scholarly journals Demographic Performance of Helicoverpa zea Populations on Dual and Triple-Gene Bt Cotton

Toxins ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 551 ◽  
Author(s):  
Marcelo M. Rabelo ◽  
Silvana V. Paula-Moraes ◽  
Eliseu Jose G. Pereira ◽  
Blair D. Siegfried
Keyword(s):  
Population Growth ◽  
Helicoverpa Zea ◽  
Agricultural Landscape ◽  
Insect Pests ◽  
Field Resistance ◽  
Corn Earworm ◽  
Bt Cotton ◽  
Bt Toxins ◽  
Cotton Plants ◽  
Demographic Performance

Insecticidal toxins from Bacillus thuringiensis (Bt) are valuable tools for pest management worldwide, contributing to the management of human disease insect vectors and phytophagous insect pests of agriculture and forestry. Here, we report the effects of dual and triple Bt toxins expressed in transgenic cotton cultivars on the fitness and demographic performance of Helicoverpa zea (Boddie)—a noctuid pest, known as cotton bollworm and corn earworm. Life-history traits were determined for individuals of three field populations from a region where H. zea overwintering is likely. Triple-gene Bt cotton cultivars that express Cry and Vip3Aa toxins killed 100% of the larvae in all populations tested. In contrast, dual-gene Bt cotton that express Cry1Ac+Cry1F and Cry1Ac+Cry2Ab allowed population growth with the intrinsic rate of population growth (rm) 38% lower than on non-Bt cotton. The insects feeding on Bt cotton plants that express Cry1Ac+Cry2Ab, Cry1Ac+Cry1F, or Cry1Ab+Cry2Ae exhibited reduced larval weight, survival rate, and increased development time. Additionally, fitness parameters varied significantly among the insect populations, even on non-Bt cotton plants, likely because of their different genetic background and/or previous Bt toxin exposure. This is the first report of the comparative fitness of H. zea field populations on dual-gene Bt cotton after the recent reports of field resistance to certain Bt toxins. These results document the population growth rates of H. zea from an agricultural landscape with 100% Bt cotton cultivars. Our results will contribute to the development and validation of resistance management recommendations.

scholarly journals Demographic Performance of Helicoverpa zea Populations on Dual and Triple-Gene Bt Cotton

2020 ◽  
Author(s):  
Marcelo M. Rabelo ◽  
Silvana V. Paula-Moraes ◽  
Eliseu Jose G. Pereira ◽  
Blair D. Siegfried
Keyword(s):  
Population Growth ◽  
Helicoverpa Zea ◽  
Agricultural Landscape ◽  
Insect Pests ◽  
Field Resistance ◽  
Corn Earworm ◽  
Bt Cotton ◽  
Bt Toxins ◽  
Cotton Plants ◽  
Demographic Performance

Insecticidal toxins from Bacillus thuringiensis (Bt) are valuable tools for pest management worldwide, contributing to the management of human disease insect vectors and phytophagous insect pests of agriculture and forestry. Here, we report the effects of dual and triple Bt toxins expressed in transgenic cotton cultivars on the fitness and demographic performance of Helicoverpa zea (Boddie), a noctuid pest known as cotton bollworm and corn earworm. Life-history traits were determined for individuals of three field populations from a region where H. zea overwintering is likely. Triple-gene Bt cotton cultivars expressing Cry and Vip3Aa toxins killed 100% of the larvae in all populations tested. In contrast, dual-gene Bt cotton expressing Cry1Ac+Cry1F and Cry1Ac+Cry2Ab2 allowed population growth with the intrinsic rate of population growth (rm) 38% lower than on non-Bt cotton. The insects feeding on Bt cotton plants expressing Cry1Ac+Cry2Ab2, Cry1Ac+Cry1F, or Cry1Ab+Cry2Ae exhibited reduced larval weight, survival rate, and increased development time. Additionally, fitness parameters varied significantly among the insect populations, even on non-Bt cotton plants, likely because of their different genetic background and/or previous Bt toxin exposure. This is the first report of the comparative fitness of H. zea field populations on dual-gene Bt cotton after the recent reports of field resistance to certain Bt toxins. These results document the population growth rates of H. zea from an agricultural landscape with 100% Bt cotton cultivars. Our results will help to refine models designed to predict resistance evolution and improve insect resistance management for Bt crops.

