The Genome of the Two-Spotted Spider Mite Has Been Decoded

An international group of scientists, including University of Utah biologist Richard M. Clark and researchers at a research institute called Ghent VIB in Belgium, has decoded the genome of the two-spotted spider mite (Tetranychus urticae). Interestingly, this is also the first genome of any arachnid that has been sequenced. It was revealed that this arthropod has 18,414 genes, 15,397 of which are expressed by being used to make proteins. In comparison with other arthropods, the spider mite uses a different molting hormone to shed its exoskeleton while it is growing, has only eight Hox genes (while most other arthropods are known to have 10), has only two main body segments instead of three because of its lack of Hox genes, and makes silk that is similar to spider silk except that it is 185-435 times stronger and spun from its head region rather than from its abdomen. Clark also mentioned that this silk may be useful for making biodegradable bandages and sutures because it is easy to obtain.

[caption id="attachment_2858" align="alignright" width="400" caption="The two-spotted spider mite, shown here, is less than one millimeter long."][/caption]

Having knowledge of the genome of two-spotted spider mites is important because they are related to house dust mites and other parasitic ticks that can transmit serious diseases to both humans and animals. They are also an invasive species and are a threat to global food production due to their need to suck plants such as tomatoes, peppers, cucumbers, strawberries, corn, soybeans, apples, grapes and citrus fruits dry, which often results in reduced harvests for farmers since they are able to consume over 1,100 different plant species, including the ones already mentioned. Alarmingly, scientists predict that due to global warming, spider mite plagues will increase because they reproduce faster at higher temperatures. The annual cost for pesticides used against these mites is about 0.5 to 1 billion dollars, and they are known to show resistance to different kinds of pesticides – the sequenced genome actually contains genes for detoxifying pesticides. The continuing study of their genome will be important in understanding how they are able to adapt to consuming new types of plants as well as resist pesticides, which will hopefully be the first step in reducing their numbers and understanding arthropods in general with more depth, which are fascinating enough simply due to the fact that they account for more than 83% of all described animal species.

The original research article is available here.