Red Velvet Mite's Vivid Color Protects Them From Harmful UV Rays, Study Confirms

On the rugged landscape of rocks and concrete lives the red velvet mite formally known as Balaustium murorum. These small, velvety, bright red mites are often seen crawling around on tree trunks, planters, rocks, or on the ground, especially right after a rain. As non-parasitic mites, they do not bite or sting humans but threaten small insects like flies, aphids, and other mites.

These critters can be easily spotted due to their striking bright red coloration. Such a feature makes them a subject of both wonder and fear since the red color is associated with danger. Until now, their vivid color has not particularly interested the scientific community.

Uncovering the Secret of the Red Velvet Mite's Pigment

According to Professor Satoshi Shimano from Hosei University, many people do online searches related to red velvet, especially during early spring. Some of them think that the bright red color of this insect is proof that it has sucked blood. However, he confirms that the red velvet mite never acts as a parasite on other organisms.

Other insects display red coloration, although none can be as visually striking as the red velvet mites. This characteristic is also exhibited by spider mites (Panonychus citri) which remain active during the day and are prone to intense sunlight. Constant exposure to solar radiation produces harmful reactive oxygen compounds in the body that cause oxidative stress. To adapt to oxidative stress, the spider mites store carotenoid astaxanthin in its body. The accumulation of this powerful antioxidant is displayed as a deep red color in the spider mite's body.

If these mites are mostly harmless, one might wonder about the purpose of their distinct red color. A group of researchers from Hosei University and Kyoto University investigated the possible protective role of the mite's bright pigment by identifying and quantifying the carotenoids present in its body. They conducted a chemical-profiling analysis which revealed that the carotenoids in the insect's body are mostly made up of astaxanthin (60%) and 3-hydroxyechinenone (38%), both known as powerful antioxidants.

The concentration of astaxanthin in red velvet mites is 127 times higher than that of a spider mite which is famous for being rich in this compound. This is one of the highest known levels of microarthropods, such as crustaceans, according to Professor Masahiro Osakabe from Kyoto University. Therefore, the bright pigmentation of the red velvet mite results from the high concentrations of keto-carotenoids. This substance is an antioxidant against reactive oxygen compounds formed in harsh environments, protecting the insect from strong ultraviolet rays and radiant heat.

Significance of Red Velvet Mite to the Environment

Also known as true velvet mites, the red velvet mites belong to the Trombidiidae family, with 300 known species globally. They are closely related to spider mites and harvest mites.

Red velvet mites are members of a group of soil arthropods that are very useful for decomposition rates in woodlands. Since they spend much of their lives in the soil, they interact with other soil organisms. This means that these insects play a crucial role in maintaining healthy soils and keeping the overall ecosystem's structure.