Figure 3.

Number of male and female Hylurgopinus rufipes responding in Y-tube olfactometers to a 4-component lure (4CL) of synthetic (−)-β-pinene, (−)-α-cubebene, (+)-spiroaxa-5,7-diene and (+)-δ-cadinene at a natural ratio (20 : 1.5 : 1.25 : 175; determined in volatile blend of diseased elm (figure 1)) of components (experiment 3), or at a non-natural ratio (1 : 1 : 1 : 1) of components (experiments 4, 5). One GHE=1 g-h equivalent=amount of semiochemicals released from 1 g of ground diseased elm wood during 1 h of volatile acquisition. Number of insects responding to each stimulus given in bars, number of insects tested given in parenthesis. For each experiment an asterisk (*) indicates a significant preference for a particular treatment; χ² test with Yates correction for continuity, treatment versus control; *p<0.05.