Liberibacter is a group of plant pathogenic bacteria, transmitted by insect vectors, psyllids (He... more Liberibacter is a group of plant pathogenic bacteria, transmitted by insect vectors, psyllids (Hemiptera: Psylloidea), and has emerged as one of the most devastating pathogens which have penetrated into many parts of the world over the last 20 years. The pathogens are known to cause plant diseases, such as Huanglongbing (citrus greening disease), Zebra chip disease, and carrot yellowing, etc., threatening some very important agricultural sectors, including citrus, potato and others. Candidatus Liberibacter asiaticus (CLas), the causative agent of citrus greening disease, is one of the most important pathogens of this group. This pathogen has infected most of the citrus trees in the US, Brazil and China, causing tremendous decline in citrus productivity, and, consequently, a severely negative impact on economic and personnel associated with citrus and related industries in these countries. Like other members in this group, CLas is transmitted by the Asian citrus psyllid (ACP, Diaphor...
Environmental science and pollution research international, Jan 7, 2017
Contamination of environment and food from the prevalent spores and mycotoxins of Aspergillus nig... more Contamination of environment and food from the prevalent spores and mycotoxins of Aspergillus niger has led to several diseases in humans and other animals. The present study investigated the control activity of plant essential oils against three strains of A. niger. In the elaborate assays done through microdilution plate assay and agar disk diffusion assay in the lab condition and in vivo assay on the stored wheat grains, the essential oil of Thymus vulgaris depicted overall superior efficacy. In microdilution plate assay, the oil of Anethum graveolens showed best fungistatic activity, while best fungicidal activity was depicted by Syzygium aromaticum oil. The oil of T. vulgaris showed moderate control efficacy against A. niger strains with its antifungal activity resulting mainly due to killing of microorganism rather than growth inhibition. In agar disk diffusion assay, T. vulgaris oil with a zone of inhibition (ZOI) of 23.3-61.1% was the most effective fungicide. The in vivo as...
The control potential of seven plant essential oils was evaluated against Fusarium proliferatum (... more The control potential of seven plant essential oils was evaluated against Fusarium proliferatum (Matsushima) Nirenberg and Fusarium verticillioides Sheldon. The fungicidal activity was assessed through microtiter plate assay to determine the minimum inhibitory and fungicidal concentration of essential oils. The essential oil of Mentha arvensis was adjudged as best for inhibiting the fungal growth, while oil of Thymus vulgaris and Anethum graveolens showed high efficacy in terms of fungicidal activity. The oil of M. arvensis and T. vulgaris also showed good inhibition activity in agar disc diffusion assay. M. arvensis essential oil was analysed for its composition using gas chromatography/mass spectrometry revealing menthol (63.18 %), menthone (15.08 %), isomenthyl acetate (5.50 %) and limonene (4.31 %) as major components. Significant activity of M. arvensis essential oil against F. proliferatum and F. verticillioides isolates obtained, pave the way for its use as antifungal control...
Beauveria bassiana infection to the host insects involves penetration of insect cuticle through e... more Beauveria bassiana infection to the host insects involves penetration of insect cuticle through enzymatic and mechanical degradation (St. Leger et al., 1996; Parani et al., 2011). The insect cuticle is made of chitin framework, protected by protein and lipid. The fungal conidia adhere to the cuticle surface to produce a penetration structure called appresoria, which produces a series of extracellular enzymes; chitinase, protease and lipase, involved in the enzymatic degradation of chitin, protein and lipid layer of insect cuticle, respectively (Inglis et al., 2001; Dhar and Kaur, 2010; Kumar et al., 2011). The enzymes are not only involved in host penetration but have also been positively correlated with entomopathogenic fungal pathogenesis (Mustafa and Kaur, 2010; St. Leger et al., 1996).
The essential oil of M. × piperita L. was formulated into a topical gel. The prepared gel was cha... more The essential oil of M. × piperita L. was formulated into a topical gel. The prepared gel was characterized for its pH, viscosity, spreadiblity, consistency and extrudiblity, while its stability was evaluated under different temperature conditions. The prepared M. × piperita oil gel was clear and transparent. The pH value of developed gel was 6.6, while its viscosity was 1200 cP. Spreadability and consistency of the M. × piperita oil gel was 10.7 g.cm/sec and 7 mm, respectively. The prepared gel showed good extrudiblity. During the stability studies, no significant change in pH and viscosity as a function of time for gel was observed, indicating stability of prepared formulation. The gel developed in this study is expected to forward the usage of M. × piperita essential towards commercial application.
