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.

scholarly journals Hybridizing transgenic Bt cotton with non-Bt cotton counters resistance in pink bollworm

2017 ◽  
Vol 114 (21) ◽  
pp. 5413-5418 ◽  
Author(s):  
Peng Wan ◽  
Dong Xu ◽  
Shengbo Cong ◽  
Yuying Jiang ◽  
Yunxin Huang ◽  
...  
Keyword(s):  
First Generation ◽  
Resistance Management ◽  
Genetically Engineered ◽  
Pink Bollworm ◽  
Bt Cotton ◽  
Bt Toxin ◽  
Random Mixture ◽  
Cotton Plants ◽  
Evolution Of Resistance ◽  
Insecticide Sprays

Extensive cultivation of crops genetically engineered to produce insecticidal proteins from the bacteriumBacillus thuringiensis(Bt) has suppressed some major pests, reduced insecticide sprays, enhanced pest control by natural enemies, and increased grower profits. However, these benefits are being eroded by evolution of resistance in pests. We report a strategy for combating resistance by crossing transgenic Bt plants with conventional non-Bt plants and then crossing the resulting first-generation (F1) hybrid progeny and sowing the second-generation (F2) seeds. This strategy yields a random mixture within fields of three-quarters of plants that produce Bt toxin and one-quarter that does not. We hypothesized that the non-Bt plants in this mixture promote survival of susceptible insects, thereby delaying evolution of resistance. To test this hypothesis, we compared predictions from computer modeling with data monitoring pink bollworm (Pectinophora gossypiella) resistance to Bt toxin Cry1Ac produced by transgenic cotton in an 11-y study at 17 field sites in six provinces of China. The frequency of resistant individuals in the field increased before this strategy was widely deployed and then declined after its widespread adoption boosted the percentage of non-Bt cotton plants in the region. The correspondence between the predicted and observed outcomes implies that this strategy countered evolution of resistance. Despite the increased percentage of non-Bt cotton, suppression of pink bollworm was sustained. Unlike other resistance management tactics that require regulatory intervention, growers adopted this strategy voluntarily, apparently because of advantages that may include better performance as well as lower costs for seeds and insecticides.

Helicoverpa zea (Lepidoptera: Noctuidae) Oviposition and Larval Vertical Distribution in Bt Cotton Under Different Levels of Nitrogen and Irrigation

2019 ◽  
Vol 112 (3) ◽  
pp. 1237-1250 ◽  
Author(s):  
Lewis R Braswell ◽  
Dominic D Reisig ◽  
Clyde E Sorenson ◽  
Guy D Collins
Keyword(s):  
Vertical Distribution ◽  
Helicoverpa Zea ◽  
Bt Cotton ◽  
Lepidoptera Noctuidae ◽  
Different Levels

scholarly journals Modeling the Evolution of Resistance in Cotton Bollworm to Concurrently Planted Bt Cotton and Bt Maize in China

2021 ◽  
Author(s):  
Wenhui Wang ◽  
Feng Xu ◽  
Yunxin Huang ◽  
Hongqiang Feng ◽  
Peng Wan
Keyword(s):  
First Generation ◽  
Resistance Management ◽  
Northern China ◽  
Cotton Bollworm ◽  
Bt Cotton ◽  
Bt Maize ◽  
Bt Toxins ◽  
Evolution Of Resistance ◽  
The One ◽  
Lepidoptera Noctuidae

