Tetranychus urticae

Tetranychus urticae (common names include red spider mite and two-spotted spider mite) is a species of plant-feeding mite generally considered to be a pest. It is the most widely known member of the family Tetranychidae or spider mites. Its genome was fully sequenced in 2011, and was the first genome sequence from any chelicerate.

Tetranychus urticae
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Chelicerata
Class: Arachnida
Subclass: Acari
Order: Trombidiformes
Family: Tetranychidae
Genus: Tetranychus
Species:
T. urticae
Binomial name
Tetranychus urticae

Distribution

T. urticae was originally native only to Eurasia, but has acquired a cosmopolitan distribution.[1]

Description
Colony of red spider mites

T. urticae is extremely small, barely visible with the naked eye as reddish or greenish spots on leaves and stems; the adult females measure about 0.4 mm long.[2] The red spider mite, which can be seen in greenhouses and tropical and temperate zones, spins a fine web on and under leaves.[2]

Ecology
Some T. urticae adults and eggs on the underside of a pepino leaf.

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.[2] It is the most prevalent pest of Withania somnifera in India.[3] 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.[2] Although the individual lesions are very small, attack by hundreds or thousands of spider mites can cause thousands of lesions, thus can significantly reduce the photosynthetic capability of plants.[2]

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.[2]

Other than certain aphids, T. urticae is the only animal known to be able to synthesise carotenoids. As in aphids, the genes for carotene synthesis appear to have been acquired through horizontal gene transfer from a fungus.[4][5]

Lifecycle

T. urticae reproduces through arrhenotoky, a form of parthenogenesis in which unfertilized eggs develop into males.[6]

The egg of T. urticae is translucent and pearl-like.[1] It hatches into a larva, and two nymph stages follow: a protonymph, and then a deutonymph, which may display quiescent stages. The adults are typically pale green for most of the year, but later generations are red; mated females survive the winter in diapause.[1]

Inbreeding avoidance

Inbreeding is detrimental for fitness in T. urticae.[7] 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.[7]

Genomics
Genomic information
NCBI genome ID2710
Ploidyhaploid (males) / diploid (females)
Genome size90.82 Mb
Year of completion2011

The genome of T. urticae was fully sequenced in 2011, and was the first genome sequence from any chelicerate.[8]

References
  1. Raworth DA, Gillespie DR, Roy R, Thistlewood HM (2002). "Tetranychus urticae Koch, twospotted spider mite (Acari: Tetranychidae)". In Mason PG, Huber JT (eds.). Biological Control Programmes in Canada, 1981–2000. CAB International. pp. 259–265. ISBN 978-0-85199-527-4.
  2. Fasulo TR, Denmark HA (December 2009). "Twospotted spider mite". Featured Creatures. University of Florida / Institute of Food and Agricultural Sciences. Retrieved May 20, 2011.
  3. Sharma A, Kumar Pati P (2012). "First record of the carmine spider mite, Tetranychus urticae, infesting Withania somnifera in India" (PDF). Journal of Insect Science. 12 (50): 50. doi:10.1673/031.012.5001. PMC 3476950. PMID 22970740.
  4. Altincicek B, Kovacs JL, Gerardo NM (April 2012). "Horizontally transferred fungal carotenoid genes in the two-spotted spider mite Tetranychus urticae". Biology Letters. 8 (2): 253–7. doi:10.1098/rsbl.2011.0704. PMC 3297373. PMID 21920958.
  5. Bryon A, Kurlovs AH, Dermauw W, Greenhalgh R, Riga M, Grbić M, et al. (July 2017). "Tetranychus urticae". Proceedings of the National Academy of Sciences of the United States of America. 114 (29): E5871–E5880. doi:10.1073/pnas.1706865114. PMC 5530703. PMID 28674017.
  6. Feiertag-Koppen CC (December 1976). "Cytological studies of the two-spotted spider mite Tetranychus urticae Koch (Tetranychidae, trombidiformes). I: Meiosis in eggs". Genetica. 46 (4): 445–56. doi:10.1007/BF00128090.
  7. Tien NS, Massourakis G, Sabelis MW, Egas M (June 2011). "Mate choice promotes inbreeding avoidance in the two-spotted spider mite". Experimental & Applied Acarology. 54 (2): 119–24. doi:10.1007/s10493-011-9431-y. PMC 3084432. PMID 21400191.
  8. Grbić M, Van Leeuwen T, Clark RM, Rombauts S, Rouzé P, Grbić V, et al. (November 2011). "The genome of Tetranychus urticae reveals herbivorous pest adaptations". Nature. 479 (7374): 487–92. Bibcode:2011Natur.479..487G. doi:10.1038/nature10640. PMC 4856440. PMID 22113690.
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