Cotton Squares Research Articles

Role of Endophytic Entomopathogenic Fungi in Mediating Host Selection, Biology, Behavior, and Management of Tarnished Plant Bug, Lygus lineolaris (Hemiptera: Miridae).

Non-insecticidal control strategies using entomopathogens, nematodes, and endophytes provide sustainable and safer alternatives for managing crop pests. This study investigated the potential of different fungal endophytes, specifically Beauveria bassiana strains, in colonizing cotton plants and their efficacy against tarnished plant bug, Lygus lineolaris. The effect of endophytes on plant growth parameters and cotton yield were measured during different plant growth stages. The entomopathogenicity of these fungi was studied in diet cup bioassays using L. lineolaris adults. The behavior of adult males and females toward endophytic cotton squares was analyzed using olfactometer assays. The experiments showed that the fungal endophytes colonized the plant structures of cotton plants, which resulted in an increase in the number of cotton squares, plant height, and weight compared to control plants. B. bassiana strains/isolates such as GHA, NI-8, and JG-1 caused significant mortality in Lygus adults compared to controls. Also, male and female Lygus adults exhibited repellence behavior towards endophytic cotton squares containing JG-1 isolate of B. bassiana and to other B. bassiana strains such as NI-8, GHA, and SPE-120. No differences were observed in the survival and development of L. lineolaris second-instar nymphs on endophytic cotton, and no yield differences were observed in the field experiments.

Drought-induced cell wall degradation in the base of pedicel is associated with accelerated cotton square shedding

Drought significantly impacts cotton square (flower buds with bracts) shedding, directly affecting yield. To address the internal physiological mechanisms of drought affecting cotton square shedding, a polyethylene glycol-simulated drought study was conducted with Dexiamian 1 and Yuzaomian 9110 to investigate cell wall degradation changes in the base of pedicel where the detachment of cotton square takes place, and its relationship with cotton square shedding. Results revealed significant decreases in cellulose, hemicellulose, and pectin contents in the base of square pedicel, leading to cell wall degradation and consequent square shedding. Furthermore, drought stress exacerbated the hydrolysis of cellulose and pectin in the base of pedicel, although not hemicellulose, resulting in more noticeable alterations in the morphology and structure of the base of pedicel, such as more significant degradation in the epidermis, cortex, and phloem. Regarding the cellulose hydrolysis, drought mainly increased the expression of genes β-glucosidase (GhBG1) and endoglucanase (GhEG1), and the activity of β-glucosidase and endoglucanase in the base of pedicel, promoting the conversion of cellulose to cellobiose, and eventually glucose. Regarding the pectin hydrolysis, drought significantly enhanced the expression of the gene pectin methylase (GhPE1), thereby accelerating pectin hydrolysis to generate polygalacturonic acid. Additionally, drought increased the expression of genes pectin lyase (GhPL1) and polygalacturonase (GhPG1), as well as the activity of pectin lyase, which further accelerated the hydrolysis of polygalacturonic acid into galacturonic acid. These findings suggest that drought mainly promotes cellulose and pectin hydrolysis in the base of pedicel, hastening cell wall degradation and final cotton square shedding.

Evaluation of Cotton Fleahopper (Pseudatomoscelis seriatus (Reuter)) Feeding on Mpp51Aa2-Traited Cotton Utilizing Electrical Penetration Graph (EPG) Waveforms.

Prior to the recent implementation of the Mpp51Aa2 pesticidal protein (ThryvOn), transgenic cotton cultivars have historically offered no control of the cotton fleahopper (Pseudatomocelis seriatus (Reuter)). To evaluate the feeding behavior of cotton fleahoppers on ThryvOn cotton, electropenetrography (EPG) using a Giga-8 DC instrument was used to monitor the probing activity of fourth- and fifth-instar cotton fleahopper nymphs on both ThryvOn and non-ThryvOn cotton squares. Nymphs were individually placed on an excised cotton square for 8 h of EPG recording, after which resulting waveforms were classified as non-probing, cell rupturing, or ingestion. Although there were significantly more cell rupturing events per insect on ThryvOn (mean ± SEM, 14.8 ± 1.7) than on non-ThryvOn squares (mean ± SEM, 10.3 ± 1.6), there was no difference attributable to ThryvOn in the average number of ingestion events per insect. However, the average duration of ingestion events was significantly shorter on squares with ThryvOn (mean ± SEM, 509 ± 148 s) than on squares without (mean ± SEM, 914 ± 135 s). This suggests that cotton fleahoppers continued to probe despite their inability to sustain ingestion. These results provide conclusive evidence that the Mpp51Aa2 pesticidal protein affects the feeding behavior of cotton fleahopper nymphs.

