Baseline toxicity data of insecticides against the common cutworm Spodoptera litura (Fabricius( and a comparison of resistance monitoring methods

Abstract

A susceptible strain of Spodoptera litura (Fab.( was obtained and the baseline toxicity of more than 10 insecticides was established by both topical application and the leaf dipping method. Insecticide resistance was then monitored using insects collected from Nanjing, Jiangsu Province and Hexian, Anhui Province, China. Topical application was more sensitive for monitoring resistance to contact insecticides, and the leaf dipping method more sensitive for monitoring resistance to insecticides with stronger stomach action. The two field populations were shown to have high resistance to pyrethroids and moderate resistance to organophosphates and carbamates; however, the Nanjing population had low resistance to profenofos and methomyl. No resistance to monosultap, abamectin, hexaflumuron and fipronil was found in these populations. We propose that for control of this pest in these areas, pyrethroid insecticides should be prohibited, use of organophosphates and carbamates should be limited, and the other insecticides with no resistance, e.g., monosultap, abamectin, hexaflumuron and fipronil, should be used rationally and in rotation to delay resistance development.

Keywords:

• Spodoptera litura
• insecticide resistance
• resistance monitoring
• resistance management

Acknowledgements

We thank Dr Ian Denholm (Rothamsted Experiment Station, UK) for his kind corrections and comments, and Dr Guo Huifang (Institute of Plant Protection, Jiangsu Academy of Agricultural Science, China) for kindly providing the JAAS strain and HX strain of S. litura, and Jiang Xufang for rearing the insects. This study was financed by the National Natural Science Foundation of China (NSFC, Grant no. 30530530), and China Agricultural Ministry project (Grant no. 2004BA520A15).