scholarly journals Development of Economic Thresholds Toward Bollworm (Lepidoptera: Noctuidae), Management in Bt Cotton, and Assessment of the Benefits From Treating Bt Cotton With Insecticide

2021 ◽  
Author(s):  
Wilfrid Calvin ◽  
Fei Yang ◽  
Sebe A Brown ◽  
Angus L Catchot ◽  
Whitney D Crow ◽  
...  
Keyword(s):  
Helicoverpa Zea ◽  
Field Experiments ◽  
Management Program ◽  
Bt Cotton ◽  
Cotton Production ◽  
Economic Injury Level ◽  
Insecticide Application ◽  
Yield Increase ◽  
Injury Threshold ◽  
Economic Thresholds

Abstract Widespread field-evolved resistance of bollworm [Helicoverpa zea (Boddie)] to Cry1 and Cry2 Bt proteins has threatened the utility of Bt cotton for managing bollworm. Consequently, foliar insecticide applications have been widely adopted to provide necessary additional control. Field experiments were conducted across the Mid-South and in Texas to devise economic thresholds for foliar insecticide applications targeting bollworm in cotton. Bt cotton technologies including TwinLink (TL; Cry1Ab+Cry2Ae), TwinLink Plus (TLP; Cry1Ab+Cry2Ae+Vip3Aa), Bollgard II (BG2; Cry1Ac+Cry2Ab), Bollgard 3 (BG3; Cry1Ac+Cry2Ab+Vip3Aa), WideStrike (WS; Cry1Ac+Cry1F), WideStrike 3 (WS3; Cry1Ac+Cry1F+Vip3Aa), and a non-Bt (NBT) variety were evaluated. Gain threshold, economic injury level, and economic thresholds were determined. A 6% fruiting form injury threshold was selected and compared with preventive treatments utilizing chlorantraniliprole. Additionally, the differences in yield from spraying bollworms was compared among Bt cotton technologies. The 6% fruiting form injury threshold resulted in a 25 and 75% reduction in insecticide applications relative to preventive sprays for WS and BG2, respectively. All Bt technologies tested in the current study exhibited a positive increase in yield from insecticide application. The frequency of yield increase from spraying WS was comparable to that of NBT. Significant yield increases due to insecticide application occurred less frequently in triple-gene Bt cotton. However, their frequencies were close to the dual-gene Bt cotton, except for WS. The results of our study suggest that 6% fruiting form injury is a viable threshold, and incorporating a vetted economic threshold into an Integrated Pest Management program targeting bollworm should improve the sustainability of cotton production.

Economic Injury Levels for Bt-resistant Helicoverpa zea (Lepidoptera: Noctuidae) in Cotton

2021 ◽  
Author(s):  
Alejandro I Del Pozo-Valdivia ◽  
Dominic D Reisig ◽  
Lewis Braswell ◽  
Jeremy K Greene ◽  
Phillip Roberts ◽  
...  
Keyword(s):  
Helicoverpa Zea ◽  
The United States ◽  
Yield Response ◽  
Bt Cotton ◽  
Larval Population ◽  
Cry Toxins ◽  
Economic Thresholds ◽  
Cry Toxin ◽  
Economic Injury ◽  
Larval Number

Abstract Thresholds for Helicoverpa zea (Boddie) in cotton Gossypium hirsutum L. have been understudied since the widespread adoption of Bt cotton in the United States. Our study was possible due to the widespread presence of H. zea populations with Cry-toxin resistance. We initiated progressive spray timing experiments using three Bt cotton brands (Deltapine, Stoneville, and Phytogen) widely planted across the U.S. Cotton Belt expressing pyramided toxins in the Cry1A, Cry2, and Vip3Aa19 families. We timed foliar insecticide treatments based on week of bloom to manipulate H. zea populations in tandem with crop development during 2017 and 2018. We hypothesized that non-Bt cotton, cotton expressing Cry toxins alone, and cotton expressing Cry and Vip3Aa19 toxins would respond differently to H. zea feeding. We calculated economic injury levels to support the development of economic thresholds from significant responses. Pressure from H. zea was high during both years. Squares and bolls damaged by H. zea had the strongest negative yield associations, followed by larval number on squares. There were fewer yield associations with larval number on bolls and with number of H. zea eggs on the plant. Larval population levels were very low on varieties expressing Vip3Aa19. Yield response varied across experiments and varieties, suggesting that it is difficult to pinpoint precise economic injury levels. Nonetheless, our results generally suggest that current economic thresholds for H. zea in cotton are too high. Economic injury levels from comparisons between non-Bt varieties and those expressing only Cry toxins could inform future thresholds once H. zea evolves resistance to Vip3Aa19.

