scholarly journals Fitness Costs Associated with Cry1Ac-Resistant Helicoverpa zea (Lepidoptera: Noctuidae): A Factor Countering Selection for Resistance to Bt Cotton?

2008 ◽  
Vol 101 (4) ◽  
pp. 1421-1431 ◽  
Author(s):  
Konasale J. Anilkumar ◽  
Marianne Pusztai-carey ◽  
William J. Moar
Keyword(s):  
Helicoverpa Zea ◽  
Bt Cotton ◽  
Fitness Costs ◽  
Selection For ◽  
Lepidoptera Noctuidae

scholarly journals Seasonal Declines in Cry1Ac and Cry2Ab Concentration in Maturing Cotton Favor Faster Evolution of Resistance to Pyramided Bt Cotton in Helicoverpa zea (Lepidoptera: Noctuidae)

2019 ◽  
Vol 112 (6) ◽  
pp. 2907-2914 ◽  
Author(s):  
Yves Carrière ◽  
Ben Degain ◽  
Gopalan C Unnithan ◽  
Virginia S Harpold ◽  
Xianchun Li ◽  
...  
Keyword(s):  
Parent Strain ◽  
Helicoverpa Zea ◽  
Transgenic Crop ◽  
Bt Cotton ◽  
F1 Progeny ◽  
Evolution Of Resistance ◽  
Selection For ◽  
Accelerate Evolution ◽  
Lepidoptera Noctuidae ◽  
Laboratory Bioassays

Abstract Under ideal conditions, widely adopted transgenic crop pyramids producing two or more distinct insecticidal proteins from Bacillus thuringiensis (Bt) that kill the same pest can substantially delay evolution of resistance by pests. However, deviations from ideal conditions diminish the advantages of such pyramids. Here, we tested the hypothesis that changes in maturing cotton producing Cry1Ac and Cry2Ab affect evolution of resistance in Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae), a pest with low inherent susceptibility to both toxins. In terminal leaves of field-grown Bt cotton, the concentration of both toxins was significantly higher for young, squaring plants than for old, fruiting plants. We used laboratory bioassays with plant material from field-grown cotton to test H. zea larvae from a strain selected for resistance to Cry1Ac in the laboratory, its more susceptible parent strain, and their F1 progeny. On young Bt cotton, no individuals survived to pupation. On old Bt cotton, survival to pupation was significantly higher for the lab-selected strain and the F1 progeny relative to the unselected parent strain, indicating dominant inheritance of resistance. Redundant killing, the extent to which insects resistant to one toxin are killed by another toxin in a pyramid, was complete on young Bt cotton, but not on old Bt cotton. No significant fitness costs associated with resistance were detected on young or old non-Bt cotton. Incorporation of empirical data into simulations indicates the observed increased selection for resistance on old Bt cotton could accelerate evolution of resistance to cotton producing Cry1Ac and Cry2Ab in H. zea.

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.

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.

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

scholarly journals Bacterial Microbiota of Field-Collected Helicoverpa zea (Lepidoptera: Noctuidae) from Transgenic Bt and Non-Bt Cotton

2021 ◽  
Vol 9 (4) ◽  
pp. 878
Author(s):  
Jean M. Deguenon ◽  
Anirudh Dhammi ◽  
Loganathan Ponnusamy ◽  
Nicholas V. Travanty ◽  
Grayson Cave ◽  
...  
Keyword(s):  
Helicoverpa Zea ◽  
Cotton Bollworm ◽  
Bt Cotton ◽  
Bacterial Populations ◽  
Bt Toxin ◽  
Molecular Approaches ◽  
Bacterial Microbiota ◽  
Bacterium Bacillus ◽  
The Impact ◽  
Lepidoptera Noctuidae

The bollworm, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae), is an important agricultural pest in U.S. cotton and is managed using transgenic hybrids that produce insecticidal proteins from the bacterium, Bacillus thuringiensis (Bt). The reduced efficacy against H. zea caterpillars of Bt plants expressing Cry toxins is increasing in the field. In a first step towards understanding Bt cotton–bollworm–microbiota interactions, we investigated the internal bacterial microbiota of second–third stadium H. zea collected in the field from non-Bt versus Bt (WideStrike) cotton in close proximity (in North Carolina, USA). The bacterial populations were analyzed using culture-dependent and -independent molecular approaches. We found that WideStrike samples had a higher bacterial density and diversity per larva than insects collected from non-Bt cotton over two field seasons: 8.42 ± 0.23 and 5.36 ± 0.75 (log10 colony forming units per insect) for WideStrike compared to 6.82 ± 0.20 and 4.30 ± 0.56 for non-Bt cotton for seasons 1 and 2, respectively. Fifteen phyla, 103 families, and 229 genera were identified after performing Illumina sequencing of the 16S rRNA. At the family level, Enterobacteriaceae and Enterococcaceae were the most abundant taxa. The Enterococcaceae family was comprised mostly of Enterococcus species (E. casseliflavus and another Enterococcus sp.). Members of the Enterococcus genus can acidify their environment and can potentially reduce the alkaline activation of some Bt toxins. These findings argue for more research to better understand the role of cotton–bollworm–bacteria interactions and the impact on Bt toxin caterpillar susceptibility.

scholarly journals Fitness Costs of Chlorantraniliprole Resistance Related to the SeNPF Overexpression in the Spodoptera exigua (Lepidoptera: Noctuidae)

2021 ◽  
Vol 22 (9) ◽  
pp. 5027
Author(s):  
Changwei Gong ◽  
Xinge Yao ◽  
Qunfang Yang ◽  
Xuegui Wang ◽  
Yuming Zhang ◽  
...  
Keyword(s):  
Insect Pest ◽  
Ryanodine Receptors ◽  
Oviposition Rate ◽  
Fitness Cost ◽  
Fitness Costs ◽  
Male Adult ◽  
Mating Response ◽  
Transmembrane Segments ◽  
High Level ◽  
Lepidoptera Noctuidae

Spodopteraexigua, a multifeeding insect pest, has developed a high level of resistance to chlorantraniliprole, which is a benzoylurea insecticide that targets the ryanodine receptors (RyRs). Herein, the resistant strain (SE-Sel) and sensitive strain (SE-Sus) were obtained by bidirectional screening for six generations. The potential oviposited eggs and oviposition rate of the SE-Sel strain were dramatically lower than those of the SE-Sus strain; on the contrary, the weights of prepupae and preadult were significantly increased. As a post-mating response, the higher number of non-oviposited eggs in the SE-Sel strain was caused by a lower mating rate. In addition, the expression levels of vitellogenin (SeVg) and its receptor (SeVgR) in the SE-Sel strain were consistently lower than those in the SE-Sus strain. An RyRI4743M mutation, contributing to the resistance to chlorantraniliprole, was located in the S3 transmembrane segments and might have affected the release of calcium ions; it led to the upregulated expression of the neuropeptide SeNPF and its receptor SeNPFR, and the mating and oviposition rate were significantly recovered when the SeNPF was knocked down though RNA interference (RNAi) in the male adult of the SE-Sel strain. Moreover, the expression of the juvenile hormone-binding proteins SeJHBWDS3 and SeJHBAN in the male adult of the SE-Sel strain was significantly decreased, which proved the existence of a fitness cost from another angle. Therefore, these results indicate that the fitness cost accompanied by chlorantraniliprole resistance in S. exigua may be related to the decrease in mating desire due to SeNPF overexpression.

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