The introduced five-spined bark beetle, Ips grandicollis, in Victorian radiata pine plantations.  I. First progress report.  F. G. Neumann and J. L. Morey.  December 1983.  31 pp. (unpubl.)

SUMMARY

The North American five-spined bark beetle, Ips grandicollis (Eichhoff), was found established in radiata pine (Pinus radiata D. Don) plantations west of Dartmoor in south-western Victoria in February 1982. The insect has also occurred in mill yards at Colac and Benalla within inner bark on pine logs from south-eastern South Australia, where it became established in the late 1970s. A natural eastward spread is inevitable, as geographic barriers are absent and susceptible pine material is abundant along the route.

The insect is essentially a ‘secondary’ pest of inner bark on green logging slash, and on recently felled, windthrown, wind-fractured, snow-damaged, or lightning-killed trees, though it can become ‘primary’ in late summer/early autumn, when healthy trees may be killed following massive ‘feeding’ attacks and the destruction of the inner bark by adults of both sexes. The wood of infested material is degraded during winter by beetle-borne blue-stain fungi. Few trees have so far been killed, and most have been located in peripheral rows of 3 to 17-year-old plantations in the vicinity of infested logging coupes. Plantations extensively damaged by protracted drought and other physical or biotic agencies provide suitable environments for a build-up of large tree-killing populations; most vulnerable are expected to be those located near major softwood industries where large quantities of susceptible green slash occur close to concentrations of logs awaiting conversion.

In South-western Victoria, three generations are produced between spring and autumn, and a fourth between late autumn and mid-spring. Many of the late-autumn adults hibernate below bark until mid-spring. Population levels decline during winter, hence beetle numbers are low in early spring, when dispersal flights resume and breeding commences in green, unbarked, dead pine material. The number of beetles and tree deaths may be kept low by applying certain silvicultural measures and by mass-trapping of airborne adults along outer rows of susceptible plantations with commercially available, synthetic, species-specific pheromones. More timely utilisation procedures could reduce the insect’s rate of spread. Future research will concentrate on ways of maximising the mass trapping of beetles with pheromones, and on a Victoria-wide distribution survey of the insect by means of pheromones.

Also published:

Neumann, F.G. and Morey, J.L. (1984)  Studies on the introduced bark beetle (Ips grandicollis (Eichhoff)) in Victorian radiata pine plantations.  Aust. For. Res. 14(4): 283-300.