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PubMed2003

Enhanced fungal resistance in transgenic cotton expressing an endochitinase gene from Trichoderma virens.

Mycoparasitic fungi are proving to be rich sources of antifungal genes that can be utilized to genetically engineer important crops for resistance against fungal pathogens. We have transformed cotton and tobacco plants with a cDNA clone encoding a 42 kDa endochitinase from the mycoparasitic fungus, Trichoderma virens. Plants from 82 independently transformed callus lines of cotton were regenerated and analysed for transgene expression. Several primary transformants were identified with endochitinase activities that were significantly higher than the control values. Transgene integration and expression was confirmed by Southern and Northern blot analyses, respectively. The transgenic endochitinase activities were examined in the leaves of transgenic tobacco as well as in the leaves, roots, hypocotyls and seeds of transgenic cotton. Transgenic plants with elevated endochitinase activities also showed the expected 42 kDa endochitinase band in fluorescence, gel-based assays performed with the leaf extracts in both species. Homozygous T2 plants of the high endochitinase-expressing cotton lines were tested for disease resistance against a soil-borne pathogen, Rhizoctonia solani and a foliar pathogen, Alternaria alternata. Transgenic cotton plants showed significant resistance to both pathogens.

Journal Article↗
PubMed2006

Circumvention of over-excitation of PSII by maintaining electron transport rate in leaves of four cotton genotypes developed under long-term drought.

We investigated the patterns of response to a long-term drought in the field in cotton cultivars (genotypes) with known differences in their drought tolerance. Four cotton genotypes with varying physiological and morphological traits, suited to different cropping conditions, were grown in the field and subjected to a long-term moderate drought. In general, cotton leaves developed under drought had significantly higher area-based leaf nitrogen content (N (area)) than those under well irrigation. Droughted plants showed a lower light-saturated net photosynthetic rate (A (sat)) with lower stomatal conductance (g (s)) and intercellular CO (2) concentration (C (i)) than irrigated ones. Based on the responses of A (sat) to g (s) and C (i), there was no decreasing trend in A (sat) at a given g (s) and C (i) in droughted leaves, suggesting that the decline in A (sat) in field-grown cotton plants under a long-term drought can be attributed mainly to stomatal closure, but not to nonstomatal limitations. There was little evidence of an increase in thermal energy dissipation as indicated by the lack of a decrease in the photochemical efficiency of open PSII (F (v)'/F (m)') in droughted plants. On the basis of electron transport (ETR) and photochemical quenching (q (P)), however, we found evidence indicating that droughted cotton plants can circumvent the risk of excessive excitation energy in photosystem (PS) II by maintaining higher electron transport rates associated with higher N (area), even while photosynthetic rates were reduced by stomatal closure.

Biological Transport↗
PubMed1975

Responses to cotton dust.

Twelve cotton textile workers were studied: (1) to compare standard measures of volume and expiratory flow, maximal expiratory flow volume (MEFV) curves, closing volume (CV), and closing capacity (CC) in detection of airway narrowing with cotton dust exposure; (2) to evaluate the response of arterial blood gases to exposure; (3) to measure changes in leukocytes in peripheral blood and airway secretions; and (4) to assess the temporal relationships and correlations between measures. Change in expiratory flow (FEV) most consistently and significantly discriminated between the control and cotton dust exposures. Vmax50%FVC was a more sensitive indicator, but variance was increased proportionately. CV and CC changed inconsistently with relatively large variances. The PaO-2 decreased overall and two subjects had large decrements. Peripheral blood and polymorphonuclear cell counts increased with exposure to cotton dust and polymorphonuclear leukocytes were recruited to the nasal mucosa. Chest tightness and decreased flow were temporally correlated with leukocyte recruitment that may be important in respiratory disease among cotton textile workers and therefore deserves further investigation.

Adult↗
PubMedDate not supplied

Acute health effects of community exposure to cotton defoliants.

In September and October of 1987, the California Department of Health Services responded to community complaints by investigating the relationship between health symptoms and community exposure to cotton defoliants. Symptoms experienced during the 1987 cotton defoliation season by 232 residents of cotton-growing communities were compared with symptoms of 175 residents of non-cotton-growing agricultural communities. Fatigue, eye irritation, rhinitis, throat irritation, nausea, and diarrhea were statistically elevated in rates adjusted for age, sex, and race and were reported 60-100% more frequently by respondents living or working near sprayed cotton fields than by the comparison group. These symptom rate elevations were substantially unchanged even after adjustment by a model of potentially confounding factors that included cigarette smoking, chronic illness, and some additional demographic variables.

