عنوان مقاله [English]
نویسندگان [English]چکیده [English]
Beet armyworm, Spodoptera exigua (HÃ¼bner) is an important pest of field crops with a wide range of host plants. Using safer insecticides with different modes of action and lower possibility of development of resistance such as insect growth regulators (IGRs) would be useful for effective control of this pest. In this study, effects of three IGRs namely methoxyfenozide, lufenuron and flufenoxuron were assessed on 1st instar larvae of S. exigua. To investigate the effect of insecticides, bioassays were performed using diet incorporation and leaf dipping methods. Mortalities were recorded 144 h after treatment. The LC50 values obtained for methoxyfenozide, flufenoxuron and lufenuron were 0.154, 0.254 and 2.398 mg ai/l, in diet incorporation method; and 1.302, 0.427and 3.510 mg ai/l in leaf dipping method, respectively. Comparison of the LC50 values for the insecticides revealed that the LC50 values for the treated insecticides were significantly different in both bioassay methods. The results indicated that in both bioassay methods, lufenuron had the lowest toxicity against the 1st instars of beet armyworm. It was revealed that all insecticides tested were effective against 1st instars of beet armyworm at low concentrations. If similar results are obtained in field conditions, due to fewer unwanted effects of these insecticides, they can be considered in beet armyworm control programs.