New research has shown woodchips to be the secret weapon to keeping ticks off recreational woodland trails, including eliminating nearly all Lyme disease-carriers when treated with insecticide.
The two-year experimental field study led by Katarina Ost, doctoral candidate at the School of Epidemiology and Public Health at the University of Ottawa under Manisha A. Kulkarni 's supervision, and in collaboration with researchers from Bruyere Health Research Institute, Université de Montréal, and Dalhousie University, provided evidence that both treated and untreated woodchip interventions can effectively reduce tick populations in a recreational context, a simple and cost-effective way for communities to combat these critters.
"This study shows that different environmental management strategies can be effective in reducing the number of host-seeking ticks along trail edges, where people are likely to encounter them," said Dr. Kulkarni, a Full Professor at the Faculty of Medicine's School of Epidemiology and Public Health.
Incidences of Lyme disease have increased in central and eastern regions of North America due to the expansion of the tick's habitable range because of changes in climate, land use, and host reservoir populations. In Canada, the highest rates of Lyme disease occur in Nova Scotia and in the southern areas of Manitoba, Ontario, and Quebec.
NCC Greenbelt, an open-air lab
Reported cases have increased seven-fold over a decade, with Ottawa showing up to eight times as many cases over that period.
Working with the National Commission Capital's biology team, Kulkarni and her team evaluated the effectiveness of natural, untreated woodchips and those combined with acaricide, a chemical agent better known as deltamethrin, which is commonly used to keep ticks and mites off agricultural crops. These two types of woodchips were placed along a pair of recreational trails with established tick populations within Ottawa's Greenbelt, where there is a high density of infected ticks within the nation's capital.
This studynorth_eastexternal link demonstrates that modifying trail sides with woodchip borders, deltamethrin-treated or untreated, substantially reduces questing tick density, offering a tool for integrated tick management in recreational settings. Both interventions were successful in significantly reducing the density of adult and nymphal (smaller) blacklegged ticks, who are the primary vectors of Lyme disease in eastern North America, of all species and stages. The deltamethrin-treated woodchips provided 99 % reduction over two seasons of intervention while the untreated woodchips a 48 % reduction.
Eco-friendly, practical tool
The use of ash trees woodchips for trail management conditions provides a natural, biodegradable material representing a low-impact alternative to conventional chemical control strategies. Effectiveness did not erode over time either, meaning this cost-effective treatment had lasting impact throughout a single tick season.
"In terms of managing ticks in popular woodland trails, this could be a practical tool for popular trails where the environmental conditions are appropriate for targeted treatment," added Ms. Ost. "This may also offer up opportunities to integrate locally sourced woodchips from existing tree maintenance or removal programs."
The authors did note environmental considerations (like distance from bodies of water) could restrict the application of this type of insecticide with further research necessary to study the impact of the insecticide on the surrounding organic matter and non-target organisms. Longevity beyond the two-year time frame should also be assessed.
