Comparative Efficacy of Bacillus thuringiensis Commercial Formulations against Leaf Worm, Spodoptera litura Fabricius under Laboratory Conditions (original) (raw)
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Journal of Entomological Society of Iran, 2021
Tomato leaf miner (TLM), Tuta absoluta (Meyrick), is a destructive insect pest in greenhouses and fields on tomato plants. In this study, the efficacy of seven insecticides: spinosad (Laser ®), chlorantraniliprole (Coragen ®), indoxacarb (Steward ®), abamectin (Vertimec ®), metaflumizone (Alverde ®), azadirachtin (NeemAzal ®), and Bacillus thuringiensis was evaluated against T. absoluta during 30 days from spraying. Tomato plants were sprayed by half and a quarter of the recommended field concentrations of the insecticides. Thirty 2 nd instar larvae were placed on the treated plants, 2, 4, 7, 10, 13, 17, 22, 26, and 30 days after treatment, and mortality was recorded 48 hours later. The results showed that spinosad and chlorantraniliprole in the half of the field recommended concentration caused maximum efficacy on T. absoluta larvae, 100 and 80 % mortality at the end of 30 days, respectively. On the other hand, indoxacarb caused 57 % mortality on the 22 nd day after exposure to the quarter of the field recommended concentration. In the quarter field-recommended concentration, abamectin and metaflumizone also had moderate mortality (52 and 54 % on the 10 th day). The application of these three compounds can be considered suitable for preventing an increasing pest population from reaching the economic injury level. Bacillus thuringiensis var. kurstaki and azadirachtin insecticides had slight mortality and short persistence on this pest. Experts and farmers can select the appropriate compounds to control this pest based on the pest population status according to the obtained results.
Journal of Applied Entomology, 2018
The tomato leafminer, Tuta absoluta, is one of the most destructive pests of tomato worldwide. Management of the pest is mainly based on chemical insecticides. Reliance on insecticides is difficult to sustain because of unintended long-term adverse effects on the environment and human health. Consequently, there is a need to develop pest management strategies that ensure the production of high-quality products, while at the same time ensuring environmental sustainability and maximum consumer protection. We evaluated the efficacy the biopesticides: Azadirachtin, Bacillus thuringiensis, Steinernema feltiae and Beauveria bassiana individually and in combination against T. absoluta under laboratory and greenhouse conditions. When second instar larvae were exposed to tomato leaf discs treated with Azadirachtin (3 g/L), B. thuringiensis (0.5 g/L) or B. bassiana (1.5 g/L), 70%-86%, 55%-65%, and 45.5%-58.5% mortality was observed, respectively. Steinernema feltiae (1,000 IJs/ml) was the least effective biopesticide, with 26%-42% mortality. In the greenhouse trials on tomato, pest infestation (mines/10 leaves/plant) and fruits damaged were significantly lower on plants treated with Azadirachtin + B. thuringiensis or Azadirachtin + B. bassiana compared to plants treated with Azadirachtin, B. thuringiensi, B. bassiana or S. feltiae alone. Azadirachtin + B. thuringiensis and Azadirachtin + B. bassiana resulted in 90% and 81% reduction in fruits damaged in the summer experiments, respectively, and 96% and 91% in winter. The most severe pest infestation was observed on plants treated with S. feltia. The results indicate that the biopesticides, except S. feltia, can contribute to T. absoluta control in greenhouse tomato crops. In particular, the combined use of Azadirachtin with B. thuringiensis or B. bassiana provided the highest level of control of the pest. The potential for including these biopesticides in an overall sustainable integrated pest management programme for T. absoluta is discussed.
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.
Tomato pin worm Tuta absoluta (Meyrick) is one of the most destructive pests causing damage to of tomato. This field study undertaken in a randomized block design evaluated seven treatments during kharif, 2019 at farmers field in Theni district. The insecticides evaluated include-chlorantraniliprole 18.5SC 0.3ml/ l, spinosad 45SC 0.3ml/ l, indoxacarb 14.5SC 1ml/ l, Bt var. kurstaki HD1 2g/ l, Bt var. kurstaki HD73 2g/ l and Dipel at 2ml/ l. Chlorantraniliprole was observed to be best with 81.48% reduction in incidence. In comparison, 80.58 and 79.10% reduction were observed with B. thuringiensis var. kurstaki HD1 and spinosad, respectively; and B. thuringiensis var. kurstaki HD73 was the least effective.
