scholarly journals Genetic Resistance to Bacillus thuringiensis Alters Feeding Behaviour in the Cabbage Looper, Trichoplusia ni

PLoS ONE ◽  
2014 ◽  
Vol 9 (1) ◽  
pp. e85709 ◽  
Author(s):  
Ikkei Shikano ◽  
Jenny S. Cory
Keyword(s):  
Bacillus Thuringiensis ◽  
Trichoplusia Ni ◽  
Feeding Behaviour ◽  
Genetic Resistance ◽  
Cabbage Looper

scholarly journals Characterization of Chimeric Bacillus thuringiensis Vip3 Toxins

2006 ◽  
Vol 73 (3) ◽  
pp. 956-961 ◽  
Author(s):  
Jun Fang ◽  
Xiaoli Xu ◽  
Ping Wang ◽  
Jian-Zhou Zhao ◽  
Anthony M. Shelton ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Trichoplusia Ni ◽  
European Corn Borer ◽  
Insect Pest ◽  
Chimeric Protein ◽  
Fall Armyworm ◽  
Terminal Region ◽  
Cabbage Looper ◽  
Cross Resistance ◽  
Corn Borer

ABSTRACT Bacillus thuringiensis vegetative insecticidal proteins (Vip) are potential alternatives for B. thuringiensis endotoxins that are currently utilized in commercial transgenic insect-resistant crops. Screening a large number of B. thuringiensis isolates resulted in the cloning of vip3Ac1. Vip3Ac1 showed high insecticidal activity against the fall armyworm Spodoptera frugiperda and the cotton bollworm Helicoverpa zea but very low activity against the silkworm Bombyx mori. The host specificity of this Vip3 toxin was altered by sequence swapping with a previously identified toxin, Vip3Aa1. While both Vip3Aa1 and Vip3Ac1 showed no detectable toxicity against the European corn borer Ostrinia nubilalis, the chimeric protein Vip3AcAa, consisting of the N-terminal region of Vip3Ac1 and the C-terminal region of Vip3Aa1, became insecticidal to the European corn borer. In addition, the chimeric Vip3AcAa had increased toxicity to the fall armyworm. Furthermore, both Vip3Ac1 and Vip3AcAa are highly insecticidal to a strain of cabbage looper (Trichoplusia ni) that is highly resistant to the B. thuringiensis endotoxin Cry1Ac, thus experimentally showing for the first time the lack of cross-resistance between B. thuringiensis Cry1A proteins and Vip3A toxins. The results in this study demonstrated that vip3Ac1 and its chimeric vip3 genes can be excellent candidates for engineering a new generation of transgenic plants for insect pest control.

scholarly journals Modified Bacillus thuringiensis Toxins and a Hybrid B. thuringiensis Strain Counter Greenhouse-Selected Resistance in Trichoplusia ni

2009 ◽  
Vol 75 (17) ◽  
pp. 5739-5741 ◽  
Author(s):  
Michelle T. Franklin ◽  
Christal L. Nieman ◽  
Alida F. Janmaat ◽  
Mario Sober�n ◽  
Alejandra Bravo ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Trichoplusia Ni ◽  
Genetically Modified ◽  
Cabbage Looper ◽  
Hybrid Strain ◽  
Thuringiensis Strain

ABSTRACT Resistance of greenhouse-selected strains of the cabbage looper, Trichoplusia ni, to Bacillus thuringiensis subsp. kurstaki was countered by a hybrid strain of B. thuringiensis and genetically modified toxins Cry1AbMod and Cry1AcMod, which lack helix α-1. Resistance to Cry1AbMod and Cry1AcMod was >100-fold less than resistance to native toxins Cry1Ab and Cry1Ac.

scholarly journals Novel Isolate of Bacillus thuringiensis subsp. thuringiensis That Produces a Quasicuboidal Crystal of Cry1Ab21 Toxic to Larvae of Trichoplusia ni

2007 ◽  
Vol 74 (4) ◽  
pp. 923-930 ◽  
Author(s):  
Izabela Swiecicka ◽  
Dennis K. Bideshi ◽  
Brian A. Federici
Keyword(s):  
Bacillus Thuringiensis ◽  
Trichoplusia Ni ◽  
Single Copy ◽  
Cabbage Looper ◽  
Beet Armyworm ◽  
Vegetable Crops ◽  
Gene Coding ◽  
Novel Variant ◽  
Northeastern Poland ◽  
Midgut Lumen

ABSTRACT A new isolate (IS5056) of Bacillus thuringiensis subsp. thuringiensis that produces a novel variant of Cry1Ab, Cry1Ab21, was isolated from soil collected in northeastern Poland. Cry1Ab21 was composed of 1,155 amino acids and had a molecular mass of 130.5 kDa, and a single copy of the gene coding for this endotoxin was located on a ∼75-kbp plasmid. When synthesized by the wild-type strain, Cry1Ab21 produced a unique, irregular, bipyramidal crystal whose long and short axes were both approximately 1 μm long, which gave it a cuboidal appearance in wet mount preparations. In diet incorporation bioassays, the 50% lethal concentrations of the crystal-spore complex were 16.9 and 29.7 μg ml−1 for second- and fourth-instar larvae of the cabbage looper, Trichoplusia ni, respectively, but the isolate was essentially nontoxic to larvae of the beet armyworm, Spodoptera exigua. A bioassay of autoclaved spore-crystal preparations showed no evidence of β-exotoxin activity, indicating that toxicity was due primarily to Cry1Ab21. Studies of the pathogenesis of isolate IS5056 in second-instar larvae of T. ni showed that after larval death the bacterium colonized and subsequently sporulated extensively throughout the cadaver, suggesting that other bacteria inhabiting the midgut lumen played little if any role in mortality. As T. ni is among the most destructive pests of vegetable crops in North America and has developed resistance to B. thuringiensis, this new isolate may have applied value.

