Effect of Okra entries on biology of two spotted spider mite Tetranychus urticae (Koch.)

Morphological trait namely trichomes (length & numbers) exhibited negative effect on the mite population and development. Laboratory experiments on antibiosis of various resistant categories of okra revealed that fecundity of Tetranychus urticae females was significantly less on the resistant wild type Kasturi bhendi (41.5 eggs/female) compared to the susceptible check Mahyco 10 (77.1 eggs/female). The developmental period of larva, protonymph and deutonymph was shorter on the susceptible Mahyco 10 (10 days), while it was the longest (19.8 days) on the resistant entry, Kasturi bhendi among the accessions tested. Adult longevity and sex ratio analysed on the selected test entries depicted that irrespective of the levels of resistance, the females lived longer than the males. The higher fecundity (77.1eggs/female), lesser incubation period (3.4 days), higher egg hatchability (86.5%) and lower mortality of developmental stages in susceptible entry and the reduced rate of reproduction on resistant entries explained the cumulative effect of antibiosis.