scholarly journals MORTALITY OF APPLE LEAFROLLER EXPOSED TO DIFFERENT Bacillus thuringiensis SUBSPECIES IN ARTIFICIAL DIET, IN THREE ASSESSMENT PERIODS

2018 ◽  
Vol 40 (1) ◽  
Author(s):  
Jonathan Pereira ◽  
Lino Bittencourt Monteiro ◽  
Daniel Ricardo Sosa Gómez
Keyword(s):  
Bacillus Thuringiensis ◽  
Artificial Diet ◽  
Neonate Larvae

ABSTRACT Bioinsecticides based on Bacillus thuringiensis are the entomopathogen most marketed worldwide. The aim of this study was to evaluate the bioactivity of kurstaki, aizawai subspecies and kurstaki x aizawai hybrid on B. salubricola larvae fed on artificial diet in different assessment periods. Mortality was assessed on the seventh, tenth and fifteenth days after treatment. Microplates containing 150 µl of diet in each cell were used. Suspensions containing Bt subspecies was deposited on the surface of the diet, then neonate larvae were released. The mortality assessment performed after fifteen days of treatment was significant for all three subspecies. Bt kurstaki was more efficient in all assessment periods, except for fifteen days, which was similar to Bt aizawai. Assessments performed up to seven days were more efficient to determine mortality. The three subspecies have influenced the ability for instar change, regardless of concentration. The LC50 of Bt kurstaki on the seventh and tenth days of assessment was from three to six times smaller than that observed in Bt aizawai x kurstaki, and Bt aizawai, respectively.

AN IMPROVED TECHNIQUE FOR DOSING LARVAE OF THE SPRUCE BUDWORM, CHORISTONEURA FUMIFERANA (LEPIDOPTERA: TORTRICIDAE), WITH MEASURED QUANTITIES OF BACILLUS THURINGIENSIS VAR. KURSTAKI

1982 ◽  
Vol 114 (1) ◽  
pp. 89-91 ◽  
Author(s):  
A. Moore ◽  
O. N. Morris
Keyword(s):  
Bacillus Thuringiensis ◽  
Artificial Diet ◽  
Antimicrobial Agents ◽  
Choristoneura Fumiferana ◽  
Spruce Budworm ◽  
Test Sample ◽  
Serial Dilution ◽  
Artificial Diets ◽  
Improved Technique

Bioassays of Bacillus thuringiensis (Bt.) are commonly performed by applying a serial dilution of the test sample to either foliage or artificial diet (Burges and Thompson 1971). In these assays the ingested dose is not measured directly, but is assumed to be proportional to the concentration of the sample applied to the diet. This assumption is valid only if the total amount of food ingested during the experiment is the same at all dosage levels. However, this assumption may not be true because Bt. inhibits feeding of some lepidoptera larvae (Burges and Thompson 1971). Furthermore, artificial diets usually contain nutrients and possibly antimicrobial agents which may interact with Bt.

scholarly journals Soybean protease inhibitors increase Bacillus thuringiensis subs. israelensis toxicity against Hypothenemus hampei

2020 ◽  
pp. 461-478
Author(s):  
Esteve A. Mesén-Porras ◽  
Sergio Dahdouh-Cabia ◽  
Catherine Jim´énez-Quirós ◽  
Rebeca Mora Castro ◽  
César Rodríguez ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Protease Inhibitors ◽  
Artificial Diet ◽  
Control Method ◽  
Dependent Manner ◽  
Soybean Flour ◽  
Hypothenemus Hampei ◽  
Concentration Dependent Manner ◽  
Mortality Effect ◽  
Soybean Extract

