ABSTRACT

From 1974 to 1981 field tests in lower Rio Grande valley (LRGV) “island” of TX showed resistance to cyfluthrin [Baythroid], cypermethrin [Ammo] and tralomethrin [Scout] and susceptibility to deltamethrin [Decis] by the tobacco budworm, Heliothis virescens (F.), (TBW). Resistance was indicated when <80% control was determined. TBW was resistant to esfenvalerate [Asana], cypermethrin and cyfluthrin in 1985 in the trans-Pecos “island”. TBW was resistant to lambda cyhalothrin [Karate] and cyfluthrin in 2000-2001 in the lower coastal bend “island”. In 1989 and 1990, from field tests in the Brazos valley, cypermethrin controlled >85% of larval populations of TBW season long. Populations were susceptible. In 1986 and 2001 esfenvalerate showed >80% control of TBW in the LRGV and lower coastal bend “island”, respectively; populations were susceptible. Resistance or susceptibility to pyrethroids in field experiments conducted from 1974-1999 are the historical aspects of resistance while tests conducted in 2000-2001 indicate the active aspects of resistance or susceptibility of the populations across TX today. This is because the inherited resistance patterns of TBW populations in the 2000s may be completely different from those determined in earlier y in the same or different “islands”. Moths can disperse from one “island” to another. Pyrethroids should be evaluated each y in each “island” where high populations of TBW are found. From 1974 to 2001, when the last field test was conducted, cross resistance of TBW populations to the eight pyrethroids was not shown.