Prevalence of Helicoverpa zea (Lepidoptera: Noctuidae) on late season volunteer corn in Mississippi: Implications on Bt resistance management

2014 ◽  
Vol 64 ◽  
pp. 207-214 ◽  
Author(s):  
Arun Babu ◽  
Donald R. Cook ◽  
Michael A. Caprio ◽  
K. Clint Allen ◽  
Fred R. Musser
Keyword(s):  
Helicoverpa Zea ◽  
Resistance Management ◽  
Late Season ◽  
Bt Resistance ◽  
Volunteer Corn ◽  
Lepidoptera Noctuidae

Performance of Feral and Cry1Ac-Selected Helicoverpa zea (Lepidoptera: Noctuidae) Strains on Transgenic Cottons Expressing One or Two Bacillus thuringiensis ssp. kurstaki Proteins Under Greenhouse Conditions

2004 ◽  
Vol 39 (1) ◽  
pp. 46-55 ◽  
Author(s):  
R. E. Jackson ◽  
J. R. Bradley ◽  
J. W. Van Duyn
Keyword(s):  
Bacillus Thuringiensis ◽  
Helicoverpa Zea ◽  
Positive Impact ◽  
Resistance Management ◽  
Larval Survival ◽  
Greenhouse Study ◽  
Bt Resistance ◽  
Fruit Damage ◽  
Lepidoptera Noctuidae

Efficacy of Bollgard (DP50B) and Bollgard II (DP50BX) cottons that express either one or two Bacillus thuringiensis Berliner proteins, respectively, along with the conventional sister genotype (DP50), was determined for a feral strain of bollworm, Helicoverpa zea (Boddie), and a Cry1Ac-selected bollworm strain in 1999. In 2000, a greenhouse study was designed to compare the efficacy of three transgenic cottons expressing either the Cry1Ac endotoxin alone (DP50B), the Cry2Ab endotoxin alone (DP50X), or both the CrylAc and Cry2Ab endotoxins (DP50BX) against a feral and a Cry1Ac-selected bollworm strain. Results from the 1999 greenhouse study evaluating both a feral and a Cry1Ac-selected bollworm strain demonstrated that when averaged across bollworm strains, the Bollgard II genotype significantly reduced larval survival and fruit penetration by bollworm compared to the Bollgard variety. Also, the Cry1Ac-selected bollworm strain displayed increased larval survival, superficial fruit damage, and fruit penetration compared to the feral strain when averaged across genotypes. In the 2000 study, the Bollgard II genotype significantly reduced fruit penetration by bollworm below that of the Bollgard variety when averaged across strains; however, the single Cry2Ab-producing genotype performed similarly to both Bollgard and Bollgard II with respect to fruit penetration. The Cry1Ac-selected bollworm strain exhibited significantly greater larval survival and superficial fruit damage on the Bollgard variety compared to the feral strain, but no differences among larval strains were evident for other genotypes. Also, when averaged across genotypes, the Cry1Ac-selected bollworm strain penetrated a higher proportion of cotton fruit compared to the feral strain. These results suggest that commercialization of Bollgard II cottons would significantly reduce bollworm survival and damage compared to that experienced by current Bollgard varieties. Bollgard II plantings also should have a positive impact on Bt resistance management of bollworm.

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 Genome evolution in an agricultural pest following adoption of transgenic crops

2021 ◽  
Vol 118 (52) ◽  
pp. e2020853118
Author(s):  
Katherine L. Taylor ◽  
Kelly A. Hamby ◽  
Alexandra M. DeYonke ◽  
Fred Gould ◽  
Megan L. Fritz
Keyword(s):  
Genome Analysis ◽  
Helicoverpa Zea ◽  
Resistance Management ◽  
Holistic Approach ◽  
Transgenic Crops ◽  
Whole Genome ◽  
Whole Genome Analysis ◽  
Genomic Change ◽  
Bt Resistance ◽  
Molecular Signals

Replacing synthetic insecticides with transgenic crops for pest management has been economically and environmentally beneficial, but these benefits erode as pests evolve resistance. It has been proposed that novel genomic approaches could track molecular signals of emerging resistance to aid in resistance management. To test this, we quantified patterns of genomic change in Helicoverpa zea, a major lepidopteran pest and target of transgenic Bacillus thuringiensis (Bt) crops, between 2002 and 2017 as both Bt crop adoption and resistance increased in North America. Genomic scans of wild H. zea were paired with quantitative trait locus (QTL) analyses and showed the genomic architecture of field-evolved Cry1Ab resistance was polygenic, likely arising from standing genetic variation. Resistance to pyramided Cry1A.105 and Cry2Ab2 toxins was controlled by fewer loci. Of the 11 previously described Bt resistance genes, 9 showed no significant change over time or major effects on resistance. We were unable to rule out a contribution of aminopeptidases (apns), as a cluster of apn genes were found within a Cry-associated QTL. Molecular signals of emerging Bt resistance were detectable as early as 2012 in our samples, and we discuss the potential and pitfalls of whole-genome analysis for resistance monitoring based on our findings. This first study of Bt resistance evolution using whole-genome analysis of field-collected specimens demonstrates the need for a more holistic approach to examining rapid adaptation to novel selection pressures in agricultural ecosystems.

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