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At least 199 records · Page 11Linked to original sources
PubMed2003

Field evaluation of a Helicoverpa zea (Lepidoptera: Noctuidae) damage simulation model: effects of irrigation, H. zea density, and time of damage on cotton yield.

Helicoverpa zea (Boddie) is an important pest of cotton, Gossypium hirsutum L., for which many economic injury and population models have been developed to predict the impact of injury by this species on cotton yield. A number of these models were developed using results from simulated damage experiments, despite the fact that no studies have demonstrated that simulated damage is comparable to real H. zea damage. Our main objective in this study was to compare the effect on yield of H. zea larvae feeding on cotton fruiting structures at different irrigation levels, larval densities, and cotton physiological ages with damage produced artificially by removing fruiting structures by hand using simulated estimates of H. zea injury. To accomplish this, we used two irrigation levels, each divided into real and simulated damage plots. In real damage plots, H. zea larvae were placed on plants and allowed to feed; whereas in simulated damage plots, fruiting structures were removed by hand using a simulation model of H. zea damage to determine numbers and amounts of fruiting structures to remove. Each of these plots was further divided into one undamaged control plot and nine treatment plots. Each treatment plot was randomly assigned one of three damage times (early, middle, or late season) and one of three H. zea densities. In 1998, we found that only artificial H. zea damage (performed by hand removal of fruiting structures) at the highest density and during the late season decreased yield; whereas real damage caused by H. zea larvae placed on plants, and artificial damage occurring at earlier time periods and lower H. zea densities did not affect yield. In 1999, both real and artificial damage decreased yield at the higher H. zea densities compared with the lowest density, but, as in 1998, this was only true when damage occurred late in the season. The most important finding of this study was that high H. zea densities had no effect on cotton yield unless they occurred late in the season. In particular, this was true for artificial H. zea damage. The second most important finding of this study was that, with the exception of late in the season, our model for simulating H. zea damage to cotton through removal of fruiting structures resulted in similar yields as real H. zea larvae damage to cotton.

Agriculture↗
PubMed2005

Simple sequence repeat marker associated with a natural leaf defoliation trait in tetraploid cotton.

Cotton (Gossypium hirsutum L.) leaf defoliation has a significant ecological and economical impact on cotton production. Thus the utilization of a natural leaf defoliation trait, which exists in wild diploid cotton species, in the development of tetraploid cultivated cotton will not only be cost effective, but will also facilitate production of very high-grade fiber. The primary goal of our research was to tag loci associated with natural leaf defoliation using microsatellite markers in Upland cotton. The F2 populations developed from reciprocal crosses between the two parental cotton lines--AN-Boyovut-2 (2n = 52), a late leaf defoliating type, and Listopad Beliy (2n = 52), a naturally early leaf defoliating type--demonstrated that the naturally early leaf defoliation trait has heritability values of 0.74 and 0.84 in the reciprocal F2 population. The observed phenotypic segregation difference in reciprocal crosses suggested a minor cytoplasmic effect in the phenotypic expression of the naturally early leaf defoliation trait. Results from the Kruskal-Wallis (KW) nonparametric test revealed that JESPR-13 (KW = 6.17), JESPR-153 (KW = 9.97), and JESPR-178 (KW = 13.45) Simple sequence repeat (SSR) markers are significantly associated with natural leaf defoliation in the mapping population having stable estimates at empirically obtained critical thresholds (P < .05-.0001). JESPR-178 revealed the highest estimates (P < .0001) for association with the natural leaf defoliation trait, exceeding maximum empirical threshold values. JESPR-178 was assigned to the short arm of chromosome 18, suggesting indirectly that genes associated with natural leaf defoliation might be located on this chromosome. This microsatellite marker may have the potential for use to introgress the naturally early leaf defoliation quantitative trait loci (QTL) from the donor line Listopad Beliy to commercial varieties of cotton through marker-assisted selection programs.

Chromosomes, Plant↗
PubMed1990

Hispid cotton rats (Sigmodon hispidus) as a source for infecting immature Dermacentor variabilis (Acari: Ixodidae) with Rickettsia rickettsii.

