non-Bt Cotton Research Articles

Life table study of Rachiplusia nu (Lepidoptera: Noctuidae) on different food sources and artificial diet.

Rachiplusia nu Guenée is a polyphagous species able to develop on several cultivated and non-cultivated host plants. However, basic life history information about this pest on hosts is scarce. In this study, R. nu larvae did not survive on leaves of non-Bt corn, wheat, Bt cotton that expresses proteins Cry1Ac+Cry2Ab2 or on Intacta2 Xtend soybean that expresses the Cry1A.105/Cry2Ab2/Cry1Ac proteins. Rachiplusia nu showed a viable egg-to-adult biological cycle (54%-66.3%) on non-Bt soybean, sunflower, canola, vetch, Persian clover, alfalfa, bean, and forage turnip hosts, similar to larvae raised on the artificial diet. In addition, R. nu was unable to complete larval development on non-Bt cotton, and only 45.2% of R. nu larvae reached the pupal stage when fed leaves of intacta RR2 PRO soybean that expresses the Cry1Ac protein. Larval and pupal mass of surviving insects on Cry1Ac soybean leaves were also lower (larval: 0.104g; pupal: 0.099g) in relation to other food sources (larval: 0.165-0.189g; pupal: 0.173-0.192g). The total fecundity of R. nu on Cry1Ac soybean leaves was ≈65% lower in relation to other food sources. This fact caused ≈60% the net reproductive rate (Ro) and intrinsic rate of increase (rm) when compared to other food sources. Our findings indicate that the Cry1Ac soybean negatively affects the biological parameters of R. nu. Non-Bt soybean, sunflower, canola, vetch, Persian clover, alfalfa, bean, and forage turnip are viable food sources for the survival and development of R. nu.

Influence of Weather Parameters on the Development of Grey Mildew Disease in Cotton

A study was conducted at the Regional Agricultural Research Station in Warangal to investigate the impact of environmental factors on the development of grey mildew (Ramularia aerola Atk) in cotton. The research spanned from the Kharif season of 2019-20 to 2022-23 and focused on both Bt and non-Bt cotton genotypes grown in vertisols. Disease scores were recorded weekly on randomly selected labeled plants, and the percentage of disease intensity (PDI) was analyzed in relation to various weather parameters. Grey mildew was observed during the boll development stage up to the boll bursting stage, reaching its peak during the latter phase. Correlation analysis revealed significant negative associations between PDI and maximum temperature, minimum temperature, morning relative humidity, evening relative humidity, rainfall, and the number of rainy days. These findings indicate that these environmental factors influenced the development of the disease in both Bt and non-Bt genotypes. Furthermore, multiple linear regression analysis of PDI demonstrated that one percent increase in evening relative humidity led to a corresponding increase in the percent disease index of grey mildew. Specifically, in Bt (RCH 2 BG II) genotype, the increase was 0.38%, while in non-Bt (LRA-5166) genotype, it was 1.87%. Consequently, the study suggests the implementation of preventive and/or protective measures, such as the use of recommended fungicides like 0.3% wettable sulphur or 0.1% carbendazim.

Incidence of Cotton Thrips (Thrips tabaci Lindeman) and Its Correlation with Weather Parameters

Investigations on incidence of cotton thrips (Thrips tabaci Lindeman) on Bt and non-Bt cotton hybrid were carried out at Main Cotton Research Station, Navsari Agricultural University, Surat (Gujarat) during Kharif, 2017-18. The thrips incidence initiated from fourth week of June and it continued till first week of December in Bt and non-Bt cotton. The peak activity of thrips was observed during third week of August in Bt hybrid and the higher fluctuation of thrips was observed during the second week of August to third week of September and first week of October. Thrips population had significant negative correlation with maximum temperature in Bt cotton. In case of non-Bt, the peak activity of thrips was found during first week of September. As far as association with abiotic factors was concerned, maximum temperature and bright sunshine hours had significantly negatively correlation, while minimum temperature and morning relative humidity were positively associated.

