scholarly journals New Resistance Mechanism in Helicoverpa armigera Threatens Transgenic Crops Expressing Bacillus thuringiensis Cry1Ac Toxin

2005 ◽  
Vol 71 (5) ◽  
pp. 2558-2563 ◽  
Author(s):  
Robin V. Gunning ◽  
Ho T. Dang ◽  
Fred C. Kemp ◽  
Ian C. Nicholson ◽  
Graham D. Moores
Keyword(s):  
Bacillus Thuringiensis ◽  
Helicoverpa Armigera ◽  
Resistance Mechanism ◽  
Transgenic Cotton ◽  
In Vivo Studies ◽  
Cry1ac Toxin ◽  
Helicoverpa Armígera ◽  
History Of

ABSTRACT In Australia, the cotton bollworm, Helicoverpa armigera, has a long history of resistance to conventional insecticides. Transgenic cotton (expressing the Bacillus thuringiensis toxin Cry1Ac) has been grown for H. armigera control since 1996. It is demonstrated here that a population of Australian H. armigera has developed resistance to Cry1Ac toxin (275-fold). Some 70% of resistant H. armigera larvae were able to survive on Cry1Ac transgenic cotton (Ingard) The resistance phenotype is inherited as an autosomal semidominant trait. Resistance was associated with elevated esterase levels, which cosegregated with resistance. In vitro studies employing surface plasmon resonance technology and other biochemical techniques demonstrated that resistant strain esterase could bind to Cry1Ac protoxin and activated toxin. In vivo studies showed that Cry1Ac-resistant larvae fed Cy1Ac transgenic cotton or Cry1Ac-treated artificial diet had lower esterase activity than non-Cry1Ac-fed larvae. A resistance mechanism in which esterase sequesters Cry1Ac is proposed.

scholarly journals Bacillus thuringiensis Bel Protein Enhances the Toxicity of Cry1Ac Protein to Helicoverpa armigera Larvae by Degrading Insect Intestinal Mucin

2009 ◽  
Vol 75 (16) ◽  
pp. 5237-5243 ◽  
Author(s):  
Shangling Fang ◽  
Li Wang ◽  
Wei Guo ◽  
Xia Zhang ◽  
Donghai Peng ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Helicoverpa Armigera ◽  
Trichoplusia Ni ◽  
Knockout Mutant ◽  
Gene Encoding ◽  
In Vitro Degradation ◽  
Intestinal Mucin ◽  
Helicoverpa Armígera ◽  
Cry1ac Protein

ABSTRACT Bacillus thuringiensis has been used as a bioinsecticide to control agricultural insects. Bacillus cereus group genomes were found to have a Bacillus enhancin-like (bel) gene, encoding a peptide with 20 to 30% identity to viral enhancin protein, which can enhance viral infection by degradation of the peritrophic matrix (PM) of the insect midgut. In this study, the bel gene was found to have an activity similar to that of the viral enhancin gene. A bel knockout mutant was constructed by using a plasmid-free B. thuringiensis derivative, BMB171. The 50% lethal concentrations of this mutant plus the cry1Ac insecticidal protein gene were about 5.8-fold higher than those of the BMB171 strain. When purified Bel was mixed with the Cry1Ac protein and fed to Helicoverpa armigera larvae, 3 μg/ml Cry1Ac alone induced 34.2% mortality. Meanwhile, the mortality rate rose to 74.4% when the same amount of Cry1Ac was mixed with 0.8 μg/ml of Bel. Microscopic observation showed a significant disruption detected on the midgut PM of H. armigera larvae after they were fed Bel. In vitro degradation assays showed that Bel digested the intestinal mucin (IIM) of Trichoplusia ni and H. armigera larvae to various degrading products, similar to findings for viral enhancin. These results imply Bel toxicity enhancement depends on the destruction of midgut PM and IIM, similar to the case with viral enhancin. This discovery showed that Bel has the potential to enhance insecticidal activity of B. thuringiensis-based biopesticides and transgenic crops.

scholarly journals Potensi Nematoda Patogen Serangga Steinernema spp. dalam Pengendalian Hama Utama Tanaman Kapas

2016 ◽  
Vol 1 (2) ◽  
pp. 101
Author(s):  
Heri Prabowo ◽  
I.G.A.A. Indrayani
Keyword(s):  
Helicoverpa Armigera ◽  
Insect Pests ◽  
Soil Surface ◽  
Tenebrio Molitor ◽  
Pectinophora Gossypiella ◽  
Helicoverpa Armígera ◽  
Soy Bean Oil