Defoliants, Chemical↗
PubMed2005

Characterization of a cDNA encoding metallothionein 3 from cotton (Gossypium hirsutum L.).

A cDNA encoding metallothionein (MT) was isolated from a library constructed with poly A(+) RNA purified from 48 h etiolated cotton (Gossypium hirsutum L.) cotyledons. This cDNA encodes a deduced protein with 63 residues and a molecular weight of 6.3 kDa. The protein has 10 cysteines of which 4 are within the CXXCXCXXXXXC amino-terminus motif and six are within the CXCXXXCXCXXCXC carboxyl-terminus motif characteristic of the type III MT (MT3). The cotton MT3 protein sequence is 76.2, 69.8, 66.7, 60.3 and 33.5% identical to MT3 from Carica papaya, Rubus idaeus, Ribes nigrum, Citrus unshiu, and Gossypium hirsutum type I MT, respectively. A fusion protein was constructed by producing PCR primers for the 5' and 3' ends of the cotton MT3 cDNA and ligating the PCR product inframe at the 3' end of a bacterial glutathione S-transferase (GST) gene in the pGEX3 vector. The 5' PCR primer incorporated a segment of the cotton MT3 noncoding region, resulting in an addition of 9 residues to the MT3 (after Factor Xa digestion site) which increased the size of the expressed protein to 72 residues and 7.6 kDa. Expression of the 7.6 kDa protein in bacteria was confirmed by SDS-PAGE. Induction and accumulation of the GST-MT3 protein began inhibiting bacterial growth after 1 h. Addition of Cu (1 muM to 1 mM), 1 mM cysteine, or 1 mM cystine to the media did not rescue growth. Additionally, this protein was evaluated for its ability to bind Cd, Cu, Ni and Zn in the bacterial expression system. We found that cotton MT3 preferentially binds Cu.

Amino Acid Motifs↗
PubMed2002

Occupational exposure to cotton dust in cottonseed oil mills.

Air samples were collected at breathing height in the hulling-separation department of a modern cottonseed oil mill in Uzbekistan. The average elutriated mass concentration measured by standard cotton dust samplers was 4.6 mg/m3, much lower than the average total dust concentration measured by stationary personal samplers, 12.49 mg/m3, and by personal samplers attached to workers, 14.53 mg/m3. Differences in readings among the vertical elutriators, stationary personal samplers, and roving personal samplers are attributed to the distinct sampling nature and dynamics of these samplers. The data suggest that most of the dust consisted of particles larger than 15 microm, the particle size cutoff of the vertical elutriator. Differences in readings among stationary and roving personal samplers are statistically significant, presumably representing biased sampling by the roving personal samplers of regions characterized by high dust concentration (due to machines malfunctioning), the nonstatic nature of the sampling, and the interaction between the sampler and the worker (the personal cloud). Cotton dust concentrations in the hulling-separation room were nonuniform, peaking in front of and between the huller-separator pairs. The high total mass readings show that workers were exposed to very high levels of nonthoracic airborne dust, which upon inhalation tends to deposit in the extrathoracic airways. The high elutriated mass concentrations suggest that workers were exposed to respirable cotton dust at levels higher than 1 mg/m3 mean concentration, the current Occupational Safety and Health Administration (OSHA) Permissible Exposure Limit (PEL) for cotton dust. Regressions between dust concentrations measured by stationary vertical elutriators and by personal samplers attached to workers serve for estimating the potential occupational exposure to cotton dust of workers in the hulling-separation room.

Air Pollutants, Occupational↗
PubMed2003

Ecotoxicological risks associated with land treatment of petrochemical wastes. II. Effects on hepatic phase I and phase II detoxification enzymes in cotton rats.