Survival and alterations in reproductive organs of the cotton boll weevil, Anthonomus grandis grandis, fed alternative food

AbstractThe cotton boll weevil, Anthonomus grandis grandis Boheman (Coleoptera: Curculionidae), is one of the most important insect pests of cotton, causing significant yield losses. This insect completes its life cycle only on the flower structures of some Malvaceae species, with cotton being its preferred host. However, during the cotton off‐season, the boll weevil enters a reproductive dormancy state, in tropical regions, with important alterations in their reproduction organs. During this period, a remaining insect population survives feeding on a variety of other food sources, but the insects do not reproduce. We hypothesized that these alterations in the insect's reproductive organs are associated with the nutritional levels provided by alternative food sources during the cotton off‐season. To test our hypothesis, we first investigated food sources that sustain insect survival for long periods, such as weed species and fruits of cultivated crops. Then, we evaluated how various food sources affect the reproductive organs and reproductive capacity of the boll weevil. Among the alternative food sources tested, insect longevity was highest on banana (Musa paradisiaca L.), mango (Mangifera indica L.), papaya (Carica papaya L.), milkweed (Euphorbia heterophylla L.), and lilac tasselflower (Emilia sonchifolia L.). However, only banana and mango resulted in greater longevity than cotton squares. Banana was the preferred food and resulted in the highest levels of nutrients in the insects. Additionally, insects previously fed on banana made more oviposition punctures on cotton squares than those fed only on cotton squares, which resulted in a significantly higher number of emerged adults. Histological analysis of the insects' reproductive organs showed that feeding on papaya resulted in morphological changes and testicle degradation. In conclusion, we present evidence that boll weevils fed on alternative food sources (other than cotton squares or similar‐quality food) display a nutritional imbalance, associated with substantial alterations in the reproductive tissues of this insect, which may trigger the reproductive dormancy state.

Monitoring cotton squares with opened and/or yellowed bracts to determine the need and efficency of chemical control against the cotton boll weevil.

The technique of terrestrial sampling of boll weevil (BW) populations is expensive and inefficient over large areas, but may be cheaper and more efficient without involving the manipulation of cotton squares. The aim of this study was to develop a technique to sampling cotton squares based on the observation of opened and/or yellowing bracts to determine the need and efficacy of chemical control of BW in cotton crops. The first experiment aimed to estimate the ratio between the number of cotton squares with opened and/or yellowed bracts and that of squares with BW oviposition punctures. The second experiment, aimed to determine the efficacy of chemical control for BW by sampling cotton squares with opened and/or yellowed bracts. The ratio between the number of opened and/or yellowed bracts and the number of cotton squares with oviposition punctures was 2:1. The level and efficiency of chemical control of BW, based on the percentage and sampling of cotton plants with opened and/or yellowed bracts, was 5% and did not differ from the one based on the observation of cotton plants with 10% cotton squares with oviposition punctures by BW females. The control level based on sampling cotton plants with open and/or yellowing bracts was 5%. The efficiency of chemical insecticides using this economic threshold against the BW did not differ from that based on sampling cotton plants with 10% of cotton squares with oviposition punctures by BW females. This indicates that the chemical control of cotton boll weevil can be carried out based on cotton squares with open and/or yellowed bracts.

Choice and No-Choice Feeding Assays of Cotton Fleahoppers (Pseudatomoscelis seriatus) on Cotton Expressing the Mpp51Aa2 Protein