Environmental Science and Pollution Research, 2015
Entomopathogenic fungi that manifest infections by overcoming insect&... more Entomopathogenic fungi that manifest infections by overcoming insect's immune response could be a successful control agent for the house fly, Musca domestica L. which is a major domestic, medical, and veterinary pest. In this study, the immune response of house fly to Beauveria bassiana infection was investigated to reveal fundamental aspects of house fly hemocyte biology, such as hemocyte numbers and size, which is poorly understood. The total hemocyte counts (THCs) in B. bassiana-infected house fly showed an initial increase (from 6 to 9 h), followed by subsequent decrease (9 to 12 h) with increase in time of infection. The THCs was slightly greater in infected flies than the non-infected ones. Insight into relative hemocyte counts depicted a significant increase in prohemocyte (PR) and decrease in granulocyte (GR) in infected house flies compared to non-infected ones. The relative cell area of hemocyte cells showed a noticeable increase in PR and intermediate cells (ICs), while a considerable reduction was observed for plasmatocyte (PL) and GR. The considerable variation in relative cell number and cell area in the B. bassiana-infected house flies indicated stress development during infection. The present study highlights changes occurring during B. bassiana invasion to house fly leading to establishment of infection along with facilitation in understanding of basic hemocyte biology. The results of the study is expected to help in better understanding of house fly immune response during fungal infection, so as to assist production of more efficient mycoinsecticides for house fly control using B. bassiana.
Environmental science and pollution research international, Jan 21, 2015
The hexane and ether extracts of leaves, bark and roots of Jatropha curcas were screened for thei... more The hexane and ether extracts of leaves, bark and roots of Jatropha curcas were screened for their toxicity against different developmental stages of housefly. The larvicidal, pupicidal and adulticidal activities were analysed at various concentrations (0.78-7.86 mg/cm(2)) of hexane and ether extracts. The lethal concentration values (LC50) of hexane extract of J. curcas leaves were 3.0 and 0.27 mg/cm(2) for adult and larval stages of housefly, respectively, after 48 h. Similarly, the ether extract of leaf showed the LC50 of 2.20 and 4.53 mg/cm(2) for adult and larval stages of housefly. Least toxicity was observed with hexane root extract of J. curcas with LC50 values of 14.18 and 14.26 mg/cm(2) for adult and larvae of housefly, respectively, after 48 h. The variation in LC50 against housefly pupae was found to be 8.88-13.10 mg/cm(2) at various J. curcas extract concentrations. The GC-MS analysis of J. curcas leaf extract revealed the presence of trans-phytol (60.81 %), squalene (2...
A new Beauveria bassiana isolate, showing high activity against Musca domestica L. (Diptera: Musc... more A new Beauveria bassiana isolate, showing high activity against Musca domestica L. (Diptera: Muscidae) adults (mortality-100.0 %), larvae (mortality-72.3 %) and pupae (Infection in emerged flies-96.7 %) was used. The isolate was subjected to a combinational approach towards selection of process parameters for its growth optimization. Initial screening of several carbon and nitrogen sources revealed glucose and NaNO3 as the most suitable source for optimal biomass and spore production. Further, optimization through Placket-Burman and a 2(5) full factorial central composite design revealed highly significant effect of glucose and pH. The optimum composition for maximum biomass yield was (g/l): glucose 28; NaNO3 2.43; KH2PO4 1.32; MgSO4 0.60; and pH 7.00. Glucose concentration showed almost linear relationship with biomass yield, indicating its significant contribution in medium composition for fungal growth. Highly significant interactions were observed between glucose and pH, followed by glucose and NaNO3 concentration.
