Sources of infestation of the rice sheath mite, Steneotarsonemus spinki Smiley (Acari: Tarsonemidae), in West Bengal, India.

The Rice Sheath Mite, Steneotarsonemus spinki Smiley (Acari: Tarsonemidae) is a pest of Kharif Rice (wet rice) of West Bengal, causing losses every year. It initially infests leaf sheaths, moving later onto the grains. It is not known how the mite survives in the off season, which is important for devising management strategies. The present investigation was conducted to find out the sources of infestation of S. spinki. It was concentrated on four types of substrates: rice associated weeds, soil, rice grains of different ages (before and after harvesting) and rice stubbles. Mites detected in any of those possible sources were slide mounted in modified Berlese medium and examined under phase and differential interference contrast microscope for identification. Tarsonemid mites were found on some grassy weeds, but not Steneotarsonemus spinki Smiley. No tarsonemid mite was found in soil samples from infested fields. Steneotarsonemus spinki was found on rice grains of different ages and in stubbles. Hence, both rice grains and rice stubbles could be important sources of infestation of S. spinki to new plants at each season. [ABSTRACT FROM AUTHOR]