Transitioning Lygus Chemical Controls to More Selective Options for Arizona Cotton

Abstract

Lygus hesperus (Knight) has been the number one pest of Arizona cotton since 1998. With advances in the selective management of Arizona cotton’s other two key pests (i.e., Bemisia tabaci and Pectinophora gossypiella), there has been less opportunity for collateral control of this yield-limiting pest. There has also been a new premium placed on locating less disruptive, even selective, control methods that are compatible with existing selective technologies. Our laboratory routinely screens candidate compounds for efficacy against Lygus hesperus under desert conditions. Promising leads are further developed and evaluated in the field for efficacy, spectrum of activity and safety for beneficial arthropods. Our recent findings have identified three compounds with potential for delivering economic control of Lygus hesperus with greater safety for beneficial arthropods than current standards of control. At the same time, our work has importantly identified many compounds that are ineffective against our Lygus, despite reported success against a related species, the tarnished plant bug, Lygus lineolaris (e.g., acetamiprid, imidacloprid, indoxacarb, pyrethroids, thiamethoxam). Flonicamid, a pyridine carboxamide, is under development by FMC in the U.S. This aphicide has shown excellent results in controlling our Lygus in cotton. Novaluron, a chitin inhibitor under development by Uniroyal (as Diamond®) in the U.S., has rate sensitive activity against Lygus in cotton. Metaflumizone (BAS320I), under development by BASF in the U.S., is a semi-carbazone chemistry with significant efficacy against Lygus hesperus. These three or potentially other new leads in insecticide discovery may play an important role in transitioning Arizona cotton growers away from neuro-toxic, broad-spectrum, and disruptive organophosphates and carbamates currently used to control Lygus in cotton. The potential benefits to natural enemy conservation should help stabilize insect pest management in Arizona cotton, thus minimizing the chances of secondary pest outbreaks and costly pest resurgences. Until selective alternatives are found and registered, acephate (e.g., Orthene 97 by Valent USA) and oxamyl (Vydate C-LV by DuPont) remain our standard recommendations for Lygus control in Arizona cotton.