Bacillus Thuringiensis Var Kurstaki Research Articles

Residual toxicity of pesticide active substance commonly used in tomato crop on the predator Nesidiocoris tenuis (Heteroptera: Miridae)

AbstractNesidiocoris tenuis (Reuter) (Heteroptera Miridae) is a key biological control agent of the tomato leaf miner Tuta absoluta (Meyrick). However, in cases of prey scarcity, this predator switches into a phytophagous pest causing ring injuries in stems of tomato plants. The aim of this study was to assess the side effects of dry residues and explore the presence of target site resistance mutations of 10 insecticides, two bioinsecticides, an acaricide and a fungicide widely applied in IPM, on adults of N. tenuis collected from two different regions of Crete; the Western and the Eastern side of the island during two successive years. Lethal toxicity trials were performed on sprayed tomato stems and toxicity of adults of N. tenuis was recorded 2 h, 7 and 14 days after exposure. At both populations, chlorpyrifos, acetamiprid and thiamethoxam were moderately harmful at the application day and slightly harmful 7 days after the application. Only chlorpyrifos maintained its toxicity for more than 7 days. All the rest tested pesticides (emamectin benzoate, abamectin, chlorantraniliprole+abamectin, chlorantraniliprole, deltamethrin, tebufenpyrad, spinosad, Bacillus thuringiensis var kurstaki, metaflumizone and myclobutanil) were classified as harmless. Additionally, analysis of insecticide target site sequences indicated the absence of resistance mutations in both populations. Overall, our findings illustrate the impact of 15 pesticides and their residual toxicity on the mortality rates of N. tenuis adults.

Physical and bio-control methodologies for integrated management of buffalo fly-Haematobia exigua (Diptera: Muscidae)

Haematobia exigua, the buffalo fly, is a common ectoparasite of buffaloes and cattle in India causing economic losses and underlines the necessity of effective control strategies against them. The present study was planned to evaluate larvicidal activity of few methods for physical and biological control for integarated management of Haematobia exigua flies. Out of four bacterial bio-control agents evaluated by in-vitro assay and Probit analysis, two bacteria i. e. Bacillus thuringiensis var israelensis and Bacillus thuringiensis var kurstaki showed excellent larvicidal activity against H. exigua with LC50 value of 134 and 135 mg per liter of water respectively. Whereas, other two bacteria i. e. Bacillus weihenstephanensis WSBC and KBAB4 failed to show desired larvicidal activity. It can be concluded that B ti and B tk have future as effective bacterial agents (BCAs) in the control and integrated management of buffalo and horn fly. An experiment was conducted in the laboratory and on field for judging the efficacy of a physical method of tightly covering dung pats with polythene sheet for control of larvae of H. exigua. The laboratory result showed only 14.73% larvae were survived and developed per 100 gm of the faeces in the pot covered with polythene sheet as against significantly higher number 78.33% in the control group. During field trial, average larval count from dung pits before the experiment was 86.33 per 250 gm of faeces and it has been significantly reduced to 11.80 after covered with polythene sheets for two weeks. It indicated that physical method of covering the dung pits works immensely and thus can be inducted in IPM program as one of the effective physical control alternatives.

Comparative Efficiency of Some Novel Insecticides against Fall Army Worm, Spodoptera frugiperda in Maize