Molecular Characterization of Helicoverpa armigera (Hubner) Populations from Punjab, India

Helicoverpa armigera Hubner (Lepidoptera: Noctuidae) is a highly polyphagous and migratory pest of several economically important crops in parts of Africa, Asia, Australia and Europe. Molecular variability of H. armigera infesting different crops viz. non-Bt cotton, pigeon pea, Egyptian clover, sunflower and tomato mostly from the areas near Ludhiana, Punjab, India and inter-location variability on Egyptian clover across three agroclimatic zones of Punjab was studied by mitochondrial cytochrome oxidase I sequence alignments. Based on sequence analysis of mitochondrial cytochrome oxidase I gene, the Ludhiana population differed from Gurdaspur population by the 0.2% and from Abohar population by 0.5% while the latter two differed from each other by 0.7%. Among populations infesting various host plants, cotton population differed from sunflower by 0.2%, Egyptian clover by 0.3% and tomato and pigeon pea by 0.4% suggesting little genetic variation among populations collected from different regions of Punjab and infesting various hosts.

Biochemical appraisal of different plant parts of BT and non-BT cotton genotypes

Biochemical appraisal of different plant parts of BT and non-BT cotton genotypes

Yield and yield attributes of non-bt cotton genotypes under different protection measures for sucking pest

Yield and yield attributes of non-bt cotton genotypes under different protection measures for sucking pest

Variability in bacterial endophytes in leaves of transgenic Bt and non-Bt cotton crop varieties and their role in suppression of bacterial leaf blight pathogen X. a. pv. malvacearum and the incited disease reaction

Microbial epiphytes and endophytes are an integral part of the plant system and are known to play various roles in crop growth and crop health management. The transgenic crop plays an important role in crop pest management, however, environmentalists and ecologists have reservations about the cultivation of these crops. Whether the transgenic Bt cotton and non-Bt cotton vary in their microbial habitat ecology is not yet studied. In the present investigations, the leaf endophytic bacteria were detected in the leaves of both transgenic Bt and non-Bt cotton hybrids. However, there were differences in the endophytic bacterial types and their population densities i.e. bacterial colony-forming units (cfu) in the leaves of Bt and non-Bt cotton varieties. At least ten different leaf endophytic bacteria were detected from two cotton varieties i.e. RCH-2 and Bunny (of transgenic Bt and non-Bt versions). A maximum of four types of leaf endophytic bacteria was present in RCH-2 Bt cotton leaves. The population density of leaf endophytic bacteria ranged from 50 cfu/leaf to 5 x 103 cfu/leaf and varied with individual leaf endophyte and cotton variety. These bacterial leaf endophytes were observed to inhibit or suppress the growth of bacterial leaf blight pathogen Xanthomonas axonopodis pv. malvacearum (Xam) under in-vitro test. Leaf endophyte no.7 was more effective followed by leaf endophyte no.4 in suppressing the Xam population and population of other endophytes in the interaction studies. Interaction of leaf endophytes and Xam in cotton leaves suggested that endophytes of transgenic Bunny-Bt were effective on Xam in transgenic Bunny–Bt hybrid only and so these changed the induction of susceptible water-soaking disease reaction into hypersensitive browning resistance reaction (HR). However, these endophytes of Bt-cotton were not effective in the non-Bt version in changing the susceptible reaction of Xam into an HR reaction. This indicated that the endophytes of the respective Bt and non-Bt crops were able to change the susceptible reaction of Xam into a hypersensitive one in their respective host, indicating that the use of leaf endophytes can be effective in their own habitat crop as a biocontrol agent against Xam. The specificity of leaf endophytes has to be considered in biological disease management programs.

Weed Population Dynamics under Organic, Bio-dynamic, Conventional Bt and Non-Bt Cotton (Gossypium hirsutum)

Aim: In order to compare the weed seed bank and population dynamics under organic, biodynamic, Bt-conventional, and non-Bt conventional management systems of cotton (Gossypium hirsutum), a field experiment was carried out.
 Study Design: Randomized Block Design (RBD)
 Place and Duration of Study: bioRe-FiBL research trails, bioRe Association, Kasrawad, Khurgone, Madhya Pradesh during the kharif season of 2020-21.
 Methodology: Five distinct crop management techniques were used in the field experiment, each duplicated four times, and the experiment was set up using a randomized block design. The treatments were distributed at random to different plots. The five management treatments were Absolute Control (no fertilizers), Conventional management of non-Bt cotton, Conventional management of Bt cotton, Bio-dynamic and Organic management of cotton. For the duration of the experiment, four 1 m × 1 m (1 m2) quadrats were randomly placed on each experimental plot's four sides, and different biometric observations were recorded from each quadrant according to its treatment. For the purpose of collecting the necessary observations, two of these quadrants were regularly weeded every 20 days, while the other two were left unweeded for the duration of the experiment.
 Results: The dominant weed species includes Panicum dichotomiflorum, Cyperus rotundus, Paspalum dilatatum, Euphorbia hirta, Acalypha indica and Digeria arvensis. Poaceae was the dominant family in terms of composition. There was very less variation in the weed flora between the treatments. Significantly higher weed seed bank, weed species, weed density and weed dry weight were observed in Organic and Biodynamic cotton than in the Conventional cotton. Weed control efficiency was found to be maximum in the Conventional cotton compared to the Organic and Biodynamic cotton.
 Conclusion: From the experiment, it can be concluded that the Conventional cotton especially Conventional management Bt Cotton was found to be most efficient among all the treatments. However, the Organic cotton was observed with high number of overall plant species and best in conserving the plant species biodiversity.

