Silverleaf whiteflies show no increase in insecticide resistance
Steve Castle, USDA-ARS
Tom Henneberry, USDA-ARS
Nick Toscano, UC Riverside
Nilima Prabhaker, UC Riverside
Steve Birdsall, Imperial County Agricultural Commissioner's Office
Dick Weddle, Imperial County Agricultural Commissioner's Office
California Agriculture 50(1):18-23. DOI: 10.3733/ca.v050n01p18.
The silverleaf whitefly (Bemisia argentifolii Bellows & Perring) continues to be a difficult pest to control in California's desert valleys. To gain a better understanding of the possible role that insecticide resistance plays in its annual outbreaks, a resistance monitoring program was established to document susceptibilities of whiteflies to various insecticides through time. Continuous monitoring during 1993 and 1994 detected no trend toward higher resistance levels. Higher toxicities of insecticide mixtures compared to single insecticides were regularly observed in bioassay results. Various factors including diverse insecticide use and altered cropping patterns may have helped to avoid serious insecticide resistance problems in the Imperial Valley so far.
S. Castle is Research Entomologist, USDA-ARS, Brawley; T. Henneberry is Laboratory Director, USDA-ARS, Western Cotton Research Laboratory, Phoenix, AZ; N. Toscano is Cooperative Extension Entomologist, Department of Entomology, UC Riverside; N. Prabhaker is Postdoctoral Associate, Department of Entomology, UC Riverside; S. Birdsall is Agricultural Commissioner, Imperial County Agricultural Commissioner's Office, El Centro; D. Weddle is Entomologist, Imperial County Agricultural Commissioner's Office, El Centro;
Special thanks to Howard Jencks for his manifold contributions to the program. Thanks also to Jolene Carson, Brent Bolin and Shelly Osuna for their assistance with resistance monitoring. This research was supported in part by Imperial County Whitefly Management Committee; Cotton Incorporated; and the Insecticide Resistance Action Committee (IRAC).
For details on the silverleaf whitefly, see November-December 1991, January-February 1992 and January-February 1993 issues of California Agriculture.