The purpose of this study was to evaluate possible exposure and resultant hepatic effects of petrochemical waste on cotton rats (Sigmodon hispidus) living on landfarmed sites. Male and female cotton rats were collected in summer, fall, and winter from four landfarm sites and four ecologically similar reference sites. Hepatic methoxyresorufin O-deethylase (MROD) activity was significantly induced in male and female rats collected from landfarms compared to rats collected from reference sites. In contrast, changes in ethoxyresorufin O-deethylase (EROD) activity were inconsistent due to season, sex, and treatment variation. A significant decrease in EROD and MROD activity was found in cotton rats held for 48 h prior to sacrifice compared to rats euthanized on the day of capture. These results indicate that when using hepatic EROD and MROD activities as biochemical markers of exposure to aryl hydrocarbon receptor agonists, animals should be euthanized as quickly as possible after capture. The cotton rats collected from one landfarm unit exhibited a pattern of consistent elevation of EROD, MROD, and pent-oxyresorufin O-deethylase (PROD) activity. This unit also had a pattern of elevated CYP1A2 protein expression determined by Western blotting. There were no consistent alterations from contaminant exposure on hepatic glutathione S-transferase (GST) activity, glutathione levels, or CYP1A1 protein. Hepatic EROD and MROD activities varied considerably between seasons and sex of rats. In conclusion, consistent induction of hepatic EROD and MROD activities in cotton rats was found in three out of four sampled landfarm sites compared to the rats collected from the reference sites, indicating exposure to contaminants-likely polyaromatic hydrocarbons.

Agriculture↗
PubMed2003

Ecotoxicological risks associated with land treatment of petrochemical wastes. III. Immune function and hematology of cotton rats.

Landfarming is a widely used method of treating petrochemical waste through microbial bio-degradation. The effects of residual petrochemical contamination on wildlife, especially terrestrial mammals, are poorly understood. The effects of contaminants on the immune system and hematology of cotton rats (Sigmodon hispidus) living on five abandoned petrochemical landfarms (units 1-5) in Oklahoma were studied. Cotton rats were sampled seasonally (summer and winter) from each landfarm and from five ecologically matched reference sites for 2 yr (1998-2000) and returned to the laboratory for immunological and hematological assays. Overall analysis indicated that rats inhabiting landfarms exhibited decreased relative spleen size compared to rats collected from reference sites, with the landfarm at unit 1 showing the greatest reduction. Cotton rats collected from landfarms also had increased hemoglobin, hematocrit, and platelet levels and decreased blood leukocytes during summer. During winter, an increase in the number of popliteal node white blood cells was observed from rats collected on landfarms. No marked difference was detected for lymphocyte proliferation in response to concanavalin A, pokeweed, or interleukin-2. Lymphokine-activated killer cell lytic ability showed a seasonal pattern, but no treatment differences. No differences between landfarm and reference sites were detected in the hypersensitivity reaction of rats given an intradermal injection of phytohemagluttinin (PHA-P). Comparisons within individual sites indicated that two sites (units 1 and 3) had the greatest effects on immune function and hematology of cotton rats. The results of this study suggest that residual petrochemical waste affects the immune system and hematology of cotton rats living on abandoned landfarms during summer and is complicated by variation in the contaminants found on individual petroleum sites.

Agriculture↗
PubMed1990

Stimulation and release of prostaglandins and thromboxane from macrophages by cotton dust associated lipopolysaccharides.

Decreases in the ventilation capacity of human lungs following the inspiration of cotton dust correlates more closely with the concentration of endotoxin in the dust than with any other parameter measured thus far. A lipopolysaccharide isolated from the endotoxin of Enterobacter agglomerans, a common bacterial contaminant of cotton fiber, stimulated isolated rat macrophages to produce and release prostaglandins 6 keto-PGF1 alpha, PGF2 alpha, PGE2, PGD2, PGA2, and PGB2 and thromboxane B2. If in vivo human pulmonary macrophages respond in a similar fashion by releasing these arachidonic acid metabolites or their immediate precursors in response to stimulation by cotton dust associated lipopolysaccharides, some of the acute pulmonary changes observed in humans following inspiration of cotton dust could be caused by increased release of these biologically active compounds. Daily release of arachidonic acid metabolites at concentrations significantly above normal homeostatic levels could produce some of the pathophysiologic pulmonary changes observed in byssinotics. This paper reports the results of an experiment to quantitate arachidonic acid metabolite production following macrophage stimulation by E. agglomerans lipopolysaccharide. Procedures are described for the stimulation of macrophages by cotton dust associated lipopolysaccharide, for the separation and identification of arachidonic acid and its metabolites by high-performance liquid chromatography, and for the quantification of those products by radioisotope techniques.

Animals↗
PubMed2004

The cotton rat: an underutilized animal model for human infectious diseases can now be exploited using specific reagents to cytokines, chemokines, and interferons.

