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ARS Home » Pacific West Area » Maricopa, Arizona » U.S. Arid Land Agricultural Research Center » Pest Management and Biocontrol Research » Research » Publications at this Location » Publication #299396
Title: Baseline susceptibility of Bemisia tabaci B biotype (Hemiptera:Aleyrodidae) populations from Californis and Arizona to spirotetramat

Author
item PRABHAKER, NILIMA - University Of California
item Castle, Steven
item PERRING, THOMAS - University Of California

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/9/2014
Publication Date: 4/1/2014
Citation: Prabhaker, N., Castle, S.J., Perring, T. 2014. Baseline susceptibility of Bemisia tabaci B biotype (Hemiptera:Aleyrodidae) populations from Californis and Arizona to spirotetramat. Journal of Economic Entomology. 107:773-778.

Interpretive Summary: The development of safer and more effective insecticides over the past 20 years has enabled better management of agricultural insect pests. However, development of pest resistance to these insecticides remains a serious threat to the continued availability of these materials. Documentation of the effectiveness of new insecticides during their initial years of use, as a baseline reference, is an important first step in monitoring for future resistance. Laboratory studies of a new insecticide, spirotetramat, against sweetpotato whiteflies collected from 19 populations in Arizona and California over two years generally indicated a high level of effectiveness. Variation in the effectiveness of spirotetramat among whiteflies from different locations was limited, but somewhat more variation in effectiveness was observed between years. Testing against whitefly strains that were resistant to other insecticides indicated such resistance did not also confer resistance to spirotetramat. Finally, tests of spirotetramat against different age classes of immature whiteflies indicated similar effectiveness against all age classes. These results establish baseline information that can be used to ensure spirotetramat-resistance in whiteflies is detected early enough to facilitate continued availability of this material.

Technical Abstract: Baseline toxicity levels to foliarly applied spirotetramat were established for 19 field populations of whiteflies, Bemisia tabaci B biotype from Arizona and California in 2008 and 2009. The susceptibility data was determined against the 2nd instar of B. tabaci field collections before the registration and widespread use of spirotetramat in California. Three strains of whitefly, resistant to either bifenthrin, imidacloprid or pyriproxyfen, were also tested to determine the potential for cross-resistance to spirotetramat. No significant geographic variation in susceptibility to spirotetramat was observed among regions within Arizona. The LC50 values for the Arizona populations spanned a fourteen-fold range between populations during the two year sampling tests including a low LC50 of 0.91 (ug(AI)/ml) and a high LC50 of 13.47 (ug(AI)/ml). The field populations from California exhibited limited variation in susceptibility to spirotetramat in general (1.02-7.02 ug(AI)/ml) with one exception (27.98 ug(AI)/ml). Variation in susceptibility among the resistant strains was about 8-fold at the LC50 level with the PYR-strain showing the highest susceptibility to spirotetramat at 3.79 (ug(AI)/ml). Additionally, comparisons of relative susceptibilities among three older immature instars of two field populations showed no significant differences. These results establish a regional baseline that can serve as a reference for future monitoring and management of B. tabaci resistance to spirotetramat.