Hispid cotton rats (Sigmodon hispidus Say and Ord) were susceptible to infection with Rickettsia rickettsii Wolbach under laboratory conditions and were capable of serving as sources for infecting ticks with rickettsiae. Cotton rats developed rickettsemias that could be detected for as long as 6 h following intraperitoneal inoculation of 10(5) plaque-forming units (PFUs) of R. rickettsii (Morgan strain). An estimate of the median infectious dose (ID50) was made by inoculating six groups (eight animals per group) with serial dilutions of 10(1) to 10(6) PFUs. In this experiment, cotton rats became infected after exposure to relatively few organisms (ID50 = 37 PFUs). None of the 48 cotton rats succumbed to infection, and only 6 of the 48 rats failed to seroconvert. Dermacentor variabilis (Say) larvae were fed on rickettsemic cotton rats to determine whether this species could serve as a source for infecting ticks with R. rickettsii. A small percentage (0.9-3.0%) of larval ticks that fed on three of the four cotton rats had R. rickettsii in their tissues when examined as nymphs. A fourth cotton rat died 7 d after inoculation with R. rickettsii and infected a much higher percentage of ticks (64.0%) than the other three animals.

Animals↗
PubMed1999

Characterization of a palmitoyl-acyl carrier protein thioesterase (FatB1) in cotton.

The relatively high level of palmitic acid (22 mol%) in cotton seeds may be due in part to a palmitoyl-acyl carrier protein (ACP) thioesterase (PATE), which prefers C16:0-ACP as its substrate. In embryo extracts, PATE activity was highest at the maximum rate of reserve accumulation (oil and protein), occurring about 30-35 d post anthesis. Thioesterase activity toward oleoyl-ACP was relatively similar at all developmental stages examined, but was considerably lower than the PATE activity. In developing seeds and in cotyledons and hypocotyls of seedlings, the PATE activity predominated. A cotton PATE cDNA clone isolated by screening a cDNA library with a heterologous Arabidopsis FatB1 probe has a 1.7-kb insert sequence with an open reading frame of 410 amino acids, lacking codons for the three N-terminal amino acids. The predicted amino acid sequence of the cotton PATE preprotein has a characteristic stromal-targeting domain and a 63% identity to the Arabidopsis long-chain acyl ACP-thioesterase FatB1 sequence. Alkaline blot hybridization of cotton genomic DNA with the Arabidopsis FatB1 probe suggested the presence of at least two FatB1 thioesterase genes in cotton. Relative cotton FatB1 transcript abundance was compared by RT-PCR and slot blot analysis in total RNA extracts from embryos, seedlings and leaves of mature plants. The cotton FatB1 mRNA apparently was expressed in all tissues but paralleled the profiles of PATE enzyme activity and seed oil accumulation in embryos.

Acyl Carrier Protein↗
PubMed2005

Expression of an Arabidopsis vacuolar sodium/proton antiporter gene in cotton improves photosynthetic performance under salt conditions and increases fiber yield in the field.

Drought and salinity are two major limiting factors in crop productivity. One way to reduce crop loss caused by drought and salinity is to increase the solute concentration in the vacuoles of plant cells. The accumulation of sodium ions inside the vacuoles provides a 2-fold advantage: (i) reducing the toxic levels of sodium in cytosol; and (ii) increasing the vacuolar osmotic potential with the concomitant generation of a more negative water potential that favors water uptake by the cell and better tissue water retention under high soil salinity. The success of this approach was demonstrated in several plants, where the overexpression of the Arabidopsis gene AtNHX1 that encodes a vacuolar sodium/proton antiporter resulted in higher plant salt tolerance. Overexpression of AtNHX1 increases sodium uptake in vacuoles, which leads to increased vacuolar solute concentration and therefore higher salt tolerance in transgenic plants. In an effort to engineer cotton for higher drought and salt tolerance, we created transgenic cotton plants expressing AtNHX1. These AtNHX1-expressing cotton plants generated more biomass and produced more fibers when grown in the presence of 200 mM NaCl in greenhouse conditions. The increased fiber yield was probably due to better photosynthetic performance and higher nitrogen assimilation rates observed in the AtNHX1-expressing cotton plants as compared with wild-type cotton plants under saline conditions. Furthermore, the field-grown AtNHX1-expressing cotton plants produced more fibers with better quality, indicating that AtNHX1 can indeed be used for improving salt stress tolerance in cotton.

Adaptation, Physiological↗
PubMed1970

Factors involved in the opening of the hypocotyl hook of cotton and beans.

