Survival rates of white-backed planthopper ( Sogatella furcifera ) nymphs at 20°C , 25°C and 28°C. Sample sizes at 20°C for the viruliferous, non-viruliferous, and control populations were 61, 12, and 36 individuals, respectively; at 25°C were 32, 37, and 38, respectively; and at 28°C were 41, 36, and 38, respectively at 28°C. Values shown are means ± SE. Different letters above the columns for a given instar and temperature indicate that the means that differ significantly at the P = 0.05 level by the SNK test. Numbers of surviving nymphs at each instar, as well as the F, df, and P values, are presented below the columns.