scholarly journals Mechanism of Resistance to Bacillus thuringiensis Toxin Cry1Ac in a Greenhouse Population of the Cabbage Looper, Trichoplusia ni

2006 ◽  
Vol 73 (4) ◽  
pp. 1199-1207 ◽  
Author(s):  
Ping Wang ◽  
Jian-Zhou Zhao ◽  
Ana Rodrigo-Sim�n ◽  
Wendy Kain ◽  
Alida F. Janmaat ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Binding Site ◽  
Trichoplusia Ni ◽  
Specific Binding ◽  
Laboratory Strain ◽  
Cabbage Looper ◽  
Cross Resistance ◽  
Resistance Pattern ◽  
Recessive Trait ◽  
Mechanism Of Resistance

ABSTRACT The cabbage looper, Trichoplusia ni, is one of only two insect species that have evolved resistance to Bacillus thuringiensis in agricultural situations. The trait of resistance to B. thuringiensis toxin Cry1Ac from a greenhouse-evolved resistant population of T. ni was introgressed into a highly inbred susceptible laboratory strain. The resulting introgression strain, GLEN-Cry1Ac-BCS, and its nearly isogenic susceptible strain were subjected to comparative genetic and biochemical studies to determine the mechanism of resistance. Results showed that midgut proteases, hemolymph melanization activity, and midgut esterase were not altered in the GLEN-Cry1Ac-BCS strain. The pattern of cross-resistance of the GLEN-Cry1Ac-BCS strain to 11 B. thuringiensis Cry toxins showed a correlation of the resistance with the Cry1Ab/Cry1Ac binding site in T. ni. This cross-resistance pattern is different from that found in a previously reported laboratory-selected Cry1Ab-resistant T. ni strain, evidently indicating that the greenhouse-evolved resistance involves a mechanism different from the laboratory-selected resistance. Determination of specific binding of B. thuringiensis toxins Cry1Ab and Cry1Ac to the midgut brush border membranes confirmed the loss of midgut binding to Cry1Ab and Cry1Ac in the resistant larvae. The loss of midgut binding to Cry1Ab/Cry1Ac is inherited as a recessive trait, which is consistent with the recessive inheritance of Cry1Ab/Cry1Ac resistance in this greenhouse-derived T. ni population. Therefore, it is concluded that the mechanism for the greenhouse-evolved Cry1Ac resistance in T. ni is an alteration affecting the binding of Cry1Ab and Cry1Ac to the Cry1Ab/Cry1Ac binding site in the midgut.

Specificity of Ukrainian Bacillus thuringiensis Berliner Strains for Agricultural Pests of the Southeastern United States

2007 ◽  
Vol 42 (2) ◽  
pp. 272-285 ◽  
Author(s):  
Iryna A. Isakova ◽  
Yegor B. Isakov ◽  
Svetlana E. Rymar ◽  
Vitalii A. Kordium ◽  
James R. Fuxa
Keyword(s):  
Bacillus Thuringiensis ◽  
Trichoplusia Ni ◽  
Fall Armyworm ◽  
Boll Weevil ◽  
Cabbage Looper ◽  
Tobacco Budworm ◽  
Anthonomus Grandis ◽  
Agricultural Pests ◽  
Genes Encoding ◽  
Soybean Looper

Insecticidal proteins naturally produced by Bacillus thuringiensis Berliner (Bt) present an environmentally friendly alternative to the conventional chemicals used for the pest control. We identified crylA, crylB, and cry1C genes encoding the toxic proteins in 13 Bt strains isolated in Ukraine and then determined the toxicity of these strains against lepidopteran and coleopteran pests from the southeastern U.S. Five of the Bt strains were highly toxic to two lepidopteran pests: three against the soybean looper (Pseudoplusia includens Walker), and two others against the cabbage looper (Trichoplusia ni Hübner). None of the strains had more than moderate toxicity against the tobacco budworm (Heliothis virescens F.), the sugarcane borer (Diatraea saccharalis F.), or fall armyworm (Spodoptera frugiperda J.E. Smith). Cry1 toxins from three Bt strains were solubilized and trypsinized for bioassay against the boll weevil (Anthonomus grandis grandis Boheman) and sweet potato weevil (Cylas formicarius Summers). Toxicity of all three strains was higher or comparable to that of the commercial Bt product Foil® (ECOGEN Inc., Langhorne, PA) containing Cry3 toxin specific for coleopterans. Two of the Ukrainian Bt strains containing Cry1B toxins were toxic to both lepidopteran and coleopteran pests. This study thus revealed new Bt strains toxic to lepidopteran and coleopteran pests from the southeastern U.S. indicating specific target pests for a broad spectrum of Cry1 toxins, including natural and trypsin-activated forms of CrylB proteins.

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