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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

Studies were conducted in Phoenix, Ariz., to determine the occurrence of boll weevil, Anthonomus grandis grandis Boheman, infestations in late-season cotton bolls, and the pattern of boll weevil emergence and survival and mortality in the bolls. Boll weevils emerged from bolls buried in moist vermiculite over a period of 232 to 239 d, from 29 January to 2 August. Higher percentages of emergence and lowest mortality in bolls occurred in bolls collected in November as compared with bolls collected in December. Few boll weevils emerged from bolls held under dry conditions in an outdoor in sectary for 174 d. However, an average of 16% of the weevils were found alive in the dry bolls in late May.

After ethephon and thidiazuron were applied in late season to small plots of Upland cotton ( Gossypium hirsutum L.) to terminate fruiting chemically, the numbers of green bolls and pink bollworm, Pectinophora gossypiella (Saunders), diapausing larval populations, and yields were determined. Tests were conducted during 1985 and 1986 on the Maricopa Agricultural Center, Maricopa, Ariz., and on the Irrigated Desert Research Station, Brawley, Calif. Also, at Brawley in both years, we determined the combined effects of early irrigation cut-off and chemical termination. Results show that rates of 1.12 kg (AI)/ha of ethephon or higher and rates of 0.056 or 0.112 kg (AI)/ha of thidiazuron were needed for effective termination of cotton fruiting as indicated by reductions in number of green bolls. These rates of each chemical also reduced the number of squares and blooms after treatment, and sequential applications resulted in greater reductions than a single application. Last irrigation in mid-July resulted in reduced yields. However, irrigation cut-off in late July or early August resulted in yields as high as when the last irrigation was in September. Yields were not reduced by chemical termination treatments except by thidiazuron at Brawley in 1986, when last irrigation was in mid-July. Diapausing pink bollworm larval populations were reduced by chemical termination treatments and early irrigation termination.

Constant temperatures between 32–35°C or higher and fluctuating temperatures with a mean of 32°C or higher generally resulted in reproductive failure of pink bollworms, Pectinophora gossypiella (Saunders), if the exposure occurred in the larval and pupal, pupal, or adult stages. This failure usually occurred because the male exposed to high temperature did not mate and/or effectively transfer sperm to the spermatheca of the female. Short exposures to high temperature in the late larval-early pupal stage caused mortality but had little effect on reproduction. Sperm was often found in the transferred spermatophores, an indication that death of the sperm, reduced sperm motility, or some other mechanism prevented movement of sperm to the spermatheca. Both eupyrene and apyrene sperm were affected. Females exposed to these temperatures had reduced egg laying and egg viability.

In comparative tests, Allied Chemical Corp. compound GL-6506 (dimethyl p -(methylthio) phenyl phosphate) applied as a stern treatment to cotton in small-plot field tests gave more effective control of the bollworm, Heliothis zea (Boddie), and the tobacco budworm, H. virescens (F.), than monocrotophos or methomyl; however, no stem treatment was as effective as foliar applications of monocrotophos. The Heliothis nuclear polyhedrosis virus ( Heliothis NPV), applied as a foliar spray 3 times/week, was as effective as monocrotophos (applied as a foliar spray at 5-, to 7-day intervals) in increasing the yields of cotton, but when the Heliothis NPV was applied 1 or 2 times/week, yields were inferior to that achieved with monocrotophos.

Boll weevils, Anthonomus grandis Boheman, in Arizona continued to emerge until 23 May from infested bolls collected in December and placed above or on the soil surface under emergence cages during January or early February. Practically no emergence occurred when infested bolls were buried under 15 cm of soil under cages. Boll weevil captures in grandlure-baited traps were near zero during the summer (June–August), began to increase in the fall, reached maximum numbers in January and February, and began to decline in April of each year. The decline in numbers caught occurred at approximately the same time that the emergence from bolls was nearly complete. The relatively large catches of boll weevils during periods when no host was available suggests that emergence from bolls is occurring throughout this period and that large segments of the populations during the winter are not in a resting state, but are actively seeking host material or mates.

A cultural system for short-season cotton, Gossypium spp., incorporating narrow rows (two rows ca. 36 cm apart on beds spaced ca. 102 cm apart) and early irrigation cutoff resulted in early-maturing cotton in Imperial Valley, Calif., with harvests completed by 24 August 1978. Yields were over 4,000 kg of seed cotton per ha with no insecticide applied for insect control. Cotton yields in systems with full-season, conventional-row (one row on a bed, 102 cm between rows) cultivation without insecticide treatments but with five additional irrigations were significantly lower than those in the short-season system in August and after full-season production on 15 November 1978. The early maturation of the crop in the short-season system avoided infestations of late-season, Pectinophora gossypiella (Saunders), reduced larval population in the bolls, trash, and soil (75%) in the fall, and reduced spring emergence of moths from overwintered larvae (81%) relative to the same parameters from the conventional full-season cotton crop. Cotton yields in full-season narrow-row and conventional-row systems were significantly higher when the top crop was protected from pink bollworm losses with insecticides. Cotton yields of several short-season and full-season cotton varieties and cultivars, grown under the narrow-row, short-season system, were not significantly different. Thus, currently available commercial cultivars and short-season variety genotypes are adaptable to short-season cotton growing conditions in the Southwest.