Beauveria bassiana HQ917687 virulence to housefly larvae and adult was assessed at different rela... more Beauveria bassiana HQ917687 virulence to housefly larvae and adult was assessed at different relative humidity, RH (50, 75, 90, and 100 %) and temperature (15, 20, 25, 30, 35, 40, 45 °C) conditions at the fungal dose of 10(8) conidia/ml. Depending on the temperature and RH regime tested, difference in mortality rates of housefly adult and larvae were detected. During assay on adult housefly, 100 % mortality was achieved at RH, 90 and 100 % while the temperature of 30 °C showed maximum mortality at all the tested humidity conditions. Lethal time, LT50 was 2.9 days at 100 % RH. Larval mortality at different humidity conditions varied between 30 and 74 %, with maximum mortality at 100 % RH and 30 °C. Optimum temperature for B. bassiana virulence to housefly larvae was also found to be 30 °C. The interaction between temperature and RH revealed significant effect of RH at moderate temperature range (20-35 °C), while such an interaction was not observed at extreme temperatures. The results obtained in this study have useful implications in understanding the pathogen behavior under actual field conditions. This in turn may help devising suitable entomopathogen release schedules for maximum fungal infection.
Pathogenic potential of five native Beauveria isolates was assessed against housefly adult and la... more Pathogenic potential of five native Beauveria isolates was assessed against housefly adult and larvae in laboratory bioassays. Beauveria isolate Beauveria bassiana HQ917687 showed highest virulence with 72.3 and 100 % mortality of larvae and adults of Musca domestica, respectively. Other Beauveria isolates caused 36-52 % housefly larval mortality while the adult mortalities varied between 72 and 82 %. B. bassiana HQ917687 also showed the fastest killing activity with LT(50) of 4 days (for larvae) and 3 days (for adults). This isolate showing highest virulence was selected for its growth optimization in terms of biomass and spore production using response surface methodology. The optimum value of temperature, yeast extract, and pH for maximum biomass and spore production was predicted as 27 °C, 5.00 g/l, and 6.75, respectively. Temperature was found to be the most critical factor influencing biomass and spore yield of the fungus and even nullified the effects of other factors at sufficiently higher value. The results obtained in this study depict the significance of appropriate strain selection and process parameter optimization in order to facilitate mass production of biocontrol agents.
Liberibacter is a group of plant pathogenic bacteria, transmitted by insect vectors, psyllids (He... more Liberibacter is a group of plant pathogenic bacteria, transmitted by insect vectors, psyllids (Hemiptera: Psylloidea), and has emerged as one of the most devastating pathogens which have penetrated into many parts of the world over the last 20 years. The pathogens are known to cause plant diseases, such as Huanglongbing (citrus greening disease), Zebra chip disease, and carrot yellowing, etc., threatening some very important agricultural sectors, including citrus, potato and others. Candidatus Liberibacter asiaticus (CLas), the causative agent of citrus greening disease, is one of the most important pathogens of this group. This pathogen has infected most of the citrus trees in the US, Brazil and China, causing tremendous decline in citrus productivity, and, consequently, a severely negative impact on economic and personnel associated with citrus and related industries in these countries. Like other members in this group, CLas is transmitted by the Asian citrus psyllid (ACP, Diaphor...
Environmental science and pollution research international, Jan 7, 2017
Contamination of environment and food from the prevalent spores and mycotoxins of Aspergillus nig... more Contamination of environment and food from the prevalent spores and mycotoxins of Aspergillus niger has led to several diseases in humans and other animals. The present study investigated the control activity of plant essential oils against three strains of A. niger. In the elaborate assays done through microdilution plate assay and agar disk diffusion assay in the lab condition and in vivo assay on the stored wheat grains, the essential oil of Thymus vulgaris depicted overall superior efficacy. In microdilution plate assay, the oil of Anethum graveolens showed best fungistatic activity, while best fungicidal activity was depicted by Syzygium aromaticum oil. The oil of T. vulgaris showed moderate control efficacy against A. niger strains with its antifungal activity resulting mainly due to killing of microorganism rather than growth inhibition. In agar disk diffusion assay, T. vulgaris oil with a zone of inhibition (ZOI) of 23.3-61.1% was the most effective fungicide. The in vivo as...