The present study was carried out at the instructional farm, College of Agriculture, Bidhan Chandra Krishi Viswavidyalaya, Farm Gate, Kalna Road, Burdwan Sadar, West Bengal, India for successive 2 terms of crop during kharif (June to September, 2020) and rabi (December to March, 2020–21). The bio-efficacy of some chemicals (Cyantraniliprole, Chlorantraniliprole, Emamectin benzoate, Flubendiamide, Spinosad, Emamectin benzoate, Broflanilide, Chlorfenapyr, Spinetoram and Teflubenzuron) and bio-pesticides (Bacillus thuringiensis var kurstaki, Beauveria bassiana, Metarhizium anisopliae, Azadirachtin and Steinernema sp.) were evaluated against Fall Army Worm (FAW) in corn at the field condition. The major parameters considered for comparing the treatments were based on percent reduction in larval population, leaf damage (%) followed by headonic scoring (0–9 scale) and attack intensity (%). All the chemical insecticides except teflubenzuron resulted more or less higher percent population reduction of FAW larva (75.39–89.17%), lower leaf damage (20.13–31.21%) along with low damage score (1.45–1.95) and lower attack intensity (3.03–6.09%). All these effects were at moderate range in case of bio-pesticides. Based on the present findings, better selection of suitable insecticides is possible to manage FAW in corn.

Evaluation of Selected Bio-insecticides on Tuta absoluta and Liriomyza trifolii on Tomato in Open Fields in Tharaka Nithi County, Kenya

A field experiment to determine the effect of Azadirachtin, Bacillus thuringiensis, Pyrethrin + Garlic extract, and Petroleum mineral oil in managing the tomato leaf miner (Tuta absoluta) and serpentine leaf miner (Liriomyza trifolii) was conducted for two seasons between December 2016 and November 2017 at Chuka, Tharaka-Nithi County. Tomato variety, Kilele F1, was planted in the field to evaluate the effect of selected commercial products on T. absoluta and L. trifolii. The product included Azadirachtin 0.03%, Pyrethrin + Garlic extract, Bacillus thuringiensis var Kurstaki 5% w/w), and Petroleum mineral oil 98.8%. There were five treatments in a randomized complete block design (RCBD) in three replicates. There was an application of sterile water in the control experiment. There was a significant difference (P < 0.05) between the biocontrol products and the control. The Azadirachtin at 0.03% treatments had the least number of leaves damaged by T. absoluta (0.43; 1.67) in the control treatment (1.7; 5.27) in both seasons. In both seasons, there were significant differences (P < 0.05) between treatments in the number of leaflets damaged by L. trifolii. In season 1, the least damaged fruits per plant (1.33) were recorded in Azadirachtin at 0.03%, compared to the highest damage (5.0) in the untreated control. In the second season, the low fruit damage (0.67) was recorded in Petroleum mineral oil, and the highest (2.33) was in the untreated control. The study concluded that Azadirachtin 0.03%, Bacillus thuringiensis var Kurstaki 5% w/w, and Petroleum mineral oil were efficacious in managing T. absoluta and L. trifolii and be integrated into the existing tomato pest management strategies.

Efficacy of Some Insecticides, Biopesticides and Botanicals against Shoot and Fruit Borer (Leucinodes orbonalis G.) on Brinjal (Solanum melongena L.)

A field experiment was conducted during kharif 2020 at Dhule ,Maharashtra (India) to determine efficacy of some insecticides, biopesticides and botanicals against shoot and fruit borer (Leucinodes orbonalis Guenee.) on brinjal (Solanum melongena L.). The efficacy result showed that the Emamectin benzoate 5% SG (10.35% and 15.91%) found most effective followed by Cypermethrin 25%EC (11.49 and 17.32%), Spinosad 45%SC (14.06 and 18.77%), NSKE 5% (15.43 and 20.31%), Bacillus thuringiensis var kurstaki 54% (15.96 and 22.30%) and Beauveria bassiana 1×108 CFU (16.53% and 23.45%) was next effective treatment. Among all the treatments Garlic Bulb extract 3% (17.15% and 24.69%) is found be least effective but comparatively superior over the control. The best and most economical treatment was Emamectin benzoate 5%SG (1:3.3), followed by Cypermethrin 25% EC (1:3.1), Spinosad 45% SC (1:2.6), NSKE 5% (1:2.5), Bacillus thuringiensis var kurstaki (1:2.4), Beauveria bassiana 1×108 CFU (1:2.1), Garlic Bulb extract 3% (1:1.9) as compared to control (1:1.1). Emamectin benzoate 5%SG (179q/ha) followed by Cypermethrin 25% EC (163q/ha).

