scholarly journals Insecticidal Effects of Organotin(IV) Compounds on Plutella Xylostella (L.) Larvae. II. Inhibitory Potencies Against Acetylcholinesterase and Evidence for Synergism in Tests With Bacillus Thuringiensis(BER.) and Malathion

1994 ◽  
Vol 1 (1) ◽  
pp. 1-17 ◽  
Author(s):  
Nazni W. Ahmad ◽  
Tay Siew Huang ◽  
S. Balabaskaran ◽  
K. M. Lo ◽  
V. G. Kumar Das
Keyword(s):  
Bacillus Thuringiensis ◽  
Plutella Xylostella ◽  
Resistant Strain ◽  
Synergistic Effects ◽  
Diamondback Moth ◽  
Ache Inhibition ◽  
Microbial Insecticide ◽  
In Vitro Inhibition ◽  
Sublethal Concentrations

Features of pesticide synergism and acetylcholinesterase (AChE) inhibition (in vitro) were studied using a selected range of organotin compounds against the early 4th instar larvae of a highly resistant strain of the diamondback moth (DBM), Plutella xylostella, a major universal pest of cruciferous vegetables.Fourteen triorganotin compounds were evaluated for their ability to enhance the toxicity of the microbial insecticide, Bacillus thuringiensis (BT) and of the commercial insecticide, Malathion to Plutella xylostella larvae. Supplemental synergism was observed with triphenyl- and tricyclopentyltin hydroxides in combinations with Bacillus thuringiensis. Increased synergism was observed with an increase in the number of cyclopentyl groups on tin in the mixed series, CypnPh3-n SnX, where X = OH, and 1-(1,2,4-triazolyl). The combination of (p-chlorophenyl)diphenyltin N,N-dimethyldithiocarbamate at LD10 and LD25 concentrations with sublethal concentrations of Malathion as well as of tricyclohexyltin methanesulphonate at the 0.01% (w/v) concentration with Malathion exerted strong synergistic effects (supplemental synergism) with toxicity index (T.I) values of 7.2, 19.8 and 10.1, respectively.Studies on the in vitro inhibition of acetylcholinesterase prepared from the DBM larvae showed that while most of the triorganotin Compounds tested were without effect on the enzyme, compounds containing the thiocarbamylacetate or the dithiocarbamylacetate moieties demonstrated appreciable levels of inhibition, being comparable in efficacy to commercial grades of Malathion and Methomyl.

scholarly journals Susceptibility of a Field-Derived, Bacillus thuringiensis-Resistant Strain of Diamondback Moth to In Vitro-Activated Cry1Ac Toxin

2001 ◽  
Vol 67 (9) ◽  
pp. 4372-4373 ◽  
Author(s):  
Ali H. Sayyed ◽  
Roxani Gatsi ◽  
Thaleia Kouskoura ◽  
Denis J. Wright ◽  
Neil Crickmore
Keyword(s):  
Bacillus Thuringiensis ◽  
Plutella Xylostella ◽  
Resistant Strain ◽  
Diamondback Moth ◽  
Resistance Mechanism ◽  
Lethal Concentration ◽  
Susceptible Population ◽  
Resistant Population ◽  
Susceptible Populations

ABSTRACT Resistant and susceptible populations of the diamondback moth (Plutella xylostella) were tested with crystalline, solubilized, and partially and fully activated forms of theBacillus thuringiensis Cry1Ac δ-endotoxin. Fully activated toxin greatly reduced the resistance ratio (ratio of the 50% lethal concentration for the resistant population to that for the susceptible population) of the resistant population, suggesting that a defect in toxin activation is a major resistance mechanism.

scholarly journals Cyt1Aa from Bacillus thuringiensissubsp. israelensis Is Toxic to the Diamondback Moth,Plutella xylostella, and Synergizes the Activity of Cry1Ac towards a Resistant Strain

2001 ◽  
Vol 67 (12) ◽  
pp. 5859-5861 ◽  
Author(s):  
Ali H. Sayyed ◽  
Neil Crickmore ◽  
Denis J. Wright
Keyword(s):  
Bacillus Thuringiensis ◽  
Plutella Xylostella ◽  
Resistant Strain ◽  
Diamondback Moth ◽  
Laboratory Population

ABSTRACT The Bacillus thuringiensis subsp.israelensis cytolytic protein Cyt1Aa was found to be toxic to an insecticide-susceptible laboratory population ofPlutella xylostella. Cry1Ac-resistant populations ofP. xylostella showed various degrees of resistance to Cyt1Aa. Cyt1Aa/Cry1Ac mixtures showed a marked level of synergism in the Cry1Ac-resistant populations.

scholarly journals Assessing the Single and Combined Toxicity of Chlorantraniliprole and Bacillus thuringiensis (GO33A) against Four Selected Strains of Plutella xylostella (Lepidoptera: Plutellidae), and a Gene Expression Analysis

Toxins ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 227
Author(s):  
Muhammad Zeeshan Shabbir ◽  
Ling He ◽  
Changlong Shu ◽  
Fei Yin ◽  
Jie Zhang ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Plutella Xylostella ◽  
Synergistic Effects ◽  
Diamondback Moth ◽  
Management Strategies ◽  
Combined Toxicity ◽  
Glutathione S Transferase ◽  
Expression Of Genes ◽  
Brassica Vegetables ◽  
Positive Correlations

