Aquatic extract of camellia sinensis l. As the inducer of cucumber systemic resistance to bemisia tabaci gennadius (hem.: Aleyrodidae)

Whitefly, Bemisia tabaci Gennadius (Hem.: Aleyrodidae), is a globally important pest of many vegetables including cucumber. In this study, for the first time, the effect of tealeaf extract, Camellia sinensis (L.) Kuntze (Theacea), on the induction of a plant (cucumber) resistance to a phloem feeder insect, namely, B. tabaci, was investigated under laboratory conditions. The cucumber plants were irrigated using different concentrations of C. sinensis leaf extracts (0, 0.001, 0.003, 0.006, and 0.009 g mL^-1). Life table parameters of B. tabaci were determined on the treated and control plants using two-sex life table method. Our data indicated that the whitefly longevity at the concentrations 0.006 and 0.009 g mL^-1 were significantly more than control. Moreover, net Reproductive rate (R₀) and intrinsic rate of increase (r) were 68.8 and 47.7% or 82.6 and 79.1% lower than control at the concentrations 0.006 or 0.009 g mL^-1, respectively. Therefore, these concentrations (0.006 and 0.009 g mL^-1) caused significant adverse effects on the biological traits of the pest implying the induction of cucumber resistance to the whitefly. Chemical analyses of the treated and control plants indicated that the treatment with tea extract led to significant increase in total tannin, phenol and flavonoid contents of treated cucumber, while considerably reducing alkaloid and saponin contents. Totally, the concentrations 0.006 and 0.009 g mL^-1 of aquatic extract of tea can be used as resistance inducer of cucumber to the whitefly.