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 Multiple Known Mechanisms and a Possible Role of an Enhanced Immune System in Bt-Resistance in a Field Population of the Bollworm, Helicoverpa zea: Differences in Gene Expression with RNAseq

2020 ◽  
Vol 21 (18) ◽  
pp. 6528
Author(s):  
Roger D. Lawrie ◽  
Robert D. Mitchell III ◽  
Jean Marcel Deguenon ◽  
Loganathan Ponnusamy ◽  
Dominic Reisig ◽  
...  
Keyword(s):  
Gene Expression ◽  
Serine Proteases ◽  
Helicoverpa Zea ◽  
Insect Pests ◽  
Global Gene Expression ◽  
Field Resistance ◽  
Bt Resistance ◽  
Imd Pathway ◽  
Immune Pathway

Several different agricultural insect pests have developed field resistance to Bt (Bacillus thuringiensis) proteins (ex. Cry1Ac, Cry1F, etc.) expressed in crops, including corn and cotton. In the bollworm, Helicoverpa zea, resistance levels are increasing; recent reports in 2019 show up to 1000-fold levels of resistance to Cry1Ac, a major insecticidal protein in Bt-crops. A common method to analyze global differences in gene expression is RNA-seq. This technique was used to measure differences in global gene expression between a Bt-susceptible and Bt-resistant strain of the bollworm, where the differences in susceptibility to Cry1Ac insecticidal proteins were 100-fold. We found expected gene expression differences based on our current understanding of the Bt mode of action, including increased expression of proteases (trypsins and serine proteases) and reduced expression of Bt-interacting receptors (aminopeptidases and cadherins) in resistant bollworms. We also found additional expression differences for transcripts that were not previously investigated, i.e., transcripts from three immune pathways-Jak/STAT, Toll, and IMD. Immune pathway receptors (ex. PGRPs) and the IMD pathway demonstrated the highest differences in expression. Our analysis suggested that multiple mechanisms are involved in the development of Bt-resistance, including potentially unrecognized pathways.

scholarly journals Resistance of Trichoplusia ni Populations Selected by Bacillus thuringiensis Sprays to Cotton Plants Expressing Pyramided Bacillus thuringiensis Toxins Cry1Ac and Cry2Ab

2014 ◽  
Vol 81 (5) ◽  
pp. 1884-1890 ◽  
Author(s):  
Wendy Kain ◽  
Xiaozhao Song ◽  
Alida F. Janmaat ◽  
Jian-Zhou Zhao ◽  
Judith Myers ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Trichoplusia Ni ◽  
Resistance Mechanisms ◽  
Vegetable Production ◽  
Bt Cotton ◽  
Content Type ◽  
Bt Toxin ◽  
Bt Toxins ◽  
Cotton Plants ◽  
Incomplete Resistance

ABSTRACTTwo populations ofTrichoplusia nithat had developed resistance toBacillus thuringiensissprays (Bt sprays) in commercial greenhouse vegetable production were tested for resistance to Bt cotton (BollGard II) plants expressing pyramided Cry1Ac and Cry2Ab. TheT. nicolonies resistant toBacillus thuringiensisserovar kurstaki formulations were not only resistant to the Bt toxin Cry1Ac, as previously reported, but also had a high frequency of Cry2Ab-resistant alleles, exhibiting ca. 20% survival on BollGard II foliage. BollGard II-resistantT. nistrains were established by selection with BollGard II foliage to further remove Cry2Ab-sensitive alleles in theT. nipopulations. The BollGard II-resistant strains showed incomplete resistance to BollGard II, with adjusted survival values of 0.50 to 0.78 after 7 days. The resistance to the dual-toxin cotton plants was conferred by two genetically independent resistance mechanisms: one to Cry1Ac and one to Cry2Ab. The 50% lethal concentration of Cry2Ab for the resistant strain was at least 1,467-fold that for the susceptibleT. nistrain. The resistance to Cry2Ab in resistantT. niwas an autosomally inherited, incompletely recessive monogenic trait. Results from this study indicate that insect populations under selection by Bt sprays in agriculture can be resistant to multiple Bt toxins and may potentially confer resistance to multitoxin Bt crops.