Introduction. The coffee berry borer (Hypothenemus hampei Ferrari, CBB) is one of the most devastating pests on coffee plantations around the world. Although CBB is susceptible to the effect of δ–endotoxins of Bacillus thuringiensis subs. israelensis (Bti) at laboratory level, the efficacy of this control method is poor in the field, presumably due to the inactivation by digestive proteases different to those required for protoxin activation. Objective. To study whether the addition of a soybean flour extract enriched with protease inhibitors (PI), mixed with Bti crystals and spores (Bti-sc) in an artificial diet, could improve the toxicity of Bti against CBB. Materials and methods. This study was performed in San José, Costa Rica, between 2012 and 2013. A set of adult female CBB insects was exposed to a mixture containing different concentrations of a partially purified soybean meal extract with active PI and lyophilized Bti-sc, and were tested through a bioassay in artificial diet to estimate the sub-lethal concentration (LC50). The mortality results were validated by observing the dissected midgut, whose ultrastructure was analyzed by transmission electron microscopy. Results. The soybean extracts partially degraded the Bti-sc complex, it reduced its LC50 by almost four times (from 1.135 to 0.315 µg µl-1) and enhanced CBB mortality in a concentration-dependent manner. Histological analyses of the midgut confirmed this synergistic effect, since severe epithelial damage to the intestinal epithelium of CBB exposed to Bti-sc + PI was visualized compared to Bti-sc alone. Conclusions. The combination of a soybean extract enriched in PI and Bti-sc enhanced the mortality effect over CBB, which was confirmed by the midgut collapse. Soybean flour is a cost-effective supplement that could increase Bti effectiveness against CBB and delay the appearance of biological resistance.

Introgression of a disrupted cadherin gene enables susceptibleHelicoverpa armigerato obtain resistance toBacillus thuringiensistoxin Cry1Ac

2008 ◽  
Vol 99 (2) ◽  
pp. 175-181 ◽  
Author(s):  
Y.-H. Yang ◽  
Y.-J. Yang ◽  
W.-Y. Gao ◽  
J.-J. Guo ◽  
Y.-H. Wu ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Artificial Diet ◽  
Development Time ◽  
Larval Growth ◽  
Loss Of Function ◽  
Recessive Resistance ◽  
Family Selection ◽  
Replacement Rate ◽  
Significant Difference ◽  
Net Replacement

AbstractA disrupted allele (r1) of a cadherin gene (Ha_BtR) is genetically associated with incompletely recessive resistance toBacillus thuringiensistoxin Cry1Ac in a Cry1Ac-selected strain (GYBT) ofHelicoverpa armigera. Ther1allele ofHa_BtRwas introgressed into a susceptible SCD strain by crossing the GYBT strain to the SCD strain, followed by repeated backcrossing to the SCD strain and molecular marker assisted family selection. The introgressed strain (designated as SCD-r1, carrying homozygousr1allele) obtained 438-fold resistance to Cry1Ac, >41-fold resistance to Cry1Aa and 31-fold resistance Cry1Ab compared with the SCD strain; however, there was no significant difference in susceptibility to Cry2Aa between the integrated and parent strains. It confirms that the loss of function mutation ofHa_BtRalone can confer medium to high levels of resistance to the three Cry1A toxins inH. armigera. Reciprocal crosses between the SCD and SCD-r1 strains showed that resistance to Cry1Ac in the SCD-r1 strain was completely recessive. Life tables of the SCD and SCD-r1 strains on artificial diet in the laboratory were constructed, and results showed that the net replacement rate (R0) did not differ between the strains. The toxicity of two chemical insecticides, fenvalerate and monocrotophos, against the SCD-r1 strain was not significantly different from that to the SCD strain. However, larval development time of the SCD-r1 strain was significantly longer than that of the SCD strain, indicating a fitness cost of slower larval growth is associated withHa_BtRdisruption inH. armigera.

scholarly journals A Strain of Bacillus thuringiensis Containing a Novel cry7Aa2 Gene That Is Highly Toxic to Leptinotarsa decemlineata (Say) (Coleoptera; Chrysomelidae)

