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Cotton (Gossypium hirsutum L.) growers use significant quantities of insecticides to control pink bollworm (PBW), Pectinophora gossypiella (Saunders). The germplasm line WC-12NL (nectariless, okra leaf, and early maturing) and «Deltapine 61» (nectaried, normal leaf, and later maturing) were grown at Maricopa, AZ, and Brawley, CA, for three seasons. Irrigation water was terminated and plots were defoliated earlier than normal, a practice that favored the early-maturing line. Insecticides were applied as needed, based on PBW egg infestations of cotton bolls. The major objective was to determine whether insecticide use can be reduced or eliminated by growing WC-12NL

Survival of pink bollworm moths, Pectinophora gossypiella (Saunders), during the diapause period was reduced ca. 50% by irrigations during the winter and early spring. Fewer insects emerged from buried bolls than from bolls above or on the soil surface, and earlier burial of bolls resulted in greater mortality than later burial. The emergence patterns of the moths were affected by some of the treatments. Moths emerged earlier (as a percentage of total emergence) and at a faster rate from irrigated treatments than from nonirrigated treatments in 1981, but not in 1980. Moths from larvae in bolls emerged slower than moths from larvae that had cut out of bolls. The date on which 50% accumulated emergence had occurred was 11 May in 1980 and 25 April in 1981. However, the accumulated heat units (based on 12.8°C as the threshold for development) were 1,176 and 1,174 at the time of 50% emergence for 1980 and 1981, respectively. Thus, accumulated heat units may provide a more consistent indication of time of emergence than the calendar date.

Applications of plant growth regulators in late August effectively terminated the fruiting of cotton and significantly reduced populations of diapausing larvae of Pectinophora gossypiella (Saunders) (by 90% or more) in Arizona during 1972–74. As a result, fewer overwintered moths (39%) emerged the following spring from terminated plots. Applications in mid-, or late August were more effective than applications in early September. Yields were not significantly reduced by most treatments. The most effective materials tested were 2.4-D (amine salt of 2,4-dichlorophelloxy) acetic acid + chlorflurenol (methyl 2-chloro-9-hydroxyfluorene-9-carboxylate) and 2, 4-D + chlormequat ((2-chloroethyl) trimethylammonium chloride).

The pink bollworm, Pectinophora gossypiella (Saunders) overwinters as a diapausing larva in a hibernaculum in cotton seeds, bolls, ground trash, or in the soil. In tests conducted in Arizona and southern California during 1973–78, the 1st diapause larvae was found as early as Aug. 23, and as late as Sept. 10. When diapause larvae were found in late Aug. the incidence of diapause remained low ( 29°C during mid to late Sept., the incidence of diapause was low and increased when temperatures decreased and photoperiod shortened. Early irrigation termination, chemical termination treatments and varieties did not significantly affect the initiation-or the incidence of diapause.

Comparative toxicities of 23 insecticides to adult pink bollworm, Pectinophora gossypiella (Saunders), were determined by topical application. The smaller male was more susceptible than the female; however, the values were not significantly different. The moths were slightly more susceptible when the insecticides were applied to the thoracic dorsum than when they were applied to the abdominal venter. For doses applied to the dorsum, LD50, values at 48 h after treatment ranged from 0.0016 µg per male for cyfluthrin to 1.81 µg per male for malathion. These data may serve as reference values to determine if resistance to any of the insecticides develops in field populations of the pink bollworm; they may also aid in the selection of an insecticide for use in a spray program aimed at the adult moth or for use as an adulticide in a sex pheromone-insecticide (attracticide) system.

Gossyplure (1:1 mixture of Z,Z- and Z,E- isomers of 7,11 hexadecadienyl acetate) in a plastic laminate formulation was applied by air to ca. 195 ha of cotton, Gossypium spp. in Arizona. In combination with TF (1-tetradecenal formate), virelure (16:1 mixture of ( Z )-11-hexadecenal and ( Z )-9-tetradecenal or ( Z )-9 TDF[( Z )-9-tetradecen-1-ol formate], gossyplure significantly reduced catches of male pink bollworm, Pectinophora gossypiella (Saunders), moths in pheromone-baited, traps, boll infestations and female mating in gossyplure-treated cotton plots as compared with these criteria in an insecticide control and an untreated check plot.

The numbers of diapausing larvae of Pectinophora gossypiella (Saunders) found in soil and trash in the fall after harvest in cotton were reduced by early irrigation cut-off and chemical termination treatments. Also, the number of moths that emerged the following spring was reduced by the combination of the 2 treatments. The early irrigation termination reduced pink bollworm infestations in bolls and Heliothis spp. oviposition in the fall, but there was no effect due to the chemical termination.

Adult pink bollworms, Pectinophora gossypiella (Saunders), that emerged from hibernation before small squares were on the cotton plant (21 days before blooming) usually failed to produce any progeny in field cage tests. Thus all emergence up to this time may be considered suicidal. Rate of reproduction by overwintered moths ranged from

When adult Pectinophora gossypiella (Saunders) irradiated with a substerilizing dose (10 krad) of gamma irradiation were released in field cages and in a 5-acre field of cotton, larvae with chromosomal aberrations that could cause sterility in the adult stage were found in both cages and the field. Also, when 3500 partially sterile moths (mixed sexes) were released in a 1/200-acre cage over a 7-week period, sufficient larvae did not develop to cause significant damage to the cotton. Of 743 males recaptured after releases in the field, 34% were recaptured on the 2nd day following release.

In tests conducted in Riverside County, California, in 1970, overwintered pink bollworm moths, Pectinophora gossypiella (Saunders), migrated at least 35 miles to infest an isolated field of cotton. Then high temperatures during late June and early July drastically reduced the population. However, later migrants during August and September of 1970, and also in 1971, produced sufficient larvae to cause significant damage to the crop

Mass-reared female moths of the Phoenix PPD strain of Pectinophora gossypiella (Saunders), irradiated with doses of up to 40 krad were assessed for attractiveness in field traps, mating ability, and longevity. The data indicated that females irradiated with 10 or 25 krad were fully as attractive to native males as unirradiated females in the field. Hexalure (25 mg/trap) was more attractive to native males than 1–5 virgin females in the field. Although females irradiated with a sterilizing dose of 30 krad mated as frequently as unirradiated females, a significant reduction (30%) in their ability to receive sperm in their spermathecae occurred in single matings to unirradiated males. The longevity of males and females irradiated with 10 or 25 krad was not significantly different from unirradiated moths. The average LT50 and LT90 values for females held at 30°C were 20 and 24 days, respectively.

Native populations of Pectinophora gossypiella (Saunders) in 7.3×3.7×1.8-m field cages were suppressed by continuous releases of moths of a laboratory strain irradiated as adults with 10 krad. Cages receiving moths irradiated with 20 krad had populations not significantly different from those in control cages. The 1st generation of native moths increased 4–5 fold in all cages. In the 2nd generation, which developed in bolls, the control cages increased by a 36-fold rate vs. a 15-fold rate for cages receiving moths irradiated with either 10 or 20 krad. Results indicated that moths irradiated with 10 krad were more effective in suppressing native populations than moths irradiated with 20 krad.

Chemical control of Pectinophora gossypiella (Saunders) increased yield of cotton lint and seed and reduced amounts of bright greenish-yellow fluorescence associated with Aspergillus flavus Link and thus associated with aflatoxin. Levels of aflatoxin were maintained below 20 ppb when populations of pink bollworms were held at or below the economic threshold, but this was only achieved by numerous insecticide applications.