Spider mite genome sequenced; opens way for non-pesticide control methods

London, ON – An international consortium led by a researcher at the University of Western Ontario has unveiled the first genome of the second-largest group of animals on Earth: Chelicerates.

Dr Miodrag Grbic, associate professor with Western’s Department of Biology, and a research team including scientists from Spain, Belgium, France, Portugal, USA, Chile, Germany and Switzerland, have sequenced the genome of the spider mite, Tetranychus urticae.

The research was published in the November 24 issue of Nature.

Feeding on more than 1,000 different plants – including 150 of agricultural importance, such as maize, soy, strawberries, tomatoes, cucumbers and peppers – the spider mite causes damages that approaches $1 billion annually. Insects and mites currently destroy 13 per cent of all potential crops.

“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,” says Dr Grbic. “This species is renowned for developing resistance to pesticides. Within two years of introduction, spider mites are able to overcome new pesticides.”

The scientific team uncovered the genetic basis for mites’ ability to feed on many different plants, discovering that the spider mite is able to multiply and evolve new genes to detoxify toxic plant molecules and – most surprisingly – also ‘hijacks’ detoxification genes from bacteria, fungi and plants to combat the plant defences before incorporating them into its own genome.

While the spider mite is an important and harmful pest, Dr Grbic’s group, in collaboration with nano-physicists Jeff Hutter at Western and Marisela Velez at Universidad Autonoma de Madrid, also discovered a novel benefit: spider mite silk.

This naturally occurring nanomaterial of extreme lightness has potential use as a reinforcement in composite materials, nanodevices and nanoprobes for investigating the function of cells, and as a matrix for tissue engineering and drug delivery.

These efforts represent the first complete genome of chelicerates – the second-largest group of animals in the world behind insects – which include spiders, scorpions, horseshoe crabs, ticks and mites.