关键词: B型烟粉虱, 温室白粉虱, 碱性磷酸酶, 酶活力, 动力学性质

Abstract: For understanding the role of alkaline phosphatase (ALP) from Bemisia tabaci (Gennadius) biotype B and Trialeurodes vaporariorum (Westwood) in their competition and substitute, the kinetic properties of the enzyme from the two whiteflies in different developmental stages were studied and compared by the individual assay and mass assay using pNPP as the substrate. The results showed that the alkaline phosphatase activity was increasing in both whiteflies during the whole growth period and reached the highest level at the adult stage. Comparatively, the alkaline phosphatase activity in the 2nd, 3rd and 4th (pseudopupa) instar of T. vaporariorum were 2.58, 2.68 and 3.14 times that in the corresponding instar of B. tabaci B-biotype, respectively. However, at the adult stage, the enzyme activities in female and male of B. tabaci B-biotype were 1.24 and 1.26 times that in T. vaporariorum, respectively. Moreover, the enzyme activities in females of both whiteflies were significantly higher than those in males. However, the enzyme activity of the alkaline phosphatase in the 1st instar of both whiteflies was not detected. The optimum pH and temperature for the enzyme activity in both whiteflies were 7.8 and 47℃, respectively. By testing the kinetic parameters of alkaline phosphatase from both whiteflies, we found that the affinity of the enzyme from the 3rd and 4th instar of T. vaporariorum was significantly higher than that from B. tabaci B-biotype of the corresponding instar, and also the protein concentrations of the enzyme from 2nd, 3rd and 4th instar of T. vaporariorum were significantly higher than those from B. tabaci B-biotype of the corresponding instars. But at the adult stage there was no significant difference between the two whiteflies in both the affinity of the enzyme and the protein concentration of the enzyme. Besides, the energy of activation (Ea) of the enzyme from T. vaporariorum adult was significantly higher than that from B. tabaci B-biotype adult. The results suggest that although the ability of B. tabaci B-biotype to utilize the alkaline phosphatase to promote the sclerotization and development during the larval stages may not as high as that of T. vaporariorum, its ability to utilize the enzyme to metabolize and detoxify the secondary (plant) substances and insecticides in the adult stage, however, is significantly higher than that of T. vaporariorum adult.

Key words: Bemisia tabaci B-biotype, Trialeurodes vaporariorum, alkaline phosphatase, enzyme activity, kinetic properties