Conditions influencing the opening of the bean (Phaseolus vulgaris L.) and cotton (Gossypium hirsutum L.) hypocotyl hook were defined. Such hooks were shown to undergo geotropic curvature; orientation of the hook with respect to gravity greatly affected the observed opening. Cotton and bean hooks behaved exactly opposite in regard to the presence of the cotyledons and apical bud. The cotton hook required the cotyledons for opening, but the corresponding tissue slowed or inhibited opening of the bean hook. With cotton, lower hypocotyl and root tissues stimulated hook opening, but with bean, the tissues below the hook section had little effect. Kinetin and gibberellic acid both modified hook opening in light and dark; the former was inhibitory and the latter was stimulatory. Indoleacetic acid, at concentrations above 10(-5) M, caused pronounced hook closing in red light but not in the dark. These effects were generally the same with both plants. In opening of the cotton hook, the cotyledons were not necessary as a light receptor tissue. None of the growth substances tested were able to substitute completely for the cotton cotyledon. Coumarin was a pronounced inhibitor of opening of the cotton hook, and this response was expressed to such a degree as to cause hook closure with bean tissue. Reduced oxygen levels inhibited hook opening in bean. Oxygen was required in processes subsequent to the light reaction, but not for the photochemical process.

Journal Article↗
PubMed2007

Role of Pantoea agglomerans in opportunistic bacterial seed and boll rot of cotton (Gossypium hirsutum) grown in the field.

AIMS: To investigate the aetiology of seed and boll rot of cotton grown in South Carolina (SC). METHODS AND RESULTS: Bacteria were isolated from diseased locules of cotton bolls collected in a field in SC, USA and tested for the ability to cause comparable disease symptoms in greenhouse grown cotton fruit. Spontaneously generated rifampicin-resistant (Rif(r)) mutants of the isolates were used in confirmatory pathogenicity tests. Resistance to the antibiotic was both stable and effective in differentiating between an inoculated Rif(r) strain, rifampicin-sensitive contaminants and/or endophytes. A series of inoculation methods was tested at various boll developmental stages and at different fruiting nodes on the plant. Field disease symptoms were reproduced by inoculating bolls at 2 weeks postanthesis with bacterial suspensions ranging from 10(3) to 10(6) CFU ml(-1). Pathogenic isolates were categorized as Pantoea agglomerans on the basis of phenotype testing, fatty acid profiling (similarity index = 0.94), and 16s ribosomal DNA sequence analysis (99% nucleotide identity). CONCLUSIONS: Pantoea agglomerans isolates from field-collected immature, diseased cotton caused comparable infection symptoms in greenhouse produced cotton fruit. SIGNIFICANCE AND IMPACT OF THE STUDY: In 1999, significant yield losses in SC cotton resulted from a previously unobserved seed and boll rot that has since been reported in other southeastern states. This study demonstrated a role of P. agglomerans in producing opportunistic bacterial seed and boll rot of cotton.

Anti-Bacterial Agents↗
PubMed2005

Experimental Helicobacter pylori infection induces antral-predominant, chronic active gastritis in hispid cotton rats (Sigmodon hispidus).

BACKGROUND: The hispid cotton rat has proven to be an excellent animal model for a variety of human infectious disease agents. This study was performed to evaluate the use of the cotton rat as a model of Helicobacter pylori infection. MATERIALS AND METHODS: Thirty-eight inbred cotton rats were orogastrically inoculated with a human strain of H. pylori. Twenty-eight control cotton rats were dosed with vehicle only. Animals were sacrificed at 2, 4, 12, 26, or 38 weeks after inoculation for bacterial and histologic and immunologic examinations. RESULTS: Helicobacter pylori was cultured from the glandular stomach of 89% of the infected cotton rats. The level of colonization was consistently high (approximately 10(4-6) colony-forming units/g tissue). Histologically, the spiral bacteria were demonstrated on the epithelial surface and in the foveolae of the gastric mucosa with highest numbers in the antrum. H. pylori infection was associated with antral-predominant, chronic active gastritis which progressively increased in severity over time. By week 26 of infection, moderate antral gastritis had developed with frequent involvement of the submucosa and formation of lymphocytic aggregates. Splenic T cells from infected cotton rats expressed mRNAs for interferon-gamma, interleukin-4, interleukin-6, and interleukin-10 following in vitro stimulation with H. pylori. Serum levels of H. pylori-specific immunoglobulin G were significantly elevated after 12 weeks of infection. CONCLUSIONS: The H. pylori-infected cotton rat represents a novel animal model that should prove useful for studies of H. pylori-induced chronic active gastritis and factors affecting gastric colonization by this pathogen.