The cotton rat represents the best or only animal model for a large number of human infectious diseases, and it may be unique among small laboratory animals in its susceptibility to several potential agents of bioterrorism. Although the cotton rat is a reliable model to define pathologic changes produced during infection with human pathogens, the lack of specific reagents has precluded a more extensive analysis of the molecular basis of pathogenesis. Here, we report the cloning of 24 cotton rat genes encoding various cytokines, chemokines, and interferons (IFNs). Analysis of the expression of most of these genes was performed by RT-PCR in cotton rat macrophages during treatment with lipopolysaccharide (LPS) and in cotton rat lungs after infection with influenza virus. The availability of these reagents will provide the tools for molecular analysis of pathogenesis and immune responses to a wide variety of pathogens and set the basis for the development of new prophylactic and therapeutic strategies against human infectious diseases.

Animals↗
PubMed1994

Prolonged transgene expression in cotton rat lung with recombinant adenoviruses defective in E2a.

Recombinant adenoviruses have tremendous potential for gene therapy of cystic fibrosis (CF) lung disease. First-generation recombinant viruses, rendered replication defective by deleting E1, have been associated with high-level recombinant gene expression in airway epithelial cells when administered directly to the lung. Experience in mice and non-human primates indicates that transgene expression is transient (i.e., lasting less than 21 days) and associated with the development of inflammation. We suggest an hypothesis to explain these findings that is based on expression of viral proteins in genetically modified cells that leads to destructive cellular immune responses and repopulation of lung epithelia with non-transgene-containing cells. This hypothesis has been evaluated in the current study using the cotton rat model. Instillation of the first-generation lacZ virus, H5.010CBlacZ, into cotton rat airway led to high-level gene expression in conducting and respiratory airway that was transient and associated with a substantial mononuclear, CD8-dominated, infiltrates. Treatment of the animals with cyclosporine blunted the inflammatory response and prolonged recombinant gene expression in both conducting and respiratory airways. Expression of viral early and late genes was detected in a subpopulation of lacZ-expressing epithelial cells of conducting airway and alveoli. Instillation of virus into cotton rat tracheal xenografts grown in athymic nu/nu mice led to efficient and stable transgene expression in the absence of pathology, underscoring the importance of T cell-mediated immunity. A recombinant adenovirus was constructed that is disabled in its capacity to replicate by the introduction of a temperature-sensitive mutation in the E2a gene as well deletion of E1 sequences. Instillation of this virus into cotton rat airway led to high-level transgene expression that was more stable than that achieved with the first-generation virus and was associated with less early and late gene expression as well as a diminished infiltration of CD8+ T cells in conducting airway epithelium. Interestingly, the introduction of the E2a mutation had no effect on the persistence of transgene expression, the pattern of late viral gene expression, nor the CD8+ T cell response within alveolar cells. These data suggest that cell-specific variation in the cell biology of recombinant adenoviruses exists in the lung. The present studies in cotton rats confirm the role of cellular immunity in the biology of adenovirus-mediated gene therapy to the lung and suggest that modifications in the design of recombinant adenoviruses to minimize or ablate transgene expression will be useful in improving the potential of this technology for gene therapy of CF.

Adenovirus E2 Proteins↗
PubMed2005

Cotton rat tumor model for the evaluation of oncolytic adenoviruses.

Oncolytic human adenovirus (Ad) vectors exert their antitumor effect by replicating in and lysing tumor cells. These vectors are commonly evaluated in immunodeficient mice bearing human tumor xenografts. However, this model suffers because the mice are immunodeficient and are not permissive for human Ads. We have developed a cotton rat model to test the selectivity, immunogenicity, and efficacy of oncolytic Ad vectors. The cotton rat is a rodent species that is semipermissive for human Ads. We show that the cotton cancer rat cell line LCRT supports the replication of human Ad in tissue culture and that the cells are destroyed on virus replication. When injected subcutaneously, LCRT cells formed tumors in immunocompetent cotton rats, and the growth of these tumors was delayed by the injection of an oncolytic Ad vector. Replication of the Ad vector in the tumor was demonstrated by sampling tumor tissue and isolating infectious virus particles at various times after intratumoral injection of the virus. We propose that the cotton rat can be used as an animal model to evaluate oncolytic Ad vectors.

Adenovirus Infections, Human↗
PubMed2003

Effects of ultraviolet-B radiation on cotton (Gossypium hirsutum L.) morphology and anatomy.

