Resistance to cypermethrin in first generation adult bollworm and tobacco budworm (Lepidoptera: Noctuidae) populations collected as larvae on wild geranium, and in the second and third larval generations

First generation (G1) larvae of the overwintered (parent) population of bollworm, Heliothis zea (Boddie), and of the tobacco budworm, H. virescens (F.), were collected in wild geranium, Geranium dissectum L. and G. carolinianum L., and then reared on artificial diet. These first generation (G1) adults were tested with a vial bioassay for resistance to cypermethrin. Survival, at the 10 micrograms per vial rate, of the (G1) adult male and female bollworm was 2.9 and 5.6% and of the (G1) tobacco budworm--26 and 41.5%, respectively. First generation (G1) male and female tobacco budworm moths that survived the 10 micrograms per vial rate were mated, and the resulting second generation (G2) larvae were divided into two groups. One group was tested as third instars for resistance in a cotton terminal bud bioassay. The second group was reared to the adult stage, mated, and the resulting third generation (G3) larvae were treated as third instars with topical application of cypermethrin. In the cotton terminal bud bioassay, 65% of the (G2) larvae tested survived an application of Cymbush (cypermethrin) at its highest recommended field rate (0.09 kg [AI]/ha). LD50's and LD90's obtained from the topical treatment of (G3) larvae with cypermethrin were intermediate to those reported by others for tobacco budworm larvae collected from fields with control problems in the Mississippi delta. These data indicate that if the (G1) adult and (G2) larval populations in cotton in June were treated with pyrethroids, control problems would be more likely to occur later in the growing season