Influence of some environmental conditions on stability and activity of Bacillus thuringiensis formulations against the cotton leaf worm, Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae (original) (raw)

Comparative Efficacy of Bacillus thuringiensis Commercial Formulations against Leaf Worm, Spodoptera litura Fabricius under Laboratory Conditions

Pakistan Journal of Zoology, 2020

to check the efficacy of commercial biopesticides under controlled environmental conditions. Bio pesticides are important alternates for chemical control of economically damaging insect pests like leaf worm, Spodoptera litura Fabricius. In this study, two commercial products including Dipel with Bt sub speciess kurstaki and Turex with Bt sub speciess kurstaki and aizawai were tested against three early larval instars of S. litura under laboratory conditions using leaf dip method. Mortality was recorded after three and seven days of exposure. The results indicated that larval mortality increased with time and Turex (Bt sub speciess kurstaki and aizawai) after 3 days of exposure caused significantly higher mortality i.e 46.43, 43.45 and 38.69 % as compared to Dipel (Bt sub speciess kurstaki) that caused 19.05, 6.55 and 4.76 % mortality for 1 st , 2 nd and 3 rd instar, respectively. The data for 7 th day also showed significantly higher mortality as 64.29, 60.71 and 45.24 % by Turex (Bt sub speciess kurstaki and aizawai) in comparison with 55.95, 57.74 and 42.86 % mortality by Dipel (Bt sub species kurstaki) for 1 st , 2 nd and 3 rd instar, respectively. Susceptibility to both bio pesticides increased with increase in their concentration and decreased with increase in larval instar. Similarly LC 50 values suggested Turex (Bt sub species kurstaki and aizawai) to be more toxic with less LC 50 values as compared to Dipel (Bt sub species kurstaki). These results indicated that these bio pesticides if used at early insect stage can help to control this pest.

Persistence of insecticidal activity of novel bio-encapsulated formulations of Bacillus thuringiensis var. kurstaki against Choristoneura rosaceana [Lepidoptera: Tortricidae]

Phytoprotection, 2001

DiPelTM, a registered Bacillus thuringiensis var. kurstaki (Btk)-based formulation, and experimental bio-encapsulated Btk formulations were sprayed in an apple orchard. Their persistence was assessed in the laboratory against obliquebanded leafroller (Choristoneura rosaceana) larvae for three consecutive years. In 1995, DiPel and the bio-encapsulated formulation caused significantly higher larval mortality than the control at least 1 day, and up to 27 days after treatments, respectively. In 1996, although 6.4 mm of rain fell during the day of treatments, DiPel and the bio-encapsulated formulation caused respectively 21 and 33% larval mortality immediately after treatments. DiPel caused significantly higher mortality than the control for up to 3 days while the bio-encapsulated formulation caused significantly higher mortality for up to 14 days. In 1997, two Btk strains (HD-1 and BMP123) were sprayed at different concentrations in a.i. (3 and 8%) and doses (30 and 240 g 15 L-1 applied...

The Effects of Ultraviolet B on The Efficacy of Bacillus thuringiensis var. kurstaki Formulations Against Tobacco Armyworm, Spodoptera litura (Lepidoptera: Noctuidae)

HAYATI Journal of Biosciences

Tobacco armyworm (Spodoptera litura Fab.) is one of the major insect pests of crops in Indonesia. The management of this pest still depends on the use of chemical insecticides. The use of bio-insecticides, such as Bacillus thuringiensis (Bt.), are known to be alternatives, but it easily degraded by sunlight. This research aimed to study the effects of UV B on Bt. pathogenicity and to explore plant-based additives as UV B protectants for Bt. against armyworm. Thirteen plant extracts were screened based on their UV spectra absorbencies using UV spectrophotometry. The extracts, namely cloves, Jicama, Celebes pepper, turmeric, and Moringa, then used for the formulations of Bt. and exposed under UV B lights for 0, 72, and 144 h. After exposure to UV B, Bt. formulations were tested for bioassay against one- day-old 1st and one day old 2nd larval instars of tobacco armyworm. The result indicated that at 72 and 144 h of UV B exposures, the Bt. added formulations were signifcantly different co...

