Binding of Insecticidal Crystal Proteins of Bacillus thuringiensis to the Midgut Brush Border of the Cabbage Looper, Trichoplusia ni (Hübner) (Lepidoptera: Noctuidae), and Selection for Resistance to One of the Crystal Proteins

AbstractDevelopment of resistance to insecticides has generally been associated with fitness costs that may be magnified under challenging conditions. Lepidopterans which are resistant to the biopesticide Bacillus thuringiensis subsp. kurstaki (Btk) have been shown to have reduced fitness, such as lower survival when subjected to overwintering stress. Recently, resistance to Btk has been found in some populations of Trichoplusia ni Hübner in greenhouses in British Columbia. This situation provides an opportunity to investigate potential trade-offs between overwintering survival and insecticide resistance in a major pest species. Here, we assess the survival and eventual fecundity of Btk resistant and susceptible T. ni pupae exposed to cool temperatures. Contrary to our expectations, resistant T. ni had higher overwintering survival than susceptible individuals. This is the first account of a potential advantage associated with Btk resistance. Resistant and susceptible moths had reduced fecundity and smaller progeny after cold exposure compared to controls, and this may counteract the survival advantage. Nevertheless, it seems unlikely that this is sufficient to select out the resistant phenotype in the presence of strong selection for resistance and in the absence of immigration of susceptible moths. The appearance of resistance without evidence of a trade-off in overwintering survival presents a major challenge to management in production greenhouses.

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Changes in Permeability of Brush Border Membrane Vesicles fromSpodoptera littoralis Midgut Induced by Insecticidal Crystal Proteins from Bacillus thuringiensis

Applied and Environmental Microbiology ◽

10.1128/aem.64.4.1563-1565.1998 ◽

1998 ◽

Vol 64 (4) ◽

pp. 1563-1565 ◽

Cited By ~ 13

Author(s):

B. Escriche ◽

N. De Decker ◽

J. Van Rie ◽

S. Jansens ◽

E. Van Kerkhove

Keyword(s):

Bacillus Thuringiensis ◽

Brush Border ◽

Brush Border Membrane ◽

Membrane Vesicles ◽

Brush Border Membrane Vesicles ◽

Osmotic Swelling ◽

Midgut Cell ◽

Crystal Proteins ◽

Light Scattering Technique ◽

Insecticidal Crystal Proteins

ABSTRACT Bacillus thuringiensis insecticidal crystal proteins (ICPs) are thought to induce pore formation in midgut cell membranes of susceptible insects. Cry1Ca, which is significantly active inSpodoptera littoralis, made brush border membrane vesicles permeable to KCl (osmotic swelling was monitored by the light scattering technique); the marginally active ICPs Cry1Aa, Cry1Ab, and Cry1Ac did not.

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Functional domains of Bacillus thuringiensis insecticidal crystal proteins. Refinement of Heliothis virescens and Trichoplusia ni specificity domains on CryIA(c).

Journal of Biological Chemistry ◽

10.1016/s0021-9258(18)55221-2 ◽

1991 ◽

Vol 266 (27) ◽

pp. 17954-17958

Author(s):

A.Z. Ge ◽

D. Rivers ◽

R. Milne ◽

D.H. Dean

Keyword(s):

Bacillus Thuringiensis ◽

Heliothis Virescens ◽

Trichoplusia Ni ◽

Functional Domains ◽

Crystal Proteins ◽

Insecticidal Crystal Proteins

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Screening for Bacillus thuringiensis Crystal Proteins Active against the Cabbage Looper, Trichoplusia ni

Journal of Invertebrate Pathology ◽

10.1006/jipa.2000.4946 ◽

2000 ◽

Vol 76 (1) ◽

pp. 70-75 ◽

Cited By ~ 18

Author(s):

Marı́a M Iracheta ◽

Benito Pereyra-Alférez ◽

Luis Galán-Wong ◽

Juan Ferré

Keyword(s):

Bacillus Thuringiensis ◽

Trichoplusia Ni ◽

Cabbage Looper ◽

Crystal Proteins

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Receptors and Lethal Effect of Bacillus thuringiensis Insecticidal Crystal Proteins to the Anticarsia gemmatalis (Lepidoptera, Noctuidae)

ISRN Microbiology ◽

10.1155/2013/940284 ◽

2013 ◽

Vol 2013 ◽

pp. 1-7 ◽

Cited By ~ 9

Author(s):

Lidia Mariana Fiuza ◽

Neiva Knaak ◽

Rogério Fernando Pires da Silva ◽

João Antônio Pêgas Henriques

Keyword(s):

Bacillus Thuringiensis ◽

Lethal Effect ◽

Anticarsia Gemmatalis ◽

Binding Studies ◽

Crystal Proteins ◽

Binding Data ◽

Lepidoptera Noctuidae ◽

Insecticidal Crystal Proteins

Bioassays with insecticidal crystal proteins (ICPs) from Bacillus thuringiensis have demonstrated that Cry1Aa, Cry1Ac, and Cry1Ba are the most active toxins on larvae of the Anticarsia gemmatalis. The toxins Cry1Da and Cry1Ea are less toxic, and toxins Cry2Aa are not active. Binding of these ICPs to midgut sections of the A. gemmatalis larvae was studied using streptavidin-mediated detection. The observed staining patterns showed that Cry1Aa and Cry1Ac bound to the brush border throughout the whole length of the midgut. However, the binding sites of Cry1Ba were not evenly distributed in the midgut microvilli. The in vivo assays against larvae of 2nd instar A. gemmatalis confirmed the results from the in vitro binding studies. These binding data correspond well with the bioassay results, demonstrating a correlation between receptors binding and toxicity of the tested ICPs in this insect.

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