Enhancement of Activity of Bacillus thuringiensis Berliner Against Four Lepidopterous Insect Pests by Nutrient-Based Phagostimulants1

1995 ◽  
Vol 30 (1) ◽  
pp. 29-42 ◽  
Author(s):  
Robert R. Farrar ◽  
Richard L. Ridgway
Keyword(s):  
Bacillus Thuringiensis ◽  
Ostrinia Nubilalis ◽  
Helicoverpa Zea ◽  
European Corn Borer ◽  
Insect Pests ◽  
Diamondback Moth ◽  
Lethal Dose ◽  
Corn Earworm ◽  
Corn Borer ◽  
Whole Plants

To help improve control of insect pests with microbial insecticides, we investigated the interactions of four commercial, nutrient-based phagostimulants (Pheast [AgriSense], Coax [CCT Corp.], Gusto [Atochem North America, Inc.], and Entice [Custom Chemicides] with Bacillus thuringiensis Berliner and four lepidopterous insect pests (gypsy moth, Lymantria dispar [L.] [Lymantriidae]; corn earworm, Helicoverpa zea [Boddie] [Noctuidae]; European corn borer, Ostrinia nubilalis [Hübner] [Pyralidae]; and diamondback moth, Plutella xylostella [L.] [Plutellidae]). Comparisons were made of treated foliage in Petri dishes in the laboratory and of sprayed whole plants in a greenhouse. In general, phagostimulants increased mortality of all species tested, but no consistent differences among phagostimulants were found for any species. Food consumption was generally lower on the treatments that contained phagostimulants causing the highest rates of mortality, possibly as a result of more rapid ingestion of a lethal dose on these treatments. Reduced rates of feeding by insects on treatments with B. thuringiensis alone were seen, probably due in part to intoxication and, possibly, to behavioral effects as well. Indications of potentially significant interactions between host plants and both B. thuringiensis and phagostimulants also were seen.

scholarly journals Simulated Corn Earworm, Helicoverpa zea, Injury in an Indeterminate Soybean Cultivar at Various Growth Stages under Non-Irrigated Conditions in the Southern United States

Agronomy ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1450
Author(s):  
Mariane Coelho ◽  
Donald R. Cook ◽  
Angus L. Catchot ◽  
Jeff Gore ◽  
André L. Lourenção ◽  
...  
Keyword(s):  
United States ◽  
Significant Interaction ◽  
Helicoverpa Zea ◽  
Insect Pests ◽  
The United States ◽  
Corn Earworm ◽  
Growth Stages ◽  
Fruit Removal ◽  
Artificial Fruit ◽  
The Impact

Soybean is considered one of the most valuable crops in the United States of America. Helicoverpa zea (Boddie) is among several insect pests which are associated with soybean, damaging leaves when infestations occur during the vegetative stages, and flowers and pods during the reproductive stages, which can directly impact yield. Artificial fruit removal is a method used to understand insect damage and to adjust action levels for control. The objective of this work was to evaluate the impact of five levels of fruit removal (0%, 25%, 50%, 75% and 100%) at four stages (R2, R3, R4 and R5) on maturity and yield of soybean. These methods were used to simulate H. zea damage under controlled conditions in non-irrigated environments, during 2016 and 2017. There was a significant interaction between fruit removal timing and fruit removal level for the percentage of non-senesced main stems and abscised leaves. For soybean yield, there was no significant interaction between fruit removal timing and fruit removal level. Plots that received fruit removal treatments at R5 had significantly lower soybean yields compared to plots that received damage at other growth stages and the nontreated control. Plots with 100% fruit removal had significantly lower yields compared to plots that received any of the other fruit removal treatments. These data demonstrate that indeterminate midmaturity group IV soybeans that are commonly grown in the midsouthern region of the United States may be able to compensate for even severe levels of fruit loss early during the reproductive portion of the growing season if favorable growing conditions occur.

