Leveraging Nature’s Secret Weapon Against Ticks

Tick populations are increasing, especially in warm, humid areas of the United States. This puts both livestock and people at greater risk for serious tick-borne diseases. Traditional tick control methods are often costly and rely heavily on chemical treatments, which are facing growing resistance in different tick species. Scientists at the USDA’s Agricultural Research Service (ARS) are developing new, safer, and practical solutions for controlling tick populations and protecting humans and animals from tick bites.

At the ARS’s National Center for Agricultural Utilization Research (NCAUR) in Peoria, IL, Entomologist Lina Flor-Weiler, Plant Physiologist Will Hay, and their colleagues are testing the acaricidal effects—substances that are effective at killing ticks and mites—of different defatted seed meals from the mustard plant family against different tick species. 

After mustard seed crops are pressed to extract oils for food and biofuel applications, the remaining seed material is often considered a byproduct of little value. Yet, recent research shows this byproduct can be highly effective against dangerous pests. 

“The defatted seed meal retains a diverse array of compounds —one of which is glucosinolates,” said Flor-Weiler. “When defatted seed meals are hydrated, an enzyme is activated that converts glucosinolates into isothiocyanates, a gaseous compound we know to be responsible for the pungent taste of mustard and horseradish. Research has shown that these isothiocyanates have potent pesticidal properties, making them effective against certain soil insects, nematodes, and disease-causing fungi.” 

The study, published in Experimental and Applied Acarology, measured the bio-fumigation effect of three defatted seed meals from the mustard family and its effectiveness in killing three different tick species. They tested the defatted seed meals of brown mustard(Brassica juncea), garden cress (Lepidium sativum), and pennycress (Thlaspi arvense) against the Lone Star tick, the American dog tick, and the blacklegged tick.

Defatted seed meals from all three plants killed the ticks under laboratory conditions, though their effectiveness varied by tick species. Since the three mustard species differed in the type and amount of gaseous compounds they produced, the amount of seed meal needed to kill ticks also varies among the species. This suggests that certain plants may be more effective against certain tick species than others.

“Ticks spend most of their lives on the ground or in vegetation, which are ideal conditions for this plant-based method,” said Flor‑Weiler. “Understanding the levels of effectiveness of each defatted seed meals, along with understanding the tick life cycles, will help us determine the best application strategies useful in real-world conditions.” 

“For example, this method can serve as an effective pest control strategy in areas known to be favorable tick habitats such as around structures, edge habitats, and livestock areas. If successful, this approach could offer a practical, eco-friendly alternative to reduce tick populations and protect public health,” added Flor-Weiler.

This is particularly significant in the Midwest and Northeast regions of the United States, where ticks transmit a wide array of pathogens that cause serious diseases such as Lyme disease, ehrlichiosis, Rocky Mountain spotted fever, babesiosis (affecting both humans and animals), and the Powassan virus. 

The researchers are eager to expand their studies to include cattle ticks through new collaborative efforts. By targeting cattle ticks in these high-risk areas, the team hopes to further demonstrate the effectiveness of mustard seed meals as a natural tool for controlling tick populations and reducing the spread of tick-borne illnesses.

In addition to helping control ticks, this research also benefits mustard seed producers in the United States by creating new market opportunities for defatted seed meals, which can be used as a natural tick biofumigant. 

Read about previous ARS studies, showing promising results against biting insects like mosquitoes and in reducing fungal contamination in grains. –by Maribel Alonso, ARS Office of Communications

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