scholarly journals Effectiveness of the natural resistance management refuge for Bt-cotton is dominated by local abundance of soybean and maize

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Benjamin Arends ◽  
Dominic D. Reisig ◽  
Shawnee Gundry ◽  
Anders S. Huseth ◽  
Francis P. F. Reay-Jones ◽  
...  
Keyword(s):  
Environmental Protection Agency ◽  
Helicoverpa Zea ◽  
Resistance Management ◽  
Management Plan ◽  
Genetically Engineered ◽  
Natural Resistance ◽  
Bt Cotton ◽  
Cotton Production ◽  
Insect Management ◽  
Management Measures

AbstractGenetically engineered crops expressing Bacillus thuringiensis (Bt) Cry toxins have transformed insect management in maize and cotton, reducing insecticide use and associated off-target effects. To mitigate the risk that pests evolve resistance to Bt crops, the US Environmental Protection Agency requires resistance management measures. The approved resistance management plan for Bt maize in cotton production regions requires a structured refuge of non-Bt maize equal to 20% of the maize planted; that for Bt cotton relies on the presence of an unstructured natural refuge comprising both non-Bt crop and non-crop hosts. We examined how abundance of Bt crops (cotton and maize) and an important non-Bt crop (soybean) component of the natural refuge affect resistance to Bt Cry1Ac toxin in local populations of Helicoverpa zea, an important lepidopteran pest impacted by Bt cotton and maize. We show refuge effectiveness is responsive to local abundances of maize and cotton and non-Bt soybean, and maize, in its role as a source of H. zea infesting cotton and non-Bt hosts, influences refuge effectiveness. These findings have important implications for commercial and regulatory decisions regarding deployment of Bt toxins targeting H. zea in maize, cotton, and other crops and for assumptions regarding efficacy of natural refuges.

Economic threshold levels for Chilo partellus (Lepidoptera: Pyralidae) control on resistant and susceptible sorghum plants

1997 ◽  
Vol 87 (1) ◽  
pp. 89-93 ◽  
Author(s):  
J. van den Berg ◽  
G. D. J. van Rensburg ◽  
M. C. van der Westhuizen
Keyword(s):  
Chilo Partellus ◽  
Yield Loss ◽  
Threshold Level ◽  
Field Trials ◽  
Economic Injury Level ◽  
Economic Threshold ◽  
Insecticide Application ◽  
Yield Increase ◽  
Linear Relationships ◽  
Economic Injury

AbstractThe effect of various infestation levels of Chilo partellus Swinhoe on resistant and susceptible sorghum genotypes was assessed under artificial infestation in two field trials, conducted over two seasons. In the first season, infestation levels were 0, 10, 20, 40, 60 and 80 larvae per 2 m plot row. In the second season, additional treatments of one and two larvae per plot were included. A series of all infestation levels on susceptible plants was also included with an insecticide application 5 days after inoculation. Non-linear relationships between infestation level and yield loss were observed. In susceptible plants, small increases in initial larval infestation levels resulted in sharp increases in yield loss. An opposite tendency was observed in resistant plants where a tolerant reaction at lower infestation levels was observed. Gain threshold (GT) value, indicating the yield increase necessary to compensate for control costs, economic injury level (EIL) and economic threshold level (ETL) at which control actions should be initiated were determined for each genotype. Insecticide application on susceptible plants resulted in a 10% reduction in yield loss. However, the yield was still less than that of unsprayed resistant plants. The GT values indicated that insecticide application was economically warranted at an ETL of 20% and 2% of plants with visible symptoms of whorl damage, for the resistant and susceptible genotypes respectively.

