Domatia were originally described in the late 1800s by Swedish naturalist Axel Lundstrom, who proposed that these structures offer mutual benefits to both the plants and to certain protective insects and mites. His notion lay dormant until about a decade ago when a few research groups around the world began to probe its validity. One of the striking features of domatia is that they seem to be inhabited strictly by insects and mites that feed on other bugs rather than on plants, further evidence of a mutually beneficial relationship between plants and the domatia residents. Exploration of this phenomenon was a natural for researchers in the laboratory of Richard Karban, who has been studying the relationship between plant-eating insects and their plant hosts for some 15 years. The mites essentially spit on the cotton leaf to pre-digest it, then proceed to slurp it up.
Most growers apply sulfur, oils and mostly chemical miticides in an attempt to control spider mites.
If untreated, a cotton field can be thoroughly devastated by the mites. Commercial cotton varieties have no domatia, so Karban and Agrawal decided to see what would happen if they added some of these tiny structures to the cotton leaves. Furthermore, yield of cotton bolls was boosted 30 percent in cotton plants that had domatia added to their leaves early in the season. The researchers also tried adding the simulated domatia to field cotton in the middle of the growing season. In those plants, levels of spider mites remained below the pest status.