Bio-ecology and management of rice mites – A review

Sheath mite, Steneotarsonemus spinki and leaf mite, Oligonychus oryzae are the two most important mite species damaging rice crop. S. spinki remains in the leaf-sheath below epidermis and in association with sheath rot fungus, Acrocylindrium oryzae, it causes grain discolouration, ill filled and chaffy grains. Rice is the major host of S. spinki and it survives in stubbles and ratoons during off-season. There is facultative parthenogenesis in S. spinki. Optimum temperature for its development and multiplication is 25 to 28°C. During a crop season, S. spinki becomes very serious from 80 DAT and reaches its peak between 100 to 120 DAT. There are no known sources of high level of host plant resistance to S. spinki although some indica types have exhibited lower grain sterility. Predatory mite, Amblyseius taiwanicus is the most important natural enemy. Leaf mite, O. oryzae damages rice by sucking the sap of mesophyl tissue of leaves. Bright sunny weather followed by slight rainfall is congenial for its multiplication. Profenophos @ 500 g a.i./ha, spiromesifen @ 72 g a.i./ha, milbemectin @ 2.5 g a.i./ha and dicofol @ 500 g a.i./ha are some acaricides effective against O. oryzae.