scholarly journals Perception and Use of Economic Thresholds Among Farmers and Agricultural Professionals: A Case Study on Soybean Aphid in Minnesota

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Natalie Hoidal ◽  
Robert L Koch
Keyword(s):  
Soybean Aphid ◽  
Educational Outreach ◽  
Economic Injury Level ◽  
Economic Thresholds ◽  
Foundational Principle ◽  
Economic Injury ◽  
Fundamental Misunderstanding ◽  
The Difference ◽  
Commercial Pesticide ◽  
Agricultural Professionals

Abstract Economic thresholds (ETs) are a foundational principle of integrated pest management but are not always widely accepted by farmers and agricultural professionals. This article reports on a survey of Minnesota farmer and agricultural professional perceptions of the ET for soybean aphid, Aphis glycines Matsumura (Hempitera: Aphididae). We discuss insights for Extension programs on how to frame the importance of thresholds and teach stakeholders to use them effectively. Key takeaways include farmers and agricultural professionals often worry about combined effects of insect, disease, and physiological pressures, whereas effects of interactions with these other stressors are seldom discussed in educational outreach. Across groups, there is a fundamental misunderstanding about the difference between ETs and economic injury level. Many survey participants reported believing in the ET but lacked the time and capacity to fully implement it. Sales agronomists and farmers were the least likely groups to trust the university-determined soybean aphid ET, whereas commercial pesticide applicators and independent consultants were the most likely groups to trust it. Based on these results, we recommend adapting communication about ETs based on the target audience to address common misconceptions and barriers to ET use that are unique to each group.

Cover Crops Suppression of Palmer Amaranth (Amaranthus palmeri) in Cotton

2017 ◽  
Vol 32 (1) ◽  
pp. 60-65 ◽  
Author(s):  
Matheus G. Palhano ◽  
Jason K. Norsworthy ◽  
Tom Barber
Keyword(s):  
Cover Crops ◽  
Cover Crop ◽  
Field Experiments ◽  
Palmer Amaranth ◽  
Cotton Yield ◽  
Cotton Production ◽  
Seed Cotton ◽  
Cereal Rye ◽  
Seed Cotton Yield ◽  
Weed Emergence

AbstractWith the recent confirmation of protoporphyrinogen oxidase (PPO)-resistant Palmer amaranth in the US South, concern is increasing about the sustainability of weed management in cotton production systems. Cover crops can help to alleviate this problem, as they can suppress weed emergence via allelochemicals and/or a physical residue barrier. Field experiments were conducted in 2014 and 2015 at the Arkansas Agricultural Research and Extension Center to evaluate various cover crops for suppressing weed emergence and protecting cotton yield. In both years, cereal rye and wheat had the highest biomass production, whereas the amount of biomass present in spring did not differ among the remaining cover crops. All cover crops initially diminished Palmer amaranth emergence. However, cereal rye provided the greatest suppression, with 83% less emergence than in no cover crop plots. Physical suppression of Palmer amaranth and other weeds with cereal residues is probably the greatest contributor to reducing weed emergence. Seed cotton yield in the legume and rapeseed cover crop plots were similar when compared with the no cover crop treatment. The seed cotton yield collected from cereal cover crop plots was lower than from other treatments due to decreased cotton stand.

scholarly journals Yield performance and stability of modern breeding stock of spring durum wheat (Triticum durum Desf.) from Russia and Kazakhstan