Incidence pattern of pink bollworm, Pectinophora gossypiella (Saund.)on different event Bt and non-Bt cottons

A field experiment was conducted at the Agricultural Research Station, Dharwad Farm, Dharwad, Karnatakaduring 2018-19 to evaluate the performance of cultivated cotton genotypes including Bt and non-Bt against pink bollworm,Pectinophora gossypiella (Saund.) under rainfed conditions. Based on seasonal mean green boll damage, Everest (13.56%)performed better against pink bollworm over single gene BG-I Bt variety PAU Bt-1 (16.55%), BG-I Bt hybrid MRC 6918(25.88%) (Both expressing Cry1Ac) and Arjun-21 Cry1A) and BG-II hybrid MRC 7918 (15.52%).DCH-32 (Non Btinterspecific hybrid) had maximum infestation of 37.59 per cent followed by H×H hybrid DHH-263 (36.34%), Suvin(21.38%), DDhc-11 (21.59%), Sahana (20.21%) and DLSa-17 (18.65%). The maximum larval recovery was 12.66 per 20green bolls in DCH-32 followed by DHH-263 (12.58) and Suvin (11.12). In general, Non-Bt genotypes had higher incidencethan Bt genotypes. Similarly, among Bt toxin, Cry1Ac and Cry2Ab expressing genotype had lower incidence.

Rhizosphere Soil Bacterial Communities and Bacterial Root Endophytes in Cotton farming is Influence by Cultivation of Transgenic Bt and non-Bt Cotton Crop Varieties

Rhizosphere Soil Bacterial Communities and Bacterial Root Endophytes in Cotton farming is Influence by Cultivation of Transgenic Bt and non-Bt Cotton Crop Varieties

Comparison of cotton (Gossypium hirsutum) hybrids and their non-transgenic in India

It is still not clear whether differential response of Bt cotton and conventional non-Bt cotton genotypes in terms of growth, phenology and yield ability are hypothetical or realistic. This study investigated the response of three Bt cotton hybrids in comparison to their conventional non-transgenic version (near-isogenic lines) along with two locally adapted genotypes for growth, yield attributes, phenological characteristics and rooting behavior. Therefore, two experiments were conducted during summer season of year 2016 and 2017 to evaluate differences among 3 popular Bt cotton hybrids along with their non-Bt version. First field experiment was conducted as a pot study wherein shoot and root parameters of 3 Bt cotton hybrids (Ankur 3028, MRC 7017, Bioseed 6588) were compared with their non-Bt version along with 2 local checks (i.e.,hirsutum cotton Cv. F2228 and arboreum cottonCv. FDK124). Second field experiment evaluated growth, phenological characteristics, yield attributes and productivity potential of above mentioned Bt and non-Bt hybrids. Findings of pot experiment could not establish any significant difference among studied Bt and non-Bt hybrids for root and shoot characteristics. However, arboreum cotton FDK124 exhibited higher root length than all genotypes. Results of second experiment revealed significant differences for phenological characteristics, wherein Bt version of all the tested hybrids exhibited earliness for flowering initiation, 50 % flowering and days to maturity over their non-Bt version. Seed cotton yield (SCY) in all hybrids possessing Bt gene was significantly higher than their non-Bt version primarily due to higher bolls plant-1. Studies conclude that introgression of Bt gene could not alter rooting parameters of evaluated cotton genotypes but significantly affected phenological stages by inducing earliness and higher SCY in Bt versions due to improved bolls plant-1. Keywords: Bt cotton; Near-isogenic lines; Phenology; Root dry matter; Seed cotton yield

Azotobacter inoculation can enhance the resistance of Bt cotton to cotton bollworm, Helicoverpa armigera.

