The chemical ecology of sirex noctilio

The recent detection of an established Sirex noctilio F. (Hymenoptera: Siricidae) population in New York, USA highlighted an urgent need to develop a trapping system so that the wasp’s distribution and density can be monitored effectively. This review is of research that has been done on the insect’s biology and chemical ecology towards this goal. This includes detailed work on the volatile composition of pine trees and the antennal responses they elicit in S. noctilio. Despite the testing of several promising volatile blends, there is still no effective lure that is as attractive as a funnel trap placed on trees stressed by injection with a herbicide. The possibility of a pheromone attractant between the sexes has also been studied at both the morphological and chemical level. This work has led to the identification of three sex pheromone components, (Z)-7-heptacosene, (Z)-7-nonacosene and (Z)-9-nonacosene to which males respond at short range. There is currently no evidence that S. noctilio has a long-range sex pheromone. Behavioral cues for host and mate selection (olfactory, visual and/or auditory) clearly need to be investigated further if we are to develop a monitoring trap that is more effective than a chemically stressed “trap tree”.