Assessment of Microencapsulated Formulations for Improved Residual Activity of Bacillus thuringiensis

Journal of Economic Entomology, 2000

Bacillus thuringiensis Berliner is a highly efficacious bioinsecticide used to control lepidopteran pests in the field. Unfortunately, it has limited residual activity on plants because sunlight inactivates spores and crystals and they can be washed off by rain. To minimize loss of activity, formulations must contain lTV protectants, stickers, or both. We tested =80 formulations and determined optimal combinations of ingredients and spray drying conditions for improving B. thuringiensis residual activity after simulated rain and simulated sunlight. B. thuringiensis stability, after simulated sunlight (xenon Iight/8 h) and rain (5 em/50 min), was improved using formulations based on lignin, corn flours, or both, with up to 20% of the active ingredient, when compared with technical powder or Dipel 2X in laboratory assays. Two formulations, made with corn flours or lignin + pregelatinized corn flour (PCF), killed 51.6 and 75.3% of Ostrinia nubilalis (Hubner) neonates after rain, respectively, versus 27% for technical powder. When the insecticidal activity was tested after simulated sunlight, corn flour-based formulations killed 78.5% of test larvae, and the lignin + PCF formulation killed 70.4%, in contrast to technical powder which caused an average of 29% mortality. Formulations made with Dipel 2X rather than technical powder, caused 62.5% mortality (corn flour-based formulations), and 72.3% mortality (lignin + PCF), versus 53.4% for Dipel 2x after rain. When tested after simulated sunlight, formulations killed 95% of the larvae (average of both formulations) versus 82% for Dipel 2x. In a field test, formulations were applied to cabbage and insecticidal activity was determined against Trichoplusia ni (Hubner) neonates exposed to treated leaves. Insecticidal activity of the corn flour-based formulations was comparable to Dipel 2x for 4 d after treatment, but was signiflcantly better than Dipel 2x 7 d after application. A lignin and PCF-based formulation showed signiflcantly higher residual activity than Dipel 2X, 4 and 7 d after application.

Assessment of Microencapsulated Formulations for Improved Residual Activity of Bacillus thuringiensis

Journal of Economic Entomology, 2000

Bacillus thuringiensis Berliner is a highly efficacious bioinsecticide used to control lepidopteran pests in the field. Unfortunately, it has limited residual activity on plants because sunlight inactivates spores and crystals and they can be washed off by rain. To minimize loss of activity, formulations must contain lTV protectants, stickers, or both. We tested =80 formulations and determined optimal combinations of ingredients and spray drying conditions for improving B. thuringiensis residual activity after simulated rain and simulated sunlight. B. thuringiensis stability, after simulated sunlight (xenon Iight/8 h) and rain (5 em/50 min), was improved using formulations based on lignin, corn flours, or both, with up to 20% of the active ingredient, when compared with technical powder or Dipel 2X in laboratory assays. Two formulations, made with corn flours or lignin + pregelatinized corn flour (PCF), killed 51.6 and 75.3% of Ostrinia nubilalis (Hubner) neonates after rain, respectively, versus 27% for technical powder. When the insecticidal activity was tested after simulated sunlight, corn flour-based formulations killed 78.5% of test larvae, and the lignin + PCF formulation killed 70.4%, in contrast to technical powder which caused an average of 29% mortality. Formulations made with Dipel 2X rather than technical powder, caused 62.5% mortality (corn flour-based formulations), and 72.3% mortality (lignin + PCF), versus 53.4% for Dipel 2x after rain. When tested after simulated sunlight, formulations killed 95% of the larvae (average of both formulations) versus 82% for Dipel 2x. In a field test, formulations were applied to cabbage and insecticidal activity was determined against Trichoplusia ni (Hubner) neonates exposed to treated leaves. Insecticidal activity of the corn flour-based formulations was comparable to Dipel 2x for 4 d after treatment, but was signiflcantly better than Dipel 2x 7 d after application. A lignin and PCF-based formulation showed signiflcantly higher residual activity than Dipel 2X, 4 and 7 d after application.

Novel formulations of Bacillus thuringiensis var. kurstaki: an eco-friendly approach for management of lepidopteran pests

World Journal of Microbiology and Biotechnology, 2020

Bacillus thuringiensis (Bt) and entomopathogenic fungi (EPF) are in use for management of insect pests. Continuous use of Bt can lead to problem of resistance development in insect pests. Hence use of combination formulations (CF) of microbials with diverse modes of action has been attempted to slow down the process of resistance development. Suspension concentrate (SC) formulations of a local strain of Bt var. kurstaki DOR Bt-127 were developed singly and in combination with conidia of the EPF Nomuraea rileyi (Nr) and Beauveria bassiana (Bb). Electron microscopy of Bt + Bb CF treated larvae of Helicoverpa armigera revealed simultaneous infection by both microbials indicating their compatibility. Endotoxin contents in Bt-SC, Bt + Bb and Bt + Nr CFs were 5.0, 4.7 and 4.7%, respectively. These formulations were effective against larvae of Spodoptera litura, H. armigera and Achaea janata coupled with a lowering of the effective requirement of Bt and EPF. In multi-location field trials, Bt-SC and Bt + Nr CF were highly effective against S. litura and A. janata on castor as well as H. armigera and Thysanoplusia orichalcea on sunflower. However, Bt + Bb CF was highly effective only on sunflower against H. armigera and T. orichalcea. All formulations had 24 months shelf-life at room temperature. DOR Bt-127 based SC formulations developed singly and in combination with Nr and Bb were effective against major lepidopteran pests of castor and sunflower and did not lose viability under storage at room temperature. The CFs of Bt with EPF could prove promising for mitigating resistance development to Bt.