The rising trend in the cultivation of Bacillus thuringiensis (Bt) transgenic crops may cause a destabilization of agroecosystems, thus increasing concerns about the sustainability of Bt crops as a valid pest management method. Azotobacter can be used as a biological regulator to increase environmental suitability and improve the soil nitrogen utilization efficiency of crops, especially Bt cotton. A laboratory test investigated effects on the development and food utilization of Helicoverpa armigera fed with different Cry1Ab/Cry1Ac proteins and nitrogen metabolism-related compounds from cotton (transgenic variety SCRC37 vs non-Bt cotton cv. Yu2067) inoculated with Azospirillum brasilense (Ab) and Azotobacter chroococcum (Ac). The findings indicate that inoculation with Azotobacter significantly decreased the partial development and food utilization indexes (pupal weight; pupation rate; adult longevity; fecundity; relative growth rate, RGR; efficiency of conversion of digested food, ECD; and efficiency of conversion of ingested food, ECI) of H.armigera fed on Bt cotton, but contrasting trends were found among these indexes in H.armigera fed on non-Bt cotton inoculated with Azotobacter, as a result of differences in Bt toxin production. Overall, the results showed that inoculation with Azotobacter had negative effects on the development and food utilization of H.armigera fed on Bt cotton, leading to enhanced target insect resistance. Presumably, Azotobacter inoculation can be used to stimulate plant soil nitrogen uptake to increase nitrogen metabolism-related compounds and promote plant growth for Bt and non-Bt cotton, simultaneously raising Bt protein expression and enhancing resistance efficacy against cotton bollworm in Bt cotton.

NMR-Based Metabolomics: A New Paradigm to Unravel Defense-Related Metabolites in Insect-Resistant Cotton Variety through Different Multivariate Data Analysis Approaches.

Cotton (Gossypium hirsutum) is an economically important crop and is widely cultivated around the globe. However, the major problem of cotton is its high vulnerability to biotic and abiotic stresses. It has been around three decades since the cotton plant was genetically engineered with genes encoding insecticidal proteins (mainly Cry proteins) with an aim to protect it against insect attack. Several studies have been reported on the impact of these genes on cotton production and fiber quality. However, the metabolites responsible for conferring resistance in genetically modified cotton need to be explored. The current work aims to unveil the key metabolites responsible for insect resistance in Bt cotton and also compare the conventional multivariate analysis methods with deep learning approaches to perform clustering analysis. We aim to unveil the marker compounds which are responsible for inducing insect resistance in cotton plants. For this purpose, we employed 1H-NMR spectroscopy to perform metabolite profiling of Bt and non-Bt cotton varieties, and a total of 42 different metabolites were identified in cotton plants. In cluster analysis, deep learning approaches (linear discriminant analysis (LDA) and neural networks) showed better separation among cotton varieties compared to conventional methods (principal component analysis (PCA) and orthogonal partial least square discriminant analysis (OPLSDA)). The key metabolites responsible for inter-class separation were terpinolene, α-ketoglutaric acid, aspartic acid, stigmasterol, fructose, maltose, arabinose, xylulose, cinnamic acid, malic acid, valine, nonanoic acid, citrulline, and shikimic acid. The metabolites which regulated differently with the level of significance p < 0.001 amongst different cotton varieties belonged to the tricarboxylic acid cycle (TCA), Shikimic acid, and phenylpropanoid pathways. Our analyses underscore a biosignature of metabolites that might involve in inducing insect resistance in Bt cotton. Moreover, novel evidence from our study could be used in the metabolic engineering of these biological pathways to improve the resilience of Bt cotton against insect/pest attacks. Lastly, our findings are also in complete support of employing deep machine learning algorithms as a useful tool in metabolomics studies.

Managing Practical Resistance of Lepidopteran Pests to Bt Cotton in China

China is one of the major cotton producers globally with small farmers. Lepidopteran pests have always been the main factor affecting cotton production. To reduce the occurrence of and damage caused by lepidopteran pests, China has employed a pest control method focused on planting Bt (Cry1Ac) cotton since 1997. Chinese resistance management tactics for the main target pests, the cotton bollworm and pink bollworm, were also implemented. For polyphagous (multiple hosts) and migratory pests such as the cotton bollworm (Helicoverpa armigera), the "natural refuge" strategy, consisting of non-Bt crops such as corn, soybean, vegetables, peanuts, and other host crops, was adopted in the Yellow River Region (YRR) and Northwest Region (NR). For a single host and weak migration ability pest, such as the pink bollworm (Pectinophora gossypiella), the seed mix refuge strategy yields a random mixture within fields of 25% non-Bt cotton by sowing second-generation (F2) seeds. According to field monitoring results for more than 20 years in China, practical resistance (Bt cotton failure) of target pests was avoided, and there were no cases of Bt (Cry1Ac) failure of pest control in cotton production. This indicated that this Chinese resistance management strategy was very successful. The Chinese government has decided to commercialize Bt corn, which will inevitably reduce the role of natural refuges; therefore, this paper also discusses adjustments and future directions of cotton pest resistance management strategies.