Development and validation of an integrated pest management strategy against the invasive South American tomato leaf miner, Tuta absoluta in South India

Tomato is one of the most popular vegetables grown in South Asian countries, including India. Introduction of any invasive species to a new environment has always resulted in serious ecological and economical threats globally. One such widely effected invasive pest in tomato cultivation is Tuta absoluta, which was reported infesting tomato fields in India in 2014 for the first time. In order to reduce the over reliance on chemical pesticides, the effectiveness of an integrated pest management (IPM) package including microbial pesticides (Bacillus thuringiensis var kurstaki, Beauveria bassiana), neem products and a chemical pesticide, chlorantraniliprole had been evaluated. Multi-location trials were conducted for two seasons in 2018 and 2019. The findings revealed that the effect of the IPM package in reducing T. absoluta infestation was quite promising in all the experimental trials. The performance of the IPM package was on par with the Farmers' practice (calendar based application of chemical pesticides) in reducing T. absoluta infestation, without any compromise in the marketable yield. The excessive spraying of chemical pesticides in the Farmers’ practice led to an increase in the protection cost at all the experimental sites, which was nearly two times higher than that of the IPM package. Hence, the IPM package can be considered as effective and economical in managing invasive T. absoluta on tomato in South India.

Toxicological Examinations Following Oral Administration of Bacillus thuringiensis var kurstaki Biological Insecticide in Wistar Rats

Introduction: Bacillus thuringiensis var kurstaki is one of the best known biological insecticide which is used extensively in the world. This biopesticide has been broadly used against important insect pests and vectors of animals and humans. However, the controversial data was published to date considering toxicological studies on non-target species are urgent to determine probable adverse effects and risk assessment of this biopesticide. In this research, histopathological changes, hematological and some biochemical factors were evaluated following the single dose oral administration of B. thuringiensis in rats. Materials and Methods: Twelve Wistar rats were randomly divided into 2 groups including experimental and control groups. Animals were treated orally by gavage to single dose of sub-lethal dose (5000 mg/kg) of B. thuringiensis suspension. Finally, hematological factors (WBC, RBC, Hb, HCT, MCV, MCH, MCHC and PLT), some biochemical parameters (ALT, AST, ALP, BUN and Cr) and histopathological observations were evaluated. Results: The results demonstrated that oral administration of high dose of B. thuringiensis biopesticide induced some pathological complications including congestion and inflammation in vital organs of rats such as liver, heart, lung and kidney. It also caused hematological abnormalities and biochemical alterations in the experimental animals group. Conclusions: According to the findings, it can be concluded that high dose of B. thuringiensis biopesticide can induce toxicity in rats. Therefore, further investigations including subacute and chronic are recommended.

Biology and Biorational Management of Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae): A Global Challenge to Tomato Production

South American tomato pinworm, Tuta absoluta (Meyrick), a native to South America, is an emerging exotic pest of tomato and other solanaceous crops in India. In Varanasi, Uttar Pradesh the pest was first observed on the month of January, 2017. Being an invasive pest, information on its biology and ecofriendly management under local conditions are essential. Under laboratory conditions the biology of the pest reveals that, the incubation, larval and pupal periods were 4.23 ± 0.57, 9.40 ± 1.05 and 8.90 ± 1.05 days, respectively. Adult females lived longer (15.98 ± 1.36 days) than the adult males (11.68 ± 2.99). Gravid females laid 79.40 ± 6.75 eggs, whereas egg viability was 83.30 ± 3.47%. Amongst the different biopesticides, Bacillus thuringiensis var Kurstaki was found most promising causing 66.7 and 73.37% mortalities at 48 and 72 h after the treatment followed by B. subtilis-2 and the corresponding values were 53.36 and 66.70%, respectively. The present study will be helpful in developing future integrated management strategies of this exotic pest in India relevant to Indian cropping systems.