2019 ◽  
Vol 22 (8) ◽  
pp. 939-950 ◽  
Author(s):  
P. N. Mal’chikov ◽  
M. A. Rozova ◽  
A. I. Morgunov ◽  
M. G. Myasnikova ◽  
Yu. I. Zelensky
Keyword(s):  
Durum Wheat ◽  
Field Experiments ◽  
Environment Interaction ◽  
Adaptive Responses ◽  
Breeding Lines ◽  
Yield Increase ◽  
Ecological Sites ◽  
Local Environments ◽  
Modern Breeding ◽  
Research Institute

Identifcation of adaptive responses of breeding material, developed in different breeding centers, helps to purposefully correct these traits where it is necessary. Thus, 42 modern breeding lines from eight institutions of Russia and Kazakhstan were studied in comparison with the historical standard Bezenchukskaya 139 in trails of 16-17 and 18 KASIB-SDW (Kazakhstan-Siberian net for wheat improvement, spring durum wheat) in 2015–2017. Field experiments and yield measurements in each ecological cite were similar. To solve these tasks of the experiment, two-factor ANOVA, methods for adaptability assessment cluster analysis and principle component method were applied. As a result, it was established that 1) genotype and genotype – environment interaction (overall 15.8–23.5 % of total dispersion) had signifcant effect on yield variability; 2) genotype – environment interactions were of linear nature and had no destabilizing effect; 3) all the genotypes tested can be distributed in three clusters, the frst one for locally adapted varieties, the third for varieties of a wide areal, the second included genotypes with intermediate characteristics; 4) breeding centers of the Federal Altai Scientifc Centre of Agro-Biotechnologies and of the Research Institute of Agriculture of South-East produced predominantly varieties of local importance, the Samara Research Institute of Agriculture – varieties of wide area; 5) a stable trend of increased mean yield compared to historical standard Bezenchukskaya 139 over ecological sites was observed only for Samara varieties; 6) varieties of all the breeding centers had no stable difference from Bezenchukskaya 139 concerning stability and responsiveness, which can be explained by an incomplete breeding process for these parameters and confrms the importance of the KASIB program; 7) a trend of yield increase compared to Bezenchukskaya 139 under testing in defnite local environments had more stable parameters with the largest progress observed in the Altai Research Institute of Agriculture (135.4 and 163.2 % to Bezenchukskaya 139), which can be explained by a high efciency of breeding of locally adapted varieties in the breeding center.

Broad-scale suppression of cotton bollworm, Helicoverpa armigera (Lepidoptera: Noctuidae), associated with Bt cotton crops in Northern New South Wales, Australia

2016 ◽  
Vol 107 (2) ◽  
pp. 188-199 ◽  
Author(s):  
G.H. Baker ◽  
C.R. Tann
Keyword(s):  
Host Plant ◽  
Helicoverpa Armigera ◽  
Cotton Bollworm ◽  
Bt Cotton ◽  
Cotton Production ◽  
Bt Toxin ◽  
Pheromone Trapping ◽  
Eastern Australia ◽  
Helicoverpa Armígera ◽  
Broad Scale

AbstractThe cotton bollworm, Helicoverpa armigera, is a major pest of many agricultural crops in several countries, including Australia. Transgenic cotton, expressing a single Bt toxin, was first used in the 1990s to control H. armigera and other lepidopteran pests. Landscape scale or greater pest suppression has been reported in some countries using this technology. However, a long-term, broad-scale pheromone trapping program for H. armigera in a mixed cropping region in eastern Australia caught more moths during the deployment of single Bt toxin cotton (Ingard®) (1996–2004) than in previous years. This response can be attributed, at least in part, to (1) a precautionary cap (30% of total cotton grown, by area) being applied to Ingard® to restrict the development of Bt resistance in the pest, and (2) during the Ingard® era, cotton production greatly increased (as did that of another host plant, sorghum) and H. armigera (in particular the 3rd and older generations) responded in concert with this increase in host plant availability. However, with the replacement of Ingard® with Bollgard II® cotton (containing two different Bt toxins) in 2005, and recovery of the cotton industry from prevailing drought, H. armigera failed to track increased host-plant supply and moth numbers decreased. Greater toxicity of the two gene product, introduction of no cap on Bt cotton proportion, and an increase in natural enemy abundance are suggested as the most likely mechanisms responsible for the suppression observed.