Concerns about resistance development to conventional insecticides in diamondback moth (DBM) Plutella xylostella (L.), the most destructive pest of Brassica vegetables, have stimulated interest in alternative pest management strategies. The toxicity of Bacillus thuringiensis subsp. aizawai (Bt GO33A) combined with chlorantraniliprole (Chl) has not been documented. Here, we examined single and combined toxicity of chlorantraniliprole and Bt to assess the levels of resistance in four DBM strains. Additionally, enzyme activities were tested in field-original highly resistant (FOH-DBM), Bt-resistant (Bt-DBM), chlorantraniliprole-resistant (CL-DBM), and Bt + chlorantraniliprole-resistant (BtC-DBM) strains. The Bt product had the highest toxicity to all four DBM strains followed by the mixture of insecticides (Bt + Chl) and chlorantraniliprole. Synergism between Bt and chlorantraniliprole was observed; the combination of Bt + (Bt + Chl) (1:1, LC50:LC50) was the most toxic, showing a synergistic effect against all four DBM strains with a poison ratio of 1.35, 1.29, 1.27, and 1.25. Glutathione S-transferase (GST) and carboxyl-esterase (CarE) activities showed positive correlations with chlorantraniliprole resistance, but no correlation was observed with resistance to Bt and Bt + Chl insecticides. Expression of genes coding for PxGST, CarE, AChE, and MFO using qRT-PCR showed that the PxGST and MFO were significantly overexpressed in Bt-DBM. However, AChE and CarE showed no difference in the four DBM strains. Mixtures of Bt with chlorantraniliprole exhibited synergistic effects and may aid the design of new combinations of pesticides to delay resistance in DBM strains substantially.

scholarly journals Cross-Resistance and Stability of Resistance to Bacillus thuringiensis Toxin Cry1C in Diamondback Moth

2001 ◽  
Vol 67 (7) ◽  
pp. 3216-3219 ◽  
Author(s):  
Yong-Biao Liu ◽  
Bruce E. Tabashnik ◽  
Susan K. Meyer ◽  
Neil Crickmore
Keyword(s):  
Bacillus Thuringiensis ◽  
Plutella Xylostella ◽  
Resistant Strain ◽  
Diamondback Moth ◽  
Field Population ◽  
Cross Resistance ◽  
Bacillus Thuringiensis Toxin ◽  
Stability Of Resistance ◽  
Resistant Strains ◽  
Reported Data

ABSTRACT We tested toxins of Bacillus thuringiensis against larvae from susceptible, Cry1C-resistant, and Cry1A-resistant strains of diamondback moth (Plutella xylostella). The Cry1C-resistant strain, which was derived from a field population that had evolved resistance to B. thuringiensis subsp.kurstaki and B. thuringiensis subsp.aizawai, was selected repeatedly with Cry1C in the laboratory. The Cry1C-resistant strain had strong cross-resistance to Cry1Ab, Cry1Ac, and Cry1F, low to moderate cross-resistance to Cry1Aa and Cry9Ca, and no cross-resistance to Cry1Bb, Cry1Ja, and Cry2A. Resistance to Cry1C declined when selection was relaxed. Together with previously reported data, the new data on the cross-resistance of a Cry1C-resistant strain reported here suggest that resistance to Cry1A and Cry1C toxins confers little or no cross-resistance to Cry1Bb, Cry2Aa, or Cry9Ca. Therefore, these toxins might be useful in rotations or combinations with Cry1A and Cry1C toxins. Cry9Ca was much more potent than Cry1Bb or Cry2Aa and thus might be especially useful against diamondback moth.

scholarly journals Increased Responses of Phenoloxidase in Chlorantraniliprole Resistance of Plutella xylostella (Lepidoptera: Plutellidae)

2020 ◽  
Vol 20 (4) ◽  
Author(s):  
Nian-Meng Wang ◽  
Jing-Jing Li ◽  
Ze-Yu Shang ◽  
Qi-Tong Yu ◽  
Chao-Bin Xue
Keyword(s):  
Plutella Xylostella ◽  
Synergistic Effects ◽  
Diamondback Moth ◽  
Cruciferous Vegetables ◽  
Transcriptional Expression ◽  
Resistance Development ◽  
Expression Levels ◽  
Important Pest ◽  
Resistant Strains

Abstract The diamondback moth (Plutella xylostella, DBM) is an important pest of cruciferous vegetables. The use of chlorantraniliprole has been essential in the management of the DBM. However, in many countries and areas, DBM has become highly resistant to chlorantraniliprole. Three different DBM strains, susceptible (S), chlorantraniliprole-selected (Rc), and field-collected (Rb) resistant strains/populations were studied for the role of phenoloxidase in resistance development to the insecticide. By assaying the activity of phenoloxidase (PO) in the three different DBM strains, the results showed that the PO activity in the Rc strain was increased significantly compared with the S strain. The synergistic effects of quercetin showed that the resistant ratio (RR) of the QRc larvae to chlorantraniliprole was decreased from 423.95 to 316.42-fold compared with the Rc larvae. Further studies demonstrated that the transcriptional and translational expression levels of PxPPO1 (P. xylostella prophenoloxidase-1 gene) and PxPPO2 (P. xylostella prophenoloxidase-2 gene) were increased to varying degrees compared with the S strain, such as the transcriptional expression levels of PxPPO2 were 24.02-fold that of the S strain. The responses of phenoloxidase were significantly different in chlorantraniliprole-resistant DBM.

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