Effect of &lt;i&gt;BT&lt;/i&gt; and Non-&lt;i&gt;BT&lt;/i&gt; Cotton on Biology of &lt;i&gt;Thrips Tabaci&lt;/i&gt; and Its Management Using Insecticides

The development of Thrips tabaci was studied on transgenic BG I, BG II, non-Bt, and desi cotton cultivars. The oviposition period was minimum on desi cotton, FDK 124 (11.67 days) as compared to BG II (RCH 650) and non-Bt cotton (LH 2076). Female longevity was minimum on FDK 124 (17.50 days) followed by RCH 650 (23.17 days) and LH 2076 (21.83 days). Maximum female longevity was recorded on BGI cotton cultivar RCH 308 (26.83 days). Nymphal, pupal period, and total development period were minimum on FDK 124 (8.17, 2.33, and 34.00 days) as compared to Bt and non-Bt cotton cultivar, LH2076. Based on the higher oviposition period, female longevity, fecundity, and nymphal period, Bt cotton hybrids were found to be more favourable for thrips development in comparison to non-Bt cotton cultivars and desi cotton . The new generation insecticide, spinetoram 11.7SC @ 425g/ ha was most effective and also found to be safe to the predators.

Growth, yield and fiber quality characteristics of Bt and non-Bt cotton cultivars in response to boron nutrition

BackgroundBoron (B) deficiency is an important factor for poor seed cotton yield and fiber quality. However, it is often missing in the plant nutrition program, particularly in developing countries. The current study investigated B's effect on growth, yield, and fiber quality of Bt (CIM-663) and non-Bt (Cyto-124) cotton cultivars. The experimental plan consisted of twelve treatments: Control (CK); B at 1 mg·kg−1 soil application (SB1); 2 mg·kg−1 B (SB2); 3 mg·kg−1 B (SB3); 0.2% B foliar spray (FB1); 0.4% B foliar spray (FB2); 1 mg·kg−1 B + 0.2% B foliar spray (SB1 + FB1); 1 mg·kg−1 B + 0.4% B foliar spray (SB1 + FB2); 2 mg·kg−1 B + 0.2% B foliar spray (SB2 + FB1); 2 mg·kg−1 B + 0.4% B foliar spray (SB2 + FB2); 3 mg·kg−1 B + 0.2% B foliar spray (SB3 + FB1); 3 mg·kg−1 B + 0.4% B foliar spray (SB3 + FB2). Each treatment has three replications, one pot having two plants per replication.ResultsB nutrition at all levels and methods of application significantly (P ≤ 0.05) affected the growth, physiological, yield, and fiber quality characteristics of both cotton cultivars. However, SB2 either alone or in combination with foliar spray showed superiority over others, particularly in the non-Bt cultivar which responded better to B nutrition. Maximum improvement in monopodial branches (345%), sympodial branches (143%), chlorophyll-a (177%), chlorophyll-b (194%), photosynthesis (169%), and ginning out turn (579%) in the non-Bt cultivar was found with SB2 compared with CK. In Bt cultivar, although no consistent trend was found but integrated use of SB3 with foliar spray performed relatively better for improving cotton growth compared with other treatments. Fiber quality characteristics in both cultivars were improved markedly but variably with different B treatments.ConclusionB nutrition with SB2 either alone or in combination with foliar spray was found optimum for improving cotton's growth and yield characteristics.