The control potential of seven plant essential oils was evaluated against Fusarium proliferatum (... more The control potential of seven plant essential oils was evaluated against Fusarium proliferatum (Matsushima) Nirenberg and Fusarium verticillioides Sheldon. The fungicidal activity was assessed through microtiter plate assay to determine the minimum inhibitory and fungicidal concentration of essential oils. The essential oil of Mentha arvensis was adjudged as best for inhibiting the fungal growth, while oil of Thymus vulgaris and Anethum graveolens showed high efficacy in terms of fungicidal activity. The oil of M. arvensis and T. vulgaris also showed good inhibition activity in agar disc diffusion assay. M. arvensis essential oil was analysed for its composition using gas chromatography/mass spectrometry revealing menthol (63.18 %), menthone (15.08 %), isomenthyl acetate (5.50 %) and limonene (4.31 %) as major components. Significant activity of M. arvensis essential oil against F. proliferatum and F. verticillioides isolates obtained, pave the way for its use as antifungal control...
Beauveria bassiana infection to the host insects involves penetration of insect cuticle through e... more Beauveria bassiana infection to the host insects involves penetration of insect cuticle through enzymatic and mechanical degradation (St. Leger et al., 1996; Parani et al., 2011). The insect cuticle is made of chitin framework, protected by protein and lipid. The fungal conidia adhere to the cuticle surface to produce a penetration structure called appresoria, which produces a series of extracellular enzymes; chitinase, protease and lipase, involved in the enzymatic degradation of chitin, protein and lipid layer of insect cuticle, respectively (Inglis et al., 2001; Dhar and Kaur, 2010; Kumar et al., 2011). The enzymes are not only involved in host penetration but have also been positively correlated with entomopathogenic fungal pathogenesis (Mustafa and Kaur, 2010; St. Leger et al., 1996).
The essential oil of M. × piperita L. was formulated into a topical gel. The prepared gel was cha... more The essential oil of M. × piperita L. was formulated into a topical gel. The prepared gel was characterized for its pH, viscosity, spreadiblity, consistency and extrudiblity, while its stability was evaluated under different temperature conditions. The prepared M. × piperita oil gel was clear and transparent. The pH value of developed gel was 6.6, while its viscosity was 1200 cP. Spreadability and consistency of the M. × piperita oil gel was 10.7 g.cm/sec and 7 mm, respectively. The prepared gel showed good extrudiblity. During the stability studies, no significant change in pH and viscosity as a function of time for gel was observed, indicating stability of prepared formulation. The gel developed in this study is expected to forward the usage of M. × piperita essential towards commercial application.
Environmental Science and Pollution Research, 2015
Entomopathogenic fungi that manifest infections by overcoming insect&... more Entomopathogenic fungi that manifest infections by overcoming insect's immune response could be a successful control agent for the house fly, Musca domestica L. which is a major domestic, medical, and veterinary pest. In this study, the immune response of house fly to Beauveria bassiana infection was investigated to reveal fundamental aspects of house fly hemocyte biology, such as hemocyte numbers and size, which is poorly understood. The total hemocyte counts (THCs) in B. bassiana-infected house fly showed an initial increase (from 6 to 9 h), followed by subsequent decrease (9 to 12 h) with increase in time of infection. The THCs was slightly greater in infected flies than the non-infected ones. Insight into relative hemocyte counts depicted a significant increase in prohemocyte (PR) and decrease in granulocyte (GR) in infected house flies compared to non-infected ones. The relative cell area of hemocyte cells showed a noticeable increase in PR and intermediate cells (ICs), while a considerable reduction was observed for plasmatocyte (PL) and GR. The considerable variation in relative cell number and cell area in the B. bassiana-infected house flies indicated stress development during infection. The present study highlights changes occurring during B. bassiana invasion to house fly leading to establishment of infection along with facilitation in understanding of basic hemocyte biology. The results of the study is expected to help in better understanding of house fly immune response during fungal infection, so as to assist production of more efficient mycoinsecticides for house fly control using B. bassiana.
