Phil Bell (University of Tasmania/Forest Practices Authority) & Simon Cook (Forico Pty Ltd)
Controlling predation of Ptunarra brown butterfly by introduced wasps in a plantation forest estate in northwest Tasmania
Forico Pty Limited manages about 173,000 hectares of land in Tasmania. Management aims to maintain and/or enhance existing natural values and biodiversity assets for conservation purposes. This is often achieved through collaboration with ecological experts and researchers to ensure appropriate scientifically robust principles and operational prescriptions are applied for future management of the natural values. Ptunarra brown butterfly Oreixenica ptunarra is endemic to the highland Poagrasslands of Tasmania. Predation by the introduced wasp Vespula germanica has been identified as a major threat to the species. In 2017 Forico initiated a study to identify options to reduce the impact of wasps on butterflies at its Surrey Hills plantation estate in northwest Tasmania. The study has revealed that the abundance of wasps in native grasslands is related to the age of adjacent eucalypt plantations. Newly established and young plantations support a very high abundance of wasps, and wasp nests, and are the likely source of wasps predating butterflies in nearby grasslands. Results suggest that the establishment of dense forest buffers and control of wasps in plantations may reduce the abundance of wasps in adjacent grasslands. Trials to control wasps are underway and effective techniques may be applied more widely to protect populations of butterflies across the plantation estate.