Influence of Transgenic (Bt) Cotton on the Productivity of Various Cotton-Based Cropping Systems in Pakistan

Cotton (Gossypium hirsutum L.) is an important fiber crop in Pakistan with significant economic importance. Transgenic, insect-resistant cotton (carrying a gene from Bacillus thuringiensis (Bt)) was inducted in the cotton-based cropping systems of Pakistan during 2002, and is now sown in &gt;90% of cotton fields in the country. However, concerns are rising that Bt cotton would decrease the productivity of winter crops (sown after cotton), leading to decreased system productivity. This two-year field study determined the impacts of transgenic (Bt) and non-transgenic (non-Bt) cotton genotypes on the productivities of winter crops (i.e., wheat, Egyptian clover, and canola), and the overall productivities of the cropping systems including these crops. Four cotton genotypes (two Bt and two non-Bt) and three winter crops (i.e., wheat, Egyptian clover, and canola) were included in the study. Nutrient availability was assessed after the harvest of cotton and winter crops. Similarly, the yield-related traits of cotton and winter crops were recorded at their harvest. The productivities of the winter crops were converted to net economic returns, and the overall economic returns of the cropping systems with winter crops were computed. The results revealed that Bt and non-Bt cotton genotypes significantly (p &lt; 0.05) altered nutrient availability (N, P, K, B, Zn, and Fe). However, the yield-related attributes of winter crops were not affected by cotton genotypes, whereas the overall profitability of the cropping systems varied among the cotton genotypes. Economic analyses indicated that the Bt cotton–wheat cropping system was the most profitable, with a benefit–cost ratio of 1.55 in the semi-arid region of Pakistan. It is concluded that Bt cotton could be successfully inducted into the existing cropping systems of Pakistan without any decrease to the overall productivity of the cropping system.

Effect of Bt (Cry1Ac and Cry2Ab) and non-Bt cotton on the temporal variation of A. grandis and representatives of the Spodoptera complex in Tolima, Colombia

Transgenic cotton plants (Bacillus thuringiensis Berliner (Bt)) has significant influenced the integrated pest management around the world. In Colombia, Anthonomus grandis Boheman and Spodoptera complex are currently considered the main pests in cotton crops. Therefore, this study evaluated the effect of Bt (Cry1Ac and Cry2Ab) and non-Bt cotton on the population fluctuation during two years in Tolima region. A Pearson correlation matrix was carried out between the pest variables and yield, while climatic variables and insect populations were correlated in four phenological stages with Spearman rank correlations. Additionally, a factor analysis for mixed data was performed in order to compare the effect of genotypes on the population fluctuation of the insects. For A. grandis, no differences in their populations were presented. However, in yield non-Bt cotton plants showed a higher inverse correlation with the perforated bolls compared to Bt cotton. In relation to the Spodoptera complex, the Bt genotype had 67.4% fewer larvae compared to non-Bt cotton. Statistically significant differences were presented. However, there was not a total absence of the pest during the entire crop cycle. These results suggest that if refuge zones and pest management practices are not determined in the study area, Spodoptera complex could generate resistance to genetically modified plants.

Efficacy of Bt Toxins and Foliar Insecticides Against Bollworm, Helicoverpa zea (Boddie), in Dried Flower Corollas of Cotton

Foliar insecticides and insecticidal protein from Bacillus thuringiensis (Bt) in transgenic cotton are common tools used for bollworm management in cotton. Efficacy of Bt proteins and foliar insecticides can be dependent upon larval location in the plant canopy and time of year. Floral structures are known to be a common food source for bollworm. Floral components can complicate bollworm control with foliar insecticides and transgenic cotton by protecting larvae from contact with formulated insecticides and lower concentrations of Bt proteins. Mortality was measured to evaluate the effects of Bt expression and foliar insecticides in flowers of non-Bt, two-gene Bt, and three-gene Bt cotton varieties. Expression of Bt protein in white flowers provided some efficacy after three days. Bollworm mortality at three days after infestation was less than 50% for all varieties in an unsprayed environment. Larval mortality on Bollgard 3 flowers was higher than that on Bollgard II flowers. Surviving larvae feeding on Bollgard 3 flowers weighed less than larvae that fed on Bollgard II flowers, and larvae that fed on Bollgard II flowers weighed less than those that fed on non-Bt flowers. The use of chlorantraniliprole or methoxyfenozide + spinetoram provided some control of bollworms three days after application to wilting flower corollas (bloom tags). Mortality ranged from 41.9% following application of chlorantraniliprole to 61.0% following application of methoxyfenozide + spinetoram. Results from this study will be used to improve integrated pest management programs for bollworm management in cotton.

Relationship Between Damage by Cotton Bollworm Helicoverpa armigera (Hübner) and Different Plant Characteristics of Bt and Non-Bt Cotton Varieties in Pakistan

Relationship Between Damage by Cotton Bollworm Helicoverpa armigera (Hübner) and Different Plant Characteristics of Bt and Non-Bt Cotton Varieties in Pakistan