Five-spined bark beetle

A five-spined bark beetle

An adult five-spined bark beetle.

Five-spined bark beetle larvae on a pine log

Galleries in pine bark made by Ips Grandicollis larvae.

General information

The five-spined bark beetle (Ips grandicollis) is an established pest in Queensland's pine growing regions. It is usually a secondary pest, managed through good silvicultural practices. Beetle populations are also under biological control by two introduced parasitoid wasps.

Although Ips grandicollis is generally a secondary pest, it is important to manage it because it vectors blue stain fungi, which can severely affect the value and aesthetic qualities of milled timber.

Scientific name

Ips grandicollis

Other names: Five-spined beetle, eastern five-spined engraver

Description
  • Adult beetles are dark red-brown to almost black
  • 3-5 mm in length
  • May be shining, glabrous, dull, densely covered with hairs or scales
Similar species

Occurring in Queensland. These two species mainly attack the stumps or roots of dead trees, slash that is in contact with the ground, or large areas of clear fell residue:

  • Hylurgus ligniperda (goldenhaired bark beetle)
  • Hylastes ater (black pine bark beetle)

Exotics. Bark beetles include some of the most destructive forest pests overseas, and many pose significant biosecurity threats to Australia. Some of the most important of these pests are:

  • Dendroctonus frontalis (southern pine beetle)
  • Dendroctonus ponderosae (mountain pine beetle)
  • Dendroctonus brevicomis (western pine beetle)
  • Dendroctonus valens (red turpentine beetle)
  • Ips typographus (european spruce bark beetle)
  • Tomicus piniperda L. (pine shoot beetle)
Distribution
  • Widely distributed throughout Queensland´s Southern Pine plantations and in the tropics since 2009.
Hosts
  • It is a pest of many Pinus species, including the commercially grown Southern Pines: slash pine (Pinus elliottii), Caribbean pine (Pinus caribaea var. hondurensis) and their hybrids.
Biology
  • Adults bore into the outer bark of trees or slash. Males produce an aggregation pheromone that attracts more beetles to the attack site.
  • Males are polygamous, initially forming a nuptial chamber in the bark, and typically admitting 3 to 5 females. Beetles carry spores of blue-stain fungi, which grow in the phloem and sapwood.
  • Females excavate longitudinal galleries, shaped like tuning-forks in the phloem. Larval galleries, tightly packed with frass, fan out from the parent gallery. Larvae pupate in chambers constructed in the bark. Newly emerged adults (´callows adults´) feed for a short time under the bark before emerging and restarting the cycle.
  • Several generations (4 or more) are achieved per year in south-eastern Queensland, which means that populations can increase rapidly in response to favourable resources.
Damage
  • Populations of Ips can build up to damaging levels in thinning and clear fell plantation residues and in fire-damaged or other stressed, standing trees.
  • Beetles can kill trees if population levels are very high and/or if trees are debilitated by drought or fire. In southern Australia, ´feeding attacks´ by newly emerged adult beetles on young plantations adjoining clear fells have also been recorded.
  • Ips carries blue stain fungi, which can affect the value and aesthetic qualities of milled timber.
Management
  • Plantation managers in Queensland can reduce the impact of this pest in exotic pine plantations through appropriate harvesting practices, for example, by reducing slash residues and removing logs quickly offsite.
  • Beetle populations are also controlled by two introduced, biological control agents, the parasitoid wasps, Roptrocerus xylophagorum and Dendrosoter sulcatus.
Comments

There are concerns about the effects of climate change on this pest. Ips populations elsewhere in Australia are associated with large-scale tree mortality of drought-stressed pine trees. In Queensland in 1994, Ips grandicollis caused $10 million damage to fire damaged trees at Beerburrum. It is likely that the incidence of drought and fire will increase with the effects of climate change, meaning that management of this pest may become more important in the future.

Recently, Ips has been recorded attacking the trap trees used in monitoring and biological control programs for sirex wood wasp in NSW. This is preventing sirex from attacking the trap trees, and so it is reducing the effectiveness of these programs. Detecting sirex early and implementing biological control is essential for preventing sirex wasp outbreaks. Research funded by the National Sirex Coordination Committee and the ARC is examining ways to manage this problem.

Last updated 30 October 2012