Population dynamics of rice sheath mite,Steneotarsonemus spinkismiley (Acari: Tarsonemidae)

Abstract

An experiment was carried out to study the population dynamics of sheath mite, Steneotarsonemus spinki Smiley infesting rice under two types of rice cultivation systems i.e., conventional planting and SRI method. The results with conventional planting method showed that mite first appeared during first week of September (35th SMW) with 0.80 mites/leaf sheath. It gradually increased and reached peak (18.04/leaf sheath) during first week of October (40th SMW). It declined in the second week of October but was recorded till harvest (43rd SMW). In case of SRI planting method the mite incidence started from first week of September (35th SMW). Further, it gradually increased and reached peak (11.95/leaf sheath) during first week of October (40th SMW) and recorded till harvest (43rd SMW). Thus, mite incidence started from booting stage, increased gradually and reached peak during dough and milky stage. The mite population was lower in SRI method as compared to conventional method. The pooled data indicate that the maximum temperature and bright sunshine positively affects the population, while minimum temperature and relative humidity had negative effects. Rainfall did not have any major consequence on the mite.