Scope of commercial formulations of Bacillus thuringiensis Berliner as an alternative to methyl bromide against Trogoderma granarium Everts larvae (original) (raw)
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2018
The entomopathogenic bacterium Bacillus thuringiensis (Bt) has been used in crop protection for the last 70 years; however, many environmental conditions affect its activity. The present study was directed to evaluate the influence of certain environmental conditions on stability and activity of Bt samples of the two commercial formulations (Dipel 2 × 6. 4% WP and Protecto 9.4% WP), when stored under accelerated hot storage, shelf, and outdoor storage. Photo degradation of the two formulations was studied in aqueous solution. The results revealed that the loss percentage of Protecto formulation was above the permissible limits of WHO specifications after 2 years of storage at ambient conditions and the thermal stability of the Bt was affected negatively depending on the storage periods. In accordance with this trend, the bioassay tests versus neonate and second instar larvae of the cotton leaf worm, Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae), showed a decrease in toxicity of the formulations to (60%) after storage at 35 ± 2°C for 12 weeks and about (70%) after storage under sunlight for 2 days. Photolysis of aqueous solutions reduced the half-life of formulations by about 1-2 days. The stability of Bt should be evaluated prior to submission for registration as these products have showed less stability under storage at ambient conditions. The stakeholders and decision-makers can utilize these results and examine such products case by case.
Journal of Economic Entomology, 1998
The toxicity of 6 strains of Bacillus thuringiensis representing 4 serovars, aiwwai, galleriae, kurstaki, and kumamotoensis, were evaluated in laboratory and field studies for activity against 3 lepidopteran crop pests, Heliothis virescens (F.), Spodoptera eXigua (Hubner), and Trichoplusia ni (Hubner). Results oflaboratory tests showed that some B. thuringiensis strains isolated from Mexico (GM-7 and GM-10), were sufficiently toxic to warrant further investigation as potential bioinsecticides for lepidopteran control. Nixtamalized corn flour was used to create a B. thuringiensis granule formulation that remained toxic for at least 2 yr. Field tests were conducted in 1994 and 1995 on corn plots in a semiarid region in central Mexico. Granular formulations were made with 2% (wt:wt) or 4% (wt:wt) of a spore-crystal B. thuringiensis concentrate and tested with carbaryl and Dipel 2X. In 1994, the corn yields obtained from plots treated with 2 strains from the Howard Dulmage collection (HD-187 and HD-193-kurstaki and gallmae, respectively) and 1 Mexican strain (GM-10, aizawai) at 2% were significantly higher than from plots treated with Dipel 2X or the untreated control. Formulations of 4% containing strains GM-7, GM-10, HD-187, HD-193, and HD-263 provided better insect control than formulations made with C-4. These tests indicated that B. thuringiensis survived in the nixtamalized flour matrix complex and was effective in causing pest reduction. In the 1995 field test, the 3 most toxic strains were evaluated individually or by mixing 2 in the same granular formulation at a total dose of 3%. The highest yields of corn were obtained from plots treated with strain HD-263 (kurstaki), which had originally shown the highest efficacy in laboratory bioassays, and with strain GM-10 (aizawai), formulated 2 yr earlier. These data suggest that the product can be produced and retain shelf life suitable for commercialization.
Pak. J. Bot, 2008
Montreal protocol has deprived the world from Methyl bromide which had been used as one of the most effective pesticide since many decades. Alternative fumigation methods are therefore urgently required to fill this gap in relation to the pest control especially the stored grain insect pest management. Investigations were therefore carried out to evaluate the potential role of Bacillus thuringiensis (Bt) as a natural pest control agent against the rust red flour beetle. Different formulations of the pathogens were tested for their efficacy against the pest. Results revealed that two out of the three commercial formulations used in the experiment i.e., Dipel ES and Bactospeine showed moderate results with 59.33 and 54.66 % mortality. Ecotech Pro was however found to be the most effective exhibiting 79.66 % mortality after 7 days of the treatment. The results further revealed that liquid formulations yielded comparatively better results as compared to the powder formulation. Mortality exhibited in case of Ecotech Pro was perhaps due to its active ingredient transconjugant Bt kurstaki x Bt aizawi, its potency as well as more ingestion of the Bt spores and toxins because of its liquid base. Liquid formulations not only enhanced the moisture contents but also made the grain more palatable for T. castaneum adults resulting in more mortality as compared to dry formulation.
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.
2008
Montreal protocol has deprived the world from Methyl bromide which had been used as one of the most effective pesticide since many decades. Alternative fumigation methods are therefore urgently required to fill this gap in relation to the pest control especially the stored grain insect pest management. Investigations were therefore carried out to evaluate the potential role of Bacillus thuringiensis (Bt) as a natural pest control agent against the rust red flour beetle. Different formulations of the pathogens were tested for their efficacy against the pest. Results revealed that two out of the three commercial formulations used in the experiment i.e., Dipel ES and Bactospeine showed moderate results with 59.33 and 54.66 % mortality. Ecotech Pro was however found to be the most effective exhibiting 79.66 % mortality after 7 days of the treatment. The results further revealed that liquid formulations yielded comparatively better results as compared to the powder formulation. Mortality...
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.
Bacillus thuringiensis: Applications in Agriculture and Insect Resistance Management - A Review
Sustainable Agriculture, 2009
Bacillus thuringiensis (Bt) is a sporulating, Gram-positive facultative-aerobic soil bacterium. Its principal characteristic is the synthesis, during sporulation, of a crystalline inclusion containing proteins known as δ-endotoxins or Cry proteins. These proteins have insecticidal properties. The considerable diversity of these toxins, their efficacy and their relatively cheap production have made Bt the most widely used biopesticide in the world. It is used in the fight against many agricultural crop pests -mostly lepidopteran and coleopteran larvae -notably in the creation of new plant varieties expressing Bt cry genes. For human health, Bt can be used for the effective control of populations of several dipteran disease vectors. The aim of this review is to provide an overview of the use of Bt for crop protection and to deal with the problem of the emergence of insects resistant to this biopesticide. We will begin by presenting various aspects of the biology of this entomopathogenic micro-organism, focusing on the diversity and mode of action of the insecticidal toxins it produces. We will then present several examples of utilization of commercially available Bt products used as sprays or as transgenic crops. Finally, we will describe the principal strategy for the use of Bt transgenic plants, developed so as to prevent or delay the emergence of resistance in target insect populations.
Egyptian Journal of Biological Pest Control
The present study focuses on the evaluation of the potential of a Tunisian Bacillus thuringiensis (Bt) isolate named Hr1, isolated from dead and diseased pod borer, Helicoverpa armigera Hübner (Lepidoptera: Noctuidae) larvae under laboratory and field semi-controlled conditions. The bacterial strain Hr1 showed an insecticidal activity against the pest's neonates in comparison to the spinosad-based insecticide (Tracer 240 SC®) during bioassays under laboratory conditions. A carboxymethyl cellulose-talc (CMC-talc)-based formulation of the Bt isolate was prepared to evaluate the potential of the bacterium on tomato plants infested with H. armigera under semi-controlled field conditions with and without rain simulation. The results showed the efficacy of the formulation than the spinosad-based insecticide and the treatment with unformulated bacterium. The results also showed the persistence of Bt isolate activity even after rain-wash than the treatment with unformulated bacterium.
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.