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Purification and characterization of the cuticle-degrading proteases produced by an isolate of Beauveria bassiana using the cuticle of the predatory bug, Andrallus spinidens Fabricius (Hemiptera: Pentatomidae)

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Firouzbakht H., Zibaee A., Hoda H., Sohani M. M.

Journal of Plant Protection Research

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2015

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tom 55

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nr 2

The entomopathogenic fungi-like Beauveria bassiana must penetrate via the integument of an insect to reach the hemocoel. Since proteins are the molecules responsible for integument strength in insects, the proteins must synthesise the cuticle degrading proteases which will then enable the proteases to penetrate. It is important to determine the biochemical properties of these proteases so that fungal virulence can be better understood. In the current study, a recently collected isolate of B. bassiana, namely AM-118, was inoculated in liquid media containing 0.5% of Andrallus spinidens Fabricus cuticle to obtain specific proteases. The crude samples were purified via a three step process using ammonium sulfate, Sepharyl G-100, and DEAE-Cellulose Fast Flow. The results revealed two proteases known as subtilisin-like (Pr1), and trypsin-like (Pr2), with the molecular weights of 105 and 103 kDa. The optimal pH and temperature values were found to be 8 and 35°C for Pr1 and 8 and 40°C for Pr2, respectively. Inhibitors like AEBSF, EDTA, TPCK, and phenanthroline significantly affected proteolytic activities. Here, we reported two fungal proteases by high molecular weight from an Iranian isolate of B. bassiana. These findings will help us to better understand fungal virulence against insects.

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Changes in cellular immune responses of Chilo suppressalis Walker (Lepidoptera: Crambidae) due to pyriproxyfen treatment

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Mirhaghparast S. K., Zibaee A., Hoda H., Sendi J. J.

Journal of Plant Protection Research

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2015

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tom 55

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nr 3

The effects of pyriproxyfen were determined on the cellular immunity and phenoloxidase activity in the 4th instar larvae of Chilo suppressalis Walker. The bioassay results revealed the effective concentrations of: 10L : 18C, 30L : 72C and 50L : 190C μg · ml–1. The sole effect of 18 and 72 μg · ml–1 concentrations at intervals of 1–3 h caused a higher number of total hemocytes in the treated larvae than the control, but the reverse results were observed after 6–24 h. The number of plasmatocytes was lower than that of the control for intervals of 3–24 h but the number of granulocytes was higher than the control after 1–3 h although no significant differences were observed at the other times. In the treated larvae, the activities of phenoloxidase were higher and lower than those of the control after 1–3 h and 6–24 h, respectively. The combined effects of pyriproxyfen and the entomopathogenic fungus, Beauveria bassiana isolate B3 caused higher numbers of total hemocytes, plasmatocytes, and granulocytes in the treated larvae by use of the three concentrations of pyriproxyfen, at intervals of 6 and 12 h. Although the numbers of nodules in the larvae treated with concentrations of 18 μg · ml–1 were higher than those of other treatments, the overall numbers were lower than those of the control. Finally, the activity of phenoloxidase in the treated larvae was higher than that of the control, at intervals of 6 and 12 h post-treatment. Findings of the current study indicate an intervening role of pyriproxyfen in the cellular immunity of C. suppressalis to entomopathogenic objects.

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Cellular energy allocation in the predatory bug, Andrallus spinidens Fabricius (Hemiptera: Pentatomidae), following sublethal exposure to diazinon, fenitrothion, and chlorpyrifos

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Chitgar M. G., Hajizadeh J., Ghadamyari M., Karimi-Malati A., Sharifi M., Hoda H.

Journal of Plant Protection Research

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2014

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tom 54

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nr 1

It is necessary to study the biochemical changes in insects exposed to toxicants if we want to predict the potential of various chemicals on the natural enemy. Physiological energy, as a biochemical biomarker, may be affected by many pesticides including organophosphate compounds. Therefore, in this study, the sublethal effects of diazinon, fenitrothion, and chlorpyrifos on the cellular energy allocation (CEA) of the predatory bug, Andrallus spinidens Fabricius (Hemiptera: Pentatomidae), a potential biological control agent, was studied on 5th-instar nymphs. Among the energy reserves of the A. spinidens nymphs, only total protein was significantly affected by pesticide treatments, and the highest value was observed in chlorpyrifos treatment. The energy available (Ea) and energy consumption (Ec) in A. spinidens were significantly affected by these pesticides. In exposed bugs, these parameters were affected by fenitrothion and chlorpyrifos more than diazinon. The activity of the electron transport system (ETS) in the Ec assay showed that A. spinidens exposed to chlorpyrifos had the highest rate of oxygen consumption. Although, there was no significant change in CEA, the insecticides caused a marked change in the physiological balance of A. spinidens. The results suggested that the adverse effect of these insecticides on A. spinidens should be considered in Integrated Pest Management (IPM) programs.

Ograniczanie wyników

3 Journal of Plant Protection Research

3 Hoda H.

2 Zibaee A.

1 Chitgar M. G.

1 Firouzbakht H.

1 Ghadamyari M.

1 Hajizadeh J.

1 Karimi-Malati A.

1 Mirhaghparast S. K.

1 Sendi J. J.

1 Sharifi M.

1 Sohani M. M.

2 2015

1 2014

Purification and characterization of the cuticle-degrading proteases produced by an isolate of Beauveria bassiana using the cuticle of the predatory bug, Andrallus spinidens Fabricius (Hemiptera: Pentatomidae)

Changes in cellular immune responses of Chilo suppressalis Walker (Lepidoptera: Crambidae) due to pyriproxyfen treatment

Cellular energy allocation in the predatory bug, Andrallus spinidens Fabricius (Hemiptera: Pentatomidae), following sublethal exposure to diazinon, fenitrothion, and chlorpyrifos