FIGURE 4.

Concentration of pine defenses (non-volatile resin) in control and herbivory-exposed 3-year-old Maritime pine plants under a factorial combination of light availability (sunlight/darkness) applied to the plants and to the insects. Weevils were allowed to feed on the plants for 6 days. Concentration of non-volatile resin was determined in the stem section exposed to the insects (experimental part, see Figure 6). Mean ± SE, averaged across the three pine populations are shown (N = 9 for control plants and N = 18 for weevil-exposed plants). Different lowercase and uppercase letters denote significant differences (p < 0.05) between light treatments in control and herbivory-exposed plants, respectively.