FIGURE 3 . Variation potentials emitted (no.) (MEAN ± SE) by Bt and non-Bt cotton plants at different time intervals (h) after densities of 30 and 60 aphids / plant and control (absence of aphid). Mean data (points) and error bars (SE) predicted by the generalized linear quasi-Poisson model, except for the plotted values for the control used in both cotton cultivars (Bt or not Bt).