Effects of Hexaflumuron and Pyriproxyfen on the purified Phenoloxidase of Chilo suppressalis Walker (Lepidoptera: Crambidae) |
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Authors: | Seyyedeh Kimia Mirhaghparast |
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Affiliation: | Department of Plant Protection, Faculty of Agricultural Sciences, University of Guilan, Rasht, Iran. |
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Abstract: | Effects of two insect growth regulators (IGRs), hexaflumuron and pyriproxyfen, were studied on the purified phenoloxidase (PO) of Chilo suppressalis. Purification procedure revealed two isozymes of PO, namely POI and POII. IC50 concentrations of hexaflumuron and pyriproxyfen on POI were 0.36, 0.23?μg/ml and on POII were 0.105, 0.42?μg/ml, respectively. Determination of optimal pH and temperature revealed pH 5 and temperature 40?°C as the optimal values for the enzymatic activity. Treating POs with IC50 concentrations of two IGRs was pH and temperature dependent. Effects of these IGRs on POI caused significant increase of Km value versus control suggesting competitive inhibition. Hexaflumuron and pyriproxyfen cause reduction in Vmax value of POII versus control suggesting non-competitive inhibition. The current study shows direct effects of two IGRs on purified PO of C. suppressalis for the first time. These findings could be helpful to develop safe compounds with inhibitory mechanism on PO to neutralise insect immune responses against entomopathogenic agents. |
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Keywords: | Chilo suppressalis Phenoloxidase Hexaflumuron Pyriproxyfen |
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