Animals↗
PubMed2002

Control of resistant pink bollworm (Pectinophora gossypiella) by transgenic cotton that produces Bacillus thuringiensis toxin Cry2Ab.

Crops genetically engineered to produce Bacillus thuringiensis toxins for insect control can reduce use of conventional insecticides, but insect resistance could limit the success of this technology. The first generation of transgenic cotton with B. thuringiensis produces a single toxin, Cry1Ac, that is highly effective against susceptible larvae of pink bollworm (Pectinophora gossypiella), a major cotton pest. To counter potential problems with resistance, second-generation transgenic cotton that produces B. thuringiensis toxin Cry2Ab alone or in combination with Cry1Ac has been developed. In greenhouse bioassays, a pink bollworm strain selected in the laboratory for resistance to Cry1Ac survived equally well on transgenic cotton with Cry1Ac and on cotton without Cry1Ac. In contrast, Cry1Ac-resistant pink bollworm had little or no survival on second-generation transgenic cotton with Cry2Ab alone or with Cry1Ac plus Cry2Ab. Artificial diet bioassays showed that resistance to Cry1Ac did not confer strong cross-resistance to Cry2Aa. Strains with >90% larval survival on diet with 10 microg of Cry1Ac per ml showed 0% survival on diet with 3.2 or 10 microg of Cry2Aa per ml. However, the average survival of larvae fed a diet with 1 microg of Cry2Aa per ml was higher for Cry1Ac-resistant strains (2 to 10%) than for susceptible strains (0%). If plants with Cry1Ac plus Cry2Ab are deployed while genes that confer resistance to each of these toxins are rare, and if the inheritance of resistance to both toxins is recessive, the efficacy of transgenic cotton might be greatly extended.

Animal Feed↗
PubMed1975

Comparative study of the smooth muscle contractor activity of airborne dusts and of dustiness in cotton, flax, and jute mills.

A bioassay technique using isolated guinea-pig ileum was employed to compare the smooth muscle contractor activity of various dusts from mills in which the prevalence of byssinosis was known. The activity of dust from a mill spinning a coarse grade of cotton was several times greater than that in dust from a mill processing a fine grade of cotton. There was a similar order in the difference of the prevalence of byssinosis in these mills. However, the activities of fine cotton, flax, and jute dusts were very similar to each other, in spite of marked differences in the prevalence of byssinosis in these mills. For cotton dust, smooth muscle contractor activity was associated with all particle sizes, although the lowest level of activity was found in the largest sized fraction (less than 2 mm). Activity in the cotton dust extracts was not correlated with nitrogen, carbohydrate, or potassium content. However, about one-fifth of the activity of a cotton dust extract was associated with an insoluble particulate fraction. The possible chemical nature of the water-soluble contractor agent is discussed. It is concluded that, until the role of this agent in the pathogenesis of byssinosis has been established, the bioassay technique cannot be employed as a means of assessing the byssinogenic potential of cotton dust.

Air Pollutants↗
PubMed1995

Cloning and characterization of the majority of repetitive DNA in cotton (Gossypium L.).

Repetitive DNA elements representing 60-70% of the total repetitive DNA in tetraploid cotton (Gossypium barbadense L.) and comprising 30-36% of the tetraploid cotton genome were isolated from a genomic library of DNA digested with a mixture of four blunt-end cutting restriction enzymes. A total of 313 clones putatively containing nuclear repetitive sequences were classified into 1103 families, based on cross hybridization and Southern blot analysis. The 103 families were characterized in terms of genome organization, methylation pattern, abundance, and DNA variation. As in many other eukaryotic genomes, interspersed repetitive elements are the most abundant class of repetitive DNA in the cotton genome. Paucity of tandem repeat families with high copy numbers (>10(4)) may be a unique feature of the cotton genome as compared with other higher plant genomes. Interspersed repeats tend to be methylated, while tandem repeats seem to be largely unmethylated in the cotton genome. Minimal variation in repertoire and overall copy number of repetitive DNA elements among different tetraploid cotton species is consistent with the hypothesis of a relatively recent origin of tetraploid cottons.

Base Sequence↗
PubMed2005

The evolution of cotton pest management practices in China.

