## 3 Results  
### Attractiveness of Various Parts of A. altissima to Adult E. scrobiculatus and E. brandti  
In the first series of experiments, we evaluated the level of attractiveness of bare phloem of healthy and injured _A. altissima_ trees to adults of both weevil species. In the field study, we recovered 10% and 14% of the marked _E. scrobiculatus_ adults and 37% and 35% of the marked _E. brandti_ adults from bare phloem of injured trees and healthy trees, respectively. The response of the weevils differed significantly between species (\(F=17.07\), df = 1, \(p<0.05\)), but the state of the tree (i.e., injured vs. healthy) had no effect on the number of weevils responding for each species (\(F=0.03\), df = 1, \(p=0.865\)). The interaction term (weevil species \(\times\) state of tree) was non-significant (\(F=0.27\), df = 1, \(p=0.613\)). In the large-arena experiment, there were significant differences in the level of response of _E. scrobiculatus_ and _E. brandti_ to the various parts of _A. altissima_. Adults of _E. scrobiculatus_ significantly preferred phloem from the trunk (\(F=12.57\), df = 3, \(31\), \(p<0.05\)). _E. brandti_ adults responded in significantly greater numbers to the tree limb than to any other plant material. Phloem from trunk ranked second in preference, and this material was more attractive to the weevils than annual branches and seedling foliage (\(F=13.36\), df = 3, \(27\), \(p<0.05\)) (Figure 1). Results from the Y-tube olfactometer revealed that _E. scrobiculatus_ females responded positively to all types of plant material that they were exposed to when compared with air (healthy phloem versus air: \(\chi^{2}=11.267\), df = 1, \(p<0.01\); injured phloem versus air: \(\chi^{2}=10.889\), df = 1, \(p<0.01\); annual branches versus air: \(\chi^{2}=9\), df = 1, \(p<0.01\)). Similar results were found for _E. scrobiculatus_ males (injured phloem versus air: \(\chi^{2}=12.25\), df = 1, \(p<0.01\); seedling foliage versus air: \(\chi^{2}=12.25\), df = 1, \(p<0.01\); annual branches versus air: \(\chi^{2}=12.25\), df = 1, \(p<0.01\)) (Figure 2). Figure 1: Response of adult _E. scrobiculatus_ and _E. brandti_ to various types of plant material from _A. altissima_ in the large-arena experiment. Means (\(\pm\)SE) were calculated from the number of weevils responding to each treatment. For each weevil species, different letters above bars denote significant differences according to ANOVA and [PERSON]’s new multiple range test at \(p=0.05\). Contrasting gender responses were recorded for _E. brandti_. Female and male weevils showed a significant preference for phloem regardless of the condition of the tree (healthy phloem: female: \(\chi^{2}\) = 12.25; \(p\) < 0.01; males: 100% of the males responded to healthy phloem; injured phloem: female: \(\chi^{2}\) = 14.22; \(p\) < 0.01; male: \(\chi^{2}\) = 4; \(p\) < 0.05) when compared with air. However, a repellent effect was noted for females, which significantly selected the arm associated with clean air compared with the arm containing foliage from seedlings (\(\chi^{2}\) = 5.33; \(p\) < 0.05) whereas males showed a significant preference for seedling foliage. While no significant differences were observed in the response of females toward volatiles emitted from annual branches (\(\chi^{2}\) = 2.273, \(p\) > 0.05), it exerted a significant repellent effect on males (\(\chi^{2}\) = 6.25; \(p\) > 0.05) (Figure 3). Figure 3: Response of _E. brandti_ females (_n_ = 20) and males (_n_ = 20) to different parts of _A. altissima_ in the Y-tube offactometer. Injured phloem = phloem from injured trees; healthy phloem = phloem from healthy trees. _p_-values are based on [PERSON]’s chi-square test: *, \(p\) < 0.05; **, \(p\) < 0.01; ns, \(p\) \(\geq\) 0.05. Figure 2: Response of _E. scrobiculatus_ females (_n_ = 18) and males (_n_ = 18) to different parts of _A. altissima_ in the Y-tube olfactometer. Injured phloem = phloem from injured trees; healthy phloem = phloem from healthy trees. _p_-values are based on [PERSON]’s chi-square test: **, \(p\) < 0.01.