Whitefly Resistance to Insecticides in Arizona: 2002 and 2003 Results

Abstract

"Whitefly resistance to insecticides is a constant threat to successful management of sticky cotton resulting from inadequate control of Bemisia whiteflies. A three-stage resistance management program was implemented in Arizona cotton following a severe whitefly resistance crisis in 1995. This program has been highly successful for eight years. Success has been fostered by intensive investments into improved whitefly sampling and treatment decisions, coupled with conservation of natural enemies. This latter component has hinged on limited, strategic use of two insect growth regulators in cotton, use of the neonicotinoid insecticide, imidacloprid, in vegetables and melons, and tactical deployment of non-pyrethroid and pyrethroid chemicals. Statewide monitoring of whitefly resistance to insecticides in cotton, melons and greenhouse crops has permitted annual assessments of the status of whitefly resistance management in Arizona. In this paper we summarize susceptibility of whitefly collecions made in cotton in the 2002 and 2003 seasons and discuss longer term trends in resistance development. No major problems regarding field performance of insecticides against whiteflies were observed or reported in 2002 or 2003. However, monitoring confirmed the early stages of evolution of resistance to pyriproxyfen (Knack®) and showed that whiteflies possessing this resistance could be detected in all cotton-producing areas of the state. Susceptibility to buprofezin (Applaud®/Courier®) has not changed significantly since 1997. Mean susceptibility to synergized pyrethroids (e.g., Danitol® + Orthene®) has increased strikingly on a statewide basis since 1995. However, 50 and 25% of cotton fields sampled in 2002 and 2003, respectively, had resistance levels expected to result in inadequate performance of synergized pyrethroid treatments. Whiteflies from throughout Arizona were highly susceptible to imidacloprid (Admire®/Provado®) and two other neonicotinoid insecticides, acetamiprid (Intruder®) and thiamethoxam (Actara®/Centric®/Platinum®)."