Journal of Economic Entomology (2001) 94, 1538-1546

Nick C. Toscano, Nilima Prabhaker, Steven J. Castle and Thomas J. Henneberry (2001)
Inter-regional differences in baseline toxicity of Bemisia argentifolii (Homoptera: Aleyrodidae) to the two insect growth regulators, buprofezin and pyriproxyfen
Journal of Economic Entomology 94 (6), 1538-1546
Abstract: A survey of 53 Bemisia argentifolii Bellows and Perring populations from different agricultural regions in California and Arizona was conducted from 1997 to 1999 to establish baseline toxicological responses to buprofezin and pyriproxyfen. Although both compounds proved to be highly toxic even in minute quantities to specific stages, geographical and temporal differences in responses were detected using a leaf spray bioassay technique. Monitoring for three years revealed that six to seven populations had higher LC₅₀ values but not greater survival when exposed to these two insecticides. A significant difference in relative susceptibility to buprofezin was first observed in late season 1997 in San Joaquin Valley populations with LC₅₀s ranging from 16 to 22 mg (AI)/liter^-1 compared with LC₅₀s of 1 to 3 mg (AI)/liter^-1 in Imperial, Palo Verde Valley and Yuma populations. Whiteflies collected in subsequent years from these and other locations showed an increase in susceptibility to buprofezin. Regional differences in susceptibilities to pyriproxyfen were minimal within the same years. Three years of sampling revealed consistently higher LC₅₀s to pyriproxyfen in populations from Palo Verde Valley, CA, compared with whiteflies from Imperial, San Joaquin Valley or Yuma. As was the case with buprofezin, a decline in LC₅₀s to pyriproxyfen was observed in whiteflies from all locations sampled in 1999. However, no correlation was observed between buprofezin and pyriproxyfen toxicity in any of the strains. The variable toxicities observed to both compounds over a period of 3 yr may be due principally to inherent differences among geographical populations or due to past chemical use which may confer positive or negative cross-resistance to buprofezin or pyriproxyfen.
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Database assignments for author(s): Nick C. Toscano, Steven J. Castle, Nilima Prabhaker

Research topic(s) for pests/diseases/weeds:
control - general

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Bemisia tabaci biotype MEAM1		U.S.A. (SW)