Scope of commercial formulations of Bacillus thuringiensis Berliner as an alternative to methyl bromide against Trogoderma granarium Everts larvae

Pak. J. Bot, 2007

Phasing out of ozone depleting pesticides like Methyl bromide has opened a new window for searching alternative pesticides to control insect and other pests of agriculture storage sector. Besides, concern has also been expressed by small farmers of the developing world that conventional chemical insecticides may occasionally result in poisoning of humans and livestock. Fortunately, Bacillus thuringiensis (Bt) has expressed very low mammalian toxicity and is considered as a valuable safe insecticide option for farmers. Different strains of B. thuringiensis have been shown to produce a number of insect toxins, which have shown effectiveness against different insect species belonging to the orders Lepidoptera, Diptera and Coleoptera. Due to the high activity, specificity to target pest species, and non-toxicity to human, strains of Bt form the basis for a number of commercial products to be used as pest control agents. The present investigations focus on use of commercial formulations of Bacillus thuringiensis as an alternative to methyl bromide for combating T. granarium infestation in stored wheat. The results have revealed that liquid formulations yielded better results as compared to the dry formulations. Maximum mortality of the larvae was observed in Ecotech Pro treated grains followed by Dipel ES, whereas, Bactospeine had not provided promising results. Inferences were therefore drawn that insect mortality depended upon ingestion of the Bt spores and toxins. It was also concluded that liquid formulations not only enhanced the moisture contents but also made the grain more palatable for T. granarium larvae resulting in more mortality as compared to the dry formulations.

Comparative Studies on Using a Local Isolate of Bacillus Thuringiensis in Different Granule Formulations Against Cotton Leaf Worm Spodoptera Littoralis

Egyptian Journal of Agricultural Research, 2012

A Bacillus thuringiensis isolate (KIII), isolated from Egyptian soil, was produced in liquid culture using yeast extractmolt-glucose medium, where the spore-crystal complexes were recovered. The complexes were formulated into three granule formulations, then the toxicity of the isolate was evaluated in laboratory by bioassay against the cotton leafworm S. littoralis. Results exhibited that, the best formulation for keeping biological activity (both efficacy and survival) of B. thuringiensis was the alginate granules. Bioassays of the formulation containing Congo red (as UV-protectant), indicate the superiority of this additive to other in improving the effectiveness of B.t. under exposure to sunlight. Also, adding molasses + soybean flour exhibited the highest efficacy when using as feeding stimulants. Zinc sulphate also showed a remarkable effect in enhancing B.t. potency and viability.

Shelf Life and Field Evaluation of CAMB Bacillus thuringiensis Biopesticide Against Helicoverpa armigera (Hubner)(Lepidoptera: Noctuidae) on Tomato

Pakistan Journal of Biological Sciences, 2000

Previous lab report (Karim et al., 1999) had shown the efficacy of CAMB Bacillus thuringiensis preparation in potato field to control Helicoverpa armigera. In present study, CAMB Bt formulations based on locally isolated Bt strain were checked against 1st to 4th instar larvae of H. armigera by incorporating Bt proteins into artificial diet. Early instars showed significant susceptibility to Bt formulation. Laboratory assays of stored CAMB Bt formulations did not show any significant change in their toxicity towards H. armigera larvae in laboratory assays. Potency of stored Bt formulations for 12 and 24 months were also tested in small scale experiment conducted under contained conditions on tomato crop. All formulations were found effective to control H. armigera larvae in tomato crop. The present study shows that CAMB Bt formulation can be used in field applications to control target pests after long storage time.

A new formulation of Bacillus thuringiensis: UV protection and sustained release mosquito larvae studies

Scientific reports, 2016

Persistence of Bacillus thuringiensis is an important factor in determining the success of this product as a pest control agent. In this report we present the development of a highly active mosquitocidal formulation with high resistance to UV. LLP29-M19 strain of Bt, selected by repeated exposure to UV was found to be highly resistant to UV. The product was optimized and the methods used were statistically analyzed. Using single-factor experiments it was determined that the optimal concentration of sodium alginate, CaCl2 and hollow glass beads in the formulation were 1.0%, 2.0% and 3.5%, respectively. Plackett-Burman design was used to screen the interaction of the three factors, CaCl2, sodium alginate and hollow glass beads in the sustained-release formulation. The best combined concentration and mutual effects of the three factors were optimized by response surface methodology. The results showed that the most favorable composition was sodium alginate 0.78%, CaCl2 4.52%, hollow gl...