Laboratory evaluation of selected botanicals and insecticides against invasive Spodoptera frugiperda (Lepidoptera: Noctuidae)

Abstract

Background: Maize is an economical crop of China, and its production has been severely affected by the invasive Spodoptera frugiperda in recent year. Application of synthetic pesticides are one of the most effective practices against FAW as an emergency control. This pest causes serious damage to the maize crop worldwide in recent decade, especially in China. Methods: To find an alternative to synthetic insecticides there were total 16 different chemicals were used including ten botanical insecticides comprising of seven botanicals, azadirachtin, pyrethrin, nicotine, osthole, rotenone, Celastrus angulatus, matrine, and three insect growth regulators, diflubenzuron, lufenuron and buprofezin. Six synthetic insecticides, including emamectin benzoate, indoxacarb, imidacloprid and thiamethoxan, chlorantraniliprole, chlorfenapyr, were evaluated against 2nd instar of S. frugiperda larvae using leaf-dip method. Results: The results revealed that osthole, azadirachtin, buprofezin and pyrethrin were showed the significant larval mortality of 98.0, 96.7, 94.0 and 90.7%, in 120 h observation and exhibiting minimum LC50 (39.04, 35.58, 61.45 and 48.46 mg/L, respectively) and LT50 (48.91, 68.85, 58.67 and 58.57 h, respectively) values. Among tested synthetic insecticides, emamectin benzoate, chlorantraniliprole and chlorfenapyr were showed significant higher mortality against larvae of S. frugiperda (99.3, 96.0 and 89.3%, respectively) in 72 h observation by exhibiting minimum LC50 (0.26, 0.39 and 0.72 mg/L, respectively) and and LT50 (10.18, 10.57 and 13.42 h, respectively) values. More study is needed to test the laboratory findings in the field, although the efficient biorational pesticides might be utilized as part of integrated pest management against S. frugiperda. Conclusion: The effective chemicals could be used in the management for S. frugiperda. The highest discriminating concentrations of tested botanical insecticides, insect growth regulators and insecticides caused significant mortality of S. frugiperda larvae.

Keywords

• Maize
• Spodoptera frugiperda
• Botanical insecticides
• Instar
• Larval mortality