Environmental science and pollution research international, Jan 21, 2015
The hexane and ether extracts of leaves, bark and roots of Jatropha curcas were screened for thei... more The hexane and ether extracts of leaves, bark and roots of Jatropha curcas were screened for their toxicity against different developmental stages of housefly. The larvicidal, pupicidal and adulticidal activities were analysed at various concentrations (0.78-7.86 mg/cm(2)) of hexane and ether extracts. The lethal concentration values (LC50) of hexane extract of J. curcas leaves were 3.0 and 0.27 mg/cm(2) for adult and larval stages of housefly, respectively, after 48 h. Similarly, the ether extract of leaf showed the LC50 of 2.20 and 4.53 mg/cm(2) for adult and larval stages of housefly. Least toxicity was observed with hexane root extract of J. curcas with LC50 values of 14.18 and 14.26 mg/cm(2) for adult and larvae of housefly, respectively, after 48 h. The variation in LC50 against housefly pupae was found to be 8.88-13.10 mg/cm(2) at various J. curcas extract concentrations. The GC-MS analysis of J. curcas leaf extract revealed the presence of trans-phytol (60.81 %), squalene (2...
A new Beauveria bassiana isolate, showing high activity against Musca domestica L. (Diptera: Musc... more A new Beauveria bassiana isolate, showing high activity against Musca domestica L. (Diptera: Muscidae) adults (mortality-100.0 %), larvae (mortality-72.3 %) and pupae (Infection in emerged flies-96.7 %) was used. The isolate was subjected to a combinational approach towards selection of process parameters for its growth optimization. Initial screening of several carbon and nitrogen sources revealed glucose and NaNO3 as the most suitable source for optimal biomass and spore production. Further, optimization through Placket-Burman and a 2(5) full factorial central composite design revealed highly significant effect of glucose and pH. The optimum composition for maximum biomass yield was (g/l): glucose 28; NaNO3 2.43; KH2PO4 1.32; MgSO4 0.60; and pH 7.00. Glucose concentration showed almost linear relationship with biomass yield, indicating its significant contribution in medium composition for fungal growth. Highly significant interactions were observed between glucose and pH, followed by glucose and NaNO3 concentration.
Beauveria bassiana HQ917687 virulence to housefly larvae and adult was assessed at different rela... more Beauveria bassiana HQ917687 virulence to housefly larvae and adult was assessed at different relative humidity, RH (50, 75, 90, and 100 %) and temperature (15, 20, 25, 30, 35, 40, 45 °C) conditions at the fungal dose of 10(8) conidia/ml. Depending on the temperature and RH regime tested, difference in mortality rates of housefly adult and larvae were detected. During assay on adult housefly, 100 % mortality was achieved at RH, 90 and 100 % while the temperature of 30 °C showed maximum mortality at all the tested humidity conditions. Lethal time, LT50 was 2.9 days at 100 % RH. Larval mortality at different humidity conditions varied between 30 and 74 %, with maximum mortality at 100 % RH and 30 °C. Optimum temperature for B. bassiana virulence to housefly larvae was also found to be 30 °C. The interaction between temperature and RH revealed significant effect of RH at moderate temperature range (20-35 °C), while such an interaction was not observed at extreme temperatures. The results obtained in this study have useful implications in understanding the pathogen behavior under actual field conditions. This in turn may help devising suitable entomopathogen release schedules for maximum fungal infection.
Pathogenic potential of five native Beauveria isolates was assessed against housefly adult and la... more Pathogenic potential of five native Beauveria isolates was assessed against housefly adult and larvae in laboratory bioassays. Beauveria isolate Beauveria bassiana HQ917687 showed highest virulence with 72.3 and 100 % mortality of larvae and adults of Musca domestica, respectively. Other Beauveria isolates caused 36-52 % housefly larval mortality while the adult mortalities varied between 72 and 82 %. B. bassiana HQ917687 also showed the fastest killing activity with LT(50) of 4 days (for larvae) and 3 days (for adults). This isolate showing highest virulence was selected for its growth optimization in terms of biomass and spore production using response surface methodology. The optimum value of temperature, yeast extract, and pH for maximum biomass and spore production was predicted as 27 °C, 5.00 g/l, and 6.75, respectively. Temperature was found to be the most critical factor influencing biomass and spore yield of the fungus and even nullified the effects of other factors at sufficiently higher value. The results obtained in this study depict the significance of appropriate strain selection and process parameter optimization in order to facilitate mass production of biocontrol agents.
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