Abstract BackgroundTransgenic maize expressing toxins derived from the bacterium Bacillus thuringiensis (Bt) may be commercially planted in northern China where Bt cotton has been planted for more than two decades. While Bt maize brings additional benefits for insect control, it complicates the resistance management of cotton bollworm (CBW), Helicoverpa armigera (Lepidoptera, Noctuidae), a common target of Bt cotton and Bt maize.ResultsWe developed population genetic models to assess the risk of resistance in CBW when Bt cotton and Bt maize are planted concurrently. Model simulations showed that when natural refuges are absent, the time to resistance (TTR) is less than 10 generations in the case of one-toxin Bt cotton and one-toxin Bt maize, but is more than 30 generations in the case of two-toxin Bt cotton and two-toxin Bt maize. The differences in the TTR between the two cases become greater as the proportion of natural refuge increases. Among the parameters we investigated, the fitness cost has a relatively smaller effect on the TTR, while the dominance of resistance and the proportion of natural refuge have a much greater effect.ConclusionsWe concluded that planting the first generation Bt cotton with Bt maize could significantly increase the risk of CBW resistance to Bt toxins as compared to planting a pyramid two-toxin Bt cotton. The strategies for reducing the risk of CBW resistance include replacing the one-toxin Bt cotton with a pyramid two-toxin Bt cotton, adopting a pyramid two-toxin Bt maize, and maintaining a sufficient proportion of natural refuges.

Pyrethroid and carbamate resistance in Australian Helicoverpa armigera (Lepidoptera: Noctuidae) from 2008 to 2015: what has changed since the introduction of Bt cotton?

2018 ◽  
Vol 108 (6) ◽  
pp. 781-791 ◽  
Author(s):  
L.J. Bird
Keyword(s):  
Helicoverpa Armigera ◽  
Pyrethroid Resistance ◽  
New South ◽  
Resistance Management ◽  
Rapid Expansion ◽  
Bt Cotton ◽  
South Wales ◽  
Helicoverpa Armígera ◽  
High Level ◽  
Lepidoptera Noctuidae

AbstractPyrethroid and carbamate resistance was evaluated in Helicoverpa armigera from 2008 to 2015. Insects were collected as eggs primarily from cultivated hosts in the major cropping areas of New South Wales and Queensland, Australia. Larvae reared from eggs were tested for resistance to fenvalerate, bifenthrin or methomyl in the F0 generation using a topical application of a discriminating dose of insecticide. In 2008–2009, resistance to fenvalerate was 71% and no resistance to bifenthrin was recorded. In the following two seasons, resistance to pyrethroids was relatively stable with fenvalerate resistance ranging from 63% to 67% and bifenthrin resistance ranging from 5.6% and 6.4% in 2009–2010 and 2010–2011, respectively. However, in 2011–2012, pyrethroid resistance had increased to 91% and 36% for fenvalerate and bifenthrin, respectively. Resistance remained above 90% for fenvalerate and above 35% for bifenthrin in the following three seasons from 2012 to 2015. In 2008–2009, methomyl resistance was 33% and declined to 22% and 15% in 2009–2010 and 2010–2011, respectively. Methomyl resistance remained at moderate levels from 2011–12 to 2014–15, ranging from 21% to 40%. Factors that influenced selection pressure of pyrethroid and carbamate insecticides and impacted resistance frequency in H. armigera may have been associated with changes in the composition of the cropping landscape. The rapid expansion of the pulse industry and the commensurate increased use of insecticide may have played a role in reselection of high-level pyrethroid resistance, and highlights the need for an urgent and strategic response to insecticide resistance management in the Australian grains industry.

Development of Spodoptera exigua and Helicoverpa zea (Lepidoptera: Noctuidae) on Transgenic Cotton Containing CrylAc Insecticidal Protein

2000 ◽  
Vol 35 (4) ◽  
pp. 360-372 ◽  
Author(s):  
Muhammad Ashfaq ◽  
S. Y. Young ◽  
R. W. McNew
Keyword(s):  
Helicoverpa Zea ◽  
Spodoptera Exigua ◽  
Larval Mortality ◽  
Transgenic Cotton ◽  
Larval Period ◽  
Pupal Weight ◽  
Feeding Time ◽  
Bt Cotton ◽  
Cotton Pests ◽  
Lepidoptera Noctuidae

