Integrated Control in Protected Crops. Temperature Climate IOBCI\vprs Bulletin Vol. 32.2008 pp. 167-169. Prey-Stage Preference in Scolothrips longicornis Priesner(Thysanoptera: Thripidae) on Tetranychus urticae Koch (Acari: Tetranychidae) H. Pakyarr, Y. Fathipour1, M. Rezapanah3, K. Kaman1 IDepartment of Plant Protection,Islamic Azad University,Takestan Branch, Iran, E~mail: hajar.pakyari@gmail.com;2 Department of Entomology, Faculty of Agriculture, Tarbiat Modares University,P.O. Box 14115-336; Tehran, Iran, E~mail: fathi@modares.ac.ir; J Department of Biological Control, Iranian Research Institute of Plant Protection, Tehran, Iran, E~mail: rezapana@yahoo.com Abstract: The prey-stage preference of the predatory thrips, Scolothrips longicornis Priesner, for thetwo-spotted spider mite, Tetranychusurticae (Koch) was studied in 24.h laboratory experiments at 26 :l:2°C, 60 :1:5% RH and 16:8 L:D. The results showed that adult spider mites were the most preferred stage with approximately 8 individuals being eaten per day. S. longicornis has no preference between the juvenile stagesof the spider mite, the consumption being approximately 5 individuals per day. Key words: two-spotted spider mite, predatory thrips, Scolothripslongicornif. Tetranychus urticae Introduction Spider mites (Acari: Tetranychidae) are widespread agricultural pests, which often cause severe damage to various crops (Gerlach& Sengonca, .1985). The use of fertilizer, better crop management and chemical plant protection seem to enhance their intrinsic power of increase (van de Vrie el al., 1972). Biological control is an alternativeto chemical methods of plant protection. Among the natural enemies of spider mites are predaceous thrips -three thrips families (Phlaeothripidae, Aeolothripidae and Thripidae) include acarophagous species with various degreeof specializationon mites. All species of the genus Scololhrips appear to be specialized predators of spider mites (Friesner, 1950). Scololhrips longicornis Priesner is a native beneficial thrips in Iran. It is common in fields of bean, cucumber and tomato and is considered to be an important predator of numerous spider mites species. In the present study the preference of S. longicornis for different stages of spidermiteswas examined. Material and methods Rearing and general experimentalprocedures All S. longicornis were taken from laboratorycolonies maintained on mixed stages of 7: urticae. Colonies had beensustained in the laboratory with field-collected individuals added periodically. Spidermites were reared on lima bean. For experiments, leaves were placed individually on moist tissue paper in a Petri dish (60 mm diameter) with a 25-mm diameter mesh-covered hole in the lid to allow ventilation. 80 spider mites (20 eggs, 20 larvae,20 nymphs and 20 adults)and one female S. longicornis (max 24 h old) were addedto eachleaf and the numberof eachstage eaten determined after 167