Cotton (Gossypium hirsutum L.) crop, cultivated between 40 degrees N and 40 degrees S, is currently experiencing 2-11 kJ m-2 d-1 of UV-B radiation. This is predicted to increase in the near future. An experiment was conducted to study the effect of enhanced UV-B radiation on vegetative and reproductive morphology and leaf anatomy of cotton in sunlit, controlled environment chambers. From emergence to harvest, cotton plants were exposed to 0, 8 or 16 kJ m-2 d-1 of UV-B in a square wave approach for 8 h from 0800 to 1600 h. Changes in plant height, internode and branch length, mainstem node number, leaf area, length and area of petals and bracts, and anther number per flower were recorded. Epidermal cell and stomatal density, stomatal index, leaf thickness, and epidermal, palisade and mesophyll tissue thickness were also measured. Initial chlorotic symptoms on leaves turned into necrotic patches on continued exposure to enhanced UV-B. Exposure to high UV-B reduced both vegetative and reproductive parameters and resulted in a smaller canopy indicating sensitivity of cotton to UV-B radiation. Enhanced UV-B radiation increased epicuticular wax content on adaxial leaf surfaces, and stomatal index on both adaxial and abaxial leaf surfaces. Leaf thickness was reduced following exposure to UV-B owing to a decrease in thickness of both the palisade and mesophyll tissue, while the epidermal thickness remained unchanged. The vegetative parameters studied were affected only by high levels of UV-B (16 kJ m-2 d-1), whereas the reproductive parameters were reduced at both ambient (8 kJ m-2 d-1) and high UV-B levels. The study shows that cotton plants are sensitive to UV-B at both the whole plant and anatomical level.

Apoptosis↗
PubMed2003

Spontaneous ECL cell carcinomas in cotton rats: natural course and prevention by a gastrin receptor antagonist.

In our inbred strain of cotton rats (Sigmodon hispidus) 50% of the females develop spontaneous ECL cell-derived tumors in the acid-producing part of the stomach due to hypergastrinemia secondary to gastric hypoacidity. Although the mechanism behind the hypoacidity is unknown, the female cotton rat is an excellent model for studying ECL cell-related tumorigenesis. In this study we wanted to explore the malignancy potential of these tumors and the ability of a gastrin receptor antagonist (YF476) to prevent their development. First, nine hypergastrinemic female cotton rats (10 months of age) were diagnosed by laparotomy as having gastric tumors. They were killed 6 months later. Second, 18 female cotton rats (2 months of age) were dosed monthly for 6 months with YF476 (500 micro mol/kg body wt) by s.c. injection, while 21 age-matched animals received vehicle. Samples from each stomach were collected for histology, immunohistochemistry and northern blot analysis. The gastric tumors harbored cells with immunohistochemical features of ECL cells. The tumors were found at times to invade and penetrate the stomach wall and to metastasize to perigastric sites. ECL-derived tumor cells were discovered in peritoneal fluid. At death only 1 out of 18 animals given YF476 displayed carcinomas (invasive growth), compared with 7 out of 21 in the vehicle dosed control group (P = 0.048). The spontaneous gastric tumors in cotton rats derived from ECL cells. The tumors were able to penetrate the stomach wall and to metastasize by intracavital seeding. Gastrin receptor blockade lowered the incidence of such tumors. We propose that the tumors are ECL cell carcinomas and that gastrin is the driving force behind the transformation from normal to malignant ECL cells.

Animals↗
PubMed1995

Comparison of cotton and cotton/rayon tampons for effect on production of toxic shock syndrome toxin.

Studies were done to compare tampons made solely of cotton and made of both cotton and rayon for effect on growth of Staphylococcus aureus and production of toxic shock syndrome toxin-1 (TSST-1). Under stationary in vitro conditions in which tampons were either oversaturated or 50% saturated with culture media, the same amount of or more TSST-1 was made with cotton tampons than with cotton/rayon tampons. Similarly, when tested with the tampon sac method, cotton tampons yielded the same amount of or more toxin than did the cotton/rayon tampons. Bacterial cell numbers generally paralleled toxin production. These data indicate that cotton tampons neither prevent TSST-1 production nor significantly adsorb toxin onto the fibers to make toxin unavailable to cause toxic shock syndrome, in contrast to results of a previous study.

