| Species: | Tetranychus urticae | |
| Genera: | Tetranychus | |
| Family: | Tetranychidae | |
| Distribution: | T. urticae was found to be major pest of vegetables in Africa, Canada, China, Egypt, Germany, Greece, India, Israel, Korea, Turkey and USA | |
| Host Crops: | More than 1000 host crops are reported in literature belonging to families Acanthaceae, Aceraceae, Actinidiaceae, Agavaceae, Aizoaceae, Alliaceae, Amaranthaceae, Amaryllidaceae, Anacardiaceae, Annonaceae, Apiaceae (Umbelliferae), Apocynaceae, Aquifoliaceae, Araceae, Araliaceae, Araucariaceae, Arecaceae (Palmae), Aristolochiaceae, Asclepiadaceae, Asparagaceae, Asteraceae, Balsaminaceae, Bambusaceae, Berberidaceae, Betulaceae, Bignoniaceae, Bombacaceae, Boraginaceae, Brassicaceae (Cruciferae), Bromeliaceae, Buxaceae, Campanulaceae, Cannabaceae, Cannaceae, Capparaceae, Caprifoliaceae, Caricaceae, Caryocaraceae, Caryophyllaceae, Celastraceae, Chenopodiaceae, Cistaceae, Clethraceae, Combretaceae, Commelinaceae, Convolvulaceae, Cornaceae, Cucurbitaceae, Cupressaceae, Cyperaceae, Dipsacaceae, Dipterocarpaceae, Ebenaceae, Elaeagnaceae, Equisetaceae, Ericaceae, Euphorbiaceae, Fabaceae, Fagaceae, Flacourtiaceae, Fumariaceae, Gentianaceae, Geraniaceae, Gesneriaceae, Goodeniaceae, Guttiferae, Hippocastanaceae, Hippuridaceae, Hydrophyllaceae, Iridaceae, Juglandaceae, Lamiaceae (Labiatae), Lauraceae, Liliaceae, Linaceae, Lobeliaceae, Loganiaceae, Lythraceae, Magnoliaceae, Malvaceae, Marantaceae, Meliaceae, Menispermaceae, Moraceae, Musaceae, Myoporaceae, Myrtaceae, Nyctaginaceae, Olacaceae, Oleaceae, Onagraceae, Orchidaceae, Oxalidaceae, Papaveraceae, Passifloraceae, Pedaliaceae, Phytolacaceae, Pinaceae, Pittosporaceae, Plantaginaceae, Platanaceae, Plumbaginaceae, Poaceae, Polemoniaceae, Polygonaceae, Pontederiaceae, Portulacaceae, Primulaceae, Punicaceae, Ranunculaceae, Resedaceae, Rhamnaceae, Rosaceae, Rubiaceae, Rutaceae, Salicaceae, Sapindaceae, Saxifragaceae, Scrophulariaceae, Simaroubaceae, Solanaceae, Sterculiaceae (Byttneriaceae), Strelitziaceae, Theaceae, Thymelaeaceae, Tiliaceae, Tropaeolaceae, Ulmaceae, Urticaceae, Verbenaceae, Violaceae, Vitaceae, Zingiberaceae, Zygophyllaceae. Important ones are apple, beans, brinjal, citrus, cotton, capsicum, cabbage, chrysanthemum, castor, dahlia, fenugreek, lobia, lettuce, marigold, moong, mint, mash, moth bean, okra, pigeonpea, papaya, pear, raspberry, rose, spinach, soyabean, strawberry, tomato. | |
| Nature of Damage: | Prefer lower leaf surface. Chlorotic patches on leaves appear which turn brownish and drop off. Blackening of leaves, decrease in fruit size and yield is observed in pear. The webbings produced by spider mites hamper the photosynthetic activity, cause biotic stress to its host plant and adversely affects many physiological and biochemical processes. Mites puncture cells from one spot to another in the form of a circle, which results in the formation of small rounded chlorotic spots and changes in cell cytology, physiological and biochemical processes of punctured as well as non-punctured adjacent cells. In case of severe infestation, plants show yellowing and general drying of leaves, which drop prematurely. Tetranychus urticae becomes more severe during summer months particularly during April to June, resulting in significant yield loss. Strata wise, maximum population of mites was recorded from the middle strata followed by top and bottom strata. During severe infestation, T. urticae density was recorded as 50.5 motile stages/sq. cm leaf, 348 mites/ leaf on okra crop, 75-90 mites/ leaf in cucumber, 39.8 mites per trifoliate leaf of brinjal. T. urticae population showed significant positive correlation with maximum and minimum temperature and significant negative correlation with relative humidity. | |
| Life Cycle: | There are five stages in the life cycle of these mites i.e. egg, larva, protonymph, deutonymph and adult stage. The nymphal and adult stages are initiated during the inactive period called protochrysalis, deutochrysalis and teliochrysalis. Mite fixes itself to a leaf or to its webbing during this period, legs are bent upon and a new cuticle is formed before casting off exuviae. They can develop from egg to adult in six to ten days. The duration of larval, protonymphal, deutonymphal period is 1.89, 1.89, and 1.83 days, respectively. Egg laying by adult females can begin as soon as one or two days following maturity. Each female may lay up to 100 eggs in her 30 day lifespan. They occur on the underside of leaves, making coverage difficult. The rapid developmental rate, high reproductive potential, and arrhenotokous parthenogenesis results in outbreaks and contributing to the development of acaricide resistance. | |