scolytus, Newman-Keuls test). A low release rate of 4-methyl-3-heptanone (Treatment C) did not have a significant effect on beetle capture, but the higher release rates (Treatments D and E) led to reductions in the numbers of beetles trapped. Regression analysis showed a significant inverse linear relationship between the numbers of female beetles caught and the release rate of 4-methyl-3-heptanone (P=0.05 for S. multistriatus, P < 0.01 for S. scolytus). The effect on male beetles of both species was close to significance at P=0.05. Thus the release of an appreciable amount of 4-methyl-3-heptanone interrupted (sensu Wood [4]) the response of both Sco-Iytus species to the attractant mixture of 4-methyl-3-heptanol and (-)-c~-cubebene. However, present results (this paper and [2]), suggest this ketone, like some other bark beetle metabolites [3, 5] may have multiple functions in the behaviour of these Scolytus species.
Further work on the effect of 4-methyl-3heptanone on these species is warranted, since it has been suggested that substances which interrupt attraction might be used in the control of bark beetles [6].