Florida consists of Chaetopsis massyla, Euxesta eluta, E. stigmatias, and E. annonae (Diptera: Ulidiidae). These flies are highly damaging to fresh market sweet corn and are the targets of numerous insecticidal sprays during sweet corn’s reproductive stages.  In recent years, scouts have commented that the flies are becoming more difficult to control.  Laboratory bioassays were performed during 2012-2013 to determine whether or not there were susceptibility differences to commercially-used insecticides among C. massyla, E. eluta, and E. stigmatias.  Results indicate that E. stigmatias is more tolerant to several pyrethroids than the other two tested species.  This tolerance can be countered with the addition of the synergist piperonyl butoxide, indicating metabolic pyrethroid degradation.