scholarly journals Toxicity of Bacillus thuringiensis-Derived Pesticidal Proteins Cry1Ab and Cry1Ba against Asian Citrus Psyllid, Diaphorina citri (Hemiptera)

Toxins ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 173 ◽  
Author(s):  
Maria Fernandez-Luna ◽  
Pavan Kumar ◽  
David Hall ◽  
Ashaki Mitchell ◽  
Michael Blackburn ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Asian Citrus Psyllid ◽  
Diaphorina Citri ◽  
Cry Toxins ◽  
Diverse Range ◽  
Additional Tool ◽  
Incurable Disease ◽  
Important Pest ◽  
Bacterium Bacillus ◽  
The Individual

The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama (Hemiptera), is an important pest of citriculture. The ACP vectors a bacterium that causes huanglongbing (HLB), a devastating and incurable disease of citrus. The bacterium Bacillus thuringiensis (Bt) produces multiple toxins with activity against a diverse range of insects. In efforts to provide additional control methods for the ACP vector of HLB, we identified pesticidal proteins derived from Bt for toxicity against ACP. The trypsin proteolytic profiles of strain-derived toxins were characterized. Strain IBL-00200, one of six strains with toxins shown to have basal activity against ACP was selected for liquid chromatography-mass spectrometry (LC-MS/MS) identification of the individual Cry toxins expressed. Toxicity assays with individual toxins derived from IBL-00200 were then performed. The activated form of the Cry toxins Cry1Ab and Cry1Ba were toxic to ACP with LC50 values of approximately 120 µg/mL. Disruption of the midgut epithelium was associated with the toxicity of both the IBL-00200-derived toxin mixture, and with Cry1Ba. With further optimization of the efficacy of Cry1Ab and Cry1Ba, these toxins may have practical utility against ACP. Bt toxins with activity against ACP may provide an additional tool for management of ACP and the associated HLB disease, thereby providing a more sustainable and environmentally benign approach than repeated application of broad-spectrum insecticides.

scholarly journals Comparative analysis of the individual protoxin components in P1 crystals of Bacillus thuringiensis subsp. kurstaki isolates NRD-12 and HD-1

1990 ◽  
Vol 269 (2) ◽  
pp. 507-512 ◽  
Author(s):  
L Masson ◽  
G Préfontaine ◽  
L Péloquin ◽  
P C K Lau ◽  
R Brousseau
Keyword(s):  
Bacillus Thuringiensis ◽  
Choristoneura Fumiferana ◽  
Insect Cell Line ◽  
Gene Products ◽  
Bacillus Thuringiensis Subsp ◽  
Independent Verification ◽  
Lepidopteran Larvae ◽  
Bacterium Bacillus ◽  
The Individual

Two commercially important strains (NRD-12 and HD-1) of the entomopathogenic bacterium Bacillus thuringiensis subsp. kurstaki each contain three genes of partially identical sequence coding for three classes of 130-135 kDa protoxins (termed the 4.5, 5.3 and 6.6 protoxins) that display toxicity towards various lepidopteran larvae. These gene products combine to form the intracellular bipyramidal P1 crystal. Each of the genes from both strains was cloned and expressed in Escherichia coli. Analysis of the cloned genes at the restriction-endonuclease level revealed no detectable differences among genes within a particular gene class. The composition of the P1 crystal from both strains was quantitatively analysed by CNBr cleavage of the purified P1 crystal, with the purified recombinant gene products as reference proteins. Independent verification of the presence of high 6.6-protoxin gene product in the P1 crystal was provided by a rapid in vitro lawn cell toxicity assay directed against a Choristoneura fumiferana (CF-1) insect cell line. The results indicate that, although all three gene products are represented within the P1 crystal of either NRD-12 or HD-1, only the contents of the 4.5 and 5.3 protoxins vary between the two crystals, whereas the 6.6 protoxin contents are similar and represent approximately one-third of the P1 crystal in either strain.

scholarly journals Evaluating Cross-resistance Between Vip and Cry Toxins of Bacillus thuringiensis

