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Wasp management takes the sting out of the forest


Anyone who has spent time tramping in beech forest, or even picnicking on the roadside, will be aware of the presence and impact of introduced wasps. What most people don’t realise is that New Zealand forests contain one of the highest densities of wasp population in the world.

With up to 370 wasps per m2 wasps are so widespread that their biomass alone exceeds the collective biomass of all other birds, invertebrate and mammals put together!

Honeydew is a vital source of carbohydrates that many of our unique native birds and insects depend upon, however with wasps consuming over 90% of beech forest honeydew, birds such as Tui, Bellbird and Kaka are starved of a vital food resource. When teamed with introduced possums and predators such as stoats and rats, wasps contribute a level of suppression that is keeping our once plentiful birdlife struggling for survival.

Nestled hard against the forest in the splendid Mariua Valley the tiny Maruia Primary school is under attack. Principle Peter King reports that around March every year wasp numbers increase to a stage where the children are unable to play outside for fear of being stung.

For NZSFP forester Brendon Horrell the opportunity to trial wasp control advancements in conjunction with the Maruia Primary School was a fantastic opportunity.

"Integrating pest control with productive forest management has always been a goal, but tools to achieve this are light on the ground. By gaining permission to trial entecol bait we feel we are looking at a cost effective and efficient way to enhance forest biodiversity but also directly improve the health and well-being of the Maruia Primary School children and community."

Technical expertise in planning the trial was provided by Nelson based company Entecol Ltd which has a temporary license to trial wasp control baits. As part of a school project on forest biodiversity, Maruia school pupils monitored the wasp levels of abundance and foraging activity throughout February and March. When wasp numbers reached a threshold, NZSFP forest managers were notified and together with the assistance of DOC volunteers, 60 bait stations were dispersed throughout a 35-hectare forest area, and around the Maruia school and community margins. NZSFP funded the trial and Entecol’s newly developed weatherproof bait stations, designed to improve the longevity and effectiveness of baits were used. Maruia school pupils will continue to monitor the wasp numbers over coming days and as well as forming areal school project, this information will be used by NZSFP to plan for 2012-2013 wasp control efforts.

For Brendan Horrell the process reinforces the fact that biodiversity protection and timber production are not mutually exclusive goals.

The ultimate success of the trial will be the long-term benefit to the invertebrate and bird-life resulting from successive knock-down of wasp populations. If Entecol trials like this result in the bait being legally licensed in New Zealand and allow it to be used in the fight for our forests, then foresters and conservation managers alike will have gained a powerful weapon.

In the meantime the success of the trial is evidenced by the buy in and commitment shown by locals,community groups and other interests. NZSFP wish to thank Peter King and the Maruia Primary School community, The Macbeth Family Forest Trust, Richard Toft of Entecol Ltd and the Department of Conservation for assistance in the project.