Bacterial Toxins↗
PubMed2004

Effect of cotton cultivar on development and reproduction of Aphis gossypii (Homoptera: Aphididae) and its predator Propylaea japonica (Coleoptera: Coccinellidae).

The effects of three cotton cultivars with low ('ZMZ13'), medium ('HZ401'), and high ('M9101') gossypol contents on the development, reproduction, and survival of Aphis gossypii Glover and its predator Propylaea japonica (Thunberg) were investigated. Developmental duration and immature survivorship did not vary between aphids on the three cultivars, whereas A. gossypii feeding on M9101 (high gossypol cultivar) displayed significantly shorter adult longevity and lower fecundity than aphids fed on 'ZMS13' and 'HZ401'. Free fatty acid content in cotton aphids reared on 'M9101' was greater than in those reared on 'HZ401' and 'ZMS13'. No significant differences in survival and lifetime fecundity of P. japonica were observed between P. japonica fed cotton aphids reared on the three different cultivars. P. japonica fed aphids from 'M9101' showed a significantly shorter developmental period and greater adult weight than those fed aphids from the other two cultivars. The decreased larval developmental duration and increased adult weight of P. japonica fed cotton aphids reared on the high gossypol-containing cultivar might have been caused by the high fatty acid content of the prey aphids. Our results indicate that high gossypol in host cotton had an antibiotic effect on A. gossypii and showed a positive effect on growth and development of P. japonica at the third trophic level. This suggests compatibility between one form of host plant resistance and biological control by predators. The allelochemical contents should be taken into account in integrated pest management for their effects on both herbivores and entomophagous insects.

Animals↗
PubMed2005

Seasonal expression profiles of insecticidal protein and control efficacy against Helicoverpa armigera for Bt cotton in the Yangtze River valley of China.

Seasonal levels of Bacillus thuringiensis (Bt) insecticidal protein and its control efficacy against Helicoverpa armigera (Hübner) in Bt transgenic cotton GK19 (carrying a Cry1Ac/Cry1Ab fused gene) and BG1560 (carrying a Cry1Ac gene) were investigated in Tianmen County, Hubei Province, located in the Yangtze River valley of China, in 2001 and 2002. The results showed that the toxin content in Bt cotton changed significantly over time, and that the structure, growth stage, and variety were significant sources of variability. Generally, insecticidal protein levels were high during the early stages of cotton growth; they declined in mid-season, and rebounded in late season. On most dates sampled, the toxin contents in leaf, square, petal, and stamens (including nonovule pistil tissue) were much higher than those in ovule and boll. Compared with BG1560, the expression of Cry1Ac/Cry1Ab protein in GK19 was more variable during the whole growth period of cotton. The field evaluation on larval population dynamics of H. armigera in Bt and conventional cotton showed that the larval densities in BG1560 and GK19 fields decreased, respectively, 92.04 and 81.85% in 2001, and 96.84 and 91.80% in 2002.

Animals↗
PubMed2006

Population dynamics and gene flow of Helicoverpa armigera (Lepidoptera: Noctuidae) on cotton and grain crops in the Murrumbidgee Valley, Australia.

The population dynamics of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) in the Murrumbidgee Valley, Australia, has been characterized using five highly variable microsatellite loci. In the 2001-2002 growing season, there were very high levels of migration into the Murrumbidgee Valley with no detectable genetic structuring, consistent with previous analyses on a national scale. By contrast, there was significant genetic structuring over the 2002-2003 growing season, with three distinct genetic types detected. The first type corresponded to the first two generations and was derived from local individuals emerging from diapause and their progeny. The second genetic type corresponded to generation 3 and resulted from substantial immigration into the region. There was another genetic shift in generation 4, which accounts for the third genetic type of the season. This genetic shift occurred despite low levels of immigration. During the third generation of the 2002-2003 growing season, different population dynamics was characterized for H. armigera on maize, Zea mays L., and cotton Gossipium hirsutum L. Populations on cotton tended to cycle independently with very little immigration from outside the region or from maize within the region. Maize acted as a major sink for immigrants from cotton and from outside the region. If resistance were to develop on cotton under these circumstances, susceptible individuals from maize or from other regions would not dilute this resistance. In addition, resistance is likely to be transferred to maize and be perpetuated until diapause, from where it may reemerge next season. If low levels of immigration were to occur on transgenic cotton, this may undermine the effectiveness of refugia, especially noncotton refugia.

Animals↗