Srinivasa, N.SAFEENA MAJEED, A.A.2021-09-222021-09-222018-08-01Th-12022https://krishikosh.egranth.ac.in/handle/1/5810176081Biology, reproduction and demography of four spider mite species infesting three medicinal plants was carried out at four different constant temperature & humidity conditions (20°-32°C; 62-85%) including damage symptomology and leaf biochemical changes subsequent to mite feeding. Female of Schizotetranychus baltazari on Murraya koenigii and Oligonychus mangiferus & Oligonychus thelytokus on Ichnocarpus frutescens developed faster (8.50, 7.10 & 8.74 days, respectively) at 30⁰C, while development of Tetranychus hirsutus female on Gymnema sylvestre was faster (10.12 days) at 32⁰C. Demography of these spider mite species revealed higher Intrinsic Rate of Natural Increase (rm) values of 0.097, 0.091, 0.095 & 0.095 females/female/day and higher Net Reproductive Rates (Ro) of 33.24, 26.60, 68.11 & 68.11 female offsprings/female/generation for S. baltazari, O. mangiferus, O. thelytokus & T. hirsutus, respectively. Higher fecundity (21-31 eggs/female) and lower Mean Generation Time (14-29 days) of O.mangiferus explained the reason for its greater abundance compared to O. thelytokus (19-27 eggs & 15–32 days) on the same host plant, I.frutescens. Adaxial feeding of S.baltazari on curry leaves resulted in grey spotting, discrete peelings of leaf cuticle, greyish-white appearance of the entire leaf, withering & defoliation. O. mangiferus & O. thelytokus feeding caused yellowish white spots, drying, withering & premature leaf-drop and T. hirsutus feeding produced orange-yellow spots & profuse webbings with large number of congregating individuals showed intuition for dispersal. Spider mites’ sap feeding damage on leaves resulted in significant reduction in carbohydrates (42–91%), proteins (55–69%) and flavonoids (18–65%), but alkaloid content increased in damaged leaves by 92% in M. koenigii, 220% in I. frutescens and 14% in G. sylvestre.EnglishThesis