author(s)
B Poovizhiraja, C Chinniah and A Ravi Kumar

abstract
The present investigation was conducted during 2015 at Agricultural College and Research Institute, Madurai to study the influence of host plants and different nutritional status (Nitrogen and Phosphorus) on biological parameters and population buildup of two spotted spider mite Tetranychus urticae Koch. The higher dose of nitrogen positively influenced T. urticae with shortened egg and larval period in cassava (2.1±0.06 days; 1.1±0.04 days), french bean (2.0±0.06 days; 1.0±0.07 days) and pumpkin (2.1±0.06 days; 1.1±0.03 days). Further, protonymphal period, duetonymphal period, adult longevity, pre-oviposition period and post-oviposition period were also shortened on host plants in higher dose of nitrogen. But the oviposition period in cassava, french bean and pumpkin (17.7±0.45 days; 17.0±0.32 days; 17.5±0.59 days) was found to be higher. Similalrly sex ratio (♂:♀) (1:4.31; 1:3.46; 1:4.07) and fecundity (112/♀; 127/♀; 108/♀) also found maximum in french bean, cassava and pumpkin. The level of nitrogen available in host plants determined the feeding preference of TSSM. When the mites had access to leaf tissues, they preferred to feed on leaf discs and also severity of webbing also was found influenced from plants grown at high nitrogen availability. Among these host plants, cassava, french bean and pumpkin were distinct from other hosts in their reaction. Application of nitrogen had a definite and positive influence on the buildup of population with reference to T. urticae. But an increase in the levels of phosphorus in host plants does not favour the growth and development of T. urticae.