The effects of transgenic Bacillus thuringiensis (Bt)-cotton on three instars of Spodoptera exigua (Hübner) and Helicoverpa zea (Boddie) were studied. First, third and fifth instars were fed field-collected Bt-cotton leaves for 1, 2, 3, 4 and 7 d or until pupation, and then transferred to artificial diet. Larval mortality at pupation, length of larval and pupal periods, pupal weights and survival time from hatch to adult were recorded for regular and Bt-cotton. Larval mortality at pupation in S. exigua fed Bt-cotton was low for all instars exposed and feeding periods on Bt-cotton. The mortality in H. zea was high for first and third instars and significantly increased with the increase in feeding period on Bt-cotton (P < 0.05). The length of larval period increased in both species when first and third instars but not fifth instars were fed Bt-cotton. In H. zea, the larval period increased when larvae were on Bt-cotton leaves for only 2 d. Pupal weight was reduced with an increase in feeding time on Bt-cotton in all three instars in both species. An increase in length of feeding time on Bt-cotton reduced survival to adults in both species on Bt-cotton in first and third instars but not in fifth instars. Survival to adults was much lower in H. zea than S. exigua for all instars exposed and feeding periods on Bt-cotton. These results demonstrate the large differences in effectiveness of Bt-cotton against lepidopteran cotton pests, as well as the adverse effects on larvae developing on Bt-cotton.

Preexisting resistance in cotton bollworm increases the risk of resistance to the concurrently planted Bt cotton and Bt maize

2020 ◽  
Author(s):  
Wenhui Wang ◽  
Feng Xu ◽  
Yunxin Huang ◽  
Hongqiang Feng ◽  
Peng Wan
Keyword(s):  
Population Genetic ◽  
Genetic Model ◽  
Resistance Management ◽  
Northern China ◽  
Cotton Bollworm ◽  
Bt Cotton ◽  
Bt Maize ◽  
Bt Toxin ◽  
Lepidoptera Noctuidae ◽  
Common Target

Abstract Background Transgenic maize expressing toxins derived from the bacterium Bacillus thuringiensis (Bt) may be commercially planted in northern China where Bt cotton has been planted for more than two decades. While Bt maize brings additional benefits for insect control, it complicates the resistance management of cotton bollworm (CBW), Helicoverpa armigera (Lepidoptera, Noctuidae), a common target of Bt cotton and Bt maize. Results We used a two-locus population genetic model to assess the risk of resistance in CBW when Bt cotton and Bt maize are planted concurrently. Results of model simulations showed that planting Bt maize together with Bt cotton significantly increases the risk of resistance if Bt cotton and Bt maize share a similar Bt toxin. The risk of resistance is higher in the case of one-toxin Bt maize than in the case of two-toxin Bt maize. Parameters associated with the preexisting resistance in CBW all could impact on the risk of resistance but with different extents. Among them, the most notable ones are the dominance of resistance and fitness cost, which can dramatically affect the risk of resistance, especially when the proportion of natural refuges is reduced. Conclusions We concluded that the preexisting resistance in CBW to Bt cotton can significantly increase the risk of resistance when Bt maize and Bt cotton are planted concurrently and that using two-toxin Bt cotton and maize instead of one-toxin ones are needed in order to reduce the risk of resistance.

Synergistic Interactions Between Cry1Ac and Natural Cotton Defenses Limit Survival of Cry1Ac-resistant Helicoverpa Zea (Lepidoptera: Noctuidae) on Bt Cotton

2009 ◽  
Vol 35 (7) ◽  
pp. 785-795 ◽  
Author(s):  
Konasale J. Anilkumar ◽  
Sakuntala Sivasupramaniam ◽  
Graham Head ◽  
Robert Orth ◽  
Edzard Van Santen ◽  
...  
Keyword(s):  
Helicoverpa Zea ◽  
Bt Cotton ◽  
Synergistic Interactions ◽  
Lepidoptera Noctuidae
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