Laboratory evaluation of selected insecticides on field-collected populations of tobacco budworm (Heliothis virescens) and bollworm (Helicoverpa zea) in Georgia-2012 update

Bollworm (CEW) and tobacco budworm (TBW) larvae and adults were collected from a variety of host crops and evaluated for their susceptibilities to MVP II^®, cyperemthrin and spinosad (Tracer^®) during the 2012 season.  Results were compared to historical data collected throughout an eighteen-year study period beginning in 1995.     During this study period, tobacco budworm (TBW) and bollowrm (CEW) populations in Georgia remained relatively susceptible to MVP II^®; however, the data from year-to-year have been highly variable.  Some of the highest LC₅₀ values for MVP II^® were recorded during the 2010 season while some of the lowest LC₅₀ values were noted during the 2012 season.  Although pyrethroid insecticides remain effective for the control CEW larvae in cotton, evaluations have indicated that TBWand CEW populations across the state continue to become more tolerant to the effects of cypermethrin.  Results from treated diet and adult vial test (AVT) bioassays have consistently demonstrated an increase in LC₅₀s and survival throughout the study period.  No substantial fluctuations in the activity of spinosad against TBW and CEW larvae have been noted; spinosad (Tracer^®) has remained highly effective in the control of TBW and CEW populations in Georgia.