Bacillus thuringiensis – Based Biopesticides Against Agricultural Pests in Latin America (original) (raw)
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Bacillus thuringiensis (Bt) is more than a special agent for biological control of pests
Journal of Applied Biotechnology & Bioengineering
Bacillus thuringiensis (Bt) is a bacterial genus known mainly for its capability to synthesize, in addition to spores, a parasporal body or crystal (δ––endotoxin), comprised of proteins which are toxic to pest insects, i.e., Coleoptera, Diptera and Lepidoptera, and other orders. As well as plant pathogenic nematode and many other applications as endophytic plant growth promoting bacteria, or cleaning enviornmental form some chemicals polluting agents, and even in human medicine for cancer prevention. The Bt coexists in a close relationship with insects to which eventually infects and poisons. It is likely that these unfavorable changes occurred during the evolutionary pathway in the interactions Bacillus–insect, which resulted in the present biochemical diversity between these species. The goal of this minireview is to show role of Bt in comparation with other genus Bacillus and explain why Bt is of interest for biological control of pests in conventional, protected and organic agri...
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.
Journal of Applied Biotechnology and Bioengeenier, 2022
Bacillus thuringiensis (Bt) is a bacterial genus known mainly for its capability to synthesize, in addition to spores, a parasporal body or crystal (δ-endotoxin), comprised of proteins which are toxic to pest insects, i.e., Coleoptera, Diptera and Lepidoptera, and other orders. As well as plant pathogenic nematode and many other applications as endophytic plant growth promoting bacteria, or cleaning enviornmental form some chemicals polluting agents, and even in human medicine for cancer prevention. The Bt coexists in a close relationship with insects to which eventually infects and poisons. It is likely that these unfavorable changes occurred during the evolutionary pathway in the interactions Bacillusinsect, which resulted in the present biochemical diversity between these species. The goal of this minireview is to show role of Bt in comparation with other genus Bacillus and explain why Bt is of interest for biological control of pests in conventional, protected and organic agriculture regarding other biotechnological applications to fully exploit the beneficial potential of Bt.
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.
Journal of Applied Entomology, 2019
Spoladea recurvalis (Fbr.) (Lepidoptera: Crambidae) larvae can cause up to 100% foliage loss on amaranths during severe outbreaks. The Bacillus thuringiensis Subsp. kurstaki product Halt® is a biologically safe biopesticide recommended for the management of Spodoptera exigua (Hübner) and Plutella xylostella (Linnaeus). Spoladea recurvalis larvae are less susceptible to the product. Thirteen chemical additives to improve the efficacy of a Bt spray for control of S. recurvalis were evaluated in laboratory bioassays against second-instar larvae. All the additives except calcium chloride caused an increase in mortality when applied in mixtures with Bt. Among the seven inorganic salts, boric acid was the only inorganic acid that caused more than 50% larval mortality. Boric acid at a concentration of 0.05% increased the activity of B. thuringiensis by 2.9-fold. Boric acid had the shortest LT 50 values of 5.3 days compared with all other combinations. Two nitrogenous compounds, peptone and sodium nitrate, caused 54 and 51% larval mortalities; however, this increase in efficacy was not significantly different from the mortalities caused by Bt applied without any additive. Urea increased larval mortality from 40% to 51%, although the increase was not significant from a Bt spray application only. Citric acid had no significant effect on the efficacy of Bt spray against S. recurvalis larvae. Overall, among the additives evaluated, the efficacy of Bt spray was most enhanced by boric acid and could be further evaluated under field conditions for validation, and integration into an Integrated Pest Management (IPM) strategy for S. recurvalis management.
Spodoptera albula susceptibility to Bacillus thuringiensis-based biopesticides
Journal of invertebrate pathology, 2018
Single concentration and virulence (mean lethal concentration) bioassays were performed to evaluate the susceptibility of S. albula second instar larvae to seven Bacillus thuringiensis-based biopesticides. Bioassays were conducted using three replicates and repeated three times at 25 °C, 70 ± 10% RH, and a 12:12 (light/dark) photoperiod; mortality was recorded seven days after treatment. The results were subjected to a Tukey's test and Probit analysis. Agree, DiPel SC, and XenTari achieved mortality rates of up to 80%, with the first of these being the most virulent against S. albula. Different Dipel formulations showed different degrees of larvicidal activity.
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.
Biopesticide Production from Bacillus thuringiensis: An Environmentally Friendly Alternative
Recent Patents on Biotechnology, 2009
Since its discovery as a microbial insecticide, Bacillus thuringiensis has been widely used to control insect pests important in agriculture, forestry, and medicine. The wide variety of formulations based on spore-crystal complexes intended for ingestion by target insects, are the result of many years of research. The development of a great variety of matrices for support of the spore-crystal complex enables many improvements, such as an increase in toxic activity, higher palatability to insects, or longer shelf lives. These matrices use many chemical, vegetable or animal compounds to foster contact between crystals and insect midguts, without harming humans or the environment.