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Results of laboratory and field studies showed that adults of Anthonomus grandis grandis Boheman, captured in Leggett traps baited with grandlure or collected from surface leaf litter and duff during the non-cotton season (September to April) of 1978–1979 and 1979–1980 in a subtropical area near Brownsville, Tex., were unique in that they remained physiologically active throughout the winter. Boll weevils were trapped even on days when minimum temperatures were as low as 1.5°C. Females caught during the fall remained sexually mature, mated, and stored viable sperm in their spermatheca, but egg hatch was not observed under laboratory conditions (artificial diet) during ca. 2 months in the winter. However, these females oviposited fertile eggs when fed for at least 10 days with fresh cotton squares. Catches of teneral weevils were very common throughout the winter, an indication that weevils could remain reproductive through the winter when proper nourishment was available from cotton regrowths or seedling plants in unattended or abandoned fields.

Male pupae of Heliothis virescens (F.) reared on diets containing 0.1% (wt/vol) reserpine and then exposed to 15 or 20 krad of gamma irradiation, all substerile doses for the strain, gave rise to P1 males that transmitted delayed sterility to their F1 and F2 progeny. This delayed sterility had its greatest expression in the F1 ♀ progeny. Irradiation of the ♂ pupae with 10, 15, 20 or 25 krad adversely affected the emergence of F1 females, and the greater the dose, the fewer females produced. Oviposition, egg fertility, and the number of F1 progeny produced per female were not dependent on mating frequency.

Five insect growth regulators (IGR's) applied as sprays to cotton in field cages had a pronounced juvenilizing effect on larvae of the tobacco budworm, Heliothis virescens (F.). The F1 generation averaged 20, 17, and 14 days longer, respectively, than the control when larvae developed on plots treated with A13-70119 ( E )-4-[(6,7-epoxy-3-ethyl-7-methyl-2-nonenyl)oxy]-1,2-(methylenedioxy) benzene, A13-70356 (1-chloro-4-[6,7-epoxy-3, 7-dimethyl-2-nonenyl)oxy] benzene (mixed isomers)), and A13-33972 (methyl 10,11-epoxy-7-ethyl-3,11-dimethyl-2,6-tridecadienoate). Also, the fecundity of the F2 generation was reduced as a result of treatment with A13-70350 (ethyl 10,11-epoxy-3,7,10,11-tetramethyl-2,6-dodecadienoate) and A13-703S6, since fewer F2 larvae were found in plots treated with A13-70356. Although the F3 egg population was higher in plots treated with A13-70119 than in other plots, no small larvae were found in these plots. Since these IGR's did not appear to affect parasitization of Trichogramma sp., or cause the tobacco budworm to be sterile, they may be compatible with this parasite and might perhaps have potential in an integrated control program.

Female Heliothis virescens (F.) sterilized with a combination of substerile doses of reserpine (0.1% wt/v) and gamma irradiation (10 and 15 krad) competed on an equal basis with untreated females for untreated males. The observed percent reduction in hatch of eggs when the ratios of treated to untreated adults was 0:1, 1:1, 4:1, 9:1, and 19:1 was generally comparable to or exceeded the theoretical percentage, especially at the higher dose of irradiation. Collections in light traps showed no differences in the flight potential or mating frequency between untreated moths and moths reared as larvae on diets containing 0.1 reserpine with or without Calco® Red dye (0.0625% wt/v) and later irradiated as pupae with 7-5 krad. The distribution of reserpine in the test diets was homogenous, based on the observed biological activity of the treated insects.

Newly emerged adult Pectinophora gossypiella (Saunders), when exposed to 25 or more krad of gamma irradiation and allowed to mate with untreated insects of the opposite sex, produced no fertile adult progeny. First and 2nd-filial-generation adults from adults treated with 5-18 krad exhibited varying degrees of sterility. This feature was not so pronounced in the 3rd, filial-generation adults. Irradiation of mated females at 10 to 30 krad gave results similar to those of mating of males and females irradiated at these dosages prior to their mating.

When a new formulation of the β-exotoxin of Bacillus thuringiensis Berliner of the International Minerals and Chemical Corporation (IMC 10,001) was tested against Heliothis virescens (F.), it was about 1/5 as toxic to neonate larvae as a preparation of the θ-endotoxin that had a potency of 16,000 international units/mg. Its primaly anion against larvae less than 4 days old was insecticidal; larvae that survived emerged as normal adults. However, when IMC 10,001 was incorporated into the diet of 4- or 8-day-old larvae, the length of the proboscis was reduced in those animals surviving to adulthood. When a spray of the formulation containing 40,000 μg/ml was applied to leaves of cotton plants the biological activity persisted between 6 and 12 days after application.

The LC50 of diflubenzeron, (N-[[(4-chlorophenyl) amino]carbonyl]-2,6-difluorobenzamide), for neonate larvae of the tobacco budworm, Heliothis virescens (F.), was 1.3 × 10−3% wt/vol when it was incorporated into the diet. The LC50for pupae was 1.3 ×x 10-4%wt/volin the larval diet. With diets containing 1 × 10-2%, 86–100% of the larvae died, and no adults emerged. In a field-cage test following spray applications of diflubenzeron (0.25 lb/acre in 10% cottonseed oil) to cotton plants, 89% of the tobacco budworm larvae were in the 1st or 2nd instar at a time when the check only had 52% in those stages, indication of a retardation of the larval cycle. Also, emergence of F1 boll weevils, Anthonomus grandis Boheman, from ⅓-grown and full-grown squares was reduced 66 and 27%, respectively.

Sixteen juvenile hormone analogues possessing a common acyclic terpenoid chemical structure but differently arranged moieties were applied topically to Heliothis Virescens (F.), and to cotton plants in the laboratory to determine their hormonal activity on this insect. Certain synthetic hormones affected larval and pupal development, adult eclosion, and fertility of treated insects. Although none were effective enough to be considered practical biocides, several showed potential as chemosterilants.

The sterilizing dose per adult female, pectinophora gossypiella (Saunders) was 60 µg of technical metepa applied topically. In laboratory tests, females treated (T) with 30-60 µg/female compared equally with untreated (U) females in mating with males when the ratio of females was 4 T:1 U. In field-cage tests, females treated with 45 µg of metepa (10 T:1 U) controlled only 58% of the population, an indication that they were not fully competitive. Sterile males were fully competitive and reduced the population 90%. However, when the ratio in the field cages of females treated with 30 or 60 µg was 20 T:1 U, populations decreased an estimated 80 and 86%, respectively.

As the ratio of male to female Heliothis virescens (F.) in laboratory cages was increased, fecundity was decreased, numbers of matings per female increased, and numbers of matings per male decreased. The length of time males were confined with females also affected fertility and number of matings. Four pairs of moths held in a lantern globe (6-Iiter volume) were more fecund and mated more frequently than 1, 2, 8, 16, 32, 64, or 128 pairs held in the same size globes. Also, when 64 and 128 pairs of moths were kept in the globes, 77% or more of the adults were dead after 72 hours, as compared with a 25% mortality obtained when 1 pair was used.

Field-cage releases of adult female Heliothis virescens (F.) reared on larval diets containing reserpine and irradiated as pupae with 20 krad of gamma irradiation reduced the F1 larval generation ca. 70% from that of the check when the ratio of releases was 9:1 irradiated to unirradiated. Releases of both sexes of irradiated insects at the same ratios reduced F1 larval populations ca. 39%. An additional reduction was obtained when irradiated females were released into populations of F1 moths. The fecundity of P1 and F1 moths was reduced 18 and 28%, respectively, when irradiated females were released once and 33 and 42% when they were released twice.