Eco-toxicological risk and impact of pesticides on important parasitoids of cabbage butterflies in cruciferous ecosystem

Eco-toxicological risk and impact of pesticides was estimated on three important parasitoids of butterflies viz., Hyposoter ebeninus, Cotesia glomerata and Pteromalus puparum. Four commonly used pesticides were evaluated using standard protocol (of IOBC/WPRS-group). In laboratory tests, the survival of the female wasps decreased significantly on fresh contact and ingestion of deltamethrin, spinosad and azadirachtin; whereas Bacillus thuringiensis var kurstaki (Btk) was found harmless pesticide. Under semi-field conditions, parasitoid mortality decreased significantly on fresh contact with the pesticides. Although, at 72 h after treatment, spinosad and deltamethrin were found harmful (Class-IV) and azadirachtin was moderately harmful (Class-III), whereas Btk was harmless (Class-I). Furthermore, 15-day-old residues of pesticides (except deltamethrin) were harmless to all parasitoid species under semi-field conditions. Notably, adult emergence and pupal duration in pesticide-treated cocoons were not significantly affected; however, their survival decreased after emergence except in Btk. The contact and oral toxicity trends of the pesticides were almost similar for three species of parasitoid females and pupae; however little variability was observed in toxicity to the host caterpillars parasitized by H. ebeninus (HCPHE) and C. glomerata (HCPCG). In semi-field tests, fresh residues of all the pesticides were harmful to HCPHE and HCPCG. However, action of Btk was slightly delayed and toxicity was rather low for HCPCG. In 15-day-old residues, deltamethrin and azadirachtin were slightly harmful to the parasitized caterpillars, whereas those of Btk and spinosad were harmless. Since, Btk appeared to be safe for parasitoids; it could be used for managing cabbage butterflies in brassicaceous crops.

Efficacy of different bio-pesticides against sucking pests of okra (Abelmoschus esculentus L. Moench)

The field experiment was carried out in the pre-kharif season of 2013 at Bidhan Chandra Krishi Viswavidyalaya, Kalyani, Nadia, West Bengal, India to evaluate the efficacy of different bio-pesticides against sucking pests of okra. The experiment was laid out in randomized complete block design with three replications for each treatment. The treatments viz. annonin 1% EC, karanjin 2% EC, Azadirachtin 1% EC, Metarrhizium anisopliae, Verticillium lecanii , Beauveria bassiana , Bacillus thuringiensis var Kurstaki, spinosad 45 % SC and imidacloprid 17.8% SL were applied at 15 days interval starting from seedling stage when whitefly and jassid infestation started. Results revealed that the overall best performance of insecticides against whitefly was recorded in imidacloprid treated plots with lowest mean population of whitefly (3.91 whitefly/15 leaves) followed by karanjin (4.16 whitefly/15 leaves) and azadirachtin (5.16 whitefly/15 leaves while the order of efficacy aginst jassid were imidacloprid (15.27 jassids/15 leaves) > karanjin (33.91jassids/15leaves)>azadirachtin(40.38jassids/15leaves). Effectiveness of test insecticides on the yield of okra wasspinosad>Bt>B. bassiana>azadirachtin>imidacloprid>annonin>karanjin>M. anisopliae.

Biological, biochemical and histological effects of spinosad, Bacillus thuringiensis var. kurstaki and cypermethrin on the Cotton leafworm, Spodoptera littoralis (Boisd.).

The insecticidal, biological, biochemical and histological effects of bioagent spinosad, Diple 2x (Bacillus thuringiensis var kurstaki) and one pyrethroid compound (cypermethrin) were evaluated on 4th instar larvae of Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae). Based on the LC50 values Cypermethrin is the more toxic to S. littoralis than that of the two other compounds. Female longevity, fecundity and fertility were significantly reduced at all treatments compared to control. Furthermore, different levels of significant changes in the total protein, carbohydrate contents, phosphatasis activity and carbohydrasis, were recorded. Moreover, different abnormal histological structures of ovary were noticed.

