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Title: EFFECT OF SYNERGISTS ON PYRETHROID AND ORGANOPHOSPHATE RESISTANCE IN BEMISIA TABACI

Author
item PRABHAKER, NILIMA - UNIV OF CA, RIVERSIDE
item TOSCANO, NICK - UNIV OF CA, RIVERSIDE
item Castle, Steven
item Henneberry, Thomas

Submitted to: Sweetpotato Whitefly Progress Review Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 8/1/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: A field strain of Bemisia tabaci (Gennadius) from Imperial Valley, CA was selected with bifenthrin and chlorpyrifos for 25 generations under greenhouse conditions. Resistance increased rapidly under selection to bifenthrin (RR=109) and moderately to chlorpyrifos (RR=30). Selective synergists were used to study the involvement of hydrolytic or oxidative enzymes (or both) in the resistance mechanisms of these two strains. Resistance levels were decreased when DEF (S,S,S-tributyl phosphorotrithioate) synergised chlorpyrifos and to a more limited extent bifenthrin, suggesting the involvement of increased detoxication by esterases as part of the resistance mechanism. Piperonyl butoxide (PB) synergised both bifenthrin and chlorpyrifos to different degrees in both susceptible and resistant strains, thus indicating the importance of oxidative metabolism in whitefly resistance. Because use of the synergists DEF and PB did not increase the toxicity in the resistant strains to that of the susceptible strain, an unidentified resistance factor, possibly insensitive acetylcholinesterase, may be of importance in OP resistance. A nonmetabolic knockdown resistance mechanism (kdr) may be a factor in bifenthrin resistance because neither DEF nor PB suppressed resistance completely.