Fitness evaluation of Encarsia sophia parasitizing Aleurocybotus indicus on two rice cultivars

Banker plant system has been widely used to control vegetable pests through the use of different combinations of host plant-alternative host natural enemy. In order to control the destructive pest Bemisia tabaci (Gennadius, 1889) (Hemiptera: Aleyrodidae) with banker plant system, estimating the reproductive potential of parasitoid Encarsia sophia (Girault & Dodd, 1915) (Hymenoptera: Aphelinidae) parasitizing and feeding on alternate host rice whitefly Aleurocybotus indicus (Hymenoptera: Aphelinidae) is critically necessary. Two rice cultivars ('Changyou' and 'Jinjing') were used as banker plant. Our research showed that the longevity of E. sophia female adult in 'Changyou' treatment was significantly longer than that in 'Jinjing' treatment. The intrinsic rate of increase (r) and net reproductive rate ([R.sub.0]) of E. sophia parasitizing A. indicus on 'Changyou' rice plant were 0.2295 [d.sup.-1] and 34.6 eggs, respectively, and significantly greater than those on 'Jinjing' (0.0.2001 [d.sup.-1] and 26.4 eggs) rice plant. Additionally, the net host feeding rate ([q.sub.x]) of E. sophia feeding on A. indicus in 'Changyou' (36.6 rice whitefly) treatment was significantly greater than that (23.7) in 'Jinjing' treatment. In conclusion, between two rice cultivars that were tested in this study, 'Changyou' rice plant could serve as a suitable banker plant for rearing E. sophia in biological control programs. The established banker plant system might provide growers with a new option for long-term control of B. tabaci in vegetable production. Key words: Biological control, banker plant, Encarsia sophia, life table, rice whitefly, silver leaf whitefly.