In Texas, the cotton fleahopper (Pseudatomoscelis seriatus (Reuter)) is considered a highly economically damaging pest of cotton (Gossypium hirsutum L.). Current control methods rely heavily on foliar chemical insecticides throughout the growing season. Considering the cost of insecticides and the critical timeliness of their application, chemical control methods are often not optimized to reduce potential yield losses. The Mpp51Aa2.834_16 gene in cotton (ThryvOn) has shown effectiveness against thrips and several piercing and sucking mirid insect pests, suggesting it has the potential to mitigate yield losses caused by the cotton fleahopper. Choice and no-choice caged feeding assays were conducted to assess the impact of cotton fleahoppers on ThryvOn cotton square retention under controlled laboratory conditions. In the choice assay, feeding by cotton fleahoppers significantly reduced square retention in the gene-lacking cotton to 46%, while the ThryvOn cotton retained 60% of the squares. In the no-choice assay, cotton fleahopper nymph feeding significantly reduced square retention in the cotton not expressing Mpp51Aa2 to 61%, whereas the ThryvOn cotton was unaffected. Based on the differences in square retention observed in both the choice and no-choice feeding assays, our findings indicate that the Mpp51Aa2 protein influences cotton fleahopper feeding preferences and the susceptibility of cotton plants to damage caused by cotton fleahoppers. Our study offers confirmation of the activity of ThryvOn on cotton fleahoppers observed in the field. The ThryvOn trait’s activity towards cotton fleahoppers is consistent with that found for other mirid pests in cotton.

Efficient cotton population photosynthetic production synergistically increases seedcotton yield and fiber quality through straw incorporation with appropriate nitrogen fertilization in wheat-cotton rotation system

ContextStraw incorporation with appropriate nitrogen (N) fertilization could increase seedcotton yield, but it is unknown whether and how straw incorporation with N fertilization can synergistically improve seedcotton yield and fiber quality. ObjectiveContinuous years of positioning field wheat-cotton double cropping experiments were conducted from 2015 to 2021 to investigate the effects of straw incorporation and N fertilization on seedcotton yield and fiber quality. MethodsFour N rates (0, 75, 150 and 300 kg N ha−1) and two straw managements (wheat-cotton straw incorporation and straw removal i.e. CK) were used as experimental treatments. The canopy photosyhthetic capacity, biomass, seedcotton yield and fiber quality were measured. Meanwhile, the dynamics of cotton square nuber and boll number during the efficient photo-thermal periods (approximately from 25th July to 30th August) were monitored. ResultsIn the study from 2019 to 2021, the canopy apparent photosynthesis rate, leaf area index and chlorophyll relative content increased with straw incorporation and increasing N rates. The maximum daily square appearance rate of 6.9 × 104 no. ha−1 and the maximum daily boll setting rate of 3.4 × 104 no. ha−1 during the efficient photo-thermal periods were obtained under straw incorporation with 150 kg N ha−1. Where the maximum boll setting ratio and boll weight ratio were observed. Straw incorporation with 150 kg N ha−1 also produced the maximum boll number (87.3–98.1 × 104 no. ha−1), seedcotton yield (3998–4544 kg ha−1) and the longest fiber length of 30.3–31.2 mm across from 2019 to 2021, and the strongest fiber strength and the lowest micronaire in 2019 and 2020. The results of 13CO2 feeding to cotton plants in 2019 and 2020 showed that straw incorporation promoted 13C allocation into cotton fiber and the maximum cotton fiber 13C proportion appeared under straw incorporation with 150 kg N ha−1. Besides, straw incorporation and increasing N rates increased seed hull 13C proportion for fiber development. In addition, long-term straw incorporation could reduce chemical N fertilizer by approximatly 30% from 150 kg N ha−1 to achieve the seedcotton yield under 150 kg N ha−1 without significant influence on fiber quality. ConclusionIn wheat-cotton rotation system, straw incorporation with a 30% reduction from 150 kg N ha−1 was appropriate to increasing seedcotton yield and fiber quality synergistically by improving canopy photosynthetic capacity, increasing cotton square and boll number during the efficient photo-thermal period, and optimizing photosynthate allocation in cotton boll.

Morphology and Morphometry of the Reproductive Tract of the Cotton Boll Weevil after Prolonged Feeding on Alternative Diets.