2019 ◽  
Vol 113 (2) ◽  
pp. 553-561 ◽  
Author(s):  
Bruce E Tabashnik ◽  
Yves Carrière
Keyword(s):  
Bacillus Thuringiensis ◽  
Genetically Engineered ◽  
Cross Resistance ◽  
Published Data ◽  
Data Sets ◽  
Cry Proteins ◽  
Cry Toxins ◽  
Bt Crops ◽  
Resistant Strains ◽  
Bacterium Bacillus

Abstract Crops genetically engineered to produce insecticidal proteins from the bacterium Bacillus thuringiensis (Bt) have revolutionized control of some major pests. Some recently introduced Bt crops make Vip3Aa, a vegetative insecticidal protein (Vip), which reportedly does not share binding sites or structural homology with the crystalline (Cry) proteins of Bt used widely in transgenic crops for more than two decades. Field-evolved resistance to Bt crops with practical consequences for pest control includes 21 cases that collectively reduce the efficacy of nine Cry proteins, but such practical resistance has not been reported yet for any Vip. Here, we review previously published data to evaluate cross-resistance between Vip and Cry toxins. We analyzed 31 cases based on 48 observations, with each case based on one to five observations assessing cross-resistance from pairwise comparisons between 21 resistant strains and 13 related susceptible strains of eight species of lepidopteran pests. Confirming results from previous analyses of smaller data sets, we found weak, statistically significant cross-resistance between Vip3 and Cry1 toxins, with a mean of 1.5-fold cross-resistance in 21 cases (range: 0.30–4.6-fold). Conversely, we did not detect significant positive cross-resistance between Vip3 toxins and Cry2Ab. Distinguishing between weak, significant cross-resistance, and no cross-resistance may be useful for better understanding mechanisms of resistance and effectively managing pest resistance to Bt crops.

scholarly journals Characterization of electrical penetration graphs of the Asian citrus psyllid,Diaphorina citri, in sweet orange seedlings

2010 ◽  
Vol 134 (1) ◽  
pp. 35-49 ◽  
Author(s):  
J. P. Bonani ◽  
A. Fereres ◽  
E. Garzo ◽  
M. P. Miranda ◽  
B. Appezzato-Da-Gloria ◽  
...  
Keyword(s):  
Sweet Orange ◽  
Asian Citrus Psyllid ◽  
Diaphorina Citri ◽  
Electrical Penetration Graphs

Insecticide sprays, natural enemy assemblages and predation on Asian citrus psyllid, Diaphorina citri (Hemiptera: Psyllidae)

2014 ◽  
Vol 104 (5) ◽  
pp. 576-585 ◽  
Author(s):  
C. Monzo ◽  
J.A. Qureshi ◽  
P.A. Stansly
Keyword(s):  
Natural Enemy ◽  
Early Spring ◽  
Citrus Greening ◽  
Asian Citrus Psyllid ◽  
Late Winter ◽  
Diaphorina Citri ◽  
Citrus Groves ◽  
Arthropod Fauna ◽  
Predator Exclusion ◽  
Insecticide Sprays

AbstractThe Asian citrus psyllid (ACP), Diaphorina citri Kuwayama is considered a key citrus pest due to its role as vector of ‘huanglongbing’ (HLB) or citrus greening, probably the most economically damaging disease of citrus. Insecticidal control of the vector is still considered a cornerstone of HLB management to prevent infection and to reduce reinoculation of infected trees. The severity of HLB has driven implementation of intensive insecticide programs against ACP with unknown side effects on beneficial arthropod fauna in citrus agroecosystems. We evaluated effects of calendar sprays directed against this pest on natural enemy assemblages and used exclusion to estimate mortality they imposed on ACP populations in citrus groves. Predator exclusion techniques were used on nascent colonies of D. citri in replicated large untreated and sprayed plots of citrus during the four major flushing periods over 2 years. Population of spiders, arboreal ants and ladybeetles were independently assessed. Monthly sprays of recommended insecticides for control of ACP, adversely affected natural enemy populations resulting in reduced predation on ACP immature stages, especially during the critical late winter/early spring flush. Consequently, projected growth rates of the ACP population were greatest where natural enemies had been adversely affected by insecticides. Whereas, this result does not obviate the need for insecticidal control of ACP, it does indicate that even a selective regimen of sprays can impose as yet undetermined costs in terms of reduced biological control of this and probably other citrus pests.

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