Figure 1.

Mortality of Helicoverpa armigera caterpillars treated with methomyl after exposure to plant volatiles. Newly molted fifth instars were individually exposed to volatile 2-heptanone (Hept), cis-3-hexenyl acetate (Hylac), limonene (Limo) and nerolidol (Nero) at a dose of 1 µL per cup for 48 h in a sealed cup and then treated with methomyl (50 μg per caterpillar). No volatile exposure served as control (CK). Piperonyl butoxide (PBO, 3 µL), a known P450 inhibitor, was applied to larval pronotum 1 h before insecticide application. Mortality was recorded 24 h after methomyl treatment. Values are means + standard errors from three replicates with 20 caterpillars/replicate. Significant differences (p < 0.05 using ANOVA followed by a Tukey test for post-hoc comparison) among treatments in a group are indicated by different letters above the bars.