Anthonomus grandis Boheman (Coleoptera: Curculionidae) survives on alternative diets; however, this induces reproductive diapause. The objective was to evaluate the morphology and morphometry of the reproductive tract of this weevil after feeding on alternative diets. The experimental design was completely randomized with 160 replications and treatments arranged in a factorial design 3 × 3, represented by A. grandis adults fed on 3 food types (fragments of banana (T1) or orange (T2) endocarp, or with cotton squares of cultivar BRS 286 (T3, control)) and three evaluation periods (30, 60, and 90 days) and after each of these periods they were fed with cotton squares for 10 days. The reproductive tract of 100% of A. grandis females fed banana endocarp, orange endocarp, and cotton squares for 30 and 60 days and then cotton squares were morphologically adequate for reproduction, and after 90 days, only 50% of those fed cotton squares were in this condition. The length of the ovarioles and the width of the mature oocyte were greater for A. grandis fed on cotton squares and smaller in those with banana and orange endocarps. Histological sections reveal that male testes even with strong degenerative signals are already producing spermatozoa. On the other hand, females displayed ovaries with nurse cells in the tropharium and some maturing oocytes in the vitellarium. The body length was longer and the testis area and diameter smaller in males fed on cotton squares than in those with banana and orange endocarp. Anthonomus grandis females fed for ≥90 days with alternative food sources do not recover the functionality of their reproductive tract, even after consuming, for 10 days, a diet that favors reproduction. On the other hand, the males remain with their reproductive organs functional with this condition.

Locating the Madras Kerchief in Global Textile Trade: Convergences Between Connecting Threads and the Dutch Textile Trade Project

This essay presents collaborative research related to the National Endowment for the Humanities-Arts and Humanities Research Council grant-funded project Connecting Threads, a website that brings together academics and curators across the United Kingdom and the United States who seek to contribute to wider decolonization work in the humanities and engage communities whose contributions to global cultures of textiles and fashion have historically been ignored. The Connecting Threads research team uses the Dutch Textile Trade Project’s data and web applications to deepen understanding of the Madras kerchief, a large checked cotton square cloth that circulated in Afro-diasporic communities in the Caribbean during the eighteenth and nineteenth centuries.

Mortality of the cotton boll weevil in drip and sprinkler irrigated cotton crops.

The cotton boll weevil, Anthonomus grandis grandis Boheman (Coleoptera: Curculionidae), is a key cotton crop pest in Brazil. Adverse climatic factors, such as high temperatures and low soil moisture, dehydrate oviposited cotton squares (bud flowers) on the ground and cause high mortality of its offspring within these plant structures. The objective of this research was to evaluate the mortality of the cotton boll weevil in drip and sprinkler irrigated cotton crops. The experimental design was in randomized blocks with two treatments: drip (T1) and sprinkler (T2, control) irrigated cotton crops with sixteen replications. Each parcel had one emergence cage, installed between two cotton rows per irrigation system, with 37 cotton squares with opened oviposition punctures and yellowish bracts, to capture adult cotton boll weevils. The average number of boll weevils that emerged from the cotton squares and the causes of mortality at different development stages were determined per treatment. Third-generation life tables of the boll weevil were prepared using the natural mortality data in drip and sprinkler irrigation treatments and plus actual, apparent and indispensable mortality rates and the lethality of each mortality cause. We conclude that the application of water directly to the root zone of the plants in a targeted manner, using the drip irrigation system, can cause high mortality of the cotton boll weevil immature stages inside cotton squares fallen on the ground. This is because the cotton squares fallen on the drier and hotter soil between the rows of drip-irrigated cotton dehydrates causing the boll weevils to die. This is important because it can reduce its population density of the pest and, consequently, the number of applications of chemical insecticides for its control. Thus, contributing to increase the viability of cotton production, mainly in areas of the Brazilian semiarid region where the cotton is cultivated in organic system.

Heterologous expression of cry1Ia12 insecticidal gene in cotton encodes resistance against pink bollworm, Pectinophora gossypiella (Lepidoptera: Gelechiidae); an alternate insecticidal gene for insect pest management.

Cotton is continuously exposed to sucking and chewing insect pest pressure since emergence to harvesting. Pink bollworm (Pectinophora gossypiella) has become major chewing insect pest to reduce the cotton yield and results in bad lint quality even in transgenic crops. The efficiency of insecticidal genes has been compromised due to extensive utilization of transgenic crops. The present study was conducted to evaluate the efficacy of an alternate cry1Ia12 insecticidal gene against pink bollworm (PBW) in cotton. Agrobacterium tumefaciens strain LBA4404 harboring pCAMBIA2300 expression vector containing cry1Ia12 gene under the control of 35S CaMV was used to transform a local cotton cultivar GS-01. The various molecular analyses revealed the transgene integration and expression in primary transformants. Among five selected transgenic plants, tcL-08 showed maximum (16.06-fold) mRNA expression of cry1Ia12 gene whereas tcL-03 showed minimum (2.33-fold) expression. Feeding bioassays of 2nd and 3rd instar pink bollworm (PBW) larvae on immature cotton bolls, flowers and cotton squares revealed up to 33.33% mortality on tcL-08 while lowest mortality (13.33%) was observed in tcL-03 and tcL-15. Furthermore, the average weight and size of survived larvae fed on transgenic plants was significantly lesser than the average weight of larvae survived on non-transgenic plants. The present study suggests the cry1Ia12 gene as an alternate insecticidal gene for the resistance management of cotton bollworms, especially PBW.

