Studies on biology of leaf (or) web mite, Schizotetranychus andropogoni Hirst (Acari: Tetranychidae) on varieties of Sugarcane

The biology of sugarcane leaf mite/web mite, Schizotetranychus andropogoni was studied on three varieties of sugarcane leaves viz., Co 86032, Co 356 and Co 7015 in in vitro condition at A.C.R.I., Madurai. Among three varieties, Co 86032 recorded on egg period of 3.50 ± 0.62 days, oviposition period of 16.75 ± 0.62 days, fecundity of (15.08 ± 0.50), hatching percentage (92.3) and sex ratio (1: 1.50); followed by Co 7015 (3.45 ± 0.62 days, 16.24 ± 0.62 days, 13.75 ± 0.50 nos., 88.23% and 1: 1.40) and the lowest in Co 356. Larva (1.85 ± 0.50 & 1.81± 0.50 days), protonymphal period (2.96 ± 0.50 & 2.88 ± 0.50 days), deutronymphal (3.28 ± 0.44 & 3.22 ± 0.50 days), adult longevity (−11.92 ± 0.44 and 11.33 ± 0.44 days and-10.60 ± 0.50, 10.00 ± 0.50), pre-oviposition (0.65 ± 0.62 & 0.63 ± 0.62 days) and post oviposition period of 3.88 ± 0.50 and 3.08 ± 0.50 days which was maximum in Co 356 and Co 7015 and the lowest in Co 86032. The longer life span of mite tend to more loss to crop and short life span of mite caused higher damage to the crop, because of several generations in a short span.