Journal of Economic Entomology (2008) 101, 174-181

Nilima Prabhaker, S.J. Castle, L. Buckelew and Nick C. Toscano (2008)
Baseline susceptibility of Bemisia tabaci B biotype (Hemiptera: Aleyrodidae) populations from California and Arizona to spiromesifen
Journal of Economic Entomology 101 (1), 174-181
Abstract: Susceptibility to spiromesifen, a tetronic acid derivative, was determined for three imidacloprid-resistant strains and 12 geographically discrete natural populations of Bemisia tabaci (Gennadius) (=Bemisia argentifolii Bellows and Perring) (Hemiptera: Aleyrodidae) from California and Arizona by laboratory bioassays. Newly emerged first instars were sprayed with aqueous serial dilutions of spiromesifen and evaluated for toxicity to establish baseline susceptibility data. Interpopulation variability in susceptibility to spiromesifen was observed among the natural populations of whiteflies up to 29-fold; however, there was only 30-fold difference in susceptibility among natural and resistant populations tested. In general, spiromesifen was quite toxic to first instars across most of their geographic range, with LC₅₀ values ranging from 0.210 to 6.08 μg (AI)/ml. The magnitude of variation was smaller among the three-resistant strains. These results suggest that the observed variability reflect natural variation in spiromesifen susceptibility among all the test populations, possibly due to previous exposure to insecticides at each location. The effectiveness of spiromesifen also was evaluated against all immature stages of whiteflies from three field and two resistant strains. Spiromesifen was significantly more active against early instars of whiteflies based on lower LC₅₀ values recorded compared with the fourth instars. Spiromesifen was effective against the resistant strains including a Q-biotype of B. tabaci from Spain, which is highly resistant to neonicotinoids. Results of this study indicate absence of cross-resistance between spiromesifen and more commonly used neonicotinoids. Our findings suggest that spiromesifen should be considered an ideal candidate for whitefly resistance management programs in rotation with other effective chemistries.
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Link to article at publishers website
Database assignments for author(s): Nilima Prabhaker, Steven J. Castle

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
	Bemisia tabaci biotype MED		Spain (continental)