Effects of Single Generation Selection with Insecticides on Resistance Levels in Louisiana Tobacco Budworm

B. R. Leonard, S. H. Martin, J. B. Graves, J. A. Ottea, P. A. Clay, C. A. White and G. Church


Tobacco budworm, Heliothis virescens (F.), eggs and larvae were collected at the LSU Agricultural Center's Macon Ridge Research Station (MRS) and separated into four independent colonies labelled as un-selected (UTC), pyrethroid-selected (SP), organophosphate-selected (OP) and carbamate-selected (CRB). Each respective colony was exposed to selecting doses of the pyrethroid, cypermethrin, the organophosphate, profenofos, or the carbamates, thiodicarb/methomyl, using topical application or field sprayed cotton plant terminals. The initial tests showed the MRS tobacco budworm colony to possess significant levels of resistance to pyrethroid, organophosphorus and carbamate insecticides. In tests conducted on F1 generation larvae, significant differences in mortality from cypermethrin, profenofos and methomyl were observed between the un-selected (UTC) and insecticide-selected (SP, OP, CRB) colonies. These data suggest that selection with one class of insecticides can influence tobacco budworm susceptibility to insecticides representing different classes in subsequent generations. However, the results do not indicate that a different insecticide use strategy would be more successful than the one currently recommended in the Mid-South region. Alternation among all classes of insecticides recommended for control of tobacco budworm on cotton with a greater emphasis on insecticide mixtures (primary larvacide + ovicide or Bt) will form the basis of the insecticide use strategy for 1994.

Reprinted from Proceedings of the 1994 Beltwide Cotton Conferences pp. 824 - 828
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998