Toxicity of Pyrethroids and Other Insecticides Against Susceptible and Resistant Tobacco Budworm Larvae and Synergism by Chlordimeform

C. Campanhola and F.W. Plapp, Jr.


 
ABSTRACT

The development of resistance to pyrethroid insecticides in the tobacco budworm, Heliothis virescens (F.), represents a problem to many cotton production areas In Texas and, potentially, to other areas in the United States. In an attempt to determine strategies to deal with the resistant populations, resistant and susceptible first instar larvae were exposed in glass vials to insecticides alone, or in combination with chlordimeform. Cross resistance was observed to all the pyrethroids tested. Resistance did not extend to avermectin or to the S-alkyl organophosphates profenofos and acephate, but did extend to the carbamates methomyl and thiodicarb. Chlordimeform synergized all insecticides, and synergism was higher against susceptible than against resistant larvae with organophosphate insecticides. However, no consistent pattern of synergism could be established for the different strains with synthetic pyrethroids or carbamates. The S-alkyl organophosphates seem to be a good alternative for the early season control of tobacco budworm resistant populations.



Reprinted from 1987 Proceedings: Beltwide Cotton Production Research Conferences pp. 326 - 329
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998