Toxicity interaction of fipronil and imidacloprid against Coptotermes formosanus (Isoptera: Rhinotermitidae)

Fipronil (Termidor®) and imidacloprid (Premise®) are both nonrepellent insecticides that are widely used in termite control. They have different target sites in the insects’ nervous system. Our research found there was antagonism between them. Different ratios of fipronil and imidacloprid combinations were applied to Coptotermes formosanus in the lab. Termite survival numbers were recorded to analyze the relationship between their ratio combinations and toxicity. Tunnel numbers were also recorded in the study. Results showed that very low concentrations of imidacloprid (25 ppm) significantly reduced fipronil’s toxicity. We believe that imidacloprid suppresses the termites’ activities and therefore the chances of physical contact with fipronil are decreased.