On the scent of natural solutions

On the scent of natural solutions in South Africa

The wood-boring Cossid Moth (Coryphodema tristis) has a broad range of native tree hosts in South Africa.

It was first reported on Eucalyptus nitens (E. nitens) in Mpumalanga in 2004. As E. nitens is planted on our plantations, it was important to become involved in efforts to reduce infestation.

Pheromones as lures

The Forestry and Agricultural Biotechnology Institute (FABI) initiated work on the development of a female sex pheromone to lure adult male Cossid Moths in 2012. Field experiments, testing an optimised pheromone mix and trap types during 2015, paved the way for the first possible commercial application of pheromone trapping techniques with the aim of reducing the reproductive capacity of the Cossid Moth population. A pilot mass-trapping project was implemented during 2016 in all five and six-year-old E. nitens compartments at Sappi’s Lothair plantation, using approximately 6,500 bucket type funnel traps with pheromone lures. 

The enduring allure of pheromones

The study showed that males are attracted to the lures even after a three-month maturation period in the field. At the end of May 2017, destructive sampling was conducted to evaluate the success of the mass trapping exercise. It was found that trapping significantly decreased population growth. The theoretical increase in the number of colonies with and without trapping was modelled. This indicated that if no trapping is conducted, the 1.9 colonies per tree at five years could increase to 96 colonies at eight years. However, trapping male moths for one year at the age of five could reduce the number of colonies at eight years to 53 and trapping at both five and six years could reduce the number of colonies at the age of eight years to 28.

Theoretical increase of Cossid Moth colonies in untrapped compartments, where trapping is conducted only for one year and where trapping is conducted for two consecutive years.

Theoretical increase of Cossid Moth colonies in untrapped compartments