Comparing effects of invasive plant management: a case study of biocontrol vs. herbicide
Peterson, P. G., Merrett, M. F., Fowler, S. V., Barrett, D. P., & Paynter, Q. (2020). Comparing biocontrol and herbicide for managing an invasive non‐native plant species: Efficacy, non‐target effects and secondary invasion. Journal of Applied Ecology, 57(10), 1876-1884. https://doi.org/10.1111/1365-2664.13691
Managers are faced with many decisions when it comes to invasive plant management options, yet there are benefits and drawbacks to each. This study provides a unique opportunity for comparison of herbicide and biocontrol impacts on the invasive woody shrub, Calluna vulgaris, as well as indirect effects including non-target impacts, secondary invasion, and native plant recovery. The 5-year field trial in Tongariro National Park, New Zealand, where there is a high endemicity of plants that are particularly vulnerable to invasion, offers some insight into the need for evaluating non-target impacts of invasive plant treatments and long-term monitoring for secondary invasion. In their study, Peterson et al. utilized two control methods for Calluna vulgaris, which is considered one of the worst invasive plants in the park. Researchers applied these treatments (biocontrol, herbicide, insecticide + herbicide, and control) randomly across twenty-four 5×5 meter plots and followed plant cover and species richness over 5 years. They found that biocontrol introduction of the heather beetle (Lochmaea suturalis) reduced invasive plant cover by 97%, compared to 87% reduction from herbicide (Pasture Kleen; 2,4-D ester), and a 20% increase in the control. Native dicot cover increased after biocontrol, while herbicide had major non-target effects on native dicots. Notably, secondary invasion was greatest with biocontrol because non-native dicot cover increased in newly cleared space, where herbicide almost eliminated non-native dicots. Despite secondary invasion, biocontrol did not have severe non-target impacts on native dicots compared to herbicide, and thus had the greatest benefits to native flora.
- Restoration goals are often compromised by low efficacy of target plant suppression resulting from regeneration, invasion by other weeds (secondary invasion), and native seed limitation
- Both biocontrol and herbicide application effectively controlled the target invasive in this study, but biocontrol had the best outcomes for native flora, while herbicide had dramatic non-target effects on the most species-rich native plant group
- There was no evidence of parasitism, predation of, or non-target feeding by the biocontrol agents, suggesting a long-term and sustainable control
- Biocontrol can be a more appropriate method than herbicide application at a landscape scale
- Non-target impacts of herbicide should be considered before determining if it is an appropriate control for invasive plants
- Rapidly removing the largest vegetation cover can allow space and resources for other species to invade, regardless of what control method is used
- Wherever possible, management impacts should be measured for longer than 5 years to more sufficiently quantify native plant community responses and secondary invasion
Read more of our research summaries:
"A gene drive construct that could spread to all components of the population may mean that eradication of sea lamprey from the Great Lakes is no longer an impossible dream."
This 5-year study offers considerations for monitoring the indirect effects of invasive plant treatments, such as non-target impacts, biodiversity benefits, and secondary invasion.
An international team of 19 researchers identify and summarize four critical priority areas to better advance invasion science in an era of rapid global change.
This paper summarizes current research and knowledge about one of the top invasive species in Europe to help inform management of other invasive species that cover broad ranges and span diverse habitat types.
After eluding scientists for decades, the causative agent of a deadly wildlife disease (vacuolar myelinopathy) is uncovered in a recent study, and has been linked to the colonization of invasive Hydrilla.
Functional eradication, a new framework for invasive species control, focuses on suppressing invasive species below levels that have significant negative impacts on conservation targets.
Invasive forest pests can spread when people move firewood from place to place, but this review helps to identify how we can prevent it from spreading further.
Advances in eDNA research show promise for estimating the abundance of invasive fish populations using water samples.
Garlic mustard may occupy forest understories, but mounting evidence shows that with time, populations of this ubiquitous invader are in decline.
Plant competition seemingly plays out before our eyes, but Zhang et al. find that invasive plants may gain a competitive edge through unseen soil interactions.
Buying aquarium organisms from across the world can be as easy as the click of a button, and that's the problem.