Mosquito autogeny in Aedes caspius (Diptera: Culicidae): alterations of larval nourishments reservation upon bacterial infection

The present study recorded mosquito autogeny for the first time amongst Aedes caspius species in the Eastern region of Saudi Arabia. Laboratory rearing showed an obligatory autogenous species of Ae. caspius since it foregoes blood feeding during its first ovarian cycle, even in the presence of the hosts (CD mouse), but produces its second egg batch only if ingested a blood meal. Both morphological and molecular identification confirmed that both autogenous and anautogenous strains belong to the same species of Ae. caspius. Data from biochemical analysis showed significant 2, 1.6, and 1.4 folds higher total carbohydrates, proteins, and lipids reserves respectively in the fourth larval instar of the autogenous strain compared to that of the anautogenous ones. In addition, exposing the fourth larval instars of autogenous strain to the infection stress by the mosquito larvicidal bacterium, Bacillus thuringiensis var kurstaki has significantly reduced total carbohydrates, proteins and lipids reserves by 29%, 35%, and 46%, respectively, at 12 h postinfection compared to those of uninfected ones. These reductions in nourishment reserves were more pronounced at 24 h postinfection in the case of proteins and lipids, but not carbohydrates. These results may indicate that bacterial infection is a health stress that significantly reduced nourishments reservation, which may interrupt the success of adult autogeny. However, the impact of infection-induced decline in larval nourishments reservation on successful adult autogeny is still to be investigated.

Genetics of spinosad resistance in a multi-resistant field-selected population of Plutella xylostella.

Resistance to the bacteria-derived insecticides spinosad (Conserve), abamectin (Vertimec), Bacillus thuringiensis var kurstaki (Btk) (Dipel), B thuringiensis var aizawai (Bta) (Xentari), B thuringiensis crystal endotoxins Cry1Ac and Cry1Ca, and to the synthetic insecticide fipronil was estimated in a freshly-collected field population (CH1 strain) of Plutella xylostella (L) from the Cameron Highlands, Malaysia. Laboratory bioassays at G1 indicated significant levels of resistance to spinosad, abamectin, Cry1Ac, Btk, Cry1Ca, fipronil and Bta when compared with a laboratory insecticide-susceptible population. Logit regression analysis of F1 reciprocal crosses indicated that resistance to spinosad in the CH1 population was inherited as a co-dominant trait. At the highest dose of spinosad tested, resistance was close to completely recessive, while at the lowest dose it was incompletely dominant. A direct test of monogenic inheritance based on a back-cross of F1 progeny with CH1 suggested that resistance to spinosad was controlled by a single locus.

Susceptibility pattern and development of resistance in the diamondback moth,Plutella xylostella L, toBacillus thuringiensis Berl varkurstaki in India

Base-line susceptibility for six-day-old larvae of the diamondback moth, Plutella xylostella, against Bacillus thuringiensis var kurstaki (Biobit®) was studied by a cabbage leaf disc dip bioassay technique. Diamondback moth from 13 locations in seven different states spread over a distance of about 3000 km longitudinally was used for these studies. Forty-eight-hour LC50 values varied from 1.0 to 10.97 mg AI litre−1. Further investigations on the development of resistance under laboratory conditions showed an increase in LC50 from 2.76 (for unselected F1 generation) to 5.28 mg AI litre−1 (for selected F9 generation), using a selection concentration of 6.4 mg AI litre−1. This suggested a possibility of the development of resistance under field conditions if there were to be extensive and indiscriminate use of B thuringiensis. These findings are discussed in relation to integrated pest management and the mechanisms of resistance in resistance management tactics. © 2000 Society of Chemical Industry

Mode of inheritance and stability of resistance toBacillus thuringiensis varkurstaki in a diamondback moth (Plutella xylostella) population from Malaysia