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.

Pink bollworm, Pectinophora gossypiella (Saunders), moths treated with low doses of certain insecticides had a lower percentage of mating, laid fewer eggs, and, in some cases, had a reduced number of eggs hatch. The synthetic pyrethroids cyfluthrin, fenpropathrin, fenvalerate, flucythrinate, and permethrin all caused reductions in mating during the first 24-h period after treatment. The insecticides also reduced the number of eggs laid. Reductions in mating and oviposition caused by treatment with azinphosmethyl, methylparathion, trichlorfon, carbaryl, and chlordimeform were usually associated with or were the result of high mortality. Avermectin B1, an experimental compound from Merck, Sharpe and Dohme (MK-936), completely prevented mating and oviposition at the LD10 and LD50 with little mortality among the treated insects. Hatching of eggs was also reduced by these treatment levels of Avermectin B1. These tests show that, in addition to causing mortality, treatments of moths with certain insecticides may cause population suppression through reduced mating, fecundity, and hatching of eggs.

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.

Ethephon (2-chloroethyl) phosphonic acid) (“Prep”) was applied in 1985 and 1986 to cotton, Gossypium hirsutum (L.), during early to late September to remove late season fruiting forms and to determine the effects on boll weevil, Anthonomus grandis grandis Boheman, population development, cotton quality, lint yield, fiber quality, and boll opening. In 1985, boll weevils ranged from approximately one to five per 4 m of cotton row at the time of application on 6 and 13 September. Populations decreased in ethephon-treated plots thereafter, and average numbers found in infested bolls and squares were reduced >95% as compared with infestations in untreated check plots. In 1986, boll weevils ranged from zero to less than one per 4 m of row at the time of treatments on 15, 23, and 29 September. Populations increased in all plots thereafter, but were on average 9.5 times greater in check plots than in ethephon-treated plots 30 to 44 d following treatment. In 1985, ethephon at rates of 1.12 kg (AI)/ha applied 6 or 13 September did not affect cotton lint yield, but 2.24 kg (AI)/ha applied 6 September reduced yield significantly, possibly because of delayed cotton harvest. In 1986, ethephon at 1.68 kg (AI)/ha had no effect on cotton yields or cotton fiber quality characteristics, but the fiber-length uniformity ratio was significantly higher in the ethephon-treated plots. Ethephon accelerated mature boll opening in the experimental plots in both years, demonstrating the potential for earlier harvest, stalk destruction, and cotton plow down, which are desirable cultural practices that help reduce overwintering boll weevil populations.

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.

Studies related to control of the pink bollworm (PBW) by trapping were conducted on an 80-ha farm located in Phoenix, AZ. Initial laboratory studies of trap efficiency lead to the incorporation of 10% dicrotophos into Stickem® used in traps (ca. 13% increased kill compared to traps with Stickem only). During the period April 29 to Sept. 15, 1975, a trapping program on 36 ha of cotton resulted in the capture of ca. 30,000 ♂ PBW. Nine percent of the acreage attained 10% or greater boll infestations during the season compared to 45–100% for the preceding 1972–74 seasons. Early fruiting cotton (plots of 4 rows × 7.6 m) was no more attractive to PBW than surrounding, less developed cotton. Early season trap catches indicated that male moths congregated in cotton fields regardless of where they emerged.

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

Field inspections and wing traps containing live male Anthonomus grandis Boheman were used in 1968 to study the seasonal movement of boll weevils near the High Plains of Texas. Peak populations of overwintered weevils occurred in cotton fields within 4-5 weeks after planting. Movement of boll weevils began early in the spring before cotton was planted, decreased greatly during midsummer, and increased again to a very high level late in August. Relatively large numbers of weevils were captured in both the spring and fall at distances more than 6 miles from cotton.

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.

Glabrous and hirsute experimental strains of Gossypium hirsutum L. were evaluated in cage. small-plot, and field experiments for the influence of these 2 characters against the cotton fleahopper, Psallus seriatus (Reuter). The glabrous character suppressed populations of fleahoppers below economically damaging levels and was as effective as some recommended insecticides. The sources of this character did not alter the degree of plant resistance. nor did the presence or absence of pigment glands or nectaries.

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

In-furrow and sidedress applications of aldicarb were compared with foliar applications of azinphosmethyl for suppression of populations of Athonomus grandis Boheman in an area near the Texas High Plains boll weevil control zone. The applications of aldicarb reduced populations of adult boll weevil 94–96% until long-range movement of weevils began in late August. Meanwhile, 4 applications of azinphosmethyl reduced populations only 73%. Some increase in populations of Heliothis spp. occurred in most plots treated with an insecticide; however, the greatest increases occurred in those plots treated with sidedress applications of aldicarb.

