Systemic Induced Resistance (SIR) in Zucchini by Foliar Spray of Fosfalim-K against Two-spotted Spider Mite
Heavy agricultural use of fertilizers and pesticides has caused tremendous harm to the environment as well affects human population. For concerning about food and environmental safety and avoiding pesticide resistant pests, application of alternative methods in integrated pest management (IPM) is needed. IPM is a combination of crop protection practices to keep pests below economic threshold, one of them is resistant host plant. Different factors such as application of fertilizers and pesticides, irrigation and creating optimum conditions for host plant can affect its resistance. Data from previous studies have indicated that foliar sprays of phosphate and potassium salts can induce systemic protection against foliar pathogens. To analyze the effect of foliar spray of phosphorus and potassium on induction of systemic resistance to the host plant against two-spotted spider mite its development and reproductive rate was studied on zucchini sprayed with three Fosfalim-K concentrations (1=sub-optimal, 10=optimal and 30=supra-optimal ml L-1) and control in the laboratory conditions. Foliar treatments were applied three times. The raw data were analyzed based on the age-stage, two-sex life table theory of Chi and Liu. The intrinsic rate of increase (r), the finite rate (λ), the net reproduction rate (R0) and the mean generation time (T) of T. urticae on control were 0.166d-1, 1.18d-1, 10.72 offspring and 14.17d respectively. The systemic induced resistance by Fosfalim-K is expressed in significantly decreased r, λ, R0 and T values in mites fed on plants sprayed with optimal and supra-optimal concentrations. The age-stage life expectancy and reproductive value also were calculated.