Trial moth repellent a fatal attraction

NorthTec biodiversity degree student Aaron Heap, left, and Northland Regional Council chairman Bill Shepherd with a guava moth pheromone twist tie. Photo / Supplied

Looking for love is likely to prove fatal for male guava moths if a tricky new device being tested in Whangarei messes with their senses.

In a bid to better protect fruit and nut crops, those behind the trial - which officially began this week - are attempting to use the male moths' sex drive as the instrument of their own destruction.

Lengths of plastic twist-tie laced with female moths' sex scent should spur males to hunt the non-existent mate until they literally drop dead from exhaustion.

About 80 Riverside residents have joined forces with NorthTec and the Northland Regional Council and agreed to take part in a 14-month long free trial based on the use of a naturally-occurring female moth pheromone as a biological control weapon.

Guava moth (Coscinoptycha improbana) is thought to have blown across the Tasman in its adult form in the late 1990s.

"Unfortunately, it's now a very much established and unwelcome pest, whose larvae infests and ruins a range of soft fruit and nuts, both domestic and commercial, in Northland year-round," NRC chairman Bill Shepherd said.

"The technique uses a naturally-occurring pheromone produced by female moths to attract males. This scent confuses the males who use up their limited energy reserves in a vain search for these 'phantom' females until they die.'

Female moths present in large numbers at peak breeding times, will struggle to find a male mate to fertilise their eggs.

The new moth-scamming device is less bulky than the commercially-made pheromone traps available in Whangarei. The imported ties are based on those used to lure a similar overseas moth and cost just a few cents per unit.

Mr Shepherd said the ties are not expected to be a 'silver bullet' to the guava moth problem.