Western Tarnished Plant Bug, Lygus Hesperus Knight, Management in the San Joaquin Valley: Trends and Implications

Lygus bugs have been severe pests of cotton and other crops in the San Joaquin Valley for several decades.  The severity depends, in part, on the winter precipitation patterns and timing which influences growth of native vegetation and overwintering success of this species.  In recent years, lygus bugs have been yield limiting pests, i.e., not cost-effectively managed with insecticides, in at least a portion of the cotton production area in the San Joaquin Valley.  Results from insecticide field efficacy studies examining registered and experimental insecticides will be presented; lygus population levels, populations of natural enemies, and effects of treatments on induced pests (spider mites and cotton aphids) were quantified at various intervals following application.  In addition, resistance levels in field-collected lygus bugs to insecticide representatives from key classes of chemistry (registered long-time standards and new products) via laboratory bioassays have been conducted from 2008-2011.  Data trends will be discussed.