Efficacy of insecticidal seed treatments against the wireworm Pleonomus canaliculatus (Coleoptera: Elateridae) in China

Wireworms, the larval stage of click beetles (Coleoptera: Elateridae), are a major pest in the production of winter wheat in North China, and effective population control is often essential for cost-effective crop production. In this study, six neonicotinoids alone, and three in combination with fipronil as seed treatments were investigated to determine their effects on the management of the wireworm Pleonomus canaliculatus (Faldermann) in winter wheat fields. Thiamethoxam, clothianidin and imidacloprid seed treatments at a rate of 360 g AI 100 kg−1 seed significantly reduced infestations of wireworm in wheat seedlings. Relatively higher correlations were observed between the application rates of thiamethoxam, clothianidin and imidacloprid and wireworm damage percentage, but relatively lower correlations were found between application rates and wireworm populations. Furthermore, seed treated with fipronil (40 g AI 100 kg−1 seed), thiamethoxam (360 g AI 100 kg−1 seed), thiamethoxam + fipronil and clothianidin + fipronil (360 + 40 g AI 100 kg−1 seed) significantly decreased wireworm damage and population densities of P. canaliculatus. An additive interaction was observed between thiamethoxam and fipronil. Thiamethoxam and fipronil can be combined to provide growers with an option for controlling wireworm populations and can comprise a key component in integrated management of the wireworm in winter wheat production.