<p>Steinernema spp. memiliki potensi untuk mengendalikan hama tanaman kapas seperti Helicoverpa armigera dan Pectinophora gossypiella. Steinernema spp. mampu menyebabkan mortalitas P. gossypiella dan H. armi-gera berturut-turut sebesar 31,6–55,4 dan 46,3–63,8%. Steinernema spp. memiliki kemampuan membunuh lebih baik pada P. gossypiella, sedangkan kemampuan reproduksi dalam inangnya lebih baik pada H. armi-gera. Steinernema spp. mampu menginfeksi serangga inang lebih baik pada stadium ulat lebih tua diban-dingkan stadium muda. Steinernema spp. dapat diproduksi secara in vivo dan in vitro. Produksi secara in vivo dapat menggunakan Tenebrio molitor, Tirathaba rufivena, dan Attacus atlas. Produksi secara in vitro dapat menggunakan usus ayam, lemak sapi, dan minyak kedelai. Perlu dikembangkan formulasi Steinerne-ma spp. yang murah dan efektif untuk mengendalikan hama di atas permukaan tanah. Selain itu diperlukan pencarian isolat Steinernema spp. yang virulen dan cepat membunuh hama sasaran.</p><p> </p><p>Steinernema spp. could be potentially used for controlling H. armigera and P. gossypiella on cotton. Steiner-nema spp. causes mortality on P. gossypiella and H. armigera 31,6–55,4 and 46,3–63,8% respectively. The nematode causes a higher mortality on P. gossypiella than on H. armigera, however, produces more juvenile infective on H. armigera than on P. gossypiella. Higher successful infections of Steinernema spp. occurs on late larval stadium than on early one. Production of Steinernema spp. can be in vivo using Tenebrio molitor, Tirathaba rufivena, and Attacus atlas; and in vitro using chicken intestinum, cow lipid, and soy bean oil. For effecttively use, this nematode need to be formulated especially for controlling insect pests on soil surface, as well as finding the more virulent isolates against the target insects.</p>

Phytoestrogens after breast cancer.

2001 ◽  
pp. 129-134 ◽  
Author(s):  
P This ◽  
A De La Rochefordi√®re ◽  
K Clough ◽  
A Fourquet ◽  
H Magdelenat ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Media Coverage ◽  
Breast Cancer Survivors ◽  
Hormone Replacement ◽  
Epidemiological Studies ◽  
In Vivo Studies ◽  
History Of ◽  
The Media

The current extension of the indications for adjuvant chemotherapy, which predisposes to early menopause, and the media coverage of the benefits of hormone replacement therapy (HRT) have led patients with a history of breast cancer to seek treatments for estrogen deprivation. In breast cancer survivors, most physicians avoid HRT because of concern regarding the potential promotion of growth of occult malignant cells by estrogens, due to the estrogen dependence of breast cancer. Soy phytoestrogens are being promoted as the 'natural alternative' to HRT and have been available without restrictions for several years as nutritional supplements. In this paper, data on the complex mammary effects of phytoestrogens in epidemiological studies, in in vitro studies, as well as in in vivo studies on animal carcinogenesis are reviewed. The potential benefits and risks of phytoestrogens are analyzed, and the prescription of phytoestrogens to postmenopausal women after breast cancer and the coprescription with the anti-estrogen tamoxifen are discussed. The absence of controlled trials and technical checking of extraction and titration in these preparations on 'free sale' raise a new problem in terms of public health and justify close reasoning and a cautious attitude of physicians, as well as straight information given to women, especially after breast cancer.

In Silico and in Vivo Investigations of Bioagent Helicoverpa Nucleopolyhedrovirus against Helicoverpa armigera in Chickpea

2021 ◽  
Vol 9 (2) ◽  
pp. 21-32
Author(s):  
Ritu Srivastava ◽  
◽  
Amritesh Chandra Shukla ◽  
Keyword(s):  
Green Tea ◽  
Rice Bran ◽  
Helicoverpa Armigera ◽  
Maximum Yield ◽  
3D Structure ◽  
Homology Model ◽  
In Vitro Toxicity ◽  
Helicoverpa Armígera

During investigations; homology model of 3D-structure was built for sequence of polyhedrin protein of Helicoverpa armigera nucleopolyhedrovirus, containing 246 amino acids (Accession: ACI05106.1 GI: 205946055), and evaluated through multiple tools/ applications to judge extent of accuracy in light of existing crystal structure. Further, in vivo experiments were conducted and determined response of different adjuvants with HaNPV and their efficacy. The pooled mean mortality of larvae exposed to virus mixed with 5% green tea and 5% rice bran filtrates (8.3 larvae per 25 plants) was differ significantly from control (15.8 larvae per 25 plants), suggesting that UV protectants & diet enhancer (mannitol) has ability to protect stability of virulence of the virus, under field conditions. The minimum percent pod damage of 8.6% and maximum yield of 1604.8 Kg ha-1 at harvesting was recorded with formulation of indigenous BHA virus isolate @ 2.2 x 105 POBs mL-1 mixed with Roket @50 ppm; followed by formulation with mannitol (@ 1% + green tea 5% + 5% rice bran filtrates) with percent pod damage of 16.8 % and yield of 1045.8 Kg ha-1 of chickpea. Furthermore, in vitro toxicity of fresh virus suspension @ 250 mL ha-1 was recorded more toxic in terms of percent mortality and LT50 (5.65 days). However, three months stored HaNPV formulations [(A) mannitol @ 1%+ green tea@ 5% and (B) mannitol @ 1% + green tea 5% + 5% rice bran filtrates] were more effective in larval reduction with LT50 of 7.89 and 6.00 days, respectively. Virus mixed with 5% green tea and 5% rice bran filtrates gave stability to formulation up-to one year with LT50 of 7.64 days. Findings showed that HaNPV formulations with mannitol (B) have potential that can be used in integrated manner with other IPM practices, to reduce the use of toxic synthetic pesticides in chickpea.

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