关键词: 台湾乳白蚁, 氧化苦参碱, 纤维素酶, 抑制作用

Abstract: [Objective] The formosan subterranean termite, Coptotermes formosanus (Isoptera:Rhinotermitidae), is one of important wood-feeding pest in China. To protect the ecological environment and reduce the use of the chemical pesticide in Taiwan termite prevention, it is urgently needed to search for alternative ingredients in place of the persistent organic pollutants (POPs) of the pesticide. This study investigated oxymatrine, from plants, with insecticidal activity that has inhibitory effect on cellulase activity of Taiwan termite workers, in order to provide the basis for the application of oxymatrine in the termite prevention and control.[Method] In this study, the workers of C. formosanus starved for 2 d were fed by 1% oxymatrine treated filter paper were investigated under laboratory conditions. In 6 h,12 h,1 d,3 d,5 d,7 d after treatment, digestive tracts of Taiwan termite ants were collected and the protein content was determined using the Coomassie Brilliant Blue G-250, and the filter paper activity (FPA), endo-β-1,4-glucanases (EG), β-glucosidase (BG), and cellobilohydrolase (CBH) activities were assayed using the dinitrosalicylic acid method.[Result] The results showed that 1% oxymatrine had significant inhibitory effect on filter paper activity(FPA)and the activities of endo-1,4-β-glucanase (EG),β-1,4-D-glucosidase (BG) and cellobilohydrolase (CBH) except for the activity of FPA and CBH in 6 h. The average cellulase inhibition rate was FPA > EG ≥ BG > CBH. Cellulase inhibition rate increased with the extension of treatment time, except for the EG inhibition rate in 5 d, BG inhibition rate in 3 d, and CBH inhibition rate in 12 h. Activity of C. formosanus workers exposed to 1% oxymatrine for 7 days was weakened significantly. The weight of the treated termite workers was significantly decreased compared with the control group, and the termite mortality was significantly increased.[Conclusion] This study determined that 1% oxymatrine had significant inhibitory effect on cellulas activity of C. formosanus, indicating that the inhibition of cellulase activity is one of the mechanisms of oxymatrine on insecticidal activity. Oxymatrine has chronic lethal activity on C. formosanus. The use of oxymatrine in suppressing cellulose digestibility of C. formosanus is a worth exploring methods of prevention of C. formosanus.

Key words: Coptotermes formosanus, oxymatrine, cellulase, inhibition