Scientists shed light on new quarantine methods

11 February 2008

Sightings of strange lights in the forests of Nelson’s Pigeon valley could increase this week, but the reason behind this unearthly illumination is less mysterious than it appears.  

Scientists at Crown Research Institute Scion have chosen Moutere Forest near Nelson to trial new lighting systems designed to repel insects and reduce the risk of pest contamination at wood processing sites.

Project leader Dr Steve Pawson says while most people know that standard light bulbs are highly attractive to insects at night, certain wavelengths of light in the yellow spectrum are the opposite for some insects – completely unattractive.

“The reason behind this research is because pest contamination of forest products can create quarantine issues for forest products when they go for export,” Dr Pawson says.

“Our aim is to identify which type of yellow light is most effective in deterring insects, thereby reducing insect contamination, and the need for fumigation at our ports where forest products are typically treated using methyl bromide to meet strict quarantine controls.

“If New Zealand is going to reduce methyl bromide and other chemical use, we have to start by reducing pest populations at processing sites, which involves taking completely new approaches to pest control.”

Scientists are investigating methods of insect management using a combination of lights on industrial sites.

The lighting trial has been established to replicate a typical sawmill and the effectiveness of different coloured lights in reducing insect numbers is being tested.

“Mills sited next to forests are hugely attractive to insects at night because they are flood lit with metal halide lamps. Our aim is to offer replacement lights that make the site less attractive to insects,” says Dr Pawson.

“Ultimately we envisage a strategy that manages quarantine risks using light with large yellow lights used to repel most insects from the site and highly attractive ultraviolet light traps placed within the site to mop up those that make it through the defences,” he explains.

Preliminary results after three nights’ trapping are promising and final results from the trial are expected by the end of February.