Recovery Characteristics of Cry1Ac Endotoxin Expression and Related Physiological Mechanisms in Bt Transgenic Cotton Squares after High-Temperature Stress Termination

High-temperature stress reduces the endotoxin expression of the insecticidal gene (Cry1Ac) in transgenic Bacillus thuringiensis (Bt) cotton and affects nitrogen metabolism. However, its effects on Cry1Ac endotoxin expression after high-temperature stress termination remain unclear. In order to investigate the effect of high-temperature stress on the expression of insecticidal proteins in Bt cotton squares, the conventional Sikang-1 cultivar and hybrid Sikang-3 cultivar were used as the experimental materials. The potted cotton plants in the squaring stage were moved to an artificial climatic chamber at 38 °C for 72 h and 96 h in 2017 and 2018, respectively, and plants were moved to the climate chamber where the control cotton plants were located (at 27 °C). Then, cotton squares were collected to measure the Bt protein concentration and nitrogen metabolism physiology at 0, 12, 24, 48, 72 and 96 h after high-temperature stress termination, respectively. The Cry1Ac endotoxin expression of the squares could be recovered to the corresponding control level and a longer recovery time was required as the high-temperature stress period increased. Therefore, the recovery degree of Cry1Ac endotoxin expression of cotton squares can be predicted according to the duration of high-temperature stress, which may provide a reference for the rational control of Helicoverpa armigera and related pests in cotton production.

Effects of Laboratory Housing Conditions on Core Temperature and Locomotor Activity in Mice.

Drug developers worldwide assess compound safety and efficacy using measures that include mouse core temperature and locomotor activity. Subtle differences in animal housing conditions between institutions can alter these values, impacting scientific rigor and reproducibility. In these studies, adult male NIH Swiss mice were surgically implanted with radiotelemetry probes that simultaneously monitored core temperature and locomotor activity across various housing conditions. In the first study, ambient temperature was varied between 20 °C and 28°C in groups of singly housed mice. Additional studies held the mice at a constant ambient temperature and examined the effects of cage density (housing animals singly or in groups of 3 or 6), bedding change and provision of nesting material, and the availability of a running wheel on core temperature and locomotor activity. Mice overwhelmingly maintained species-typical core temperatures across all ambient temperatures, across all housing conditions, when bedding was fresh or old, and with or without the provision of cotton squares as nesting material. However, engaging in wheel running and the combination of fresh bedding and cotton squares transiently increased core temperatures beyond the species-typical range. Similarly, the circadian distribution of locomotor activity was significantly disrupted by placing animals in cages with fresh bedding or nesting material, or by performing both of these manipulations concurrently during the light period. These findings suggest that standard husbandry practices and common housing conditions may transiently affect core temperature in adult mice. Furthermore, these practices may have profound and relatively long-lasting effects on motor activity and the regulation of circadian rhythms.

Evaluation of cotton cultivars based on the compensatory increase of cotton squares after simulating damage by the cotton boll weevil

ABSTRACT The objective of this study was to evaluate cotton cultivars based on the compensatory increase of cotton squares in response to the simulation of the boll weevil damage. The first experiment aimed to evaluate cotton cultivars with greater compensatory increase in squares removed artificially from the plant. The experimental design was in randomized blocks, in a 4 × 2 factorial scheme with 100% removal of cotton squares at 50, 70 and 90 days after the emergence of the FM975WS, TMG81WS, IMA6501B2RF and BRS432B2RF cotton cultivars and passive production (without removal) and active (with removal) of cotton squares, with four replications. In the second experiment, boll weevil damage in the TMG80WS and BRS432B2RF, with greater and lesser compensatory increase of cotton squares, after their removal at 50 days of age, was evaluated. The experimental design was in randomized blocks, in a 2 × 2 factorial scheme, with the former cultivars sprayed with carbamate or not (control). The compensatory increase of cotton squares, mainly after their artificial removal at 50 and 70 days of age, of the TMG81WS, was greater. The cotton square compensatory increase after being artificially removed in the cotton cultivars was higher during the period of exponential production of these reproductive structures and can be used to select cultivars tolerant to boll weevil damage.

