Fig. 3

Relative percentage (%) of trapped Medetera flies and Ips typographus beetles in three arrangements of different synthetic blends and solvent controls tested in the second subtractive assay using the partial factorial design (2^4–1). Three different arrangements (1, 2, and 3) of seven synthetic blends (1–7) were established. The X denotes presence of the compounds from a specific group in each blend. The control contained only the solvent heptane. The relative percentage of trapped Medetera and Ips typographus, respectively was calculated for the individual treatments relative to the overall number of trapped specimens at the same test round and site. A general linear model (GML) followed by analysis of variance (ANOVA) was used to study significant differences between the relative percentage of insects trapped by each synthetic blend based on the presence or absence of blend components. Different lowercase letters (a, b, c) indicate significant differences (P ≤ 0.05) between treatments (post hoc Tukey test following ANOVA). In arrangements 2 and 3, the data for I. typographus was not included due to the very low number of beetles collected by these synthetic blends