Biology of rice sheath mite, Steneotarsonemus spinki Smiley

Biology of the rice tarsonemid mite Steneotarsonemus spinki was studied under laboratory at 28 ± 2.1°C temperature and 88 ± 5.9 per cent relative humidity during September 2003. Both the sexes passed through three stages viz. egg, larva, and adult and a short resting period known as quiescent stage. The egg stage lasted on an average 3.32 ± 0.55 days. Average larval period for male was 1.23 ± 0.44 and for female 1.52 ± 0.52 days and quiescent period was 0.53 ± 0.22 day for male and 0.66 0.24 day for female. Adult period was

5.28 0.54 days for male and 6.68±0.98 days for female. The total life cycle was completed in 12.20 ± 1.47 days and 13.75 ± 1.17 days for male and female, respectively. The pre-oviposition, oviposition and post-oviposition periods were 1.40 ± 0.39, 4.50 ± 1.20 and 1.65 ± 0.47 days, respectively. The female laid average 20 ± 5.03 eggs during its life span. The sex ratio (female:male) was recorded 1:1.5 and 1:2.8 in laboratory and field conditions, respectively.