The development of cotton pest management practices in China has followed a pattern seen for many crops that rely heavily on insecticides. Helicoverpa armigera resistance to chemical pesticides resulted in the unprecedented pest densities of the early 1990s. Transgenic cotton that expresses a gene derived from the bacterium Bacillus thuringiensis (Bt) has been deployed for combating H. armigera since 1997. The pest management tactics associated with Bt cotton have resulted in a drastic reduction in insecticide use, which usually results in a significant increase in populations of beneficial insects and thus contributes to the improvement of the natural control of some pests. Risk assessment analyses show that the natural refuges derived from the mixed-planting system of cotton, corn, soybean, and peanut on small-scale, single-family-owned farms play an important function in delaying evolution of cotton bollworm resistance, and that no trend toward Bt cotton resistance has been apparent despite intensive planting of Bt cotton over the past several years.

Agriculture↗
PubMed1986

Cotton dust-mediated lung epithelial injury.

To determine if constituents of cotton plants might play a role in byssinosis by injuring pulmonary epithelium, we added extracts of cotton dust, green bract, and field-dried bract to human A549 and rat type II pneumocytes. Injury was measured as pneumocyte lysis and detachment, and inhibition of protein synthesis. Extracts of cotton dust and field-dried bract produced significant dose- and time-dependent lysis and detachment of both target cells, while green bract extract was less damaging. Extracts treated with polyvinylpolypyrrolidone to remove tannins produced significantly less injury. In contrast, purified 5,7,3',4'-tetrahydroxy-flavan 3,4-diol (THF), a tannin in cotton dust and bract, caused substantial cell damage. Field-dried bract extract and THF also produced dose-dependent inhibition of pneumocyte protein synthesis. Endotoxin levels did not correlate with observed injury. THF added to rat tracheal explants caused epithelial disruption and desquamation, whereas endotoxin did not. Instillation of cotton dust and field-dried bract extract in rat lungs produced disruption of bronchial epithelium and smooth muscle constriction, while polyvinylpolypyrrolidone-treated cotton dust extract produced no injury. These findings suggest that extracts of cotton plants are toxic to alveolar, tracheal, and bronchial epithelium and that THF or other tannins may be the responsible agents.

Animals↗
PubMed1985

Airway reactivity and cotton bract-induced bronchial obstruction.

Most seemingly healthy persons challenged with an aerosol of cotton bract extract develop some degree of bronchospasm. The role of nonspecific reactivity of the airways in this reaction to cotton bract extract is undefined. We examined the relationship between airway responses to cotton bract extract and to methacholine, as well as between airway responses to cotton bract extract and to a bronchodilator. Twenty-two healthy subjects were screened for sensitivity to inhaled cotton bract extract. Pulmonary function was measured using partial expiratory flow-volume curves on which flow at 60 percent of the control vital capacity below total lung capacity was measured (MEF40%[P]) following ten minutes of inhalation of cotton bract extract. In the group screened, 12 were found to be responders to the extract, with drops in MEF40%(P) of 20 percent or more, and ten were found to be nonresponders. On separate days, we measured the responses of our subjects' airways to inhaled metaproterenol and methacholine. The mean threshold dose for methacholine in the responding group was 26.8 mg/ml, as compared to 55.6 mg/ml for the nonresponders (t = 2.52; p less than 0.05). Furthermore, the mean percent increase in MEF40%(P) following inhalation of metaproterenol was 41 percent in responders and 24 percent in nonresponders (t = 2.19; p less than 0.05). We conclude that some responders to cotton bract extract exhibit greater reactivity of the airways than nonresponders.

Adult↗
PubMed2001

Treatment thresholds for stink bugs (Hemiptera: Pentatomidae) in cotton.

The green stink bug, Acrosternum hilare (Say), the southern green stink bug, Nezara viridula (L), and the brown stink bug, Euschistus servus (Say), were predominant phytophagous Pentatomidae detected during 1995-1997 in cotton in South Carolina. These species occurred in similar numbers in conventional and transgenic cotton 'NuCOTN33B', containing the gene for expression of CryIA(c) delta-endotoxin of Bacillus thuringiensis Berliner variety kurstaki. Adult stink bugs moved into cotton from wild and cultivated alternate hosts during July, and reproducing populations usually were detected in cotton from late July into September. Applications of either methyl parathion (0.56 kg [AI]/ha) directed for stink bugs or lambda-cyhalothrin (0.037 kg [AI]/ha) or cyfluthrin (0.056 kg [AI]/ha) for control of cotton bollworm, Helicoverpa zea (Boddie), provided effective control of pentatomids in NuCOTN33B or conventional 'DP5415' and increased yields compared with untreated plots. Fiber quality did not differ among treated or untreated plots of NuCOTN33B. The ground-cloth technique was used to estimate populations of stink bugs, and data indicated that treatment at one bug per 2 m of row adequately protected cotton from yield loss due to stink bug damage. Observations on boll damage indicated that treatment might be necessary if >20-25% reveal internal symptoms of feeding injury during mid- to late season. More detailed damage thresholds should be developed to complement an approach based on population monitoring. This study validated current recommendations for management of pentatomids in cotton, demonstrated the necessity of threshold use for stink bugs in transgenic cultivars expressing endotoxin from B. thuringiensis, and provided insight into further development of management options for pentatomids in the crop.

