Giant Rat's Tail Grasses

Sporobolus pyramidalis and S. natalensis are tufted, perennial grasses originating from Africa that have become highly invasive along the eastern seaboard of Australia. These two species are commonly known as giant rat’s tail grasses (hereafter ‘GRT’). GRT grow to approximately 0.6 - 1.9m tall, with an inflorescence of up to 45 cm in length. The inflorescence is originally “rat’s tail-like” in structure becoming “pyramid-shaped,” when fully matured. GRT poses a serious environmental and economic threat to pasture and grazing lands in eastern and northern Australia, due to its unpalatability to livestock which results in significantly reduced grazing capacity and high expenditure on control interventions (e.g. mechanical and chemical control). GRT infestations are estimated to cost the livestock industry approximately AU$ 60 million per annum. The failure of mechanical and chemical control options to successfully manage GRT and the observation that GRT is rapidly expanding across the invaded distribution in Australia, with approximately 60% of Queensland vulnerable to invasion, has resulted in biological control being pursued for their effective management in Australia.

Invasive grasses have traditionally been considered as “poor targets” for classical biological control due to a proposed lack of suitably host-specific and damaging natural enemies in their native distributions. However, this claim has never been critically evaluated. As such, the primary aim of this research project was to source and develop candidate biological control agents for GRT infestations in Australia. More generally, this project aimed to evaluate the suitability of invasive grasses to classical biological control using GRT, as a model study system, by integrating data from extensive field-surveys, molecular studies and laboratory trials with ecological theory. These data will hopefully yield candidate biological control agents for GRT infestations in Australia, and develop a better understanding of grass-insect interactions and the implications this has for the biological control of invasive grasses.

For anyone wanting more information regarding the potential for grass biological control, or any discussion regarding the applied nature of grass-insect/fungus interactions, please don’t hesitate to contact Guy Sutton at

Last Modified: Fri, 28 Sep 2018 14:49:57 SAST