Field bioefficacy of mahogany seed extract (Khaya senegalensis: meliaceae, (desv.) a. juss) for management of bollworm infestation on cotton in Zaria, Nigeria

Field trials were conducted at two locations in Samaru (110 11'' N, 070 38'' E and 686m above sea level) and Maigana (110 10'' N, 070 37'' E and 675m above sea level) both in Northern Guinea Savannah ecological zone of Nigeria during the 2016 wet season to determine the effects of three concentration of aqueous Khaya seed extract (KSE) (20%w/v, 30%w/v and 40%w/v) on damage on cotton (SAMCOT 9) by bollworms. The experimental design was strip plot fitted into randomized complete block design. A total of four sprays at two weeks interval beginning from 9WAS (which corresponded to the period of formation of first square to the detection of first flower) were applied. Data were recorded on the number of terminal shoot damage, number of damaged shed squares, number of damaged shed cotton bolls and number of matured green bolls damaged by bollworms. There was no significant difference in the number of terminal shoot damaged by spiny bollworm (Earias spp.) from spray application of Lambda cyhalothrin, KSE and the untreated control. Significant reduction in the number of shed cotton squares, shed cotton bolls and matured green bolls damaged by bollworms were observed on Lambda cyhalothrin and 40%w/v KSE sprayed plots than the other treatments and the untreated control.

Nest Building Behavior as an Early Indicator of Behavioral Deficits in Mice.

Nest building is an innate behavior in male and female rodents, even when raised in laboratory settings. As such, many researchers provide rodents synthetic and/or natural materials (such as twine, tissue, cotton, paper, and hay) as a gauge of their overall well-being and as an ancillary assessment to predict the possible decline in cognition. Typically, changes in nesting behaviors, such as failure to create a nest, indicate a change in health or welfare. In addition, nesting behavior is sensitive to many environmental and physiological challenges, as well as many genetic mutations underlying pathological disease states. The following protocol describes a nesting behavior paradigm that explores the usage of four types of nesting material. In addition, the protocol utilizes intraclass correlations to demonstrate that inter-rater reliability is higher when nests are constructed out of shredded paper compared to other common nesting materials such as cotton squares, paper twists, and soft cob bedding. The chosen methodology and statistical considerations (i.e., intraclass correlation) for this assay may be of interest for those conducting experiments assessing the quality of living of mice.

Nest Building Behavior as an Early Indicator of Behavioral Deficits in Mice

Nest building is an innate behavior in male and female rodents, even when raised in laboratory settings. As such, many researchers provide rodents synthetic and/or natural materials (such as twine, tissue, cotton, paper, and hay) as a gauge of their overall well-being and as an ancillary assessment to predict the possible decline in cognition. Typically, changes in nesting behaviors, such as failure to create a nest, indicate a change in health or welfare. In addition, nesting behavior is sensitive to many environmental and physiological challenges, as well as many genetic mutations underlying pathological disease states. The following protocol describes a nesting behavior paradigm that explores the usage of four types of nesting material. In addition, the protocol utilizes intraclass correlations to demonstrate that inter-rater reliability is higher when nests are constructed out of shredded paper compared to other common nesting materials such as cotton squares, paper twists, and soft cob bedding. The chosen methodology and statistical considerations (i.e., intraclass correlation) for this assay may be of interest for those conducting experiments assessing the quality of living of mice.

