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PESTS AND DISEASES OF FORESTRY IN NEW ZEALAND

Unwanted pests arrive in comfort

From Biosecurity Magazine - Issue 79, November 2007.

Figure 1: Typical couch upholstered, upholstery removed, and timber frame exposed

Recent reports by MAF's Investigation and Diagnostic Centre (IDC) have shown that wooden furniture imported from Asia (particularly China) poses a significant biosecurity risk to New Zealand. The Biosecurity Monitoring Group has taken apart a sample of imported lounge suites from China and Malaysia to find out how many pests are getting an armchair ride across the border. They found that, while there was plenty of evidence of poor-quality construction materials and hitchhiking pests, voluntary fumigation of the furniture by importers is keeping the pest risk low.

Since 1988 there have been 83 detections of exotic organisms associated with imported furniture entering New Zealand of which 41 percent came from China, Indonesia and Thailand. Over half of these detections occurred post-border after biosecurity clearance had been issued, with many being detected by members of the public.

Signs of infestation on internal sections

On several occasions, IDC investigators discovered wood-borer tracks and holes covered up with putty. Further investigations noted that some Chinese furniture manufacturers put good quality (unblemished) wood on visible surfaces, and poor quality (insect damaged and occasionally bark covered) timber in internal sections of the furniture. This practice led the IDC to believe that unseen internal timber used in the manufacture of upholstered furniture is likely to be of poor quality and therefore of higher risk of being contaminated.

The high numbers of imported couches (about 40,000 couches from China and Malaysia in 2005), coupled with the potential for poor-quality, infested materials led to a concern that upholstered furniture could be an important pathway for pests and pathogens that posed a risk to New Zealand's forestry sector. As a result, a joint project was initiated between the Biosecurity Monitoring Group (BMG) and IDC Incursion Investigation, Plants and Environment team to determine the level of contaminated wood used in imported Chinese and Malaysian upholstered furniture.

Survey initiated – poor quality materials in furniture

Figure 4: Frequency of timber types (identified to Family) found in couches (n=50) from China and Malaysia

A total of 37 lounge suites, comprising 51 individual items, were purchased from retailers who routinely import couches from China and Malaysia. The BMG survey team systematically inspected each item, beginning with the complete piece of furniture and progressively removing the outer covering and padding (Figure 1). All contaminants found were collected for identification. Small samples of each type of timber were also collected from each item of furniture for wood identification.

The first thing the surveyors found was that the construction materials used were of poor quality. A number of couches were constructed from undressed and dirty timber (even the occasional tree branch – see Figure 2), and some were heavily contaminated with borer holes and bark (Figure 3).

Of the 51 couches inspected, 39 (77 percent) were contaminated with insects, pathogens, bark, plant material or had evidence of previous insect damage (Table 1). Thirty-two couches had borer holes, and 24 couches had more than one type of contaminant.

Multiple timber types

Figure 2: Part of a tree branch used in the construction of a couch

At least 65 different types of wood (from 25 families) were used in the construction of the couches sampled (Figure 4). Most couches had more than one timber type used in their construction (Donaldson 2006). The presence of multiple timber types is of concern because by increasing the number of potential host woods imported, it increases the chance that a couch will introduce a pest or pathogen to New Zealand. Furthermore, several of the wood types identified were closely related to New Zealand natives and wood of economic importance. These may carry pests/pathogens with the potential to be of biosecurity concern.

Currently, importers commonly choose to fumigate all couch imports to accelerate the clearance process. As a result, all but one of the insects found in the couches was dead (38 in total). The only living specimen found was a species of Cardiastethus that may have entered the couch at the retailer's premises.

Overall, 11 couches were infested with fungi, and 10 of these were infested with more than one species. Fourteen specimens of viable fungi were identified from the wood samples. However, of the six fungal specimens identified to species, all were saprophytes already present in New Zealand.

Biosecurity risk low if furniture fumigated

Figure 3: Insect tunnelling and larvae under bark from a sample of timber taken from a couch

A high proportion of upholstered furniture imported into New Zealand from China and Malaysia appears to be infested with potential pests and pathogens. This may be a result of the low-grade materials used in the manufacture of the couches. However, the overall risk of upholstered furniture to biosecurity is low due to effective intervention by importers: importers voluntarily fumigate couches either overseas or in New Zealand.

In the absence of these voluntary interventions, the importation of upholstered furniture poses a potential biosecurity risk to New Zealand. Ongoing management of this pathway should focus on maintaining communication with industry to ensure that current interventions are maintained.

References

L Donaldson, 2006, Report on timber species from Chinese couches, Scion report prepared for the Ministry of Agriculture and Forestry.
Thompson G, Froud K, Pearson H, Tohovaka S, Whyte C and McCarthy B, 2007, Contaminants of upholstered furniture from China and Malaysia, June 2006, Biosecurity New Zealand, BMG 06-07/04.

Authors

Glen Thompson, Analysis and Profiling Group, MAF Biosecurity New Zealand, phone 09 909 3514, glen.thompson@maf.govt.nz
Karyn Froud, Investigation and Diagnostic Centres, MAF Biosecurity New Zealand, phone 09 909 5729, karyn.froud@maf.govt.nz
Sharon Tohovaka, Cargo Clearance Group, MAF Biosecurity New Zealand, phone 09 909 3516, sharon.tohovaka@maf.govt.nz
Victoria Allison, Analysis and Profiling Group, MAF Biosecurity New Zealand, phone 09 909 3510, victoria.allison@maf.govt.nz

 

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