2019 ◽  
Author(s):  
Mikel Dominguez- ◽  
Maite Villanueva ◽  
Ana Beatriz Fernandez ◽  
Primitivo Caballero
Keyword(s):  
Amino Acid ◽  
Bacillus Thuringiensis ◽  
Molecular Mass ◽  
Leptinotarsa Decemlineata ◽  
Insect Pests ◽  
Amino Acid Residues ◽  
Cry Protein ◽  
Sds Page ◽  
Neonate Larvae

The genome of the Bacillus thuringiensis BM311.1 strain was sequenced and assembled in 359 contigs containing a total of 6,390,221 bp. The plasmidic ORF of a putative cry gene from this strain was identified as a potential novel Cry protein of 1138 amino acid residues with a 98% identity respect to Cry7Aa1 protein and a predicted molecular mass of 129.4 kDa. The primary structure of this Cry7Aa2 protein, which revealed the presence of eight conserved blocks and the classical structure of three domains, differed in 28 amino acid residues from that of Cry7Aa1. The cry7Aa2 gene was amplified by PCR and then expressed in the acrystalliferous strain BMB171. SDS-PAGE analysis confirmed the predicted molecular mass for the Cry7Aa2 protein and revealed that, after in vitro trypsin incubation, it was degraded to a toxin of 62 kDa. However, when treated with digestive fluids from Leptinotarsa decemlineata larvae two proteinase-resistant fragments of 60 and 65 kDa were produced. Spore and crystal mixture produced by the wild-type BM311.1 strain against L. decemlineata neonate larvae resulted in a LC50 (18.8 μg/ml), which was statistically equal to the estimated LC50 (20.8 μg/mL) for the recombinant BMB17-Cry7Aa2 strain. In addition, when this novel toxin was activated in vitro with commercial trypsin, the LC50 value was reduced 4 times approximately (LC50 = 4.9 μg/mL). The advantages of Cry7Aa2 protoxin compared to Cry7Aa1 protoxin when used in the control of insect pests are discussed.

New Insecticidal Rocaglamide Derivatives from Flowers of Aglaia odorata

1997 ◽  
Vol 52 (5-6) ◽  
pp. 339-344 ◽  
Keyword(s):  
Natural Products ◽  
Insecticidal Activity ◽  
Spodoptera Littoralis ◽  
Structure Elucidation ◽  
Artificial Diet ◽  
Cd Spectroscopy ◽  
Positive Control ◽  
Pest Insect ◽  
Neonate Larvae

Abstract Flowers of A. odorata yielded six insecticidal rocaglamide derivatives including four compounds which proved to be new natural products. Structure elucidation of the new com pounds, including establishment of their absolute configurations by CD spectroscopy and NMR is described. When incorporated into artificial diet all isolated rocaglamide derivatives exhibited strong insecticidal activity towards neonate larvae of the polyphagous pest insect Spodoptera littoralis with LC50s varying from 1.5-53.4 ppm (2.9-97.1 nᴍ) . Two of the isolated compounds which showed LC50s of 1.5 and 1.6 ppm (2.9 and 3.2 nᴍ ) respectively are similar with regard to their insecticidal activity to azadirachtin (LC50 0.9 ppm [1.3 nᴍ] ) which was included into the study as a positive control.

scholarly journals The immature stages of Paramallocera hirta kirby, 1818 (Coleoptera: Cerambycidae: Elaphidionini)

2006 ◽  
Vol 66 (1a) ◽  
pp. 117-120
Author(s):  
E. Morelli ◽  
A. Sanchez ◽  
M. Bianchi
Keyword(s):  
Eucalyptus Globulus ◽  
Artificial Diet ◽  
Instar Larva ◽  
Diagnostic Value ◽  
Immature Stages ◽  
Neonate Larvae

Last instar larva and pupa of Paramallocera hirta Kirby, 1818 are described and illustrated based on specimens reared in the laboratory from neonate larvae on Eucalyptus globulus ssp. globulus logs and on an artificial diet. Characteristics of possible diagnostic value are also presented in this paper.

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