2016
The elm leaf beetle, Xanthogaleruca luteola (Müll). (Col: Chrysomelidae) is one of the most important pests on elm trees in Iran. Due to environmental issues of synthetic insecticides, biorational agents have been advised in control management programs of elm leaf beetle in urban green spaces. The susceptibility of adults and 3 rd instar larvae of this pest was evaluated to Bithiran ® (Bacillus thuringiensis var. tenebrionis) and NeemAzal ®-T/S (Neem based insecticide) using elm leaves dipped in aqueous insecticidal solutions. The mortality was recorded 24 h after treatment. The LC50 values for the third instar larvae and adults were respectively estimated to be 106.83 and 57.6 ppm for BT and 357.17 and 107.61 ppm for Neem. Bithiran ® was more effective against X. luteola larvae and adults when compared to NeemAzal ®-T/S. Further research on these biorational agents is recommended in field conditions before making any decision on their incorporation in control management programs.
International Journal of Innovation and Applied Studies, 2014
to evaluate the efficiency of the growth regulator Dimilin chitin synthesis inhibitor by three different concentrations of 0.5, 1.0 and 1.5 ppm and efficiency of bacteria Bacillus thuringiensis israelensis concentrations 6.25 × 10 9 , 6.25 × 10 10 and 6.25 × 10 11 spores / ml at different instars larval mosquito Culex pipiens. Highest mortality was 100% of the growth regulator at 1.5 ppm for a period of 48 hours and lowest mortality was 26.67 % for the 12-hours period of concentration of 0.5 ppm for the first instar larval, respectively. The highest mortality was 86.67 % of the growth regulator at 1.5 ppm within 48 hours and lowest mortality was 20 % during the 12-hours concentration of 0.5 ppm for the second instar larval, respectively. The results showed that the highest mortality was 73.33 % during the 48-hours concentration of 1.5 ppm and lowest mortality was 33.33 % of the concentration of 1.0 ppm during the 12 hours of third instar larval respectively. The highest mortality of the fourth instar larval reached 80% within 48 hours and lowest mortality was 26.67 % of the two concentrations 0.5 and 1.0 ppm for growth regulator. The results showed that the highest mortality of bio-pesticide Bti was100% of the first instar larval at 6.26 × 10 11 spores / ml within 24 to 48 hours and lowest mortality was 40% of the concentration of 6.26 × 10 9 spore / ml within 12 hours. The highest mortality of second instar larval was 100% for two concentrations 6.25 × 10 10 and 6.25 × 10 11 spores / ml within 24 and 48 hours, respectively, and lowest mortality was 53.33% of the concentration of 6.25 × 10 9 spore / ml within 12 hours and the highest mortality of the third and fourth instar larval 100%, respectively, during the 48-hours concentration of 6.25 × 1011 spores / ml, and lower ratios for killing concentration 6.25 × 109 spore / ml was 40% and 33. 33% for the two ages, respectively, within 12 hours.
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.
2016
The beet armyworm, Spodoptera exigua (Hubner), is a polyphagous pest that causes serious damages to various plants including beet, potato and cotton. In order to reduce application of chemical insecticides, two bioinsecticides, Bacillus thuringiensis and Spinosad, were evaluated for their efficacy in control of S. exigua in laboratory conditions. The LC25 and LC50 values of B. thuringiensis and Spinosad were estimated on three larval stages. Furthermore, LC50 values for B. thuringiensis treatments on 1st, 2nd and 3rd larval stages were 275. 305, 717.444 and 727.671 ppm and for Spinosad 276.715, 521.058 and 568. 914 ppm, respectively, and LC25 values of B. thuringiensis and Spinosad treatments on 1st, 2nd and 3rd larval stages were 104.105, 341.652 and 441.803 ppm and 92.812, 369.569 and 379.958 ppm, respectively. After determining the LC50 and LC25 values of both agents, to evaluate their combined effects, an experiment of completely randomized design was conducted with four treatme...
2020
Spodoptera is a polyphagous and most destructive pest of most of crops including tomato. The bioefficacy of poison baits with Methomyl and Bt formulations was observed along with male flight activity of the tobacco caterpillar in tomato open field crops. The study was conducted in three villages of Chamba district viz. Sahu, Bhanauta and Kiri during 2019-2020. Tomato is one of the important cash crops in many parts of district Chamba and a source of livelihood of small and marginal farmers of the district. It is cultivated in an area of about 294 hectares with the annual production of 11,410 MT. Tobacco caterpillar, Spodoptera litura (Fab.) (Lepidoptera: Noctuidae) is a polyphagous and sporadic pest and is nocturnal pest in nature. The bioefficacy results revealed that the % mortality of baits with insecticide (ranging from 10.24% to 83.24%), baits with BT formulation (15.64% to 81.06%) and spray of Bt formulations (14.10% to 85.60%) in fields did not differ significantly at the res...
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...