Animals↗
PubMed2001

Predicting spring moth emergence in the pink bollworm (Lepidoptera: Gelechiidae): implications for managing resistance to transgenic cotton.

Cultural control methods have been central in the southwestern United States for reducing pink bollworm, Pectinophora gossypiella (Saunders), damage to cotton. Nevertheless, it is not clear at present how such methods could be integrated within the novel pest management framework allowed by introduction of cotton producing a toxin from Bacillus thuringiensis (Bt) for pink bollworm control. Using statewide pheromone trapping and climatic data in conjunction with deterministic simulation models, we investigated whether manipulation of cotton planting date and use of other cultural control methods could represent valuable tactics for control of the pink bollworm in Arizona. Accumulation of heat units from one January accurately predicted the rate of pink bollworm emergence from diapause in 15 cotton-producing regions. Significant variation in rate of emergence from diapause was present among regions, with earlier emergence at higher altitudes. Most adults emerge from diapause too early to reproduce successfully on cotton, a phenomenon known as suicidal emergence. A method for prediction of the fraction of suicidal emergence resulting from adoption of a given cotton planting date is presented. Results from simulation models suggest that manipulation of planting date and implementation of other control cultural methods reduce the rate of application of insecticides and delay the evolution of resistance to Bt cotton in the pink bollworm.

Animals↗
PubMed2001

Fitness costs and maternal effects associated with resistance to transgenic cotton in the pink bollworm (Lepidoptera: Gelechiidae).

Transgenic cotton producing a Bacillus thuringiensis (Bt) toxin is widely used for controlling the pink bollworm, Perctinophora gossypiella (Saunders). We compared performance of pink bollworm strains resistant to Bt cotton with performance of their susceptible counterparts on non-Bt cotton. We found fitness costs that reduced survival on non-Bt cotton by an average of 51.5% in two resistant strains relative to the susceptible strains. The survival cost was recessive in one set of crosses between a resistant strain and the susceptible strain from which it was derived. However, crosses involving an unrelated resistant and susceptible strain indicated that the survival cost could be dominant. Development time on non-Bt cotton did not differ between the two related resistant and susceptible strains. A slight recessive cost affecting development time was suggested by comparison of the unrelated resistant and susceptible strains. Maternal effects transmitted by parents that had eaten Bt-treated artificial diet as larvae had negative effects on embryogenesis, adult fertility, or both, and reduced the ability of neonates to enter cotton bolls. These results provide further evidence that fitness costs associated with the evolution of resistance to Bt cotton are substantial in the pink bollworm.

Adaptation, Physiological↗
PubMed2002

Soybean looper (Lepidoptera: Noctuidae) oviposition on cotton and soybean of different growth stages: influence of olfactory stimuli.

Soybean looper, Pseudoplusia includens (Walker), oviposition in cotton, Gossypium hirsutum L., and soybean, Glycine max (L.) Merr., of various stages of plant phenological development was evaluated in field cages in 1994, 1995, and 1996. Overall, females preferred to oviposit on soybean over cotton when both crops were compared in vegetative or prebloom stages, when both crops were blooming, and when soybean was blooming or in early pod stage compared with prebloom cotton. Females preferred to deposit eggs on the lower leaf surface in the upper two-thirds of the plant canopy in cotton and soybean. Oviposition in upper and middle canopy levels varied with plant growth stage. Females tended to lay more eggs in the upper canopy compared with the middle canopy in prebloom cotton and vegetative soybean; more eggs were laid in the middle canopy of blooming cotton and reproductive stages of soybean. Females responded to both cotton and soybean volatiles in an olfactometer. There was no significant difference in response to the two sources of volatiles.

Animals↗