Tetranychus urticae

T. urticae was originally native only to Eurasia, but has acquired a cosmopolitan distribution as a common pest in a wide range of agricultural systems. ==Description==

T. urticae is extremely small, barely visible with the naked eye as reddish, yellow or black spots on plants; the adult females measure about long. Adult mites sometimes spin a fine web on and under leaves. ==Ecology==

File:Spider mites on a pepino leaf.png|Some T. urticae adults and eggs on the underside of a pepino leaf File:Red spider mite (Tetranychus urticae).jpg|A colony of T. urticae This spider mite is extremely polyphagous; it can feed on hundreds of plants, including most vegetables and food crops – such as peppers, tomatoes, potatoes, pepinos, beans, maize, and strawberries, and ornamental plants such as roses. It lays its eggs on the leaves, and it poses a threat to host plants by sucking cell contents from the leaves cell by cell, leaving tiny pale spots or scars where the green epidermal cells have been destroyed. T. urticae populations may increase rapidly in hot, dry conditions, expanding to 70 times the original population in as few as six days. The mite's natural predator, Phytoseiulus persimilis, commonly used as a biological control method, is one of many predatory mites which prey mainly or exclusively on spider mites. == Lifecycle ==

T. urticae reproduces through arrhenotoky, a form of parthenogenesis in which unfertilized eggs develop into males. The egg of T. urticae is translucent and pearl-like. Inbred progeny mature more slowly than outbred progeny, and inbred female progeny have lower reproductive output. T. urticae females apparently are capable of kin recognition and have the ability to avoid inbreeding through mate choice. == Genomics ==

The genome of T. urticae was fully sequenced in 2011, and was the first genome sequence from any chelicerate. == References ==