Spider mite finds itself in Western’s sites

If the thought of dust mites in your mattress or a spider on your ceiling is enough to make your skin crawl, just think: pesticide-resistant spider mites might also be in your home, burrowing in your house plants or slowly destroying your garden.

While the very idea of spider mites is an annoyance, the pest causes damage approaching a whopping $1 billion each year, feeding off more than 1,000 plants, among them corn, soy, strawberries, tomatoes, cucumbers and peppers. The agriculture industry suffers as a result – every year, insects and mites destroy 13 per cent of all potential crops.



But there’s good news.

New research findings, led by a professor of biology at The University of Western Ontario, could help eradicate the spider mite problem – no pesticide needed.

An international research team, led by Western’s Miodrag Grbić and featuring scientists from Spain, Belgium, France, Portugal, United States, Chile, Germany and Switzerland, has sequenced the genome of the spider mite, a member of the arthropod lineage, the second-largest group of animals on Earth.

Being familiar with the spider mite’s genome is key to developing a sustainable way of dealing with the pest.

“We have discovered this creature’s gene set and, more importantly, we believe we have found its Achilles heel so that we can begin development of non-pesticide, alternative pest control measures,” Grbić explains. “This species is renowned for developing resistance to pesticides. Within two years of introduction, spider mites are able to overcome new pesticides.”

Researchers discovered the spider mite is able to not only reproduce and generate new genes to detoxify toxic plant molecules, but it also ‘hijacks’ detoxification genes from bacteria, fungi and plants in order to combat the plant defences before incorporating them into its own genome.

Simply put, the spider mite is a resilient little pest.

This groundbreaking discovery will help breed plants resistant to spider mites. Using biotechnology-based pest control measures in place of traditional pesticides, ultimately limiting the spider mite’s ability to reproduce, would also bring about new, sustainable agriculture practices and more pesticide-free produce on Canadian tables.

While the spider mite is responsible for an agricultural deficit of nearly $1 billion each year, Grbić’s research team, together with Western nano-physicist Jeff Hutter and Marisela Velez at Universidad Autonoma de Madrid, found an advantage of having the pest around.

Spider mite silk, visible on heavily infested plants, can be used as reinforcement in composite materials in the automotive, aeronautical and medical fields.

“The (medical) industry would be greatly interested in spider mite silk,” says Western biology professor Vojislava Grbić, co-author and Grbić’s wife.

Because its straight fibres are fairly strong and not too elastic, spider mite silk has the potential to serve as a breeding environment for tissues and drug delivery and can help nanodevices and nanoprobes used for investigating cell function.

The real benefit is sequencing the spider mite genome will allow researchers to develop the pest’s silk in-vitro, so, even if the spider mite is eventually eradicated, the potential benefits of its silk will remain.

The paper, The genome of Tetranychus urticae reveals herbivorous pest adaptations, appears in the latest issue of the journal, Nature.

The work, which was conceived in Miodrag Grbić’s laboratory at Western more than 10 years ago, has been supported by the Natural Sciences and Engineering Research Council of Canada, Genome Canada, the Ontario Genomics Institute, the Ontario Research Fund – Global Leadership in Genomics and Life Sciences program and the U.S. Department of Energy.