scholarly journals A discussion on cotton transformation during the last decade (2010–2021); an update on present trends and future prospects

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
QANDEEL-E-ARSH ◽  
Muhammad Tehseen AZHAR ◽  
Rana Muhammad ATIF ◽  
Mahwish ISRAR ◽  
Azeem Iqbal KHAN ◽  
...  
Keyword(s):  
Herbicide Tolerance ◽  
Routine Activity ◽  
Fourth Generation ◽  
Bt Cotton ◽  
Gene Gun ◽  
Cotton Production ◽  
Cotton Transformation ◽  
Lepidopteran Insects ◽  
The Us ◽  
The World

AbstractThe introduction of genetically modified (GM) cotton in 1996 in the US and its worldwide spread later rejuvenated cotton production in many parts of the world. The evolution is continued since then and currently, the 3rd and fourth generation of same GM cotton is grown in many parts of the world. The GM cotton introduced in 1996 was simple Bt cotton that expressed a single Cry1Ac gene, the later generation carried multiple Cry genes along with the genes controlling herbicide tolerance. Current day GM cotton does not only give stable resistance against lepidopteran insects but also facilitates the farmers to spray broad-spectrum herbicides without harming the crop. The evolution of GM cotton is continued both on the basic and applied side and interventions have been introduced during the last decade. Earlier the cotton transformation was limited to Cocker strains which are getting possible in many other varieties, too. It is successful with both gene gun, and Agrobacterium and inplanta transformation has made it a routine activity. Apart from overexpression studies for various purposes including biotic, abiotic, and quality traits, RNAi and genome editing are explored vigorously. Through this review, we have tried to explore and discuss various interventions for improving transformation protocols, the applications of cotton transformation, and future strategies being developed to get maximum benefits from this technology during the last decade.

Helicoverpa zea (Lepidoptera: Noctuidae) Preference for Plant Structures, and Their Location, Within Bt Cotton Under Different Nitrogen and Irrigation Regimes

2019 ◽  
Vol 112 (4) ◽  
pp. 1741-1751
Author(s):  
Lewis R Braswell ◽  
Dominic D Reisig ◽  
Clyde E Sorenson ◽  
Guy D Collins
Keyword(s):  
Helicoverpa Zea ◽  
Resistance Management ◽  
Larval Feeding ◽  
Bt Cotton ◽  
Larval Distribution ◽  
Cotton Plants ◽  
Small Plot ◽  
Nitrogen Treatments ◽  
Behavioral Resistance ◽  
Lepidoptera Noctuidae

Abstract Helicoverpa zea Boddie is a common economic pest of cotton (Gossypium hirsutum L.), including transgenic cotton varieties that express Bacillus thuringiensis (Bt). Helicoverpa zea oviposition is similar in Bt and non-Bt cotton, but behavior of H. zea larvae can be different in the presence of Bt, with neonates moving away from terminals faster in single-toxin Bt than non-Bt cotton or avoiding Bt-treated diet in the lab. We quantified H. zea oviposition and larval distribution on structures within cotton plants in small plot experiments of Cry1Ac + Cry1F cotton for 2 yr under different irrigation and nitrogen treatments. More eggs were oviposited on plants receiving nitrogen application during 2016 and on leaves in the top section of irrigated plants during 2017, but other treatment effects on eggs or larvae were minimal. Helicoverpa zea eggs were most common on leaves in the top third of plants at position zero and middle section of cotton plants throughout the season, but some oviposition occurred on fruiting structures as well. First and second instars were more common on squares in the top section of plants during 2016 and bolls in the middle and lower sections during 2017 due to oviposition lower in the canopy during 2017. During both years, third through fifth instars were more common on bolls in the middle and lower section of plants closer to the main stem. These findings have resistance management implications as extended larval feeding on bolls could optimize nutrition, decrease Bt susceptibility, and potentially influence behavioral resistance.

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