Author
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PRABHAKER, NILIMA - UNIV OF CA, RIVERSIDE, CA |
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TOSCANO, NICK - UNIV OF CA, RIVERSIDE, CA |
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CASTLE, STEVE - PREVIOUS WCRL, BRAWLEY,CA |
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Henneberry, Thomas |
Submitted to: Silverleaf Whitefly: 1997 Supplement to the Five Year National Research and
Publication Type: Abstract Only Publication Acceptance Date: 8/1/1997 Publication Date: N/A Citation: N/A Interpretive Summary: Technical Abstract: The insecticide imidacloprid provides season-long control in fall vegetables and spring melons requiring fewer treatments than spray insecticides. Imidacloprid's greatest activity against whiteflies is through systemic uptake by plants. The system action of imidacloprid results in long term persistence and also generates higher selection for resistance by its more uniform occurrence in all parts of a plant compared to spray insecticides. nerefore, resistant management programs are essential for prolonging the life of imidacloprid under field conditions. A resistant strain of Bemisia tabaci was established by selection with imidacloprid for approximately two years with a resistance level of 77-fold. Susceptibility to imidacloprid was monitored using a hydroponic bioassay developed in this laboratory. Resistance to imidacloprid remained high with continuous imidacloprid selection. Lower levels of resistance to imidacloprid were observed in whiteflies subjected to a rotation regimen with different insecticides. Decline in resistance to imidacloprid was slow initially in the absence of selection but decreased considerably after a few generations to 2-fold. Our study indicates that resistance to imidacloprid declines when treatments are withdrawn. Under the alternation regimen of imidacloprid-bifenthrin selection, resistance declined but not completely, suggesting the presence of cross resistance to bifenthrin in this strain. |