PESTS AND DISEASES OF FORESTRY IN NEW ZEALAND
Pine shoot moth in Chile
Scion is the leading provider of forest-related knowledge in New Zealand
Formerly known as the Forest Research Institute, Scion has been a leader in research relating to forest health for over 50 years. The Rotorua-based Crown Research Institute continues to provide science that will protect all forests from damage caused by insect pests, pathogens and weeds. The information presented below arises from these research activities.
From Forest Health News No. 15, November 1992.
The European pine shoot moth, Rhyacionia buoliana , was first recorded in Chile in 1985 and is now considered a serious pest of P. radiata plantations there. The larva bores into and feeds on buds and shoots causing them to wilt and die. This often results in multi-leadered trees and poor height growth. While all types of control are being explored, biocontrol seems the best long term option. A braconid parasite has been successfully established but at present parasitism is only 5-10%. Some concern has been expressed of this pest becoming established in New Zealand. Probably the only way it could survive to reach New Zealand is as a larva in living pine shoots. Because our quarantine regulations prohibit this type of material from entering the country, there is very little chance of this insect becoming established here.
From Forest Health News No. 4, November 1991.
Gordon and Margaret have returned from Chile having had a thorough look at the pine shoot moth epidemic in the radiata plantations.
Rhyaciona buoliana , first detected in Chile in 1985 now infests 280,000 ha of forest, and is still spreading north at about 30km a year. The insect lays its eggs on needles near the end of growing shoots and the 1st to 3rd instars feed on the shoot surface before entering the tissue and beginning diapause for the winter period. The 4th instar emerges in spring and makes its way up the outside of the shoot to within 10-20cm of the apex. At this point it bores in and tunnels upward pupating just beneath the terminal bud. Insect damage causes breakage, deformation, or death of the shoot producing multi-leadering. In young vigorous trees a new main leader may develop and even repeated attack may have little affect on the tree. More commonly however no clear dominant leader develops and repeated attack leads to complete arrest of height growth. Three years after infestation is only now spreading into the dryer more difficult sites where damage might be expected to be more severe and the possibility of two insect generations a year exists.
A range of different control options are being trialled - insect parasites, insecticides, Bacillus thuringiensis, birds etc. However the Chilean Agricultural Research Institute has focussed on a larval parasite, Orgilus obscurator , and is promoting the intensive rearing of this insect. The effectiveness of this parasite has not been fully evaluated. Rhyaciona buoliana could clearly have a profound effect on P. radiata in New Zealand if it ever became established.
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