Recovery characteristics of Bt insecticidal protein and relative physiological mechanisms after high temperature stress termination in square of Bt cotton

The experiments were conducted at Key Laboratory of Genetics and Physiology of Yangzhou University. The conventional cultivar Sikang-1 and hybrid cultivar Sikang-3 were used as the experimental materials. The potted cotton at squaring stage was moved to artificial climatic chamber with 38°C for 72 h , and 38°C for 96 h respectively in 2017 and 2018 cotton growth season, and moved to natural conditions, then the squares were collected to measure the Bt protein concentration and nitrogen metabolic physiology at 0, 12, 24, 48, 72, 96 hours respectively after the high temperature termination. The square Bt insecticidal protein contents were able to recover to the corresponding control level, the time for the recovery was in need of longer as the stressed high temperature period increased. In 72 h high temperature treatment, the square Bt insecticidal protein content could recover to the corresponding control level at 72 h for Sikang-1 and at 48 h for Sikang-3. In 96 h high temperature treatment, the square Bt insecticidal protein content could recover to the corresponding control level at 96 h for Sikang-1 and at 72 h for Sikang-3. There were significantly positive correlations of Bt toxin content with soluble protein content, glutamate pyruvate transaminase activity and glutamate oxaloacetate transaminase activity (the correlation coefficients were 0.964**, 0.981**, and 0.971**, respectively), and significantly negative correlations of Bt toxin content with free amino acid contents, and activitied of protease and peptidase (the correlation coefficients were -0.894**, -0.912**, and -0.834**, respectively). Therefore, the recovery degree of Bt insecticidal protein content of cotton square can be predicted according to the duration of high temperature stress, reasonably controlling Helicoverpa armigera and related pests in production.

Impacts of soil salinity on Bt protein concentration in square of transgenic Bt cotton.

Insect-resistance of transgenic Bacillus thuringiensis (Bt) cotton varies among plants organs and with different environmental conditions. The objective of this study was to examine the influence of soil salinity on Bt protein concentration in cotton squares and to elucidate the potential mechanism of Bt efficacy reduction. Two cotton cultivars (NuCOTN 33B and CCRI 07, salt-sensitive and salt-tolerant) were subjected to salinity stress under four natural saline levels in field conditions in 2015 and 2016 and seven regimes of soil salinity ranged from 0.5 to 18.8 dS m-1 in greenhouse conditions in 2017. Results of field studies revealed that Bt protein content was not significantly changed at 7.13 dS m-1 salinity, but exhibited a significant drop at the 10.41 and 14.16 dS m-1 salinity. The greenhouse experiments further showed similar trends that significant declines of the insecticidal protein contents in squares were detected when soil salinity exceeded 9.1 dS m-1. Meanwhile, high salinity resulted in significant reduction in contents of soluble protein and total nitrogen, activities of nitrate reductase (NR), glutamine synthetase (GS) and glutamic-pyruvic transaminase (GPT), but increased amino acid content, activities of protease and peptidase in cotton squares. High salinity also decreased root vigor (RV), root total absorption area (RTA) and root active absorption area (RAA). The extent of decrease of Bt protein content was more pronounced in NuCOTN 33B than CCRI 07, and CCRI07 exhibited stronger enzymes activities involved in square protein synthesis and higher levels of RV, RTA and RAA. Therefore, the results of our present study indicated that insecticidal protein expression in cotton squares were significantly affected by higher salinity (equal to or higher than 9.1 dS m-1), reduced protein synthesis and increased protein degradation in squares and reduced metabolic activities in roots might lead to the decrease of Bt protein content in squares.

Boll weevil within season and off-season activity monitored using a pheromone-and-glue reusable tube trap

The boll weevil colonizes cotton fields as early as cotton squaring, causing significant losses due to feeding and protected development inside fruiting structures throughout crop phenology. Successful control depends on control of adults and their accurate detection when they colonize the crops. The commercial trap and boll weevil attract-and-control tubes (BWACT) are the only available tools to monitor and attract-and-kill boll weevil, despite limitation in efficacy, and insecticide in BWACT is not allowed in organic production. A grandlure-and-glue reusable and insecticide-free tube (GGT) made with polyvinyl chloride tube, smeared with entomological glue, and lured with pheromone was tested to detect boll weevil activity across various seasons. Boll weevil showed activity during growing season and off-season from 2009 to 2012 in the Semiarid and with higher numbers captured in GGT in comparisons to commercial traps. GGT was able to detect early weevils in the field right after planting. Further, the overall averages resulted in 34-, 16.8-, and 7.5-times more weevils captured in GGTs compared to the traps during stalk destruction in the Semiarid 2011 and Cerrado season 2012/13 and during the harvesting period in the Cerrado season 2011/12, respectively. Therefore, boll weevils were captured actively during season and off-season and early captures obtained in GGT compared to traps showed a better correlation between captures and square damage.