Effective pest control remains one of the most pressing challenges of agriculture as global food demand continues to grow.
Around the world, farmers apply around 4 million tonnes of chemical pesticides per year to protect crops and represent the $600 billion industry.
While these compounds significantly increased agricultural productivity, their widespread use has raised concerns about environmental impacts, health risks, and the long-term sustainability of modern agriculture.
To shed light on this, a research team led by Professor Arimura Shogun of the Department of Biological Science and Technology, Tokyo University of Science, tested the theory of plant pest control by closely examining the fine molecular interactions occurring between spider mites and host plants.
Restrictions on traditional pest control
Two-spot spider mites, Tetranychus urticae, exemplifies the limitations of traditional pesticide-based pest control in agriculture and horticulture.
These microscopic arcnides invade a wide range of crops and fruit trees and can be replicated very quickly.
More importantly, unlike many other pests, they rapidly develop resistance to chemical pesticides, making control efforts more difficult.
With pesticide resistance increasing, farmers around the world are urgently sought alternative, sustainable pest control strategies.
The team is T. We focused on a specific substance called elicitors secreted by urticae and examined the biological effects on various crops.
“Inducers are molecules owned by plants or pests, which can enhance the plant’s defense response,” explained Professor Arimura.
“Previous studies have identified two Tertrains labeled Tet1 and Tet2 as elicitors of the salivary glands of two spotted spider mites. These substances induce protective responses in common beans and other commercially important crops.”
Why does pesticide resistance develop?
The research team is T. We investigated the effects of an additional 18 salivary gland proteins on the resistance of common bean leaves to urticae.
According to this initial screening, they identified two new tetranines that appear to reduce the reproduction of spider mites in the plant.
After a series of experiments involving genetic engineering and advanced molecular and biochemical methods, the team revealed the role of Tet3 and Tet4 in the complex interactions between T. urticae and its host plants.
Interestingly, we found that the expression of Tet3 and Tet4 differed significantly depending on the plant that the mites are eating. Mites eating common beans, their preferred host, had significantly higher levels of TET3 and TET4 expression than those of cucumbers.
In particular, plants exposed to mites with higher expression of TET3 and TET4 showed stronger protective responses, including increased calcium ion influx, higher generation of reactive oxygen species, and increased expression of a protective gene named PR1. Separate applications of Tet3 and Tet4 to plants had different effects on plant pest control and defence responses, highlighting the specificity of the role of each elicitor.
“Together, our findings show that these tetranins respond to variable host cues that may optimize fitness in herbivores by altering the anti-mite response of host plants,” Alimura said.
Sustainable agriculture and impact on food security
These findings have two meanings.
First, understanding the molecular mechanisms underlying interactions between organisms lead to a better understanding of evolution, ecosystems, and biodiversity. Eliciters such as tetranine act as important links in these complex systems, and in-depth research is essential to uncover broader biological insights.
From an agricultural perspective, elicitors similar to tetranine offer the potential for crop improvement as insight into the eliciter sensing system helps breed more sensitive and resilient crops.
Arimura states, “Elysitors may be useful as a biostimulant that can increase potential pest resistance in plants.
“The development of such organic farming technologies is very meaningful in today’s world as the environmental and ecological consequences of pest control use become more severe.
“Hopefully, identifying elicitors secreted by pests and elucidating their function will lead to unprecedented countermeasures for spider mites.”
Continued research into plant pest control may contribute to more sustainable agriculture and food safety.
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