When 32P-labeled phosphamidon in lanolin or 14C-labeled monocrotophos in gel were applied to 5 cm of cotton stem, uptake and translocation were greater than when the treated area was 2.5 cm or less in width. Also, uptake was much less when the treatments were applied to older stems with bark than when they were applied to young waxy stems without bark and was greater when a 2nd treatment was applied to the same area. Less uptake of monocrotophos occurred when the insecticide was applied in a gel than when it was applied in lanolin. Phosphamidon was found in all plant parts, but greater amounts were found in mature leaves.

Union Carbide UC-21149, 2-methyl-2-(methylthio) propionaldehyde O-(methyIcarbamoyl) oxime, applied as a sidedressing to 4 to 5-acre plots of cotton provided effective control of Anthonomus grandis Boheman for several weeks. Mortality of released laboratory-reared boll weevils indicated control for 2-4 weeks; the number of punctured squares and adult boll weevils, sampled with a tractor-mounted insect-collecting machine, indicated control for 3-6 weeks. Two applications of 2 lb UC-21149 per acre applied 9-10 days apart were effective for 4-5 weeks, while a single application was effective for 2-4 weeks. More bollworm, Heliothis zea (Boddic), and tobacco budworm, H. virescens (F.), and fewer beneficial insects were found in treated than in the untreated plots.

Four systemic insecticides, disulfoton, dicrotophos, monocrotophos, and aldicarb were evaluated for their effect on the longevity and fecundity of Anthonomus grandis Boheman. Weevils were exposed continuously to 2 treated substrates: (1) filter paper treated with the toxicants, and (2) excised cotton leaves that had taken up known amounts of the toxicants through the petioles, Mortality increased with time and increased doses, Also, the rate of oviposition decreased during a 19-day period when the weevils were continuously exposed to sublethal doses of the insecticides; greater reductions occurred at higher doses. In all tests, aldicarb affected mortality and fecundity more than other insecticides.

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.

Greenhouse and field cage tests were conducted to determine the effectiveness of selected systemic inscticides, Temik® (2-methyl-2-(methylthio) propionaldehyde O -(methylcarbamoyl)oxime), Azodrin® (3-hydroxy- N -methyl- cis -crotonamide dimethyl phosphate), Stauffer B-10497 (O,O -dimethyl [ethyl(2-hydroxyproyl)thiocarbamoyl]phosphoramidothioate), Niagara NIA-10242 (2,3-dihydro-2,2-dimethyl-7-benzofuranyl methylcarbamate), and American Cyanamid CL-47031 (cyclic ethylene (diethoxyphosphinyl). dithioimidocarbonate) against the tarnished plant bug, Lygus lineolaris (Palisot de Beauvois). The insecticides were applied to cotton stems in a lanolin formulation and to the soil in which plants were grown in a granular formulation. Temik and Azodrin were more effective than the other insecticides. In field cage tests, Temik applied to the soil was slightly more effective than Temik or Azodrin applied to the stems. Temik reduced hatch of tarnished plant bug eggs when the insecticide was applied to the plant after the eggs were laid in various plant parts.

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.

Fewer Bucculatrix thurberiella Busck were present and less leaf damage was done in plantings of nectariless cotton, Gossypium hirsutum L., than in plantings of nectaried cotton. Also, numbers of Lygus spp. were reduced, as well as total predator populations. Consistently fewer Chrysopa spp. and Geocoris spp. were present.

The role of insect pheromones in mediating behavior of insects and the possible use of these chemical substances for control have recently attracted considerable attention. One such method of control, mating disruption by permeation of the atmosphere of crop environments with sex pheromones so as to prevent reproduction and thereby reduce infestations of economic insect pests, was first suggested by Beroza in 1960. The fact is that in most cultivated crop systems there is more than one pest species. Thus, as the technology of mating disruption has advanced, the possibility of using sex pheromones to disrupt the communication of more than one species within a same crop system has received greater attention (Mitchell, 1975; Tumlinson et al., 1976). One such complex of pest insects attacks cotton in Arizona and southern California. The most damaging species of this complex are the pink bollworm, Pectinophra gossypiella (Saunders); the bollworm, Heliothis zea (Boddie); and the tobacco budworm, H. virescens (F.).

The cotton leafperforator is a major pest on cotton grown in the greenhouse in Arizona and a continuous program of control is necessary to keep plants free of this insect. Other pests that appear sporadically and cause problems are the pink bollworm, Pectinophoragossypiella (Saunders), the cabbage looper, Trichoplusiani (Hubner), white-flies, Trialurodes spp., aphids, Aphis spp., various species of thrips and spider mites, Tetranychus spp. The 25 × 32 ft greenhouse (ca 8500 ft3) has a door in each end. One side contains two 24-inch diameter exhaust fans, and the opposite side has a full length window which, in the open position, allows air to be drawn through wet filters for evaporative cooling. As a funigation chamber, this greenhouse is not even moderately tight. In order to fumigate we simply closed the window and doors and shut off the fans. The liquid dichlorvos (technical grade, 96%) was slowly vaporized from a petri dish on a hot plate (70°C). A fan distributed the vapor within the room. We did not adhere to a strict schedule during this study and fumigated only when perforator moths were observed in the greenhouse. Biological effects were measured by exposing caged insects to greenhouse fumigation and by confining untreated insects on treated plants. A minimum of 4 replicates was used in each test.