scholarly journals Insect resistance management in Bacillus thuringiensis cotton by MGPS (multiple genes pyramiding and silencing)

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Muhammad Mubashar ZAFAR ◽  
Abdul RAZZAQ ◽  
Muhammad Awais FAROOQ ◽  
Abdul REHMAN ◽  
Hina FIRDOUS ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Insect Pests ◽  
Crop Protection ◽  
High Dose ◽  
Bt Cotton ◽  
Artificial Chromosomes ◽  
Cotton Pests ◽  
Multiple Genes ◽  
Bt Toxins ◽  
Evolution Of Resistance

AbstractThe introduction of Bacillus thuringiensis (Bt) cotton has reduced the burden of pests without harming the environment and human health. However, the efficacy of Bt cotton has decreased due to field-evolved resistance in insect pests over time. In this review, we have discussed various factors that facilitate the evolution of resistance in cotton pests. Currently, different strategies like pyramided cotton expressing two or more distinct Bt toxin genes, refuge strategy, releasing of sterile insects, and gene silencing by RNAi are being used to control insect pests. Pyramided cotton has shown resistance against different cotton pests. The multiple genes pyramiding and silencing (MGPS) approach has been proposed for the management of cotton pests. The genome information of cotton pests is necessary for the development of MGPS-based cotton. The expression cassettes against various essential genes involved in defense, detoxification, digestion, and development of cotton pests will successfully obtain favorable agronomic characters for crop protection and production. The MGPS involves the construction of transformable artificial chromosomes, that can express multiple distinct Bt toxins and RNAi to knockdown various essential target genes to control pests. The evolution of resistance in cotton pests will be delayed or blocked by the synergistic action of high dose of Bt toxins and RNAi as well as compliance of refuge requirement.

scholarly journals Effects of seasonal changes in cotton plants on the evolution of resistance to pyramided cotton producing the Bt toxins Cry1Ac and Cry1F in Helicoverpa zea

2017 ◽  
Vol 74 (3) ◽  
pp. 627-637 ◽  
Author(s):  
Yves Carrière ◽  
Ben A Degain ◽  
Gopalan C Unnithan ◽  
Virginia S Harpold ◽  
Shannon Heuberger ◽  
...  
Keyword(s):  
Seasonal Changes ◽  
Helicoverpa Zea ◽  
Bt Toxins ◽  
Cotton Plants ◽  
Evolution Of Resistance

Insect Pests and Impact on Late-Season Tomato in Arkansas

1996 ◽  
Vol 31 (2) ◽  
pp. 152-165
Author(s):  
P. J. McLeod ◽  
R. K. Katayama ◽  
M. B. Sweeden ◽  
J. G. Burleigh ◽  
W. G. Giese ◽  
...  
Keyword(s):  
Helicoverpa Zea ◽  
Insect Pests ◽  
Late Summer ◽  
Corn Earworm ◽  
Minor Importance ◽  
Stink Bugs ◽  
Fresh Market ◽  
Tomato Production ◽  
Late Season ◽  
Early Production

The recent release of heat-tolerant tomato cultivars has resulted in increased interest in expanding fresh market tomato from historically early production to late summer and fall in Arkansas. Although insects are generally of minor importance in early production, much concern exists with the greater numbers of insects occurring later during the season. Insect frequency and impact on tomato were determined in studies conducted in northwestern and southern Arkansas in 1993 and 1994. The corn earworm, Helicoverpa zea (Boddie), was the most damaging insect in both locations during both years. Corn earworm larvae were detected throughout the study and caused extensive fruit damage. At the northwestern location, 81.6% of all harvested fruit was damaged by corn earworm larvae in 1993. Although thrips were present at both locations throughout the season, no plants infected with tomato spotted wilt virus were detected. Other potential insect threats, i.e., stink bugs, flea beetles and tomato pinworms, had no apparent effect on late-season production. Corn earworm management is well developed for early tomato production and should be easily adapted to late-season production. This should insure the success of late-season tomato production in Arkansas.

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