Pyrethroid Resistance in Two Field Strains of Helicoverpa zea (Lepidoptera: Noctuidae)

Toxicity of Pyrethroids and Effect of Synergists to Larval and Adult <I>Helicoverpa zea</I>, <I>Spodoptera frugiperda</I>, and <I>Agrotis ipsilon</I>(Lepidoptera: Noctuidae)

“…These results conÞrm the previous Þnding of El-Sayed and Knowles (1984), that indicated that 72 h LD 50 values of cypermethrin was slightly more toxic than permethrin against the fourth instars of H. zea from the same strain. In contrast, Abd-Elghafar et al (1993), using third instars of the same laboratory insecticide-susceptible strain, observed 24 h LD 50 values, indicating no signiÞcant difference in the relative toxicities of the two pyrethroids. Gist and Pless (1985a) studied the toxicity of two different samples of cypermethrin and permethrin, which differed slightly in their isomeric ratios, following topical application to the thoracic dorsum of S. frugiperda third instars.…”

“…In a vial bioassay, Plapp (1979) observed that amitraz was a weak synergist of permethrin toxicity to H. zea third instars. In topical bioassays, Abd-Elghafar et al (1993), found that a binary mixture of DEF, but not the piperonyl butoxide or amitraz, with cypermethrin was synergistic to insecticide-susceptible H. zea third instars and that all three compounds were synergistic with cypermethrin and larvae of the Arkansas strain. Plapp (1979) observed that amitraz synergized the toxicity of permethrin to H. virescens third instars, and Campanhola and Plapp (1989) found that piperonyl butoxide synergized the toxicity of cypermethrin to H. virescens neonates from a pyrethroid-susceptible and -resistant strain.…”

Molecular analysis of CYP321A1, a novel cytochrome P450 involved in metabolism of plant allelochemicals (furanocoumarins) and insecticides (cypermethrin) in Helicoverpa zea

“…In addition to detoxifying allelochemicals, H. zea has acquired the ability to detoxify a large variety of insecticides including carbamates, organophosphates, organochlorines and pyrethroids (Abd-Elghafar et al, 1993;McCaffery, 1998). Detoxification of pyrethroids has also been shown to be P450-mediated (Li et al, 2000b) but the exact relationships between P450s mediating allelochemical detoxifications and insecticide detoxifications are only now becoming clear.…”

Use of Mathematical Models to Estimate Characteristics of Pyrethroid Resistance in Tobacco Budworm and Bollworm (Lepidoptera: Noctuidae) Field Populations

“…The bollworm, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae), another major cotton pest (Luttrell 1994), has also developed organochlorine and organophosphate resistance (Sparks 1981, Wolfenbarger et al 1981), but has only recently exhibited increased pyrethroid tolerance (Abd-Elghafar et al 1993, Kanga et al 1996, Brown et al 1998, Bagwell et al 2000. Pyrethroid resistance is apparently a localized phenomenon in this species (Kanga et al 1996, Brown et al 1998, and pyrethroid insecticides remain an effective bollworm control throughout the midsouth (Bagwell et al 2000).…”