scholarly journals Efficacy of Bacillus Thuringiensis (var. Kurstaki) against Diamondback Moth (Plutella Xylostella L.) Eggs and Larvae on Cabbage Under Semi-Controlled Greenhouse Conditions

2015 ◽  
Vol 7 ◽  
pp. IJIS.S23637 ◽  
Author(s):  
Mitch M. Legwaila ◽  
David C. Munthali ◽  
Baone C. Kwerepe ◽  
Motshwari Obopile
Keyword(s):  
Bacillus Thuringiensis ◽  
Plutella Xylostella ◽  
Diamondback Moth ◽  
Probit Analysis ◽  
Effective Control ◽  
College Of Agriculture ◽  
Expected Time ◽  
Eggs And Larvae

The efficacy of Bacillus thuringiensis (var. kurstaki) ( Btk) against the diamondback moth (DBM) on cabbage was studied at Botswana College of Agriculture, Gaborone, Botswana. Using five concentrations of Btk: 2, 4, 6, 8, and 10 g/L, bioassays were conducted against DBM eggs and second instar larvae at 30°C ± 5°C. Each treatment was replicated three times. Probit analysis was used to determine the LD50 and LD90 values for the treatments against eggs and larvae. When the treatments were assessed at 72, 96, 120, and 144 hours, LD90 values against larvae were 11.02, 10.22, 5.92, and 4.01 g/L, whereas they were 7.71, 6.94, and 6.24 g/L against eggs when assessed 48, 72, and 96 hours after the expected time of hatching. This indicated that Btk was effective against both eggs and larvae when exposed for long periods. The slopes of the probit lines for larvae assessed at 24, 48, 72, 96, 120, and 144 hours after application were 0.250, 1.064, 0.910, 0.383, 0.453, and 0.414, while those against eggs were 1.153, 1.246, and 0.933 when assessed 48, 72, and 96 hours after the expected time of hatching. This indicates a smaller change in mortality with increase in pesticide dosage for both eggs and larvae. Btk treatments achieved 85.7%–94.6% reduction in DBM damage on cabbage. Therefore, Btk can be used to achieve effective control of DBM eggs and larvae and reduce damage on cabbage under greenhouse conditions.

scholarly journals Effectiveness of Spinosad against Diamondback Moth (Plutella xylostella L.) Eggs and Larvae on Cabbage under Botswana Conditions

2014 ◽  
Vol 6 ◽  
pp. IJIS.S12531 ◽  
Author(s):  
Mitch M. Legwaila ◽  
David C. Munthali ◽  
Motshwari Obopile ◽  
Baone C. Kwerepe
Keyword(s):  
Plutella Xylostella ◽  
Larval Mortality ◽  
Diamondback Moth ◽  
Rapid Change ◽  
Probit Analysis ◽  
Effective Control ◽  
College Of Agriculture ◽  
Egg Mortality ◽  
Eggs And Larvae

The efficacy of spinosad against the diamondback moth (DBM) on cabbage was studied at Botswana College of Agriculture, Gaborone, Botswana in 2011. Using five concentrations of spinosad: 0.12, 0.36, 0.60, 0.84 and 1.08 g/L, bioassays were conducted against DBM eggs and second instar larvae at 30°C ± 5°C. Each treatment was replicated three times. Probit analysis was used to determine LD50 and LD90 values for the treatments against eggs and larvae. When the treatments were assessed at 72 and 96 hours, LD90 values against larvae were 0.74 and 0.59 g/L, whereas they were 0.35 and 0.32 g/L against eggs. This indicated that spinosad was more effective against eggs than against larvae. The slopes of the probit lines for larvae assessed at 48, 72 and 96 hours after application were 3.519, 3.810 and 3.427, while those against eggs were 1.725, 1.316 and 1.086. This indicates that there was a more rapid change in larval mortality with increase in pesticide dosage than in egg mortality. The study shows that spinosad can achieve effective control of DBM eggs and larvae under Botswana conditions.

scholarly journals Bio Efficacy of Bacillus thuringiensis Isolates against Diamond Back Moth (Plutella xylostella L.) on Cauliflower Plant in Tamil Nadu, India

2020 ◽  
pp. 10-20
Author(s):  
S. S. Thilagavathi ◽  
G. Prasad ◽  
A. Ramalakshmi
Keyword(s):  
Bacillus Thuringiensis ◽  
Plutella Xylostella ◽  
Tamil Nadu ◽  
Diamondback Moth ◽  
Larval Growth ◽  
Solanum Melongena ◽  
Protein Profiling ◽  
Leaf Damage ◽  
Effective Control ◽  
Third Instar Larvae

Bacillus thuringiensis (Bt) gram positive entomopathogenic bacteria being an eco-friendly biopesticide. In present study the potential of B. thuringiensis isolates was studied for the biological control of Diamond back moth (DBM). Fifteen Bt isolates were obtained from the Department of Agricultural Microbiology, TNAU Tamil Nadu. This mainly isolated from the cultivated lands Cotton (Gossypium hirsutum), Brinjal (Solanum melongena) and Tomato (Solanum lycopersicum). All the 15 isolates were identified as B. thuringiensis based on the crystalline structure. Four different types of crystalline forms were observed, in which the isolates CC, CB1, BC, TD, BD were produces cuboidal shape crystals. Then, the isolates were characterized based on presence of lepidopteron specific cry gene. Among the 15 B. thuringiensis isolates seven of them were found to be positive for lepidopteron specific cry genes include cry 1 & cry 2. Four Bt isolates were exhibited presences of both cry 1 and cry 2 genes. The selected 4 isolates further screened for protein profiling by SDS Page. Molecular weights of the protein ranging from 65 to 130 kDa. Toxicity of this four B. thuringiensis isolates were evaluated by bioassay using third instar larvae of the diamondback moth (Plutella xylostella) and isolate (CC) recorded maximum mortality of 95.33% comparable to standard strain HD1 98.31%. In quantitative bioassay, the LC50 for third instar larvae of Plutella xylostella was found to be least range 197.09 ppm with fiducial limits of 110.28 - 352.21 ppm respectively. Different concentration of the toxic protein (100, 250, 500, 750, 1000, 2000) will reduce the leaf damage and larval growth was (54-8% and 58-25%) observed. This achieved effective control of DBM in cauliflower plant.

Enhancement of δ-Endotoxin Activity by Toxin-Free Spore of Bacillus thuringiensis against the Diamondback Moth, Plutella xylostella

1994 ◽  
Vol 63 (1) ◽  
pp. 111-112 ◽  
Author(s):  
Minoru Miyasono ◽  
Shyuichiro Inagaki ◽  
Makiko Yamamoto ◽  
Katsuaki Ohba ◽  
Takeo Ishiguro ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Plutella Xylostella ◽  
Diamondback Moth ◽  
Endotoxin Activity ◽  
Free Spore

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.

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