Genetic inheritance of resistance to Bacillus thuringiensis var kurstaki (BTK) was examined in a diamondback moth (Plutella xylostella) population collected from the Melaka region of Malaysia. A BTK-selected sub-population (BTK-SEL) which was more than 100-fold resistant to BTK compared with a susceptible (ROTH) population of P xylostella was used with standard reciprocal crosses and back-crosses between ROTH and BTK-SEL. Logit regression analysis of F 1 reciprocal crosses indicated that BTK resistance was inherited as an incompletely recessive autosomal trait and controlled by a single locus. In contrast, other studies have shown that resistance to Cry1Ac is inherited as an incompletely dominant autosomal trait in a Cry1Ac-selected sub-population of the same Melaka population. The frequency of the allele responsible for resistance decreased without exposure to insecticide in the laboratory. © 2000 Society of Chemical Industry

Development of Cotesia marginiventris (Hymenoptera: Braconidae) in Tobacco Budworm (Lepidoptera: Noctuidae) Larvae Treated with Bacillus thuringiensis and Thiodicarb

Bacillus thuringiensis var kurstaki and thiodicarb were evaluated for their impact on Cortesia marginiventris (Cresson) survival in exposed Heliothis virescens larvae. B. thuringiensis tests were conducted at concentrations of 0, 10, 50, and 250 ppm in artificial diet with initial exposure at parasitization or 24 or 48 h following parasitization. Thiodicarb tests were conducted at concentrations of 0, 50, 100, and 200 ppm in artificial diet with initial pesticide exposure at parasitization or 72 h following parasitization. H. virescens mortality was directly related to B. thuringiensis concentration. Mortality trends were similar with respect to time of initial B. thuringiensis exposure. Exposure of H. virescens larvae to the combination of B. thuringiensis and C. marginiventris parasitization increased larval mortality over that of either alone. Emergence of C. marginiventris was inversely related to B. thuringiensis concentration and directly related to timing of B. thuringiensis exposure. In all instances, greater C. marginiventris emergence was noted when host exposure to B. thuringiensis was delayed for 48 h following parasitization. Mortality in thiodicarb-exposed H. virescens was influenced by both insecticide rate and parasitization. A delay in initial insecticide exposure significantly increased early larval mortality in both parasitized and nonparasitized groups. Overall, results suggest that use of both thiodicarb and B. thuringiensis would preclude maintenance of natural field populations of C. marginiventris.

An Exposure Characterization of a Large Scale Application of a Biological Insecticide,Bacillus Thuringiensis

Abstract The gypsy moth, Lymantria dispar, is one of the most destructive insect pests of trees and shrubs in the United States. Since its introduction in the United States in 1869, the gypsy moth has extensively infested areas of 13 northeastern and mid-atlantic states. Smaller, localized infestations have been found in recent years in 17 other states across the nation. When DDT was available, the gypsy moth was almost eradicated from the United States, but as DDT use was curtailed, the gypsy moth infestations became widespread. The State of Oregon has chosen to primarily use the biological insecticide Bacillus thuringiensis var kurstaki (Bt) to eradicate the gypsy moth from approximately 250,000 acres of forested and urban areas in Lane County, Oregon. Personal exposure and area air monitoring for Bt was conducted to determine occupational and general public exposure potential to Bt. Portable sampling pumps with membrane filters (MF) were used to conduct the sampling. Analysis of the MF for Bt involved ...

Occurrence of two serologically distinct groups within Bacillus thuringiensis serotype 3 ab var. kurstaki

Two groups distinguishable on the basis of crystal serology have been identified within Bacillus thuringiensis var kurstaki (serotype 3 ab). The toxicities of these two groups to Trichoplusia ni and Heliothis virescens expressed as T H ratio also differed. It is suggested that serotype 3 ab be separated into two subgroups designated as K-1 and K-73.